The global cancer report highlights a significant and abrupt surge in cancer incidence, with cancer ranking as the second leading cause of death globally1. Lung cancer is a major health concern due to its high mortality rate, making it the leading cause of cancer-related deaths worldwide. Despite advances in treatment, its impact remains significant, highlighting the urgent need for effective prevention strategies, early detection methods, and innovative therapies to improve patient outcomes and reduce the burden of this disease13.
Various compounds with diverse applications, such as antibiotic, antiviral, antifungal, and anticancer effects, have been identified and extracted from macroalgae. Regarding seaweeds, they are primitive plant-like organisms lacking roots, stems, and leaves, yet they boast a rich composition of vitamins, minerals, trace elements, proteins, and bioactive compounds.12,14
In the present study, phytochemical screening of the seaweeds showed the presence of saponins, terpenoids, steroids, anthraquinone, flavonoids, and phenols. These compounds demonstrate diverse mechanisms of action, such as inhibiting cancer cell growth and metastasis, as well as inducing cancer cell death15. This research aimed to investigate the genotoxicity and cytotoxicity of hydroalcoholic extract of brown algae C. indica in HGF and A549 lung cancer cell lines.
The strong positive correlation between the polyphenolic content of algae and its antioxidant activity has been extensively documented16,17. Phenolic compounds, commonly found in plants including seaweeds, are known for their diverse biological activities, particularly their antioxidant properties14. Consequently, the high antioxidant activities of the extracts can likely be attributed to the content of total phenolic compounds. Furthermore, in this study, C. indica exhibited antioxidant activity, possibly attributable to its elevated polyphenolic content (14.16 ± 0.46 mg GAE/g).
Total flavonoids in the seaweeds ranged from 3.9 to 12.43 mg/g. Flavonoids, known for their antioxidant and free radical scavenging properties, are key natural phenols with broad chemical and biological activities18. They serve as antioxidants against various reactive oxygen species and inhibit lipid peroxidation, suggesting potential therapeutic use against diverse diseases19. These compounds, including flavonoids, and polyphenols, found in significant amounts in C. indica, play a preventive role against diseases by scavenging free radicals.
Based on the results obtained from the study and the analysis of phytochemical, cytotoxic, and genotoxic tests, the hexane-acetone extract, containing a higher concentration of compounds such as phenols and flavonoids, exhibits greater potential for antioxidant and anticancer properties.
In this study, the antioxidant effect of algae extract was also investigated using the DPPH radical scavenging assay. The results exhibited 29.84%, 11.5%, and 43.17% radical scavenging activity for the cold water, ethanolic, and hexane-acetone extract, respectively at a concentration of 5000 µg/mL. Therefore, algae extract can serve as a potent antioxidant and protector against free radicals in cells, given its natural and safe composition with high scavenging capacity against free radicals. Additionally, it increases antioxidant enzyme levels in the body's immune system, making it a potentially useful supplement to aid the body's defense system against oxidative stress.
The Akt/mTOR pathway is considered as a potential therapeutic target for treating malignant tumors, particularly in chemotherapy and also fucoxanthin could be considered a promising antitumor agent, as it induces autophagy by inhibiting the Akt/mTOR signaling pathway20. Also, the main active compounds involved in the DPPH free-radical-scavenging method in C. indica and N. zanardinii were identified as polyphenols and fucoxanthin10. The recent surge in seaweed bioactives research has primarily focused on their antioxidant properties, driven by their potential applications as preservatives, protectors against oxidation in food and cosmetics, and functional ingredients for health purposes21,22. Brown algae, in particular, exhibit significantly higher antioxidant potential compared to red and green algae. Additionally, they contain unique compounds absent in terrestrial sources. In vitro, antioxidant chemical assays, utilized to assess their efficacy in preventing lipid oxidation in foods, have demonstrated that crude extracts, fractions, and pure components derived from brown algae are either comparable or superior to synthetic antioxidants23. The findings of these studies are consistent with the present research.
Multiple mechanisms are involved in genotoxicity, including increased production of reactive oxygen species (ROS), reduction in antioxidant capacity by decreasing GSH levels, and increased MDA production24. In this study, the genotoxic effects of aqueous, hexane-acetone, and ethanolic extracts of C. indica algae at various concentrations were investigated using the comet assay method. With increasing concentrations of these algae extracts, the Tail Moment value increased in both cell lines compared to the control group. Additionally, ROS levels increased with increasing concentrations of the extracts. Moreover, GSH production decreased with increasing extract concentrations. Lipid peroxidation assessment also showed an increase in MDA levels with increasing extract concentrations. These results indicate that C. indica algae exhibit significant genotoxic effects on both cancerous and normal cells.
Results of cytotoxic activity of certain brown algae on cancer cell lines HT-29, Caco-2, T47D, MDA-MB468, and NIH 3T3 demonstrated that extracts from various species of brown algae (Colpomenia sinuosa, Cystoseira myrica, Sargassum swartzii) collected from the Persian Gulf exhibit apoptotic properties and cytotoxicity25. Additionally, in vitro antitumor activity of a brown algae species called Padina pavonia on uterine and breast cancer cell lines investigation revealed that the methanolic extract of P. pavonia displayed cytotoxic activity with an IC50 of 45.86 µg/mL for uterine cancer cells and 59.74 µg/mL for breast cancer cells, suggesting apoptotic and cytotoxic properties of the algae extract26. Furthermore, examination of the apoptotic effects of fucoxanthin derived from brown algae on the HL-60 cell line indicated that the compound induced apoptosis through cell cycle disruption in HL-60 cells27.
In this study, the cytotoxic effect of C. indica on the cancer cell line (A549) and the normal gum cells (HGF) was examined using the MTT assay. It was observed that with increasing concentrations of various extracts, the survival rates of both cancerous and normal cells significantly decreased compared to the control group, indicating the cytotoxicity of this alga on these cell lines. Based on the results obtained from flow cytometry, the concentrations of 100 µg/mL of hot water and hexane-acetone extracts induced 54.97% and 50.66% apoptosis in A549 cancer cells, respectively, making them preferable options for further anticancer studies, especially at higher concentrations. These findings are consistent with the results of cell viability measurements using the MTT assay.