Novel flavonoid derivatives containing benzothiazole as potential antiviral agents: design, synthesis, and biological evaluation

doi:10.21203/rs.3.rs-5025191/v1

Download PDF

Research Article

Novel flavonoid derivatives containing benzothiazole as potential antiviral agents: design, synthesis, and biological evaluation

https://doi.org/10.21203/rs.3.rs-5025191/v1

This work is licensed under a CC BY 4.0 License

You are reading this latest preprint version

A series of flavonol derivatives containing benzothiazole were designed and synthesized. The structures of all the compounds were characterized by NMR and HRMS. The results of the bioactivity assay showed that some of the target compounds possessed outstanding in vivo antiviral activity against the tobacco mosaic virus (TMV). Among them, the median effective concentration (EC₅₀) of L20 was 90.5 µg/mL for curative activities against TMV, which was better than that of ningnanmycin (NNM: 252.0 µg/mL). The microcalorimetric thermophoresis (MST) and molecular docking experiments showed that L20 had a strong binding ability with TMV-CP; the malondialdehyde (MDA) and superoxide dismutase assay (SOD) activity measurements also fully confirmed that L20 stimulated the plant immune system and strengthened the plant's resistance to diseases by lowering the MDA content and increasing the SOD activity. In addition, the chlorophyll content test experiment found that L20 could reduce the destructive effect of viruses on chloroplasts, increase the content of chlorophyll, and promote photosynthesis. In conclusion, above experimental results suggested that flavonol derivatives containing benzothiazole could be further investigated as new plant virus antiviral drugs.

flavonoid

benzothiazole

antiviral activity

mechanism of action

In this paper, 26 flavonoid derivatives containing benzothiazole were designed and synthesized.
L20 exhibited excellent antiviral activity, the EC₅₀ value of curative activities was 90.5 μg/mL, which was better than that of ningnanmycin (NNM: 252.0 μg/mL)
Further mechanistic studies have shown that L20 not only has a strong binding ability with TMV-CP, but also could effectively stimulate the plant`s immune system and reduce the destructive effect of viruses on chloroplasts.

Plant virus diseases present a significant menace to global crop yields and quality annually. Plant viruses exhibit obligate parasitism within host cells; once infected with viruses, plants often remain so for their entire lifespan hence earning the moniker “plant cancer”[1, 2]. Notably among them is tobacco mosaic virus (TMV), one of the most prevalent and severe global viral pathogens that spreads via sap transmission with enduring extracellular stability. Its infections significantly compromise crop quality across various cultivars such as tobacco, tomatoes, cucumbers, and peppers along with ornamental plants[3, 4, 5], posing substantial threats to agricultural productivity and resulting in annual global losses exceeding 100 million US dollars due to TMV[6]. While conventional antiviral medications may offer some control over TMV infections, prolonged usage has led to diminished efficacy. Hence, the imperative need for developing novel, efficient, and eco-friendly antiviral agents.

Flavonoid is widely found in various plants and account for about one-third of the total flavonoid compounds. They have numerous vital pharmacological effects and biological activities, such as antioxidant[7], antibacterial[8, 9], antitumor[10, 11], antiviral[12, 13, 14], etc. As a natural active substance with multiple good physiological activities, widespread sources, and high safety, flavonoid is increasingly favored by researchers.

Benzothiazole, also known as 1,3-thiazin-2-ylidenes, is a bicyclic heterocyclic compound with a thiazole ring. Many pesticide companies have developed thiazole-based fungicides, such as benzothiostrobin and benthiavalicarb-isopropyl. Due to its excellent structural characteristics, reactivity, and coordination properties, it has a variety of biological activities, such as antibacterial[15, 16, 17], antiviral[18, 19], and insect-killing activities[20]. In addition, one of the fundamental goals of medicinal organic chemistry is to design, synthesize, and manufacture molecules that are beneficial to humans. Compounds containing thiazoles have broad potential for pharmaceutical applications, such as anti-cancer[21, 22], anti-inflammatory[23], etc. Amides are a strong active ingredient in pesticides, and studies have shown that amides have broad-spectrum antibacterial[24, 25], antiviral[26], herbicidal[27], and insecticidal activities[28].

On this basis, a series of flavonoid derivatives containing benzothiazole were synthesized. Through biological activity screening and mechanism studies, the screened L20 has significantly better antiviral activity than commercially available agent NNM (Fig. 1).

Figure 1

2.1 Chemistry

The route by which the target compounds were synthesized was shown in Scheme 1. The intermediate 1 was synthesized from different o-hydroxyacetophenone and various substituted benzaldehydes. Intermediate 2 was synthesized by intermediate 1 via Algar-Flynn-Oyamada reaction. Intermediate 3 was prepared by substitution reaction of 2-aminobenzothiazole and chloroacetyl chloride. Finally, intermediate 2 and intermediate 3 underwent a sub-stitution reaction to obtain L1-L26. The structures of the compounds were characterized by NMR and HRMS spectrums and the data were offered in the Supporting Information.

Scheme 1

2.2 Spectral characteristic of title compounds

2.3 Antiviral activity of L1-L26 against TMV in vivo

The resistance of L1-L26 to TMV at a concentration of 500 µg/mL was tested by the half-leaf spot method using NNM as positive control. As shown in Table 1, the curative activities of L17, L20, and L24 against TMV was 67.5, 71.8, and 66.4%, respectively, which was superior to that of NNM (60.1%); and the protective activities of L20 and L21 were 64.9 and 63.9%, respectively, which were both superior to that of NNM (61.2%). The tobacco leaf morphology of L20 and NNM against TMV in vivo were shown in Fig. 2. The EC₅₀ values of the compounds against TMV were further assayed and were shown in Table 2. The EC₅₀ values of curative activities of L17, L20, and L24 were 223.2, 90.5, and 146.9 µg/mL, respectively, which were superior to that of NNM (252.0 µg/mL); and the EC₅₀ values of protective activities of L20 and L21 were 202.2 and 162.6 µg/mL were better than that of the NNM (204.2 µg/mL).

Table 1

Antiviral activity of **L1-L26** against TMV at 500 µg/mL *in vivo*.^a
Compounds	R₁	R₂	Curative (%)	Protective (%)	Inactivating (%)
L1	H	5-Br	47.6 ± 1.1	35.9 ± 2.7	40.5 ± 4.1
L2	4-CH₃	5-Br	57.7 ± 5.3	53.5 ± 5.3	44.3 ± 3.7
L3	3-OCH₃	5-Br	54.3 ± 2.0	35.3 ± 7.4	31.0 ± 2.3
L4	4-F	5-Br	50.6 ± 1.9	49.4 ± 2.7	45.3 ± 4.8
L5	4-t-Bu	5-Br	53.0 ± 2.0	52.7 ± 8.3	47.0 ± 3.5
L6	H	6-Cl	46.2 ± 1.8	53.8 ± 9.1	31.1 ± 2.4
L7	4-CH₃	6-Cl	50.4 ± 2.6	34.0 ± 4.5	53.0 ± 2.8
L8	3-OCH₃	6-Cl	43.3 ± 5.2	58.7 ± 1.6	46.5 ± 2.1
L9	4-F	6-Cl	41.2 ± 4.2	25.1 ± 1.6	29.6 ± 4.1
L10	4-t-Bu	6-Cl	37.3 ± 3.4	47.4 ± 3.7	47.6 ± 4.6
L11	2-OCH₃	6-Cl	32.6 ± 3.4	49.6 ± 5.4	34.1 ± 2.2
L12	H	H	54.5 ± 3.5	43.2 ± 2.6	49.5 ± 3.2
L13	4-CH₃	H	53.0 ± 3.4	60.3 ± 3.7	52.6 ± 1.8
L14	3-OCH₃	H	25.5 ± 4.4	59.5 ± 5.1	34.9 ± 1.9
L15	4-F	H	50.1 ± 4.1	50.0 ± 4.2	42.5 ± 3.6
L16	4-t-Bu	H	55.2 ± 3.5	56.7 ± 4.5	45.0 ± 4.2
L17	4-Cl	H	67.5 ± 2.1	50.1 ± 1.7	45.5 ± 3.3
L18	H	4-CH₃	53.6 ± 1.7	52.0 ± 7.9	38.4 ± 4.3
L19	4-CH₃	4-CH₃	50.8 ± 3.3	57.6 ± 5.2	63.7 ± 1.4
L20	3-OCH₃	4-CH₃	71.8 ± 1.6	64.9 ± 1.9	55.9 ± 1.3
L21	4-F	4-CH₃	49.8 ± 0.2	63.9 ± 2.1	52.8 ± 1.1
L22	4-t-Bu	4-CH₃	52.6 ± 5.0	59.7 ± 1.6	51.3 ± 1.3
L23	4-Cl	4-CH₃	36.8 ± 4.5	30.1 ± 4.3	44.0 ± 2.1
L24	H	6-OCH₃	66.4 ± 3.5	42.2 ± 3.7	46.0 ± 4.7
L25	4-CH₃	6-OCH₃	53.3 ± 5.3	51.2 ± 5.6	34.0 ± 1.8
L26	3-OCH₃	6-OCH₃	39.2 ± 3.4	24.3 ± 4.1	23.3 ± 3.6
NNM^b	-	-	60.1 ± 4.4	61.2 ± 1.9	90.7 ± 2.6
^a Vales are mean ± SD of three replicates. ^b The commercial antiviral agent Ningnanmycin (NNM).

