The polyphenolic content and antioxidant activity of Hibiscus sabdariffa calyx in methanol, ethanol, acetone and water extract were studied. The Total Phenolic Content (TPC) was determined using folin Ciocalteu method while the Total Flavonoid Content (TFC) was determined using aluminum chloride method. Antioxidant activities were determined using 2,2-diphenyl-1-picryl hydrazine (DPPH) inhibition and lipid peroxidation inhibition. Methanol extracted the highest total phenolic content (29.2 mg GAE/g DW) and was significantly different (p<0.05) from the water and acetone extracts only. Acetone extracted the highest flavonoid content (53.6 mg QE/g DW) and was significantly different from the other solvents used. Methanol extract gave the highest inhibition to DPPH (78%) and was only significantly different (p<0.05) from acetone and water extracts. Ethanol gave the highest inhibition to lipid peroxidation (26%) but was not significantly different (p<0.05) from the other solvent extracts. There was a stronger correlation obtained between TPC and inhibition of DPPH (r = 0.969) compared to TFC and DPPH (r = 0.742). The study showed that methanol and ethanol were better solvents for the extraction of phenols of Hibiscus sabdariffa calyx compared to water and acetone. It also showed that phenols contributed more to the antioxidant activity of Hibiscus sabdariffa calyx compared to flavonoids.
Chinedu Prosper Anokwuru, Ijeoma Esiaba, Olusola Ajibaye and Ayobami O. Adesuyi, 2011. Polyphenolic Content and Antioxidant Activity of Hibiscus sabdariffa Calyx. Research Journal of Medicinal Plant, 5: 557-566.