A novel extract of Gymnema sylvestre improves glucose tolerance in vivo and stimulates insulin secretion and synthesis in vitro.
Herbal medicines, especially plant-derived extracts, have been used to treat Type 2 diabetes mellitus (T2DM) for many centuries, and offer the potential of cheap and readily available alternatives to conventional pharmaceuticals in developing countries. Extracts of Gymnema sylvestre (GS) have anti-diabetic activities and have been used as a folk medicine in India for centuries. We have investigated the effects of a novel high molecular weight GS extract termed OSA® on glucose tolerance in insulin-resistant ob/ob mice, and on insulin secretion and synthesis by isolated mouse islets. Single administration of OSA® (500 mg/kg) to ob/ob mice 30 min before an intraperitoneal glucose load improved their abnormal glucose tolerance. In vitro studies indicated that OSA® (0.25 mg/ml) initiated rapid and reversible increases in insulin secretion from isolated mouse islets at substimulatory (2 mM) and stimulatory (20 mM) glucose concentrations. In addition, prolonged treatment (24-48 h) of mouse islets with OSA® elevated the expression of preproinsulin mRNA and maintained the total insulin content of mouse islets in the presence of stimulated insulin secretion. These effects of OSA® are consistent with its potential use as a therapy for the hyperglycemia associated with obesity-related T2DM.
Diabetes Research Group, Division of Diabetes and Nutritional Sciences, School of Medicine, King's College London, London SE1 1UL, UK. altaf.al-romaiyan@kcl.ac.uk
A
A
Al-Romaiyan
A J
AJ
King
S J
SJ
Persaud
P M
PM
Jones
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000378:metabolism; D005260:Female; D018149:Glucose Intolerance / Q000188:drug therapy*; D031104:Gymnema sylvestre / Q000737:chemistry*; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D007328:Insulin / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007333:Insulin Resistance; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D009765:Obesity / Q000378:metabolism; D008517:Phytotherapy; D010936:Plant Extracts / Q000627:therapeutic use*; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D010936:Plant Extracts; D011498:Protein Precursors; D012333:RNA, Messenger; C013737:preproinsulin