Table 2

EC₅₀ values of some of the target compounds against TMV *in vivo*.^a
	Compounds	Regression equation	r	EC₅₀ (mg/mL)
Curative activity	L17	y = 1.2211x + 2.1321	0.9807	223.16
	L20	y = 0.7249x + 3.5816	0.9693	90.52
	L24	y = 0.7120x + 3.4571	0.9814	146.88
	NNM ^b	y = 0.7770x + 3.1341	0.9659	252.03
Protective activity	L20	y = 0.6666x + 3.4630	0.9866	202.18
	L21	y = 0.6521x + 3.5581	0.9794	162.55
	NNM	y = 0.7357x + 3.3005	0.9616	204.19
^a Average of three replicates. ^b The commercial antiviral agent. Ningnanmycin (NNM)

Table 1

Figure 2

Table 2

2.4 Structure-activity relationship analysis

The structure-activity relationship of the synthesized flavonol derivatives containing benzothiazole was evaluated. Combining the activity data in Table 1 and Table 2, it is evident that the substituent group has a greater influence on the anti-TMV activity of the compounds. The compounds had better anti-TMV activity when R₁ = H and R₂ was an electron-donating substituent. For example, curative activity: L24 > L6 (R₂ = OCH₃: 66.4% > R₂ = Cl: 46.2%), L18 > L1 (R₂ = CH₃: 53.6% > R₂ = Br: 47.6%). In addition, the compounds have better anti-TMV activity when R₂ is the same substituent and R₁ is an electron-donating substituent, such as when R₂ = Br, the curative activity was L2 > L4 (R₁ = CH₃: 57.7% > R₁ = F: 50.6%); when R₂ = Cl, L7 > L9 (R₁ = CH₃: 50.4% > R₁ = F: 41.2%); when R₂ = CH₃, L20 > L21 (R₁ = CH₃: 71.8% > R₁ = F: 49.8%). From the above analysis, it can be seen that when both R₁ and R₂ are electron-donating groups, it can significantly increase the anti-TMV activity of the compounds. For example, the EC₅₀ value of the antiviral curative activity of L20 (R₁ = 3-OCH₃, R₂ = 4-CH₃) was 90.5 µg/mL, which was significantly lower than that of the other compounds and NNM.

2.5 Binding ability of L20, L23, and NNM to TMV-CP

TMV-CP is a key functional protein of TMV that self-assembles with viral RNA to form virus. The interactions of L20, L23, and NNM with TMV-CP were further analyzed by MST. The smaller the value of the dissociation constant K_d, the stronger the binding ability of the compounds to TMV-CP. As shown in Fig. 3, the K_d values of L20, L23, and NNM treated with TMV-CP were 0.027 ± 0.012, 0.153 ± 0.036, and 0.061 ± 0.030 µM, respectively. The results showed that the binding ability of L20 to TMV-CP was better than that of L23 and NNM, which further indicated that L20 had better antiviral activity, which agreed with the results of the preliminary screening for anti-TMV activity.

Figure 3

2.6 Molecular docking of L20 and NNM with TMV-CP

The molecular docking results were shown in Fig. 4, where the bioactive molecules L20 and NNM were embedded in the same active protein pocket of TMV and completed self-assembly with the TMV-CP subunits to form non-covalent bonding interactions. L20 interacted with amino acid residues (ASN-73, ARG-134, LYS-253, LYS-268, ASP-266, PRO-263) of TMV-CP through traditional hydrogen-bonding, carbon-hydrogen-bonding, pi-cation, alkyl, and pi-alkyl. Among them, amino acid residue LYS-268 formed two pi-cation bonds (2.51 Å, 3.08 Å) and one hydrogen bond (2.19 Å) with the aryl ring, thiazole ring, and amino group of L20 benzothiazole, respectively. In contrast, NNM has only one hydrogen bond with the amino acid residue LYS-268 (1.92 Å). In addition, the oxygen atom on the carbonyl group in L20 forms a carbon-hydrogen bond with amino acid residue PRO-263 (2.25 Å), and NNM forms a carbon-hydrogen bond with amino acid residue GLU-131 (4.30 Å), however, the carbon-hydrogen bond formed due to L20 is shorter than that of NNM. After visualization by Pymol, it is more intuitive to realize that L20 binds to TMV-CP more tightly and with more force than NNM.

Figure 4

2.7 MDA content analysis

When the antioxidant mechanism in the body fails to maintain the generation and scavenging of reactive oxygen radicals in a balanced state during plant organ senescence or under adverse conditions, it leads to the peroxidation of membrane lipids of the tissues or organs, which in turn leads to the production of MDA. Therefore, the degree of membrane lipid peroxidation can be detected through MDA to indirectly valuate the degree of damage to the membrane system and plant stress tolerance. As shown in Fig. 5, the content of MDA in the leaves of the CK group showed an increasing trend with time, and reached its peak on the 5th day, indicating that the plants contained antioxidant enzymes in the plant body, which had a certain regulating effect during the aging process. The content of MDA in the L20 group plants was lower than that in the CK group, which indicated that L20 was able to inhibit the adversity stress in tobacco. The content of MDA in the TMV group was significantly elevated and was the highest among the treatment groups; especially on the 7th day, it was more than twice as long as the corresponding time in the CK group, which fully reflected the serious damage of TMV to tobacco. The L20 + TMV group was significantly lower than that of the TMV group, which indicated that L20 could inhibit the injury of TMV to the leaves and slow down the speed of its destruction. In summary, the L20 can inhibit TMV infected plants and enhance the antioxidant capacity and disease resistance of plants.

Figure 5

2.8 Effects of L20 on SOD activity

Superoxide Dismutase (SOD) plays a vital role in the biological antioxidant system, which can counteract and block the damage caused by oxygen radicals to the cells, and it also can repair the damaged cells in time to restore the damage caused by oxygen radicals to the cells. The increase in SOD activity can enhance the antiviral ability of plants. As shown in Fig. 6, with the growth of time, the overall SOD activity in tobacco showed a trend of increasing and then slow decreasing. The SOD activity in the TMV group was significantly higher than that in the CK group, which was due to the fact that the plant activated the SOD system for self-protection immediately after being infected by the virus; the L20 group and the L20 + TMV group reached the peak value 3rd, and after that, the SOD activity showed a slow decreasing trend, but the overall activity was higher than that of the CK group and TMV group, it can be known that L20 can increase SOD activity in plants, enhance the ability to scavenge superoxide radicals, and improve the disease resistance of plants.

Figure 6

2.9 Analysis of chlorophyll content

Chlorophyll content is closely related to photosynthesis. The virus infests tobacco and proliferates in the host body, which will destroy the chloroplasts of the plant and interfere with the synthesis of chlorophyll, thus causing the yellowing of the leaves. As can be seen from Fig. 7, the chlorophyll content of the CK group and TMV group showed a general trend of increasing and then decreasing, reaching a peak on the 5th day, and then gradually decreasing with time as the plants senesces. On the 5th day, it was obvious that the chlorophyll content of the CK-group was higher than that of the TMV group, which was due to the fact that the chloroplasts were damaged after the TMV infection. After the 3rd day, it can be seen that the difference in chlorophyll content between the groups became more and more obvious, in which the L20 group was higher than the CK-group, and the L20 + TMV group was higher than the TMV group, which revealed that the L20 could alleviate the destructive effect of the virus on the chloroplasts, increase the content of chlorophyll indexes, and promote photosynthesis, thus increasing the resistance of tobacco to the disease

Figure 7

In this study, 26 flavonol derivatives containing benzothiazole were synthesized. The antiviral activity experiments indicated that L20 possessed better inhibitory effects in terms of curative and protective activities, with EC₅₀ values of 90.5 µg/mL, which were better than those of NNM (252.0 µg/mL). It is noteworthy that the MST experiments used the TMV-CP protein as a target for the antiviral compounds, which indicated that L20 showed a strong affinity. Molecular docking simulation consequences revealed that L20 had excellent binding ability, and the results were consistent with the MST. Further experimental results showed that L20 could participate in the regulation of membrane lipid per-oxidation, preventing TMV infection in plants and thereby enhancing their antioxidant and defense abilities, and that L20 may increase the ability of the host to scavenge oxygen-free radicals in vivo and induce H₂O₂ accumulation, thus improving the activities of SOD. In addition, the chlorophyll contents of tobacco plants were tested, and it was found that L20 could be involved in regulating the chlorophyll content of plants, promoting plant photosynthesis. Therefore, flavonol derivatives containing benzothiazole have certain antiviral activity and could be used as potential antiviral agents to control plant viruses.

4.1 Instruments and chemicals

The melting point measurements were obtained by using the X-4B melting point instrument (Shanghai INESA Co., Ltd., Shanghai, China) without calibration. NMR spectral characterization data were obtained using a JEOL-ECX500 NMR instrument with deuterated dimethylsulfoxide as the solvent (Tokyo, Japan). High resolution mass spectra (HRMS) were gained through a Thermo Scientific Q Exactive hybrid quadrupole mass spectrometer (Thermo Scientific, USA). The Kd values of the compounds against TMV-CP were determined by using NanoTemper Monolith NT.115 micro-thermophoresis (NanoTemper, Germany). The reagents and solvents used in the experiment were purchased from Shanghai Titan Chemical Co., Ltd. (Shanghai, China) and Bositai Technology Co., Ltd. (Chongqing, China). The reagents and solvents used were of analytical grade and could be put into application without further purification.

4.2 Synthesis of compounds

4.2.1. Preparation of intermediate

Intermediates 1 and 2 were synthesized by the method reported[29, 30], the detailed experimental methods were provided in the Supporting Information. Substituted 2-aminobenzothiazole (1.00 g, 6.66 mmol) and K₂CO₃ (1.84 g, 13.32 mmol) were dissolved in 40 mL dichloromethane, stirred at room temperature for 30 min, and slowly added chloroacetyl chloride (0.64 mL, 7.99 mmol). The reaction mixture was stirred at room temperature for 2–3 h and monitored by TLC (petroleum ether: ethyl acetate = 1:1, v/v). After the reaction was completed, a large amount of white solid, intermediate 3 (R₂ = H), was obtained by suction filtration[31].

4.2.2. Synthesis of target compounds L1-L26

Take L1 as an example, intermediates 2 (0.6 g, 2.38 mmol) and K₂CO₃ (0.99 g, 7.14 mmol) were dissolved in 25 mL N, N-Dimethylformamide (DMF) and returned at 100 ℃ for 30 min, then intermediate 3 (0.65 g, 2.85 mmol) was added at 100 ℃ for 3–4 h. After the reaction completed, the product was poured into ice water, and the solid was deposited. After extraction and filtration, the crude product was separated and purified by column layer analysis (petroleum ether: ethyl acetate = 6:1, v/v) to obtain the target compound L1. L2-L26 was obtained by reference to the above synthesis method.

