Toxicological and antioxidant evaluations of the effects of different drying temperatures of the calyx of Hibiscus sabdariffa in experimental rats

Abstract

Hibiscus sabdariffa calyx is widely used in traditional medicine and as a food ingredient due to its antioxidant potential. This study investigated the toxicological and antioxidant effects of calyx extracts obtained after drying at four temperatures (− 58 °C, 30 °C, 40 °C, and 50 °C) in Wistar rats. Acute toxicity was assessed following the modified Lorke method (24-h observation), and chronic toxicity was evaluated over 28 days using doses of 250, 500, and 1000 mg/kg, in accordance with OECD guideline 407. Although no signs of acute toxicity or significant alterations in organ weights were observed, the antioxidant markers—GSH, CAT, and SOD—were dose-dependently enhanced, with the most potent activity recorded in extracts dried at 30 °C. These findings suggest that drying at 30 °C preserves key bioactive compounds, thereby maximizing the antioxidant potential of H. sabdariffa calyx. The study provides practical insights for optimizing processing conditions for medicinal and nutraceutical applications.