Solvent-Dependent Phytochemical Profile, Antihyperglycaemic Activity and Oral Toxicity of Gossypium herbaceum L. Leaf Extracts: An Integrated in vitro and in vivo Study in Wistar Rats
Sunday O. Bada *
Biochemistry and Toxicology Unit, Department of Science Laboratory Technology, Rufus Giwa Polytechnic, P.M.B 1019, Owo, Ondo State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Ethnopharmacological Relevance: Gossypium herbaceum L. (Malvaceae) is traditionally used in parts of Nigeria to manage diabetes and other ailments, yet integrated evidence on solvent-dependent phytochemistry, antidiabetic efficacy, and safety of its leaves remains limited.
Aim: To comparatively evaluate aqueous and 70% ethanolic leaf extracts of G. herbaceum for phytochemical composition, α-amylase and α-glucosidase inhibitory activities, antihyperglycaemic efficacy, and acute and repeated-dose oral toxicity.
Materials and Methods: Mature leaves were authenticated, shade-dried, powdered, and extracted by maceration with distilled water or 70% ethanol. Qualitative phytochemical screening employed standard methods. Enzyme inhibition was assessed against α-amylase and α-glucosidase using acarbose as a reference. Diabetes was induced in male Wistar rats with streptozotocin (40 mg/kg, i.p.). Animals received vehicle, diabetic-control treatment, glibenclamide (5 mg/kg), aqueous extract (400 mg/kg), or ethanolic extract (400 mg/kg) orally for 28 days (n = 6). Fasting blood glucose and body weight were monitored. Acute toxicity was evaluated in female rats at 2000 mg/kg according to OECD 423, while 28-day toxicity was assessed at 100, 300, and 1000 mg/kg/day using clinical, haematological, biochemical, and histopathological endpoints.
Results: The ethanolic extraction yielded more extract than the aqueous extraction (15.70 ± 0.30% vs. 12.40 ± 0.10%) and showed stronger reactions for flavonoids, phenolics, alkaloids, and tannins. The ethanolic extract showed greater α-amylase and α-glucosidase inhibitory potency (IC₅₀ = 82.6 and 58.3 μg/mL, respectively) than the aqueous extract (120.4 and 95.7 μg/mL). In diabetic rats, aqueous and ethanolic extracts reduced fasting blood glucose by 48.6% and 60.0%, respectively, compared with 71.1% for glibenclamide (p < 0.05), and improved terminal body weight. No mortality or overt toxicity occurred at 2000 mg/kg. Repeated administration up to 1000 mg/kg/day produced no significant treatment-related changes, and liver and kidney architecture remained preserved.
Conclusion: Both extracts exhibited antidiabetic activity and a favourable short-term safety profile, with the ethanolic extract demonstrating greater efficacy. Further quantitative phytochemical, mechanistic, bioactivity-guided, and longer-term toxicological studies are warranted.
Keywords: Gossypium herbaceum, leaf extract, phytochemical composition, α-amylase, α-glucosidase, antihyperglycaemic activity, Wistar rats, acute toxicity