N-(5-bromobenzo[d]thiazol-2-yl)-2-((4-oxo-2-phenyl-4H-chromen-3-yl)oxy)acetamide (L1). White solid, m.p. 212.2–213.7 ℃; yield: 43.4%. ¹H NMR (500 MHz, DMSO-d) δ 12.65 (s, 1H, -CO-NH-), 8.22 (d, J = 2.0 Hz, 1H, Ph-H), 8.13 (dd, J = 6.5, 3.0 Hz, 2H, Ph-H), 8.09 (dd, J = 8.0, 1.5 Hz, 1H, Ph-H), 7.84–7.81 (m, 1H, Ph-H), 7.76 (d, J = 8.5 Hz, 1H, Ph-H), 7.66 (d, J = 8.5 Hz, 1H, Ph-H), 7.55–7.52 (m, 4H, Ph-H), 7.48 (dd, J = 11.5, 4.5 Hz, 1H, Ph-H), 4.91 (s, 2H, -O-CH₂-CO-). ¹³C NMR (125 MHz, DMSO-d) δ 179.35 (s), 173.56 (s), 163.47 (s), 160.16 (s), 160.05 (s), 152.96 (s), 144.85 (s), 139.71 (s), 138.97 (s), 136.38 (s), 135.49 (s), 134.49 (s), 133.99 (s), 133.93 (s), 130.62 (s), 130.30 (s), 129.61 (s), 128.48 (s), 127.55 (s), 123.82 (s), 120.91 (s), 75.47 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₄H₁₆BrN₂O₄S: 508.99882, found: 508.99969.

N-(5-bromobenzo[d]thiazol-2-yl)-2-((4-oxo-2-(p-tolyl)-4H-chromen-3-yl)oxy)acetamide (L2). Purple solid, m.p. >230 ℃; yield: 38.6%. ¹H NMR (500 MHz, DMSO-d) δ 12.70 (s, 1H, -CO-NH-), 8.07 (dd, J = 8.0, 1.5 Hz, 1H, Ph-H), 8.04 (d, J = 8.5 Hz, 2H, Ph-H), 7.94–7.91 (m, 2H, Ph-H), 7.82–7.80 (m, 1H, Ph-H), 7.75 (d, J = 8.0 Hz, 1H, Ph-H), 7.49–7.46 (m, 1H, Ph-H), 7.43 (dd, J = 8.5, 2.0 Hz, 1H, Ph-H), 7.33 (s, 1H, Ph-H), 7.31 (s, 1H, Ph-H), 4.87 (s, 2H, -O-CH₂-CO-), 2.31 (s, 3H, Ph-CH₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.47 (s), 168.78 (s), 159.61 (s), 155.62 (s), 155.23 (s), 150.56 (s), 141.77 (s), 139.85 (s), 134.88 (s), 131.29 (s), 129.76 (s), 129.15 (s), 127.85 (s), 126.84 (s), 125.82 (s), 125.51 (s), 124.22 (s), 123.70 (s), 123.54 (s), 119.48 (s), 119.03 (s), 70.73 (s), 21.60 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₅H₁₈BrN₂O₄S: 521.01652, found: 521.01526.

N-(5-bromobenzo[d]thiazol-2-yl)-2-((2-(3-methoxyphenyl)-4-oxo-4H-chromen-3-yl)oxy)acetamide (L3). White solid, m.p. 183.1–184.9 ℃; yield: 48.9%. ¹H NMR (500 MHz, DMSO-d) δ 12.65 (s, 1H, -CO-NH-), 8.08 (dd, J = 8.0, 1.5 Hz, 2H, Ph-H), 7.84–7.80 (m, 1H, Ph-H), 7.77 (d, J = 8.0 Hz, 1H, Ph-H), 7.73–7.68 (m, 3H, Ph-H), 7.48 (t, J = 7.5 Hz, 1H, Ph-H), 7.46–7.41 (m, 2H, Ph-H), 7.09 (dd, J = 8.0, 2.0 Hz, 1H, Ph-H), 4.91 (s, 3H, Ph-OCH₃), 3.78 (s, 2H, -O-CH₂-CO-). ¹³C NMR(125 MHz, DMSO-d) δ 174.56 (s), 168.68 (s), 159.62 (s), 158.73 (s), 155.24 (s), 155.16 (s), 147.89 (s), 140.11 (s), 134.95 (s), 133.71 (s), 131.91 (s), 130.29 (s), 128.23 (s), 127.05 (s), 125.86 (s), 125.50 (s), 123.68 (s), 122.38 (s), 122.02 (s), 121.44 (s), 119.11 (s), 117.40 (s), 114.53 (s), 70.67 (s), 55.79 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₅H₁₈BrN₂O₅S: 537.01143, found: 537.01013.

N-(5-bromobenzo[d]thiazol-2-yl)-2-((2-(4-fluorophenyl)-4-oxo-4H-chromen-3-yl)oxy)acetamide (L4). Yellow solid, m.p. >230 ℃; yield: 50.1%. ¹H NMR (500 MHz, DMSO-d) δ 12.68 (s, 1H, -CO-NH-), 8.22–8.19 (m, 2H, Ph-H), 8.07 (dd, J = 8.0, 1.5 Hz, 1H, Ph-H), 7.92 (dd, J = 5.0, 3.0 Hz, 2H, Ph-H), 7.83–7.80 (m, 1H, Ph-H), 7.75 (d, J = 8.0 Hz, 1H, Ph-H), 7.48 (t, J = 7.0 Hz, 1H, Ph-H), 7.43 (dd, J = 8.5, 2.0 Hz, 1H, Ph-H), 7.38–7.35 (m, 2H, Ph-H), 4.93 (s, 2H, -O-CH₂-CO-). ¹³C NMR (125 MHz, DMSO-d) δ 174.44 (s), 168.79 (s), 164.93 (d, ¹J_C−F = 248.8 Hz), 159.59 (s), 155.18 (s), 154.41 (s), 150.53 (s), 139.80 (s), 134.93 (s), 131.99 (d, ³J_C−F =8.8 Hz), 131.25 (s), 127.25 (d, ⁴J_C−F = 2.5 Hz), 126.83 (s), 125.50 (s), 124.20 (s), 123.69 (s), 123.52 (s), 119.48 (s), 119.03 (s), 116.32 (d, ²J_C−F = 21.3 Hz), 116.15 (s), 70.55 (s). ¹⁹F NMR (470 MHz, DMSO-d) δ -108.47. HRMS (ESI) m/z [M + H]⁺ calcd for C₂₄H₁₅BrFN₂O₄S: 524.99144, found: 524.99030.

N-(5-bromobenzo[d]thiazol-2-yl)-2-((2-(4-(tert-butyl)phenyl)-4-oxo-4H-chromen-3-yl)oxy)acetamide (L5). White solid, m.p. 219.1–220.9 ℃; yield: 44.6%. ¹H NMR (500 MHz, DMSO-d) δ 12.71 (s, 1H, -CO-NH-), 8.07 (dd, J = 13.5, 5.0 Hz, 3H, Ph-H), 7.92 (d, J = 8.5 Hz, 2H, Ph-H), 7.83–7.79 (m, 1H, Ph-H), 7.74 (d, J = 8.5 Hz, 1H, Ph-H), 7.52–7.46 (m, 3H, Ph-H), 7.43 (dd, J = 8.5, 2.0 Hz, 1H, Ph-H), 4.88 (s, 2H, -O-CH₂-CO-), 1.23 (s, 9H, Ph-C(CH₃)₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.44 (s), 168.72 (s), 159.58 (s), 155.61 (s), 155.23 (s), 154.49 (s), 150.54 (s), 139.83 (s), 134.88 (s), 131.27 (s), 129.02 (s), 127.90 (s), 126.82 (s), 125.97(s), 125.82(s), 125.51 (s), 124.19 (s), 123.71 (s), 123.54 (s), 119.46 (s), 119.00 (s), 70.74 (s), 35.19 (s), 31.32 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₈H₂₄BrN₂O₄S: 563.06347, found: 563.06207.

N-(6-chlorobenzo[d]thiazol-2-yl)-2-((4-oxo-2-phenyl-4H-chromen-3-yl)oxy)acetamide (L6). Purple solid, m.p. 182.9–183.4 ℃; yield: 51.0%. ¹H NMR (500 MHz, DMSO-d) δ 12.66 (s, 1H, -CO-NH-), 8.13 (dd, J = 6.5, 3.0 Hz, 2H, Ph-H), 8.10–8.08 (m, 2H, Ph-H), 7.84–7.81 (m, 1H, Ph-H), 7.76 (d, J = 8.5 Hz, 1H, Ph-H), 7.72 (d, J = 8.5 Hz, 1H, Ph-H), 7.55–7.53 (m, 3H, Ph-H), 7.49 (t, J = 7.5 Hz, 1H, Ph-H), 7.42 (dd, J = 8.5, 2.0 Hz, 1H, Ph-H), 4.91 (s, 2H, -O-CH₂-CO-). ¹³C NMR (125 MHz, DMSO-d) δ 174.59 (s), 168.79 (s), 158.73 (s), 155.40 (s), 155.28 (s), 147.90 (s), 140.07 (s), 134.96 (s), 133.71 (s), 131.63 (s), 130.72 (s), 129.23 (s), 129.17 (s), 128.24 (s), 127.06 (s), 125.87 (s), 125.53 (s), 123.70 (s), 122.39 (s), 122.02 (s), 119.06 (s), 70.69 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₄H₁₆ClN₂O₄S: 463.05138, found: 463.05002.

N-(6-chlorobenzo[d]thiazol-2-yl)-2-((4-oxo-2-(p-tolyl)-4H-chromen-3-yl)oxy)acetamide (L7). White solid, m.p. 227.8-228.5 ℃; yield: 44.6%. ¹H NMR (500 MHz, DMSO-d) δ 12.65 (s 1H, -CO-NH-), 8.08 (d, J = 8.5 Hz, 2H, Ph-H), 8.04 (d, J = 8.0 Hz, 2H, Ph-H), 7.83–7.80 (m, 1H, Ph-H), 7.76 (d, J = 8.5 Hz, 1H, Ph-H), 7.72 (d, J = 8.5 Hz, 1H, Ph-H), 7.48 (t, J = 7.5 Hz, 1H, Ph-H), 7.43 (d, J = 8.5 Hz, 1H, Ph-H), 7.33 (d, J = 8.0 Hz, 2H, Ph-H), 4.87 (s, 2H, -O-CH₂-CO-), 2.32 (s, 3H, Ph-CH₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.51 (s), 168.76 (s), 158.75 (s), 155.68 (s), 155.24 (s), 147.92 (s), 141.78 (s), 139.88 (s), 134.89 (s), 133.73 (s), 129.77 (s), 129.15 (s), 128.23 (s), 127.85 (s), 127.05 (s), 125.82 (s), 125.52 (s), 123.70 (s), 122.39 (s), 122.01 (s), 119.02 (s), 70.79 (s), 21.60 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₅H₁₈ClN₂O₄S: 477.06703, found: 477.06662.

