ABSTRACT
The effects of different drying temperatures on the hypolipidemic, antioxidant, and antihypertensive potential of Hibiscus sabdariffa calyx was evaluated. The calyx were dried under different temperature conditions (- 58 °C, 30 °C, 40 °C, and 50 °C), and extracted with a solvent mixture of ethanol and water (1:4 % w/v). To induce hypertension, the rats were administered with 40 mg/kg body weight dose of N-nitro L-arginine methyl-ester (L-NAME), via the intra-gastric route. H. sabdariffa extract was administered orally, at varying doses (250, 500, and 1000 mg/kg) to the rats. Afterwards, the hypolipidemic, antioxidant, and antihypertensive potentials of the extracts were evaluated using standard validated methods. Induction with L-NAME significantly (p < 0.05) increased the total cholesterol, triglyceride, and LDL levels, significantly decreased the HDL levels; significantly (p < 0.05) increased the levels of LPO/MDA, H2O2, and decreased GPx, and SOD activities; significantly (p < 0.05) increased the pressures (diastolic and systolic); significantly (p < 0.05) increased ACE and arginase activities, glucose level, and significantly decreased nitric oxide activity. Treatment with H. sabdariffa extract significantly (p < 0.05) reversed these trends in the hypertensive experimental rats. The hypolipidemic, antioxidant, and antihypertensive properties of the extract from the calyx of H. sabdariffa, which varies with the drying temperatures of the calyx, portends its potential as a curative agent in the treatment of hypertensive conditions, and other cardiovascular diseases.
ABSTRACT
We evaluated the antioxidant and neuroprotective potentials of extracts of Hibiscus sabdariffa calyx in Wistar albino male rats injected intraperitoneally with aluminium chloride at a dose of 7 mg/kg/day. Phytochemical screening of H. sabdariffa calyx show that coumarin glycosides and steroid were absent after drying at 50 oC. At 30 oC, there were significant (p < 0.05) highest amounts of phenols, flavonoids, alkaloids, tannin, and saponin. The extracts showed significantly (p < 0.05) high dose-dependent antioxidant activities. MDA significantly (p < 0.05) increased, while GSH, GPX, SOD, CAT activities significantly (p < 0.05) decreased in the brain of the experimental rats induced with AlCl3, while treatment with the extracts reversed these effects to a relatively normal level. At doses of 500 and 1000 mg/kg body weight, the extracts of the calyx dried at 30 oC exhibited the highest capacity to increase the activities of GSH and GPx. Also, AlCl3 caused significant increases (p < 0.05) in the percentage inhibition of acetylcholinesterase and butyrylcholinesterase activities, and a significantly (p < 0.05) lower protein levels in the brain of the test rats, while treatment with the extracts, at low and high doses, significantly (p < 0.05) reversed these effects in the rat brain to near normal.H. sabdariffa exhibited a good potential to protect against oxidative stress and neurotoxicity.
