Evaluation of phytochemical composition and biological activities of ethanol extract of bark of Dialium ovoideum Thwaites

Abstract

Antioxidants have been discovered to play an important unction in protecting the body rom damage caused by reactive ree radicals via interacting with ree radicals, chelating, and serving as oxygen scavengers. Dialium ovoideum thwaites, an endemic plant in Sri Lanka, which is locally identified as Gal Siyambala. Leaves o D. ovoideum thwaites have been reported to possess antioxidant properties. Hence, this study aimed to investigate the phytochemical profile and evaluate the antioxidant properties o the ethanol extract o the bark o D. ovoideum thwaites. The extract was prepared using the Soxhlet extraction method and it was subjected to phytochemical screening using standard procedures. The gravimetric method was utilized to conduct the quantitative analysis o flavonoids, tannins, and saponins. Folin-Ciocalteau assay was used to determine the total phenolic content. DPPH radical scavenging and erric-reducing power assays were used to determine the antioxidant properties. The results o qualitative phytochemical screening showed the presence o phenols, flavonoids, saponins, steroids and tannins. In quantitative analysis, the phytochemical constituents indicated 10.7% (w/w) o flavonoids, 1.1% (w/w) o tannins and 0.9% (w/w) o saponins. The total phenolic content was 233.4±22.7 mg gallic acid equivalent/g extract while the IC50 value or the DPPH assaywas 68.5±6.3 µg/mL which is comparable to ascorbic acid (32.0±2.1 µg/mL). The reducing potential o the extract showed that it possesses a significant (p<0.05) reductive potential as compared with the ascorbic acid standard. Results revealed that the ethanol extract o the bark o D. ovoideum thwaites exhibits antioxidant properties which are positively correlated with its total phenolic content.