Anti-hyperglycemic activity of Centella asiatica is partly mediated by carbohydrase inhibition and glucose-fiber binding.
BACKGROUND
Centella asiatica (C. asiatica) was previously reported to have anti-hyperglycemic effects in animal diabetic model rats. However, its activity on organ and tissue level remains unstudied. Our study aims at exploring the possible effects, C. asiatica extract and insoluble fiber has on carbohydrate absorption, insulin secretion, insulin sensitivity and glucose utilization.


METHODS
For primary evaluation of anti-hyperglycemic activity, we measured Fasting Blood Glucose and performed Glucose Tolerance Test, in type 2 diabetic rats. To further study the pancreatic effect and glucose utilization, plasma insulin concentration, insulin secreted from isolated rat islets and liver glycogen were assayed. Effect on carbohydrate break down was assayed using intestinal disaccharidase enzyme, α-amylase inhibition assays and Six-Segment study of the GI tract. Effect of C. asiatica on glucose absorption was studied by an in-situ, perfused, intestinal model in rats and by glucose-fiber binding assay. Gastrointestinal motility was seen by a BaSO4 milk traverse test. Additionally, a complete lipid profile assay, after a chronic study, was conducted.


RESULTS
C. asiatica showed no significant change in insulin secretion in-vivo and in isolated rat islets. Additionally, no effect of the extract was seen on liver glycogen deposition. Retarded glucose absorption was seen in the in-situ perfused rat intestinal model at a dose. The extract was also found to inhibit action of both intestinal disaccharidase and α-amylase. This was confirmed, yet again, via the Six Segment study, where sucrose digestion was found to be inhibited throughout the length of the GI Tract. Significant glucose-fiber binding was demonstrated in the in-vitro models. During the chronic study, body mass of C. asiatica treated Type 2 diabetic rats returned to normal and their polydipsic and polyphagic conditions were also improved. Chronic treatment of C. asiatica also improved subject's lipid profile.


CONCLUSIONS
A combination of in-vitro, in-vivo and in-situ tests confirmed the anti-hyperglycemic activity of C. asiatica and its tissue level mechanism. Further study is required to fully elucidate the effect this extract or the active compounds have on the individual glucose transporters and the precise mechanism of glucose-fiber binding.
Department of Pharmacy, North South University, Dhaka, Bangladesh. ashraful_kabir@ymail.com.
Ashraf Ul
AU
Kabir
Mehdi Bin
MB
Samad
Ninadh Malrina
NM
D'Costa
Farjana
F
Akhter
Arif
A
Ahmed
J M A
JM
Hannan
D000818:Animals; D028041:Centella; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy; D004043:Dietary Fiber / Q000378:metabolism*; D004063:Digestion / Q000187:drug effects; D005947:Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors*; D007004:Hypoglycemic Agents / Q000494:pharmacology* / Q000627:therapeutic use; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D008055:Lipids / Q000097:blood; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008517:Phytotherapy; D010936:Plant Extracts; D051381:Rats; D013395:Sucrose / Q000378:metabolism; D014315:Triterpenes / Q000494:pharmacology* / Q000627:therapeutic use; D000516:alpha-Amylases / Q000037:antagonists & inhibitors*
C526146:Centella asiatica extract; D004043:Dietary Fiber; D007004:Hypoglycemic Agents; D007328:Insulin; D008055:Lipids; D010936:Plant Extracts; D014315:Triterpenes; D013395:Sucrose; D006026:Glycoside Hydrolases; C019822:carbohydrase; D000516:alpha-Amylases; D005947:Glucose