GC/MS and LC-MS Analysis and in-vitro Antioxidant Activity of Essential Oil and Crude Methanol Extract from the Leaves of Acacia Gerrardii Benth. Growing in Saudi Arabia

In this study, I determined the essential oil (EO) chemical composition and crude methanol extract (ME) phytochemical profile of the leaves of Acacia gerrardii (ACGL), a plant growing in Saudi Arabia. Additionally, I assessed their in vitro antioxidant activity. The gas chromatography-mass spectrometry analysis of the EO revealed a high content of oxygenated monoterpenes (79.86 %), primarily dominated by pulegone (35.11 %), carvacrol (27.36 %), and neo-dihydrocarveol (4.67 %). The ME was analyzed by liquid chromatography-mass spectrometry to determine its qualitative chemical profile. Four organic acids, eleven phenolic compounds, sixteen flavonoids, nine terpenoids (eight triterpenoids and one diterpenoid), and one coumarin were found in the ME of ACGL. This extract was found to be dominated by 5,6,4-trihydroxy-7,3-dimethoxyflavone (39.30 %), acteoside (30.27 %), nevadensin (7.55 %), isoacteoside (3.08 %) and apiin (3.23 %), and hesperidin (2.73 %). The phenolic (TPC=127.70 +/- 1.47 mg gallic acid equivalents/g of extract) and flavonoid (TFC=85.48 +/- 0.12 mg quercetin equivalents/g of extract) contents of the ME were also assessed. The in vitro antioxidant activities of both the EO and ME were evaluated using DPPH, ABTS, and ferrous ion chelating effect assays. Compared to the positive control (vit. E and Vit. C), and both extracts exhibited excellent activity.