Neuroprotective effects of Moringa oleifera: Bio-guided GC-MS identification of active compounds in diabetic neuropathic pain model.

OBJECTIVES: To explore the phytotherapeutic-activities of Moringa oleifera (MO) seeds on painful diabetic neuropathy in alloxan-induced diabetic mice.

METHODS: The bio-guided fractionation of MO utilizing column chromatography aided with GC-MS was used to detect the most active constituent of MO. Hyperalgesia, using tail-flick and hot-plate latency experiments, and mechanical-allodynia, utilizing von-Frey filaments, were evaluated before and after 8 weeks of intraperitoneal alloxan administration (180 mg/kg). Serum catalase and insulin levels, body weight and blood glucose levels (BGL), alpha-glucosidase inhibition, lipid peroxidation and glycated hemoglobin (HbA1c) were measured to evaluate both alloxan-induced diabetes mellitus and diabetic painful neuropathy (DPN).

RESULTS: Beta-sitosterol (BSL) was proved to be the most active constituent of MO. The administration of MO (40, 60 and 80 mg/kg) or BSL (18, 25 and 35 mg/kg) significantly attenuated hyperalgesia and tactile allodynia (P⩽0.05), compared with tramadol (10 mg/kg) acting as a positive control, in alloxan-treated animals (n=7 per group). Moreover, MO and BSL have improved insulin secretion, in vivo antioxidant catalase, lipid peroxidation, acute and subchronic BGL, and normalized alpha-glucosidase and HbA1c levels.

CONCLUSIONS: The observed insulin secretagogue, alpha-glucosidase inhibition, hypoglycemic and antioxidant potentials might be responsible for MO and BSL antinociception and neuroprotective mechanism. MO and BSL have shown good glycemic-control and powerful neuroprotective properties which might serve as potential lead-compounds for further analysis.