Phytochemical Constituents, and Antioxidant Activities of Sokoto-Grown Hibiscus Sabdariffa (Zobo)

Abstract

Oxidative stress is a harmful physiological condition caused by an imbalance between free radical production and the body’s antioxidant defense system. It contributes to the development of many chronic diseases, including diabetes, cardiovascular disorders, neurodegenerative diseases, and cancer. Hibiscus sabdariffa Linn., locally known as “zobo” in Nigeria, is a medicinal plant traditionally consumed as a beverage and used for various therapeutic purposes. This study evaluated the phytochemical composition and antioxidant potential of Hibiscus sabdariffa leaf extracts. Dried red and black zobo leaves were collected from Tsohuwar Kasuwa market in Sokoto and authenticated at the Laboratory, Biochemistry Department, Usmanu Danfodiyo University, Sokoto. The samples were soaked in distilled water for 24 hours, filtered, and stored. Phytochemical screening was conducted using standard qualitative and quantitative methods, while antioxidant activity was assessed using the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The phytochemical results revealed the presence of flavonoids, tannins, saponins, glycosides, cardiac glycosides, steroids, balsams, anthraquinones, and volatile oils. Quantitatively, black zobo exhibited higher flavonoid (2.26 ± 0.01%) and glycoside (3.82 ± 0.02%) contents, while red zobo contained more amount of saponins (2.78 ± 0.01%). Antioxidant activity showed that black zobo had a higher radical scavenging activity (73.86 ± 0.37%) compared to red zobo (66.42 ± 0.85%) at 0.2 mg/mL. A decline in activity was observed at higher concentrations. The results suggest that Hibiscus sabdariffa leaves, particularly the black variant, are rich in phytochemicals with significant antioxidant activity and could serve as a potential natural remedy for oxidative stress-related conditions.