N-(6-chlorobenzo[d]thiazol-2-yl)-2-((2-(3-methoxyphenyl)-4-oxo-4H-chromen-3-yl)oxy)acetamide (L8). Purple solid, m.p. 205.8-207.4 ℃; yield: 39.4%. ¹H NMR (500 MHz, DMSO-d) δ 12.65 (s, 1H, -CO-NH-), 8.09–8.07 (m, 2H, Ph-H), 7.84–7.80 (m, 1H, Ph-H), 7.77 (d, J = 8.0 Hz, 1H, Ph-H), 7.72 (d, J = 8.5 Hz, 1H, Ph-H), 7.69–7.68 (m, 2H, Ph-H), 7.48 (d, J = 7.0 Hz, 1H, Ph-H), 7.44–7.41 (m, 2H, Ph-H), 7.09 (dd, J = 8.0, 2.0 Hz, 1H, Ph-H), 4.91 (s, 2H, -O-CH₂-CO-), 3.78 (s, 3H, Ph-OCH₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.08 (s), 168.32 (s), 159.14 (s), 158.45 (s), 154.76 (s), 154.66 (s), 147.44 (s), 139.64 (s), 134.47 (s), 133.25 (s), 131.45 (s), 129.81 (s), 127.67 (s), 126.53 (s), 125.39 (s), 125.02 (s), 123.21 (s), 121.85 (s), 121.52 (s), 120.96 (s), 118.64 (s), 116.93 (s), 114.04 (s), 70.23 (s), 55.31 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₅H₁₈ClN₂O₅S: 493.06195, found: 493.06088.

N-(6-chlorobenzo[d]thiazol-2-yl)-2-((2-(4-fluorophenyl)-4-oxo-4H-chromen-3-yl)oxy) acetamide (L9). White solid, m.p. >230 ℃; yield: 41.9%. ¹H NMR (500 MHz, DMSO-d) δ 12.59 (s, 1H, -CO-NH-), 8.16 (dd, J = 8.5, 6.0 Hz, 1H, Ph-H), 8.02 (d, J = 6.0 Hz, 2H, Ph-H), 8.01–7.93 (m, 1H, Ph-H), 7.79–7.75 (m, 1H, Ph-H), 7.71 (dd, J = 16.0, 8.5 Hz, 1H, Ph-H), 7.66 (d, J = 8.5 Hz, 1H, Ph-H), 7.43 (t, J = 7.5 Hz, 1H, Ph-H), 7.40–7.27 (m, 3H, Ph-H), 4.95–4.89 (m, 2H, -O-CH₂-CO-). ¹³C NMR (125 MHz, DMSO-d) δ, 174.04 (s), 168.28 (s), 164.47 (d, ¹J_C−F = 248.6 Hz), 158.24 (s), 54.71 (s), 153.98 (s), 147.41 (s), 139.35 (s), 134.46 (s), 133.22 (s), 131.51(d, ³J_C−F = 8.8 Hz), 127.77 (s), 126.57 (s), 125.39 (s), 125.03 (s), 124.87 (s), 123.21 (s), 121.52 (s), 118.55 (s), 115.86 (d, ²J_C−F = 21.6 Hz), 70.11 (s). ¹⁹F NMR (476 MHz, DMSO-d) δ -108.46. HRMS (ESI) m/z [M + H]⁺ calcd for C₂₄H₁₅ClFN₂O₄S:481.04196, found: 481.04123.

2-((2-(4-(tert-butyl)phenyl)-4-oxo-4H-chromen-3-yl)oxy)-N-(6-chlorobenzo[d]thiazol-2-yl)acetamide (L10). White solid, m.p. 171.5–172.4 ℃; yield: 39.5%. ¹H NMR (500 MHz, DMSO-d) δ 12.66 (s, 1H, -CO-NH-), 8.09–8.06 (m, 3H, Ph-H), 8.05–8.04 (m, 1H, Ph-H), 7.81–7.79 (m, 1H, Ph-H), 7.74 (d, J = 8.0 Hz, 1H, Ph-H), 7.71 (d, J = 8.5 Hz, 1H, Ph-H), 7.53–7.50 (m, 2H, Ph-H), 7.49–7.46 (m, 1H, Ph-H), 7.43–7.41 (m, 1H, Ph-H), 4.88 (s, 2H, -O-CH₂-CO-), 1.23 (s, 9H, Ph-C(CH₃)₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.47 (s), 168.70 (s), 158.71 (s), 155.65 (s), 155.24 (s), 154.51 (s), 147.88 (s), 139.86 (s), 134.89 (s), 133.70 (s), 129.96 (s), 129.01 (s), 128.23 (s), 127.88 (s), 127.04 (s), 125.98 (s), 125.51 (s), 123.70 (s), 122.38 (s), 121.99 (s), 119.00 (s), 70.78 (s), 35.19 (s), 31.31 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₈H₂₄ClN₂O₄S: 519.11398, found: 519.11267.

N-(6-chlorobenzo[d]thiazol-2-yl)-2-((2-(2-methoxyphenyl)-4-oxo-4H-chromen-3-yl)oxy)acetamide (L11). Yellow solid, m.p. >230 ℃; yield: 43.8%. ¹H NMR (500 MHz, DMSO-d) δ 12.43 (s, 1H, -CO-NH-), 8.10–8.03 (m, 2H, Ph-H), 7.76 (t, J = 7.0 Hz, 1H, Ph-H), 7.67 (d, J = 8.5 Hz, 1H, Ph-H), 7.62 (d, J = 8.5 Hz, 1H, Ph-H), 7.53–7.50 (m, 1H, Ph-H), 7.47–7.44 (m, 2H, Ph-H), 7.38 (dd, J = 8.5, 2.0 Hz, 1H, Ph-H), 7.10 (d, J = 8.5 Hz, 1H, Ph-H), 7.01 (t, J = 7.5 Hz, 1H, Ph-H), 4.73 (s, 2H, -O-CH₂-CO-), 3.71 (s, 3H, Ph-OCH₃). ¹³C NMR (125 MHz, DMSO-d) δ 173.71 (s), 168.21 (s), 158.25 (s), 156.88 (s), 155.53 (s), 155.23 (s), 147.42 (s), 140.22 (s), 134.41 (s), 133.23 (s), 132.46 (s), 130.61 (s), 127.73 (s), 126.57 (s), 125.40 (s), 125.12 (s), 123.51 (s), 121.89 (s), 121.54 (s), 120.33 (s), 119.16 (s), 118.57 (s), 111.79 (s), 70.46 (s), 55.74 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₅H₁₈ClN₂O₅S: 493.06195, found: 493.06256.

N-(benzo[d]thiazol-2-yl)-2-((4-oxo-2-phenyl-4H-chromen-3-yl)oxy)acetamide (L12). Yellow solid, m.p. 201.9–203.8 ℃; yield: 46.2%. ¹H NMR (500 MHz, DMSO-d) δ 12.57 (s, 1H, -CO-NH-), 8.09 (m, 3H, Ph-H), 7.94 (d, J = 8.0 Hz, 1H, Ph-H), 7.83–7.80 (m, 1H, Ph-H), 7.74 (dd, J = 13.5, 8.0 Hz, 2H, Ph-H), 7.55–7.53 (m, 3H, Ph-H), 7.48 (t, J = 7.5 Hz, 1H, Ph-H), 7.40 (t, J = 7.5 Hz, 1H, Ph-H, 7.27 (t, J = 7.5 Hz, 1H, Ph-H), 4.99 (m, 2H, -O-CH₂-CO-). ¹³C NMR (125 MHz, DMSO-d) δ 174.63 (s), 168.59 (s), 165.96 (s), 157.86 (s), 155.43 (s), 155.28 (s), 140.10 (s), 134.96 (s), 131.64 (s), 130.72 (s), 130.02 (s), 129.42 (s), 129.22 (s), 126.73 (s), 125.87 (s), 125.54 (s), 124.22 (s), 123.70 (s), 122.30 (s), 121.17 (s), 119.06 (s), 70.74 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₄H₁₇N₂O₄S: 429.09035, found: 429.08932.

N-(benzo[d]thiazol-2-yl)-2-((4-oxo-2-(p-tolyl)-4H-chromen-3-yl)oxy)acetamide (L13). White solid, m.p. >230 ℃; yield: 33.4%. ¹H NMR (500 MHz, DMSO-d) δ 12.57 (s, 1H, -CO-NH-), 8.09 (d, J = 8.0 Hz, 1H, Ph-H), 8.06 (d, J = 8.0 Hz, 2H, Ph-H), 7.95 (d, J = 8.0 Hz, 1H, Ph-H), 7.82 (t, J = 7.5 Hz, 1H, Ph-H), 7.75 (dd, J = 16.5, 8.0 Hz, 2H, Ph-H), 7.49 (t, J = 7.5 Hz, 1H, Ph-H), 7.41 (t, J = 7.5 Hz, 1H, Ph-H), 7.34 (d, J = 8.0 Hz, 2H, Ph-H), 7.28 (t, J = 7.5 Hz, 1H, Ph-H), 4.87 (s, 2H, -O-CH₂-CO-), 2.33 (s, 3H, Ph-CH₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.53 (s), 168.54 (s), 157.85 (s), 155.66 (s), 155.25 (s), 149.02 (s), 141.79 (s), 139.91 (s), 134.89 (s), 132.02 (s), 129.79 (s), 129.15 (s), 127.87 (s), 126.71 (s), 125.83 (s), 125.52 (s), 124.21 (s), 123.71 (s), 122.30 (s), 121.19 (s), 119.04 (s), 70.80 (s), 21.61 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₅H₁₉N₂O₄S: 443.10600, found: 443.10461.

