Chemical Constituents and Effect of Ethanol Leaf Extract of Hibiscus articulatus Hochst. ex A. Rich. (Malvaceae) on Glucose- and Streptozotocin-Induced Hyperglycaemia using Wistar Rats

Abstract

Hibiscus articulatus is an herbaceous plant that is consumed over decades as diet, in management stomach pain and diabetes in north central Nigeria. The aim of the study is to determine the chemical constituents and evaluate the effect of ethanol leaf extract of Hibiscus articulatus (ELEHA) on glucose- and streptozotocin-induced hyperglycaemia using Wistar rats. Preliminary phytochemical screening, proximate and gas chromatography-mass spectrophotometric (GC-MS) analyses was conducted on ELEHA. Acute toxicity, blood glucose levels of ELEHA in Wistar rats was evaluated using; glycaemic index (GI) test, oral glucose tolerance test (OGTT) and streptozotocin-induced hyperglycaemia test. Secondary metabolites; alkaloids, tannins, saponins, flavonoids, triterpenes and primary metabolites; carbohydrates, proteins and fats, were present in ELEHA. Ascorbic acid, linoleic acid, coumaran, phytol hexadecanoic acid are some chemical constituents present in ELEHA. The oral median lethal dose was estimated to be > 5000 mg/kg body weight in rats. The glycaemic index and glycaemic load of ELEHA were calculated to be 41.60 % and 17.83 respectively. There was significant (p < 0.05) decrease in the blood glucose level (250 and 500 mg/kg of ELEHA administered) in OGTT and streptozotocin-induced hyperglycaemia test compared with diabetic group. Superoxide dismutase, catalase, malondialdehyde and glutathione reductase were evaluated however, only superoxide dismutase levels (250 and 500 mg/kg) were significantly (p < 0.05) increased. Moreso, the level of low density lipoprotein (125 mg/kg) and HOMA IR values (125 and 250 mg/kg) were significantly (p < 0.05) decreased when compared with diabetic group. In summary, the ethanol leaf extract of Hibiscus articulatus possesses important phytochemicals with anti-hyperglycaemic activity on Wistar rats.