Biological evaluation and molecular docking of Indonesian Gracilaria salicornia as antioxidant agents

The antioxidant activity of Gracilaria salicornia extract was investigated to develop natural product-based chemotherapeutic agents using more efficient and straightforward methods. The efficacy was determined through free radical scavenging activity against DPPH, phytochemical assays, GC-MS analysis, and molecular docking analysis through NADPH Oxidase (NOX) protein (PDB ID: 2CDU). The best antioxidant activity of several extracts was shown by ethyl acetate extract with an IC50 value about 179.81±6.38 μg/mL, classified as moderate activity. Based on the phytochemical assay, the extract contains alkaloids, steroids, phenolics, flavonoids, and saponin compounds. Further analysis of the extract by GC-MS showed the presence of secondary metabolites that have been shown to have bioactivity as antioxidant and anticancer agents, such as L-(+)-ascorbic acid 2,6-dihexadecanoate, cholest-5-en-3-ol (3.beta.), 1,2-benzenedicarboxylic acid, and phytol. The activity was also supported by molecular docking analysis. Cholest-5-en-3-ol(3.beta.), 1,2-benzenedicarboxylic acid, and phytol showed outstanding interaction with the target protein's active site (binding energy -10.90, -7.11, and -6.22 kcal/mol, respectively). The binding energy of cholest-5-en- 3-ol (3.beta.) was significantly higher than the native ligand. The binding energy describes the potential of the compound to suppress ROS production by inhibiting NOX protein activity. These findings revealed that the phytochemicals of G. salicornia can be developed as a chemotherapeutic agent. This approach can be used as a guide in developing natural product-based chemotherapeutic agents.