Insulin sensitizing and alpha-glucoamylase inhibitory action of sennosides, rheins and rhaponticin in Rhei Rhizoma.
Extracts from Rhei Rhizoma extracts (RR) have been reported to attenuate metabolic disorders such as diabetic nephropathy, hypercholesterolemia and platelet aggregation. With this study we investigated the anti-diabetic action of 70% ethanol RR extract in streptozotocin-induced diabetic mice, and determined the action mechanism of active compounds of RR in vitro. In the diabetic mice, serum glucose levels at fasting and post-prandial states and glucose area under the curve at modified oral glucose tolerance tests were lowered without altering serum insulin levels, indicating that RR contained potential anti-diabetic agents. The fractions fractionated from RR extracts by XAD-4 column revealed that 60%, 80% and 100% methanol fractions enhanced insulin sensitivity and inhibited alpha-glucoamylase activity. The major compounds of these fractions were sennosides, rhein and rhaponticin. Rhaponticin and rhein enhanced insulin-stimulated glucose uptake in 3T3-L1 adipocytes. Rhaponticin increased adipocytes with a differentiating effect similar to pioglitazone, but rhein and sennoside B decreased triglyceride accumulation. Sennoside A and B inhibited alpha-glucoamylase activity as much as acarbose. In conclusion, a crude extract of RR improves glucose intolerance by enhancing insulin-stimulated glucose uptake and decreasing carbohydrate digestion via inhibiting alpha-glucoamylase activity. Rhein and rhaponticin are potential candidates for hypoglycemic agents.
Choi
Soo Bong
SB
Department of Internal Medicine, Konkuk University, Chungjoo, Chungbuk, Korea.
Ko
Byoung Seob
BS
Park
Seong Kyu
SK
Jang
Jin Sun
JS
Park
Sunmin
S
D017667:Adipocytes / Q000187:drug effects; D000818:Animals; D000880:Anthraquinones / Q000302:isolation & purification / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D000431:Ethanol; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005087:Glucan 1,4-alpha-Glucosidase / Q000037:antagonists & inhibitors*; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007333:Insulin Resistance; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D012676:Senna Extract; D000081226:Sennosides; D012997:Solvents; D013267:Stilbenes / Q000302:isolation & purification / Q000494:pharmacology*; D014280:Triglycerides / Q000378:metabolism
D000880:Anthraquinones; D004791:Enzyme Inhibitors; D007004:Hypoglycemic Agents; D007328:Insulin; D010936:Plant Extracts; D000081226:Sennosides; D012997:Solvents; D013267:Stilbenes; D014280:Triglycerides; D000431:Ethanol; D012676:Senna Extract; D005087:Glucan 1,4-alpha-Glucosidase; C023538:rhapontin; C020491:rhein