Viphyllin, a Standardized Black Pepper Extract Exerts Antihyperglycemic Effect and Improves Sciatic Nerve Conduction in High Fat Diet/Streptozotocin-Induced Diabetic Model Rats.

Purpose: Research on plant-based formulations has drawn considerable attention in the management of diabetic neuropathy (DN) for having lesser side effects than the synthetic counterparts. Here, we have investigated for the first time the therapeutic effects of a standardized L., (black pepper) seed extract, Viphyllin in mitigating hyperglycemia and neuropathic pain of type 2 diabetes model rats.

Methods: Type 2 diabetes was induced in male Wistar rats using high fat diet and a single dose of streptozotocin (60 mg/kg .). The diabetic rats were orally administered with Viphyllin containing not less than 30% β-caryophyllene (BCP), at 25 mg, 50 mg and 100 mg/kg/day doses for 6 weeks. Changes in body weight, fasting blood glucose (FBG), glucose tolerance, and blood biochemical parameters were measured. The nociceptive response to thermal stimulus (tail flick test) and sciatic nerve conduction velocity (NCV) were recorded at the end of study.

Results: Viphyllin treatment markedly improved the body weight and glucose tolerance in diabetic rats. Also, the extract could significantly reduce the diabetes-induced elevation in FBG, liver and kidney indices. Further, Viphyllin dose-dependently increased the nociception latency in tail flick test compared to untreated diabetic rats (<0.05). Viphyllin at 100 mg/kg significantly increased the NCV (44.12±1.91*** m/s vs diabetic control 25.80±1.88 m/s). The antioxidant enzyme activities in sciatic nerve tissue were considerably increased in Viphyllin-treated groups compared to diabetic control. A 6-week treatment with Viphyllin markedly reversed the pathological manifestations of diabetes in vital organs such as liver, kidney and pancreas.

Conclusion: The study concludes that Viphyllin exerts antidiabetic effects and improves nerve conduction to mitigate neuropathic pain.