N-(benzo[d]thiazol-2-yl)-2-((2-(3-methoxyphenyl)-4-oxo-4H-chromen-3-yl)oxy)acetamide (L14). White solid, m.p. 191.5–192.0 ℃; yield: 35.6%. ¹H NMR (500 MHz, DMSO-d) δ 12.52 (s, 1H, -CO-NH-), 8.07 (d, J = 6.5 Hz, 1H, Ph-H), 7.92 (d, J = 7.0 Hz, 1H, Ph-H), 7.80–7.74 (m, 2H, Ph-H), 7.68 (s, 3H, Ph-H), 7.51–7.36 (m, 3H, Ph-H), 7.25 (s, 1H, Ph-H), 7.07 (d, J = 6.5 Hz, 1H, Ph-H), 4.89 (s, 2H, -O-CH₂-CO-), 3.76 (s, 3H, Ph-OCH₃). ¹³C NMR (125 MHz, DMSO) δ 174.53 (s), 168.42 (s), 159.59 (s), 157.79 (s), 155.20 (s), 155.11 (s), 148.94 (s), 140.09 (s), 134.88 (s), 131.96 (s), 131.88 (s), 130.25 (s), 126.65 (s), 125.81 (s), 125.45 (s), 124.15 (s), 123.64 (s), 122.25 (s), 121.38 (s), 121.12 (s), 119.06 (s), 117.37 (s), 114.47 (s), 70.65 (s), 55.74 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₅H₁₉N₂O₅S: 459.10092, found: 459.10016.

N-(benzo[d]thiazol-2-yl)-2-((2-(4-fluorophenyl)-4-oxo-4H-chromen-3-yl)oxy)acetamide (L15). White solid, m.p. 196.7–198.8 ℃; yield: 36.5%. ¹H NMR (500 MHz, DMSO-d) δ 12.52 (s, 1H, -CO-NH-), 8.22–8.18 (m, 2H, Ph-H), 8.06 (dd, J = 8.0, 1.5 Hz, 1H, Ph-H), 7.91 (d, J = 8.0 Hz, 1H, Ph-H), 7.79–7.77 (m, 1H, Ph-H), 7.74–7.72 (m, 1H, Ph-H), 7.70 (d, J = 8.0 Hz, 1H, Ph-H), 7.47–7.44 (m, 1H, Ph-H), 7.41–7.36 (m, 2H, Ph-H), 7.35–7.33 (m, 1H, Ph-H), 7.27–7.23 (m, 1H, Ph-H), 4.91 (s, 2H, -O-CH₂-CO-). ¹³C NMR (125 MHz, DMSO-d) δ 174.50 (s), 168.54 (s), 164.95 (d, ¹J_C−F = 248.8 Hz), 157.84 (s), 155.21 (s), 154.46 (s), 149.01 (s), 139.87 (s), 134.94 (s), 132.00 (d, ³J_C−F = 8.8 Hz), 127.27 (d, ⁴J_C−F = 2.5 Hz), 126.71 (s), 125.87 (s), 125.52 (s), 124.20 (s), 123.71 (s), 122.29 (s), 121.18 (s), 119.05 (s), 116.35(d, ²J_C−F = 21.3 Hz), 70.61 (s). ¹⁹F NMR (470 MHz, DMSO-d) δ -108.45. HRMS (ESI) m/z [M + H]⁺ calcd for C₂₄H₁₆FN₂O₄S: 447.08093, found: 447.07941.

N-(benzo[d]thiazol-2-yl)-2-((2-(4-(tert-butyl)phenyl)-4-oxo-4H-chromen-3-yl)oxy)acetamide (L16). Yellow solid, m.p. 182.9–184.4 ℃; yield: 32.2%. ¹H NMR (500 MHz, DMSO-d) δ 12.92 (s, 1H, -CO-NH-), 8.13–8.11 (m, 2H, Ph-H), 7.99 (dd, J = 8.0, 1.5 Hz, 1H, Ph-H), 7.90 (t, J = 8.0 Hz, 2H, Ph-H), 7.67 (d, J = 8.0 Hz, 2H, Ph-H), 7.48–7.46 (m, 2H, Ph-H), 7.41–7.34 (m, 2H, Ph-H), 7.34 (dd, J = 11.5, 4.0 Hz, 1H, Ph-H), 4.98 (s, 2H, -O-CH₂-CO-), 1.21 (s, 9H, Ph-C(CH₃)₃). ¹³C NMR (125 MHz, DMSO-d) δ 178.18 (s), 174.24 (s), 167.32 (s), 155.05 (s), 154.72 (s), 154.18 (s), 139.49 (s), 137.11 (s), 134.50 (s), 128.95 (s), 128.30 (s), 126.78 (s), 125.84 (s), 125.43 (s), 124.77 (s), 124.32 (s), 123.82 (s), 122.31 (s), 118.86 (s), 113.17 (s), 72.46 (s), 35.13 (s), 31.31 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₈H₂₅N₂O₄S: 485.15295, found: 485.15186.

N-(benzo[d]thiazol-2-yl)-2-((2-(4-chlorophenyl)-4-oxo-4H-chromen-3-yl)oxy)acetamide (L17). Yellow solid, m.p. 210.9–212.1 ℃; yield: 37.9%. ¹H NMR (500 MHz, DMSO-d) δ 12.53 (s, 1H, -CO-NH-), 8.17 (d, J = 8.5 Hz, 2H, Ph-H), 8.08 (dd, J = 8.0, 1.5 Hz, 1H, Ph-H), 7.94 (d, J = 8.0 Hz, 1H, Ph-H), 7.84–7.80 (m, 1H, Ph-H), 7.75 (d, J = 8.5 Hz, 1H, Ph-H), 7.72 (d, J = 8.0 Hz, 1H, Ph-H), 7.60 (s, 1H, Ph-H), 7.58 (s, 1H, Ph-H), 7.50–7.46 (m, 1H, Ph-H), 7.40 (dd, J = 11.0, 4.0 H, 1H, Ph-Hz), 7.29–7.26 (m, 1H, Ph-H), 4.94 (s, 2H, -O-CH₂-CO-). ¹³C NMR (125 MHz, DMSO-d) δ 174.47 (s), 168.49 (s), 157.83 (s), 155.20 (s), 154.13 (s), 149.00 (s), 140.15 (s), 136.33 (s), 134.99 (s), 132.01(s), 131.07 (s), 129.60 (s), 129.23 (s), 126.70 (s), 125.89 (s), 125.52 (s), 124.20 (s), 123.72 (s), 122.29 (s), 121.17 (s), 119.05 (s), 70.61 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₄H₁₆ClN₂O₄S: 463.05138, found: 463.05011.

N-(4-methylbenzo[d]thiazol-2-yl)-2-((4-oxo-2-phenyl-4H-chromen-3-yl)oxy)acetamide (L18). Yellow solid, m.p. 184.2–185.4 ℃; yield: 39.5%. ¹H NMR (500 MHz, DMSO-d) δ 12.56 (s, 1H, -CO-NH-), 8.16–8.13 (m, 2H, Ph-H), 8.08 (dd, J = 8.0, 1.5 Hz, 1H, Ph-H), 7.83–7.80 (m, 1H, Ph-H), 7.77–7.74 (m, 2H, Ph-H), 7.53 (dd, J = 5.5, 2.0 Hz, 3H, Ph-H), 7.48 (dd, J = 11.5, 4.5 Hz, 1H, Ph-H), 7.22 (d, J = 7.0 Hz, 1H, Ph-H), 7.17 (d, J = 7.5 Hz, 1H, Ph-H), 4.93 (s, 2H, -O-CH₂-CO-), 2.53 (s, 3H, Ph-CH₃). ¹³C NMR (125 MHz, DMSO-d) δ 173.96 (s), 167.89 (s), 156.49 (s), 154.78(s), 154.74(s), 147.60 (s), 139.48 (s), 134.42 (s), 131.10 (s), 130.32 (s), 129.98 (s), 129.54 (s), 128.76 (s), 128.67 (s), 126.71 (s), 125.35 (s), 125.04 (s), 123.67 (s), 123.28 (s), 119.19 (s), 118.58 (s), 69.90 (s), 18.01 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₅H₁₉N₂O₄S: 443.10600, found: 443.10471.

N-(4-methylbenzo[d]thiazol-2-yl)-2-((4-oxo-2-(p-tolyl)-4H-chromen-3-yl)oxy)acetamide (L19). Yellow solid, m.p. 158.8–160.3 ℃; yield: 44.3%. ¹H NMR (500 MHz, DMSO-d) δ 8.08–8.04 (m, 3H, Ph-H), 7.78 (t, J = 7.5 Hz, 1H, Ph-H), 7.73 (d, J = 8.5 Hz, 1H, Ph-H), 7.65 (d, J = 7.5 Hz, 1H, Ph-H), 7.45 (t, J = 7.5 Hz, 1H, Ph-H), 7.30 (d, J = 8.0 Hz, 2H, Ph-H), 7.14 (d, J = 7.0 Hz, 1H, Ph-H), 7.08 (t, J = 7.5 Hz, 1H, Ph-H), 4.82 (s, 2H, -O-CH₂-CO-), 2.48 (s, 3H, Ph-CH₃), 2.29 (s, 3H, Ph-CH₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.39 (s), 155.18 (s), 148.44 (s), 141.59 (s), 134.74 (s), 131.89 (s), 129.72 (s), 129.16 (s), 128.04 (s), 126.79 (s), 125.71 (s), 125.49 (s), 123.79 (s), 119.43 (s), 118.99 (s), 70.99 (s), 21.57 (s), 18.54 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₆H₂₁N₂O₄S: 457.12165, found: 457.12039.

