DPPH Antioxidant Activity of 70% Ethanol Extract of Roselle (H. sabdariffa L.) Calyces

Abstract

Oxidative stress results from an imbalance between reactive species and antioxidant defenses. Roselle (Hibiscus sabdariffa L.) calyces contain phenolic and flavonoid compounds that may contribute to radical-scavenging activity. This study evaluated the phytochemical profile and DPPH radical-scavenging activity of a 70% ethanol extract of roselle calyces. Dried calyx powder was macerated with 70% ethanol, screened qualitatively for phenolics, flavonoids, tannins, saponins, and alkaloids, and tested against DPPH at 5–25 µg/mL; vitamin C was used as a positive control. Extraction yield and moisture content were 27.81% and 1.81%, respectively. Phenolics, flavonoids, tannins, and saponins were detected, whereas alkaloids were not detected. DPPH inhibition increased with extract concentration, and linear regression (y = 3.0179x − 16.7611; R² = 0.9907) gave an IC50 of 22.12 µg/mL. Vitamin C had a lower IC50 (2.36 µg/mL), indicating greater radical-scavenging potency under the same assay conditions. The extract therefore showed substantial in vitro DPPH radical-scavenging activity, although interpretation should be limited to this chemical assay and supported by replicate variability and additional antioxidant measurements.