Phytotherapy in diabetes: Review on potential mechanistic perspectives

Histopathological and behavioral evaluations of the effects of crocin, safranal and insulin on diabetic peripheral neuropathy in rats

OBJECTIVES

Crocin and safranal, the major constituents of saffron, exert neuroprotective effects. In the present study, we investigated the effects of crocin and safranal (alone or in combination with insulin) on peripheral neuropathy in diabetic rats.

MATERIALS AND METHODS

Diabetes was induced by intraperitoneal (i.p.) injection of 60 mg/kg of streptozotocin (STZ) and confirmed by blood glucose level higher than 250 mg/dl. After confirmation of diabetes, crocin (30 mg/kg, i.p.), safranal (1 mg/kg, i.p.) (alone or in combination with insulin) and insulin (5 IU/kg, s.c.) were administered for eight weeks. Neuropathic pain was evaluated using acetone drop test. Histopathological changes of sciatic nerve were evaluated using light microscope. Blood glucose levels and sciatic nerve malondialdehyde (MDA) contents were also measured.

RESULTS

STZ caused cold allodynia, edema and degenerative changes of sciatic nerve, hyperglycemia and an elevation of sciatic nerve MDA levels. Crocin, safranal and insulin improved STZ-induced behavioral, histopathological and biochemical changes. Combined treatments produced more documented improving effects.

CONCLUSION

The results of the present study showed neuroprotective effects of crocin, safranal and insulin in a rat model of diabetic neuropathy. In addition, crocin and safranal enhanced the neuroprotective effect of insulin. The neuroprotective effects of theses chemical compounds could be associated with their anti-hyperglycemic and antioxidant properties.

Cordycepin from Cordyceps militaris prevents hyperglycemia in alloxan-induced diabetic mice

Cordyceps militaris has long been used in prescriptions of traditional Chinese medicine as a tonic for the treatment of metabolic syndrome. Cordycepin with proven immunomodulatory, antitumor, and hepatoprotective properties is the main active metabolite of C militaris. Diabetes mellitus is a group of metabolic diseases in which the body is unable to regulate blood sugar levels. Hence, we hypothesized that cordycepin can normalize blood sugar levels and improve the indicators of diabetes. The aim of this study was to investigate the possible effects of cordycepin from C militaris on diabetes in an alloxan-induced diabetic mouse model. Diabetic mice were intraperitoneally administered different doses of cordycepin (8, 24, and 72 mg/kg body weight) daily for 21 days. Acute toxicity test on normal mice was carried out by giving them maximum tolerance dose of cordycepin (3600 mg/kg) daily. A 47% reduction of the blood glucose level, 214% increase of hepatic glycogen content, and significant improvement of oral glucose tolerance were noticed after the effective dose of cordycepin was administered. Polyphagia and polydipsia, the typical symptoms of diabetes, were partly alleviated. Moreover, cordycepin offered protective effects against diabetes-related kidney and spleen injury. Maximum tolerance dose test indicated that cordycepin at the large dose of 3600 mg/kg did not show significant effect on body weight and major organ in normal mice after intraperitoneal administration for 14 days. The results showed that cordycepin from C militaris that elicited hypoglycemic activity contributes to the regulation of glucose metabolism in liver in alloxan-induced diabetic mice. Therefore, a cordycepin treatment during diabetes can improve some of the metabolic syndrome symptoms by regulation of glucose absorption in vivo. Cordycepin may serve as a therapeutic agent in the treatment of diabetes and its related complications.

Thioflavin T effect in diabetic Wistar rats: reporting the antihyperglycemic property of an amyloid probing dye

BACKGROUND

Thioflavin T (ThT) is a well-known probe of amyloid fibrils with a benzothiazole core structure. As a compound with partial inhibitory effect on alpha-amylase, the results of oral ThT administration were investigated on a streptozotocin (STZ)-induced rat model of diabetes.

METHODS

STZ was administered intraperitoneally for induction of diabetes. Afterwards, doses of 2, 8, 16, and 32 mg/kg of ThT were used in diabetic and non-diabetic rats. Blood glucose levels, lipid profiles, alpha-amylase activity, food and water intake and urine volume were assessed. Docking was also performed to evaluate the inhibitory effect of ThT on alpha-amylase.

RESULTS

Upon treatment with ThT, blood glucose levels and lipid profile of diabetic rats improved significantly. Furthermore, alpha-amylase serum levels of treated animals decreased compared to the control group, suggesting a possible effect of ThT on this digestive enzyme. On the other hand, the food intake of treated animals showed a decrease. ThT effects were also seen to some extent in the non-diabetic group.

CONCLUSION

ThT is suggested to be a potentially useful compound in treatment and prevention of diabetes and associated complications.