Phytochemical screening and antioxidant activity of the ethanol extracts of the bark of Hibiscus sabdariffa

Abstract

Hibiscus sabdariffa, commonly known as Roselle and locally referred to as 'Chukai' in Bangladesh, is renowned for its diverse medicinal properties. Although widespread research has explored the antioxidant potential of the fruit, the bark part remains under-investigated. This study inspects the phytochemical profile and antioxidant activity of bark extracted with ethanol solvent. Phytochemical screening identified the presence of carbohydrates, alkaloids, and flavonoids. Antioxidant potential was assessed through the measurement of total antioxidant capacity, total phenolic content, total flavonoid content, and the 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay. The total antioxidant capacity observed was 4.235 mg/g ascorbic acid equivalent, phenolic content was 6 mg/g gallic acid equivalents, and flavonoid content was 5.896 mg/g as quercetin equivalents. In the DPPH assay, IC50 values for ascorbic acid and bark extract were 19.9 µg/mL and 154.87 µg/mL, respectively. Overall results reveal that the Roselle bark possesses a limited antioxidant capacity compared to ascorbic acid, although having some bioactive compounds.