2-((2-(3-methoxyphenyl)-4-oxo-4H-chromen-3-yl)oxy)-N-(4-methylbenzo[d]thiazol-2-yl)acetamide (L20). White solid, m.p. 165.5-166.9 ℃; yield: 41.0%. ¹H NMR (500 MHz, DMSO-d) δ 12.54 (s, 1H, -CO-NH-), 8.07 (d, J = 8.0 Hz, 1H, Ph-H), 7.81 (t, J = 7.5 Hz, 1H, Ph-H), 7.76–7.72 (m, 2H, Ph-H), 7.69 (d, J = 8.0 Hz, 2H, Ph-H), 7.46 (d, J = 7.5 Hz, 1H, Ph-H), 7.43 (t, J = 8.0 Hz, 1H, Ph-H), 7.21 (d, J = 7.0 Hz, 1H, Ph-H), 7.16 (t, J = 7.0 Hz, 1H, Ph-H), 7.07 (d, J = 7.5 Hz, 1H, Ph-H), 4.91 (s, 2H, -O-CH₂-CO-), 3.77 (s, 3H, Ph-OCH₃), 2.52 (s, 3H, Ph-CH₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.44 (s), 168.26 (s), 159.60 (s), 156.93 (s), 155.21 (s), 155.04 (s), 148.03 (s), 139.99 (s), 134.89 (s), 131.95 (s), 131.64 (s), 130.46 (s), 130.27 (s), 127.18 (s), 125.82 (s), 125.47 (s), 124.17 (s), 123.71 (s), 121.42 (s), 119.64 (s), 119.07 (s), 117.36 (s), 114.51 (s), 70.40 (s), 55.76 (s), 18.46 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₆H₂₁N₂O₅S: 473.11657, found: 473.11505.

2-((2-(4-fluorophenyl)-4-oxo-4H-chromen-3-yl)oxy)-N-(4-methylbenzo[d]thiazol-2-yl)acetamide (L21). White solid, m.p. 200.4–201.8 ℃; yield: 51.2%. ¹H NMR (500 MHz, DMSO-d) δ 12.55 (s, 1H, -CO-NH-), 8.23 (dd, J = 7.5, 5.5 Hz, 2H, Ph-H), 8.07 (d, J = 8.0 Hz, 1H, Ph-H), 7.81 (t, J = 7.5 Hz, 1H, Ph-H), 7.76–7.72 (m, 2H, Ph-H), 7.47 (t, J = 7.5 Hz, 1H, Ph-H), 7.36 (t, J = 8.5 Hz, 2H, Ph-H), 7.21 (d, J = 7.0 Hz, 1H, Ph-H), 7.16 (t, J = 7.5 Hz, 1H, Ph-H), 4.95 (s, 2H, -O-CH₂-CO-), 2.53 (s, 3H, Ph-CH₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.32 (s), 168.34 (s), 164.91(d, ¹J_C−F = 248.8 Hz), 156.95 (s), 155.17 (s), 154.28 (s), 148.07 (s), 139.72 (s), 134.87 (s), 131.99(d, 3J_C − F = 8.8 Hz), 131.65 (s), 130.45 (s), 127.17 (s), 125.82 (s), 125.49 (s), 124.13 (s), 123.75 (s), 119.65 (s), 119.03 (s), 116.29(d, ²J_C−F = 21.3 Hz), 116.12 (s), 70.30 (s), 18.48 (s).¹⁹F NMR (470 MHz, DMSO-d) δ -108.58. HRMS (ESI) m/z [M + H]⁺ calcd for C₂₅H₁₈FN₂O₄S: 461.09658, found: 461.09515.

2-((2-(4-(tert-butyl)phenyl)-4-oxo-4H-chromen-3-yl)oxy)-N-(4-methylbenzo[d]thiazol-2-yl)acetamide (L22). Yellow solid, m.p. 180.0-181.6 ℃; yield: 45.9%. ¹H NMR (500 MHz, DMSO-d) δ 12.57 (s, 1H, -CO-NH-), 8.07–8.04 (m, 3H, Ph-H), 7.80–7.76 (m, 1H, Ph-H), 7.71 (dd, J = 7.5, 4.5 Hz, 2H, Ph-H), 7.50–7.47 (m, 2H, Ph-H), 7.45 (dd, J = 11.0, 4.0 Hz, 1H, Ph-H), 7.19 (d, J = 7.0 Hz, 1H, Ph-H), 7.16–7.13 (m, 1H, Ph-H), 4.89 (s, 2H, 2H-O-CH₂-CO-), 2.52 (s, 3H, Ph-CH₃), 1.20 (s, 9H, Ph-C(CH₃₎₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.30 (s), 168.23 (s), 156.93 (s), 155.46 (s), 155.18 (s), 154.41 (s), 148.06 (s), 139.71 (s), 134.77 (s), 131.66 (s), 130.43 (s), 129.95 (s), 128.99 (s), 127.93 (s), 127.14 (s), 125.90 (s), 125.47 (s), 124.12 (s), 123.74 (s), 119.60 (s), 118.94 (s), 70.47 (s), 35.13 (s), 31.27 (s), 18.48 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₉H₂₇N₂O₄S: 499.16860, found: 499.16733.

2-((2-(4-chlorophenyl)-4-oxo-4H-chromen-3-yl)oxy)-N-(4-methylbenzo[d]thiazol-2-yl)acetamide (L23). Yellow solid, m.p. 201.9–203.6 ℃; yield: 52.8%. ¹H NMR (500 MHz, DMSO-d) δ 12.53 (s, 1H,-CO-NH-), 8.17 (d, J = 8.5 Hz, 2H, Ph-H), 8.07 (d, J = 8.0 Hz, 1H, Ph-H), 7.82 (t, J = 7.5 Hz, 1H, Ph-H), 7.76–7.72 (m, 2H, Ph-H), 7.58 (d, J = 8.5 Hz, 2H, Ph-H), 7.48 (t, J = 7.5 Hz, 1H, Ph-H), 7.21 (d, J = 7.0 Hz, 1H, Ph-H), 7.16 (t, J = 7.5 Hz, 1H, Ph-H), 4.94 (s, 2H, -O-CH₂-CO-), 2.52 (s, 3H, Ph-CH₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.33 (s), 168.31 (s), 156.95 (s), 155.18 (s), 154.04 (s), 148.05 (s), 140.01 (s), 136.27 (s), 134.97 (s), 131.63 (s), 131.09 (s), 130.45 (s), 129.64 (s), 129.19 (s), 127.18 (s), 125.88 (s), 125.51 (s), 124.16 (s), 123.76 (s), 119.65 (s), 119.05 (s), 70.34 (s), 18.48 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₅H₁₈ClN₂O₄S: 477.06703, found: 477.06583.

N-(6-methoxybenzo[d]thiazol-2-yl)-2-((4-oxo-2-phenyl-4H-chromen-3-yl)oxy)acetamide (L24). Yellow solid, m.p. 149.1–150.9 ℃; yield: 48.5%. ¹H NMR (500 MHz, DMSO-d) δ 12.44 (s, 1H, -CO-NH-), 8.13 (dd, J = 6.5, 3.0 Hz, 2H, Ph-H), 8.09 (dd, J = 8.0, 1.5 Hz, 1H, Ph-H), 7.82–7.81 (m, 1H, Ph-H), 7.76 (d, J = 8.0 Hz, 1H, Ph-H), 7.62 (d, J = 9.0 Hz, 1H, Ph-H), 7.55–7.52 (m, 4H, Ph-H), 7.49 (dd, J = 11.0, 4.0 Hz, 1H, Ph-H), 6.99 (dd, J = 9.0, 2.5 Hz, 1H, Ph-H), 4.88 (s, 2H, -O-CH₂-CO-), 3.76 (s, 3H, Ph-OCH₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.64(s), 168.26(s), 156.72(s), 155.74(s), 155.43(s), 155.39(s), 143.08(s), 140.13(s), 134.95(s), 133.33(s), 131.64(s), 130.72(s), 129.22(s), 125.87(s), 125.54(s), 123.70(s), 121.80(s), 119.06(s), 115.52(s), 105.22(s), 70.72(s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₅H₁₉N₂O₅S: 459.10092, found: 459.09961.

N-(6-methoxybenzo[d]thiazol-2-yl)-2-((4-oxo-2-(p-tolyl)-4H-chromen-3-yl)oxy)acetamide (L25). Yellow solid, m.p. 172.4–174.3 ℃; yield: 36.5%. ¹H NMR (500 MHz, DMSO-d) δ 12.44 (s, 1H, -CO-NH-), 8.08 (d, J = 7.0 Hz, 1H, Ph-H), 8.04 (d, J = 8.0 Hz, 2H, Ph-H), 7.83–7.79 (m, 1H, Ph-H), 7.75 (d, J = 8.5 Hz, 1H, Ph-H), 7.62 (d, J = 9.0 Hz, 1H, Ph-H), 7.54–7.46 (m, 2H, Ph-H), 7.33 (d, J = 8.0 Hz, 2H, Ph-H), 6.99 (dd, J = 8.5, 2.5 Hz, 1H, Ph-H), 4.83 (s, 2H, -O-CH₂-CO-), 3.76 (s, 3H, Ph-OCH₃), 2.32 (s, 3H, Ph-CH₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.56 (s), 168.22 (s), 156.73 (s), 155.70 (s), 155.24 (s), 141.80 (s), 139.93 (s), 134.89 (s), 129.80 (s), 129.13 (s), 127.85 (s), 125.82 (s), 125.52 (s), 121.81 (s), 119.03 (s), 115.52 (s), 105.23 (s), 70.80 (s), 56.14 (s), 21.61 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₆H₂₁N₂O₅S: 473.11657, found: 473.11581.

N-(6-methoxybenzo[d]thiazol-2-yl)-2-((2-(3-methoxyphenyl)-4-oxo-4H-chromen-3-yl)oxy)acetamide (L26). White solid, m.p. 160.3–161.5 ℃; yield: 36.4%. ¹H NMR (500 MHz, DMSO-d) δ 12.42 (s, 1H, -CO-NH-), 8.11–8.06 (m, 1H, Ph-H ), 7.82 (dd, J = 11.0, 4.0 Hz, 1H, Ph-H), 7.76 (d, J = 8.5 Hz, 1H, Ph-H), 7.69 (d, J = 1.0 Hz, 1H, Ph-H), 7.68 (s, 1H, Ph-H), 7.62 (d, J = 9.0 Hz, 1H, Ph-H), 7.53 (d, J = 2.0 Hz, 1H, Ph-H), 7.48 (t, J = 6.0 Hz, 1H, Ph-H), 7.45 (dd, J = 13.5, 5.5 Hz, 1H, Ph-H), 7.12–7.07 (m, 1H, Ph-H), 6.99 (dd, J = 8.5, 2.5 Hz, 1H, Ph-H), 4.88 (s, 2H, -O-CH₂-CO-), 3.79 (s, 3H, Ph-OCH₃), 3.76 (s, 3H, Ph-OCH₃). ¹³C NMR (125 MHz, DMSO-d) δ 174.61 (s), 168.15 (s), 159.65 (s), 156.72 (s), 155.74 (s), 155.25 (s), 155.18 (s), 143.09 (s), 140.17 (s), 134.93 (s), 133.34 (s), 131.92 (s), 130.31 (s), 125.86 (s), 125.51 (s), 123.68 (s), 121.79 (s), 121.42 (s), 119.10 (s), 117.44 (s), 115.51 (s), 114.50 (s), 105.23 (s), 70.69 (s), 56.13 (s), 55.80 (s). HRMS (ESI) m/z [M + H]⁺ calcd for C₂₆H₂₁N₂O₆S: 489.11148, found: 489.11078.

