A study published in the peer-reviewed journal Cellular Physiology and Biochemistry examined the effect of the plant extract on mouse and human cells in vitro.
Sponsored by Wisconsin-based ingredient firm Ayurvedic-Life International, the study used its patented Gymnema sylvestre (GS) isolate – termed OSA – which was found to “significantly” stimulate insulin secretion without compromising pancreatic beta cell viability.
"If the stimulatory effect of OSA also occurs in vivo it would be expected to result in a reduction in blood glucose levels," said study leader Shanta Persaud.
Gymnema sylvestre, grown primarily in the Indian sub-continent, has been used India for centuries as a traditional folk remedy to help maintain optimal health.
Ayurvedic-Life claims its isolate stimulates insulin secretion similar to sulphonylureas and meglitinide analogues that are currently used for the treatment of Type 2 Diabetes.
“We found that the extract may help regulate blood glucose levels through a direct effect on the pancreatic beta cells to stimulate insulin release,” Persaud told NutraIngredients.com.
Persaud and colleagues from Kings’ College London tested the isolate in vitro on both mouse and human beta cells, which are the pancreatic cells that secrete insulin.
Mouse beta cells were incubated for 30 minutes in the presence of 0.06-2mg/ml OSA at both 2mM and 20mM glucose. Changes in insulin output were measured using the radioimmunoassay method.
Human islets – which are cell clusters containing the beta cells – were isolated and transferred to chambers containing 2mM or 20mM glucose, either in the absence or presence of OSA at 0.125 or 0.25mg/ml. Insulin content was again determined by radioimmunoassay.
“Static incubation experiments with [mouse beta cells] indicated that OSA (0.06-2mg/ml) significantly stimulated insulin secretion at 2mM glucose and potentiated 20mM glucose-stimulated insulin secretion with maximum stimulatory effects at 0.25-0.5mg/ml,” wrote the researchers.
“OSA also stimulated insulin secretion from isolated human islets of Langerhans in vitro. Thus, it can be seen (…) that the profile of insulin release from human islets at 2mM glucose response to 0.125mg/ml OSA was rapid in onset, sustained, and fully reversible upon withdrawal of OSA,” they wrote, adding that human islets showed “significant further increase” in insulin secretion in response to 20mM glucose following a sustained secretory response to 0.125mg/ml OSA at 2mM glucose.
According to the researcher, their demonstration on the effects of OSA in human cells “validates its development for clinical use”.
They added that identification of the OSA component(s) that stimulates regulated insulin exocytosis may provide promising lead targets for type 2 diabetes therapy.
Persaud told NutraIngredients.com that the study was not conducted with drug development in mind, but that it “may be” possible to transfer the findings to the use of the extract in supplements. “The next step is to conduct in vivo tests”.
Source: Characterisation of the Insulinotropic Activity of an Aqueous Extract of Gymnema Sylvestre in Mouse β-Cells and Human Islets of Langerhans
Cellular Physiology and Biochemistry 2009;23:125-132
Authors: Bo Liu, Henry Asare-Anane, Altaf Al-Romaiyan, GuoCai Huang, Stephanie A Amiel, Peter M Jones, Shanta J Persaud