A total of 72 protein targets were collected based on the above 7 active compounds. 34 AD-related targets were obtained when the 72 targets were mapped to the UniProt database for normalizing and standardizing naming. There are 8,718 AD-related targets in the GeneCards database. The targets of drug components were compared with that of AD and 23 potential targets related to the treatment of AD with Laminaria were selected (Table 2).
Construction and analysis of the “drug-components-targets-disease” network
Information about Laminaria's active components and overlapping targets was imported into Cytoscape 3.7.0 to establish a “drug-components-targets-disease” visualization network. As shown in Figure 1, the purple node represented the drug thallus Laminariae, the yellow nodes represented the active components, the green nodes represented overlapping genes between Laminaria and AD, and the pink node represented the disease AD. The same target corresponded to different active components, and vice versa, which sufficiently suggested Laminaria’s characteristics, multi-components and multi-targets.
Construction and analysis of the PPI network
The PPI network was constructed when the target proteins were introduced into the STRING database and their names were standardized under the “Homo sapiens” setting. As shown in Table 2, one node represented one protein, and the edge between the two nodes indicated the interaction between proteins. It was speculated that CASP3, PPARG, RELA, CCND1, CASP9 were the key targets for the treatment of AD with Laminarin.
Analysis of GO and pathway of targets
GO and KEGG analyses were performed on the targets of active components for the treatment of AD using the Metascape database. The threshold P ≤ 0.05 was set to select biological processes and pathways. The GO provides the logical structure of the biological functions, including three aspects: biological process, molecular function and cellular component, and how these functions are related to each other, manifested as a directed acyclic graph. Figure 3 showed the results of GO analysis for the predictive targets of the effect of Laminarin on AD, the response to steroid hormone accounted for the largest proportion in the biological process, platelet dense granule was the only one in cellular component, and steroid binding, steroid hormone receptor activity, nuclear receptor activity, transcription factor activity and direct ligand regulated sequence-specific DNA binding were at the top in molecular function.
KEGG was used to analyze the distribution of pathways for predicting the targets of Laminarin for AD. As shown in Figure 4, there were 57 enrichment pathways involved in 23 targets, including small cell lung cancer, toxoplasmosis, apoptosis, measles, hepatitis C, influenza A, tuberculosis, kaposi sarcoma-associated herpesvirus infection, Epstein-Barr virus infection, human immunodeficiency virus 1 infection and human cytomegalovirus infection. The key target proteins were enriched in the small cell lung cancer and toxoplasmosis signal pathways, further indicating the characteristics of Laminarin, multi-component and multi-pathway. The maps of small cell lung cancer and toxoplasmosis signal pathways depicted with KEGG Mapper were shown in Figure 5 and Figure 6.