4.3 In vivo antiviral activity

According to literature reports[32, 33, 34], L1-L26 were selected as the experimental objects for in vivo anti-virus testing using the semi-leaf blight method, with dimethyl sulfoxide (DMSO) solution as the negative control and commercial NNM as the positive control. The tobaccos treated were cultivated in an artificial climate chamber (28 ℃) for 2–3 d. When spots appear on the leaves, the number of spots on both sides is counted and the inhibition rate is calculated. Each drug was repeated three times. Specific experimental methods were described in the Supporting Information.

4.4 Microscale thermophoresis experiment

The modes of binding of the target compounds to tobacco mosaic virus capsid proteins (TMV-CP) and the affinity of intermolecular interactions were investigated using MST assays. The binding affinity of L20 and L23 to TMV-CP were tested with reference to the methodology reported in the literature[35, 36], and the commercial drug NNM was used as a positive control. The details of the experimental methods were described in the Supporting Information.

4.5 Molecular docking experiment

TMV-CP not only has the function of protecting nucleic acid from degradation, but also has the function of assisting TMV long-distance transport, determining the host range and participating in nucleic acid replication. TMV-CP is often used as a potential target in the study of antiviral agents. Utilizing molecular docking simulations for predicting interactions between ligand compounds and receptor proteins to validate their binding affinity. Following established methodology detailed in literature reports[37, 38], molecular docking simulations involving L20 and NNM with TMV-CP were conducted utilizing. Specific experimental methodologies were outlined within Supporting Information.

4.6 MDA content test

Previous studies have reported that the content of MDA can reflect the degree of membrane damages in tobacco leaves infected by TMV[39, 40]. The healthy, uniformly sized tobacco leaves were selected as the experimental subjects. The experiment was set up with four different treatments (CK, L20, TMV, and TMV + L20), the whole leaves were induced with 500 µg/mL L20, and 0.5% DMSO to obtain the groups CK and L20; the entire leaf was infected with 500-fold diluted virus liquid to obtain TMV group; the entire leaf was treated with 500 µg/mL L20 first, and then infected with 500-fold diluted virus liquid after 24 h to obtain TMV + L20. Each treatment had 4 tobacco plants. Samples were collected at intervals of 1, 3, 5 and 7 d. The MDA content was determined by liquid nitrogen grinding and following the instructions in the assay kit.

4.7 SOD activity measurement

According to literature reports[18, 41], the SOD activity was determined in the leaves after the L20 treatment, with the same four treatments as the MDA content determination experiment, 0.1 g of leaf tissue was weighed after the leaf veins were removed, and the SOD activity was determined following the instructions in the assay kit.

4.8 In vivo chlorophyll content test

Chlorophyll is one of the most important pigments related to photosynthesis, and its content is closely related to the health of the plant. According to the reported method[42], the change in chlorophyll content in the leaves after the L20 treatment was determined, with the same treatment and sampling steps as the MDA content determination experiment. When cells die, chlorophyll was released from the chloroplasts. Free chlorophyll is highly unstable and can be broken down by light, acid, alkali, oxygen, oxidants, etc. Therefore, leaf green content should be determined immediately after leaf sampling. Specific experimental methodologies were outlined within Supporting Information.

Acknowledgement

The authors gratefully acknowledge the Key Research and Development Program of Hainan Province (No. ZDYF2024XDNY202), the Science Foundation of Guizhou Province (No. ZK2024008), Chinese Academy of Tropical Agricultural Sciences for Science and Technology Innovation Team of National Tropical Agricultural Science Center (No. CATASCXTD202410).

The appendix: Supplementary material

The Supporting Information includes the characterization data of the target compound, NMR and HRMS spectra, and the detailed operation steps of studying the target compound matrix.

Authors' contributions

The current study is an outcome of constructive discussion with W.X; J.T and C.M.H performed synthesis and characterization experiments on the target compounds; J.T and Y.H.W completed experiments on preliminary screening and mechanism of action studies of antiviral activity; J.T, X.P.L and J.Y.L carried out the NMR and HRMS spectral analyses; J.T and H.T.P prepared figures 1-7 and table 1-3; T.J, X.W, and D.L were involved in the drafting of the manuscript and revising the manuscript. All authors read and approved the final manuscript.

Conflicts of interest

The authors declare that there are no competing financial interests.

