EVALUATION OF THE ANTIDIABETIC EFFECT OF COMBINED AQUEOUS EXTRACT OF TOMATO LEAF (SOLANUM LYCOPERSICUM) AND BITTER LEAF (VERNONIA AMYGDALINA) IN ALLOXAN-INDUCED DIABETIC WISTAR RATS

Abstract

Plant-based remedies have remained a vital source of therapeutic agents for metabolic disorders such as diabetes mellitus. This study investigated the individual and combined antidiabetic effects of aqueous leaf extracts of Solanum lycopersicum (tomato) and Vernonia amygdalina (bitter leaf) in alloxan-induced diabetic Wistar rats. Fresh leaves of S. lycopersicum and V. amygdalina were collected from Kwalkwalawa village along Usmanu Danfodiyo University, Sokoto State. The leaves were shade-dried, pulverised, and extracted with distilled water yielding 11.0% (w/w) and 15.0% (w/w) respectively. Preliminary phytochemical screening of both extracts revealed the presence of alkaloids, flavonoids, saponins, steroids, tannins, and phenolic compounds. Acute oral toxicity testing showed no mortality or behavioural changes up to 5000 mg/kg body weight (LD₅₀ > 5000 mg/kg). Diabetes was induced with alloxan monohydrate (150 mg/kg i.p.). Diabetic rats were treated orally once daily for 14 days with distilled water 10 mL/kg (diabetic control), metformin 500 mg/kg, S. lycopersicum extract 500 mg/kg, V. amygdalina extract 500 mg/kg, or their 1:1 combination 500 mg/kg. At the end of the experiment, animals were sacrificed and blood samples were collected via cardiac puncture into fluoride oxalate bottles for fasting plasma glucose estimation and lithium heparin bottles for lipid profile and malondialdehyde (MDA) analysis. The pancreas was harvested for histological examination. Results showed that the combined extract produced the most significant reduction in fasting plasma glucose (5.90 ± 0.12 mmol/L), completely normalised the deranged lipid profile, reduced MDA by approximately 46%, and remarkably restored pancreatic β-cell population and islet architecture, effects significantly superior to metformin and either extract used singly.