Evaluation of Antioxidant Activity and Phytochemical Screening of Leaves, Barks, Stems and Fruits of Alphitonia philippinensis (Rhamnaceae) From Brunei Darussalam

Phytochemical screening of Alphitonia philippinensis extracts revealed the presence of cardiac glycosides, tannins, saponins and steroids in different plant parts. Total phenolic content (TPC), total flavonoid content (TFC) and total flavonol content (TFlC) were measured using spectrophotometric methods where gallic acid and quercetin were the standards. Antioxidant activity of extracts was assessed using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2̉-azino-bis(3- ethylbenzothiazoline-6-sulfonic acid) (ABTS), free radical scavenging and ferric reducing antioxidant power (FRAP) assays using ascorbic acid and trolox were used as standards. Among the four different crude methanol extracts studies, leaves showed highest antioxidant capacity. EC₅₀ values of the leaves extract from DPPH and ABTS method found 32 and 45 μg/mL respectively. The higher antioxidant activity of the leaves extract could be correlated with the presence of higher total phenolic content, total flavonoid, and total flavonol contents. According to antioxidant contents and assay results leaves extract possesses highest antioxidant property following fruits, barks and stems.