Hao YA, Guo JC, Wang ZW, Liu YX, Li YQ, Ma DJ, Wang QM (2020) Discovery of tryptanthrins as novel antiviral and anti-phytopathogenic-fungus agents. J Agric Food Chem 68(20):5586–5595. https://doi.org/10.1021/acs.jafc.0c02101
Zhang J, He FC, Chen JX, Wang YJ, Yang YY, Hu DY, Song BA (2021) Purine nucleoside derivatives containing a sulfa ethylamine moiety: design, synthesis, antiviral activity, and mechanism. J Agric Food Chem 69(20):5575–5582. https://doi.org/10.1021/acs.jafc.0c06612
Li TX, Zhang J, Pan JK, Wu ZX, Hu DY, Song BA (2016) Design, synthesis, and antiviral activities of 1,5-benzothiazepine derivatives containing pyridine moiety. Eur J Med Chem 125:657–662. https://doi.org/10.1016/j.ejmech.2016.09.069
Wu ZX, Zhang J, Chen JX, Pan JK, Zhao L, Liu DY, Zhang A, Chen J, Hu DY, Song BA (2017) Design, synthesis, antiviral bioactivity and three-dimensional quantitative structure–activity relationship study of novel ferulic acid ester derivatives containing quinazoline moiety. Pest Manag Sci 73(10):2079–2089. https://doi.org/10.1002/ps.4579
Liu CY, Pu YD, Peng HR, Lv X, Tian SR, Wei XF, Zhang J, Zou AH, Fan GJ, Sun XC (2021) Transcriptome sequencing reveals that photoinduced gene IP-L affects the expression of PsbO to response to virus infection in nicotiana benthamiana. Physiol Mol Plant Pathol 114:101613–101623. https://doi.org/10.1016/j.pmpp.2021.101613
Boualem A, Dogimont C, Bendahmane A (2016) The battle for survival between viruses and their host plants. Curr Opin Virol 17:32–38. https://doi.org/10.1016/j.coviro.2015.12.001
De Souza Dos Santos MC, Gonçalves CFL, Vaisman M, Ferreira ACF, De Carvalho DP (2011) Impact of flavonoids on thyroid function. Food Chem Toxicol 49(10):2495–2502. https://doi.org/10.1016/j.fct.2011.06.074
Huang MG, Ruan XH, Li Q, Zhang JP, Zhong XM, Wang XB, Xie Y, Xiao W, Xue W (2017) Synthesis and antibacterial activity of novel phosphorylated flavonoid derivatives. Phosphorus, Sulfur, and Silicon and the Related Elements. 37(8):2145–2152. https://doi.org/10.1080/10426507.2017.1295963
Gong CY, Zhou YX, Zhou Q, Meng KN, Sun ZL, Zeng W, Qin YS, Luo XP, Xue W (2024) Novel flavonoid derivatives containing 1,2,4-triazolo[4,3-a]pyridine as potential antifungal agents: design, synthesis, and biological evaluation. J Saudi Chem Soc 28(2):101797–101812. https://doi.org/10.1016/j.jscs.2023.101797
Li X, Chen GL, Zhang XJ, Zhang Q, Zheng SL, Wang GD, Chen QH (2016) A new class of flavonol-based anti-prostate cancer agents: design, synthesis, and evaluation in cell models. Bioorg Med Chem Lett 26(17):4241–4245. https://doi.org/10.1016/j.bmcl.2016.07.050
Said M, Brouard I, Quintana J, Estévez F (2017) Antiproliferative activity and apoptosis induction by 3',4'-dibenzyloxyflavonol on human leukemia cells. Chemico-Biol Interact 268:13–23. https://doi.org/10.1016/j.cbi.2017.02.010
Li YT, Ye SE, Hu ZL, Hao N, Bo X, Liang HG, Tian XR (2021) Identification of anti-TMV active flavonoid glycosides and their mode of action on virus particles from clematis lasiandra maxim. Pest Manag Sci 77(11):5268–5277. https://doi.org/10.1002/ps.6569
Ma YC, Wang L, Lu AD, Xue W (2022) Synthesis and biological activity of novel oxazinyl flavonoids as antiviral and anti-phytopathogenic fungus agents. Molecules 27(20):6875–6875. https://doi.org/10.3390/molecules27206875
Zhou YX, Sun ZL, Zhou Q, Zeng W, Zhang MH, Feng S, Xue W (2024) Novel flavonol derivatives containing benzoxazole as potential antiviral agents: design, synthesis, and biological evaluation.Molecular diversity. Mol Diversity 2:10786. https://doi.org/10.1007/s11030-023-10786-5
Wang YH, Li P, Jiang SC, Chen Y, Su SJ, He J, Chen M, Zhang JP, Xu WM, He M, Xue W (2019) Synthesis and antibacterial evaluation of novel chalcone derivatives containing a benzothiazole scaffold. Monatshefte für Chemie - Chem Monthly 150:1147–1154. https://doi.org/10.1007/s00706-019-02399-2
Zubenko A, Kartsev V, Petrou A, Geronikaki A, Ivanov M, Glamočlija J, Soković M, Divaeva L, Morkovnik A, Klimenko A (2022) Experimental and in silico evaluation of new Heteroaryl benzothiazole derivatives as antimicrobial agents. Antibiotics 11(11):11111654. https://doi.org/10.3390/antibiotics11111654
Chu PL, Feng YM, Long ZQ, Xiao WL, Ji J, Zhou X, Qi PY, Zhang TH, Zhang H, Liu LW, Yang S (2023) Novel benzothiazole derivatives as potential anti-quorum sensing agents for managing plant bacterial diseases: synthesis, antibacterial activity assessment, and SAR study. J Agric Food Chem 71(17):6525–6540. https://doi.org/10.1021/acs.jafc.2c07810
Tang X, Wang ZB, Zhong XM, Wang XB, Chen LJ, He M, Xue W (2018) Synthesis and biological activities of benzothiazole derivatives bearing a 1,3,4-thiadiazole moiety. Phosphorus, Sulfur, and Silicon and the Related Elements. 194(3):241–248. https://doi.org/10.1080/10426507.2018.1539992
Tian J, Ji RJ, Wang H, Li SY, Zhang GP (2022) Discovery of novel α-aminophosphonates with hydrazone as potential antiviral agents combined with active fragment and molecular docking. Front Chem 10:1–7. https://doi.org/10.3389/fchem.2022.911453
Shang JF, Li YX, Yang N, Xiong LX, Wang BL (2022) Synthesis and evaluation of novel 1-(((6-substitutedbenzo[d]thiazol-2-yl)amino)(heteroaryl)methyl)naphthalen-2-ol as pesticidal agents. J Enzyme Inhib Med Chem 7(1):641–651. https://doi.org/10.1080/14756366.2022.2032687
Ma JJ, Bao GL, Wang LM, Li WT, Xu BX, Du BQ, Lv J, Zhai X, Gong P (2015) Design, synthesis, biological evaluation and preliminary mechanism study of novel benzothiazole derivatives bearing indole-based moiety as potent antitumor agents. Eur J Med Chem 96:173–186. https://doi.org/10.1016/j.ejmech.2015.04.018
Shaik TB, Hussaini SMA, Nayak VL, Sucharitha ML, Malik MS, Kamal A (2017) Rational design and synthesis of 2-anilinopyridinyl-benzothiazole schiff bases as antimitotic agents. Bioorg Med Chem Lett 27(11):2549–2558. https://doi.org/10.1016/j.bmcl.2017.03.089
Xu XM, Zhu ZJT, Chen SY, Fu YN, Zhang JX, Guo YY, Xu ZY, Xi YY, Wang XB, Ye FQ, Chen HJ, Yang XJ (2024) Synthesis and biological evaluation of novel benzothiazole derivatives as potential anticancer and antiinflammatory agents. Front Chem 12:1384301. https://doi.org/10.3389/fchem.2024.1384301
Liang Z, Rong Z, Cong H, Qing YD, Ming-Zhu S, Jie W, Xu LN, Jin ZC, Shang XC, Da YP (2022) Design, synthesis and antifungal activity of novel pyrazole amides derivates. J Mol Struct 1277:134881. https://doi.org/10.1016/j.molstruc.2022.134881
Antoszczak M, Maj E, Stefańska J, Wietrzyk J, Janczak J, Brzezinski B, Huczyński A (2014) Synthesis, antiproliferative and antibacterial activity of new amides of salinomycin. Bioorg Med Chem Lett 24(7):1724–1729. https://10.1016/j.bmcl.2014.02.042
Liu YH, Li JR, Gu YX, Ma L, Cen S, Peng ZG, Hu LX (2021) Synthesis and structure-activity relationship study of new biaryl amide derivatives and their inhibitory effects against hepatitis C virus. Eur J Med Chem 228:114033. https://doi.org/10.1016/j.ejmech.2021.114033
Yang S, Ding C, Liu X, Weng J, Yuan J, Tan C (2020) Synthesis and herbicidal activity of chiral aryloxyphenoxypropionic amides compounds. Chin J Org Chem 39(12):3588–3593. https://doi.org/10.6023/cjoc201905028
Zhang RF, Guo SX, Deng P, Wang Y, Dai A, Wu J (2021) Novel ferulic amide ac6c derivatives: design, synthesis, and their antipest activity. J Agric Food Chem 69(35):10082–10092. https://doi.org/10.1021/acs.jafc.1c03892
Zhou YX, Gong CY, Sun ZL, Zeng W, Meng KN, An YS, Hu YZ, Xue W (2024) Novel flavonol derivatives containing 1,3,4-thiadiazole as potential antifungal agents: design, synthesis, and biological evaluation. ACS Omega 9(15):17297–17306. https://doi.org/10.1021/acsomega.3c10294
Gong CY, Meng KN, Sun ZL, Zeng W, An YS, Zou HQ, Qiu YJ, Liu D, Xue W (2024) Flavonol derivatives containing a quinazolinone moiety: design, synthesis, and antiviral activity. Chem Biodivers 21(2):e202301737. https://doi.org/10.1002/cbdv.202301737
Zhou Q, Xia Z, Zhang Y, Sun ZL, Zeng W, Zhang N, Yuan CM, Gong CY, Zhou YX, Xue W (2024) Design of a delivery vehicle chitosan-based self-assembling: controlled release, high hydrophobicity, and safe treatment of plant fungal diseases. J Nanobiotechnol 121(22):023868. https://doi.org/10.1186/s12951-024-02386-8
Xing L, An YS, Qin YS, Xin H, Deng TY, Meng KN, Liu D, Xue W (2023) Design, synthesis, and antiviral activities of myricetin derivatives containing pyridazinone. New J Chem 48(1):117–130. https://doi.org/10.1039/d3nj04902g
Yuan CM, Tian J, Zhou Q, Xin H, Liu Y, Deng TY, Zeng W, Sun ZL, Xue W (2023) Myricetin derivatives containing the benzoxazinone moiety discovered as potential anti-tobacco mosaic virus agents. Fitoterapia 173:105812. https://doi.org/10.1016/j.fitote.2023.105812
Hu D, Zhang N, Zhang YQ, Yuan CM, Gong CY, Zhou YX, Xue W (2023) Design, synthesis and biological activity of novel chalcone derivatives containing indole. Arab J Chem 16(6):104776. https://doi.org/10.1016/j.arabjc.2023.104776
Tai GY, Zhang Q, He JQ, Li XY, Gan XH (2024) Ferulic acid dimers as potential antiviral agents by inhibiting TMV self-assembly. J Agric Food Chem 72(26):14610–14619. https://doi.org/10.1021/acs.jafc.4c03713
Peng F, Liu TT, Wang QF, Liu F, CaoX, Yang JS, Liu LW, Xie CW, Xue W (2021) Antibacterial and antiviral activities of 1,3,4-oxadiazole thioether 4H-Chromen-4-one derivatives. J Agric Food Chem 69(37):11085–11094. https://doi.org/10.1021/acs.jafc.1c03755
Cao X, Liu F, He BC, Xing L, Zhang YQ, Zhang N, Xue W (2023) Design, synthesis, bioactivity and mechanism of action of novel myricetin derivatives containing amide and hydrazide. Arab J Chem 16(4):104588. https://doi.org/10.1016/j.arabjc.2023.104588
Mao P, Xing L, He BC, Deng TY, Qin YS, Hu YZ, An YS, Xue W (2024) Antiviral activity evaluation and action mechanism of chalcone derivatives containing phenoxypyridine. Mol Diversity 24:10843. https://doi.org/10.1007/s11030-024-10843-7
He BC, Hu YZ, Qin YS, Zhang YF, Luo XP, Wang ZC, Xue W (2024) Design, synthesis and antiviral activity of indole derivatives containing quinoline moiety. Mol Diversity 17:10894. https://doi.org/10.1007/s11030-024-10894-w
Soares FAC, Filho NAK, Beretta BFS, Linden TS, Pöppl AG, González FHD (2021) Thiobarbituric acid reactive substances in dogs with spontaneous hypercortisolism. Domest Anim Endocrinol 77:106634. https://doi.org/10.1016/j.domaniend.2021.106634
Bhatia K, Mal G, Bhar R, Jyoti N, Attri C, Seth A (2018) Purification and characterization of thermostable superoxide dismutase from anoxybacillus gonensis KA 55 MTCC 12684. Int J Biol Macromol 17:1133–1139. https://doi.org/10.1016/j.ijbiomac.2018.06.031
Xing L, Mao P, He BC, Qin YS, Meng KN, Zeng W, Sun ZL, Xue W (2023) Design, synthesis, and antiviral activities of myricetin derivatives containing phenoxypyridine. J Saudi Chem Soc 27(6):101751. https://doi.org/10.1016/j.jscs.2023.101751
List of Graphical abstract, Scheme1 and Figure Titles

Scheme 1 is available in the Supplementary Files section.

No competing interests reported.

Onlinefloatimage3.png
Scheme 1 Schematic representation of the synthesis of target compounds L1-L26.
floatimage1.jpeg
Graphical Abstract
Supportinginformation.doc

Download PDF

Reviewers agreed at journal
30 Sep, 2024
Reviewers agreed at journal
15 Sep, 2024
Reviewers agreed at journal
11 Sep, 2024
Reviewers invited by journal
06 Sep, 2024
Editor assigned by journal
04 Sep, 2024
Submission checks completed at journal
04 Sep, 2024
First submitted to journal
03 Sep, 2024

You are reading this latest preprint version

Novel flavonoid derivatives containing benzothiazole as potential antiviral agents: design, synthesis, and biological evaluation

Status:

Version 1

Abstract

Figures

Highlights

1. Introduction

2 Results and discussion

2.1 Chemistry

2.2 Spectral characteristic of title compounds

2.3 Antiviral activity of L1-L26 against TMV in vivo

2.4 Structure-activity relationship analysis

2.5 Binding ability of L20, L23, and NNM to TMV-CP

2.6 Molecular docking of L20 and NNM with TMV-CP

2.7 MDA content analysis

2.8 Effects of L20 on SOD activity

2.9 Analysis of chlorophyll content

3 Discussion

4 Materials and methods

4.1 Instruments and chemicals

4.2 Synthesis of compounds

4.2.1. Preparation of intermediate

4.2.2. Synthesis of target compounds L1-L26

4.3 In vivo antiviral activity

4.4 Microscale thermophoresis experiment

4.5 Molecular docking experiment

4.6 MDA content test

4.7 SOD activity measurement

4.8 In vivo chlorophyll content test

Declarations

References

Scheme

Additional Declarations

Supplementary Files

Status:

Version 1