Differential anti-diabetic effects and mechanism of action of charantin-rich extract of Taiwanese Momordica charantia between type 1 and type 2 diabetic mice

• Published in: Food and chemical toxicology 2014-07, Vol.69, p.347-356
• Main Authors: Wang, Hsien-Yi, Kan, Wei-Chih, Cheng, Tain-Junn, Yu, Sung-Hsun, Chang, Liang-Hao, Chuu, Jiunn-Jye
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Blood Glucose - metabolism; Body Weight - drug effects; Charantin; Cucurbitaceae; Diabetes Mellitus, Experimental - drug therapy; Diabetes Mellitus, Type 1 - drug therapy; Diabetes Mellitus, Type 1 - metabolism; Diabetes Mellitus, Type 1 - pathology; Diabetes Mellitus, Type 2 - drug therapy; Diabetes Mellitus, Type 2 - metabolism; Diabetes Mellitus, Type 2 - pathology; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Food toxicology; Glucose Tolerance Test; Glucose Transporter Type 4 - metabolism; Hypoglycemic; Hypoglycemic Agents - chemistry; Hypoglycemic Agents - pharmacology; Insulin - blood; Insulin Receptor Substrate Proteins - metabolism; Insulin signaling; Male; Medical sciences; Mice, Inbred ICR; Mice, Inbred Strains; Momordica charantia; Momordica charantia - chemistry; Pancreatic β cells; Plant Extracts - chemistry; Plant Extracts - pharmacology; Toxicology; Type 2 diabetes
• ISSN: 0278-6915; 1873-6351
• DOI: 10.1016/j.fct.2014.04.008

[Display omitted] •The hypoglycemic effect of charantin-rich extract of Momordica charantia (CEMC).•CEMC decrease insulin level and promote insulin sensitivity in type 2 diabetic mice.•CEMC increase the expression of GLUT4 and of IRS-1 in type 2 diabetic mice. Momordica charantia Linn. (Cucurbitaceae), also called bitter melon, has traditionally been used as a natural anti-diabetic agent for anti-hyperglycemic activity in several animal models and clinical trials. We investigated the differences in the anti-diabetic properties and mechanism of action of Taiwanese M. charantia (MC) between type 1 diabetic (T1D) and type 2 diabetic (T2D) mice. To clarify the beneficial effects of MC, we measured non-fasting glucose, oral glucose tolerance, and plasma insulin levels in KK/HIJ mice with high-fat diet-induced diabetes (200mg/kg/day of charantin-rich extract of MC [CEMC]) and in ICR mice with STZ-induced diabetes. After 8weeks, all the mice were exsanguinated, and the expression of the insulin-signaling-associated proteins in their tissue was evaluated, in coordination with the protective effects of CEMC against pancreatic β-cell toxicity (in vitro). Eight weeks of data indicated that CEMC caused a significant decline in non-fasting blood glucose, plasma glucose intolerance, and insulin resistance in the KK/HIJ mice, but not in the ICR mice. Furthermore, CEMC decreased plasma insulin and promoted the sensitivity of insulin by increasing the expression of GLUT4 in the skeletal muscle and of IRS-1 in the liver of KK/HIJ mice; however, CEMC extract had no effect on the insulin sensitivity of ICR mice. In vitro study showed that CEMC prevented pancreatic β cells from high-glucose-induced cytotoxicity after 24h of incubation, but the protective effect was not detectable after 72h. Collectively, the hypoglycemic effects of CEMC suggest that it has potential for increasing insulin sensitivity in patients with T2D rather than for protecting patients with T1D against β-cell dysfunction.