Review of Pharmacological Evaluation of Antidiabetic Activity of Combined Extract of Gurmar Leaves and Lemon Peel in Streptozocin Induced Diabetic Rats

Abstract

Diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia, oxidative stress, and impaired insulin secretion or action. Medicinal plants with antidiabetic and antioxidant properties have gained considerable attention as complementary therapeutic agents. The present review evaluates the antidiabetic potential of a combined extract of Gymnema sylvestre (Gurmar) leaves and Citrus limon (lemon) peel in streptozotocin (STZ)-induced diabetic rat models. Gymnema sylvestre is well known for its insulinotropic and glucose-lowering effects due to the presence of gymnemic acids, while lemon peel is rich in flavonoids, phenolics, and vitamin C, contributing to its antioxidant and antihyperglycemic activity. Administration of the combined extract significantly reduces fasting blood glucose levels and improves body weight compared to diabetic control animals. Biochemical assessments reveal normalization of serum lipid profile, reduction in glycosylated hemoglobin (HbA1c), and improvement in insulin levels. The combined extract also enhances endogenous antioxidant defenses (SOD, CAT, GSH) while decreasing lipid peroxidation (MDA), indicating protection against oxidative stress. Histopathological examination of pancreatic tissue demonstrates regeneration and preservation of β-cell architecture. The findings suggest that the synergistic action of Gymnema sylvestre leaves and Citrus limon peel exerts significant antidiabetic and antioxidative effects, supporting its potential as a natural therapeutic approach for the management of diabetes mellitus.

Keywords: Gymnema sylvestre; Citrus limon; Gurmar; Lemon peel; Antidiabetic activity; Streptozotocin;  Oxidative stress; Insulin secretion.