Effect of Solvent on Antioxidant Activity of Zanthoxylum oxyphyllum Edgew and its DFT Study

Background: Free radicals can easily damage DNA, proteins and lipids within the tissue. Anti-oxidants from natural sources can diminish the actions of free radicals. The current study deals with the chemical composition and antioxidant activity of the leaves of Zanthoxylum oxyphyllum Edgew. Methods: The antioxidant activities for DPPH, FRAP, ABTS radicals, phosphomolybdate assay, reducing power, and chelating power assay were evaluated of ethanol (ET), methanol (ME), chloroform (CH), ethyl acetate (EA), and petroleum ether (PE) extracts of the leaves. The Density Functional Theory (DFT) study was carried out on major identified phytochemicals to evaluate bioactive molecules responsible for the antioxidant activity. Results: It was observed that the ME extract showed the most potent scavenging activity in DPPH, FRAP, ABTS radicals, phosphomolybdate assay, reducing power, and chelating power assay. The phenolic acids and flavonoids like quercetin, gallic acid, sinapic acid, etc. were identified. The DFT study was done for major phytochemicals of ME extract to evaluate the most responsible bioactive molecule for antioxidant activity. The Gallic acid exhibited the lowest bond dissociation energy (BDE) of 314.9 kcal/mol in gas, 309.2 kcal/mol in methanol, respectively, along with the highest value of radical stabilization energy (RSE), 29.5 kcal/mol. Conclusion: Gallic acid was found to be the most responsible antioxidant among the other compounds, and ME the best solvent system for extraction, followed by CH.