Extraction efficacy, stability assessment and seasonal variation of bioactive 'gymnemagenin' in Gymnema sylvestre.

摘要

Gymnema sylvestre (Asclepiadaceae) is a highly valued medicinal plant and being used nowadays in many poly-herbal formulations due to its potential antidiabetic activity and other health benefits. Thus, it has become important to analyse certain value standard parameters to give a contribution to the valorisation of this natural source. The present study attempts to identify the efficient extraction procedure including solvent selection and methods, stability assessment in terms of drying as well as storage and changes occurring during annual cycle using an important analytical marker 'gymnemagenin' (GM) for quality assurance of this botanical. The yield of the marker was found to be highest in acid-base hydrolysis extract (1.17%) and lowest in cold percolation (0.12%). Among different drying methods adopted, gymnemagenin content was high in shade dried leaves (1.15%) while it was significantly low in sun dried material (0.54%). The changes in the bioactive marker were found to be drastic as to the effect of one year storage. The compound showed higher degradation in polystyrene containers (1.18-0.37%) kept in light conditions while it was minimum in glass vials (1.18-0.85%) kept in dark. Estimate of yield and enriched gymnemagenin (1.01-1.23%) indicated that summer (April-July) is the ideal time to harvest G. sylvestre.