Antidiabetic Potential of Shadawi Coffee (Coffea arabica L.) Leaves: Integrated Biochemical, Antioxidant, Polyphenolic, and Pancreatic Histopathological Evaluation in Diabetic Rats

Abstract

Background: Diabetes mellitus is a chronic metabolic disorder associated with hyperglycemia, dyslipidemia, oxidative imbalance, and alterations in organ function. Coffee leaves contain diverse bioactive compounds, including phenolic acids and flavonoids, but their potential metabolic effects remain less investigated than those of coffee beans.
Objective: This study aimed to evaluate the potential antidiabetic effects of dried Shadawi coffee (Coffea arabica L.) leaf powder in streptozotocin-induced diabetic rats, with emphasis on biochemical, antioxidant, polyphenolic, and pancreatic histopathological responses.
Methods: Thirty adult male albino rats were randomly assigned to five groups (n = 6): normal control, diabetic control, and diabetic rats receiving diets supplemented with 3%, 6%, or 9% dried Shadawi coffee leaf powder for 28 days. Feed intake, body weight gain, serum glucose, insulin, lipid profile, liver enzymes, and kidney function parameters were assessed. The total phenolic and flavonoid contents, DPPH radical-scavenging activity, and individual phenolic compounds were also determined. Pancreatic tissues were examined histopathologically.
Results: Diabetes was associated with increased serum glucose, HbA1c, total cholesterol, triglycerides, LDL-C, VLDL-C, ALT, AST, urea, creatinine, and uric acid, together with decreased serum insulin, HDL-C, and hepatic glycogen. Dietary supplementation with Shadawi coffee leaf powder produced progressive changes in these parameters, with greater responses generally observed at the higher supplementation levels. The leaf powder contained measurable phenolic and flavonoid compounds and demonstrated antioxidant activity. HPLC analysis identified 17 quantified phenolic compounds, with chlorogenic acid being the predominant constituent. Histopathological examination indicated changes in pancreatic tissue associated with diabetes and varying degrees of tissue preservation following supplementation.
Conclusion: Dried Shadawi coffee leaf powder showed potential biological activity in diabetic rats, accompanied by improvements in several biochemical parameters and the presence of phenolic and antioxidant constituents. These findings support further investigation of Shadawi coffee leaves and their bioactive compounds using mechanistic and dose-response studies.