Protective Effects of Carica papaya Leaf Ethanolic Extract against Dyslipidaemia and Oxidative Stress in Streptozotocin-Induced Rats Fed a High Fat Diet: A Dose Response Study

Abstract

Diabetes mellitus, linked to dyslipidaemia and oxidative stress, often resists complete management by conventional therapies, whereas Carica papaya leaves offer potential adjunctive benefits. This study evaluated the protective effects of C. papaya leaf ethanolic extract against dyslipidaemia in streptozotocin (STZ)-induced diabetic rats fed a high-fat diet. Thirty male Wistar rats were divided into five groups (n = 6): normal control, STZ-induced diabetic control, STZ + metformin (25 mg/kg), and STZ + C. papaya ethanolic extract (200 mg/kg and 400 mg/kg). Diabetes was induced by a high-fat diet followed by a single intraperitoneal injection of STZ (40 mg/kg). Treatments were administered orally for 28 days. Fasting blood glucose, serum lipid profile (TC, TG, LDL-C, HDL-C), antioxidant enzyme activities (SOD, CAT, GSH), malondialdehyde (MDA) levels, and atherogenic indices were determined using standard biochemical assays. Data were analysed using one-way ANOVA followed by Tukey’s post hoc test at p < 0.05. Carica papaya extract produced a significant, dose-dependent reduction in fasting blood glucose and MDA levels, while enhancing SOD, CAT, and GSH activities. Lipid abnormalities induced by STZ and high-fat diet were ameliorated, with marked reductions in TC, TG, and LDL-C, and elevation of HDL-C. Atherogenic indices were significantly reduced, indicating an improved cardiovascular risk profile. The 400 mg/kg dose exhibited near-normal biochemical values comparable to those of metformin. The ethanolic leaf extract of Carica papaya exhibits dose-dependent antihyperglycaemic, antioxidant, and hypolipidaemic effects in diabetic rats.