Metabolic differentiation and quantification of gymnemic acid in Gymnema sylvestre (Retz.) R.Br. ex Sm. leaf extract and its fermented products.

Abstract

Gymnemagenin is the bioactive metabolite found in Gymnema sylvestre leaves and possesses different therapeutic potential. Due to its lower abundance and higher market potential, gymnemagenin was obtained from chemical conversion and bacterial biotransformation. To obtain the probiotic-based fermentative conversion of gymnemic acid-enriched G. sylvestre leaf extract to gymnemagenin-containing nutraceuticals and its metabolites based chromatographic comparison. Gymnema sylvestre leaves were extracted through soxhalation, and the extract was prepared and characterised. Gymnemic acid was fermented, separately, by Lactobacillus casei, Lactobacillus rhamnosus, Bifidobacterium bifidum, and by their mix co-culture. The fermented materials were analysed for their gymnemagenin content, antioxidant potential, antidiabetic potential, and metabolomics analysis. Extraction yielded about 35% w/w of raw plant material, and 8.5% was found to be as total saponin content. Extract at higher concentration (≥ 5%, w/v) significantly altered the growth behaviour of probiotics. High-performance thin-layer chromatography (HPTLC) based quantification of gymnemagenin revealed that a maximum increase of 95.5% gymnemagenin was found in extract incubated with B. bifidum followed by mix co-culture containing (B. bifidum, L. casei, and L. rhamnosus), L. casei, and L. rhamnosus. However, liquid chromatography mass spectrometry (LC-MS) analysis resulted in the identification of a total of 56 metabolites. Chromatographically profiled, and probiotic-based fermented G. sylvestre leaves can be used as a potent nutraceutical for diabetes and other metabolic disorders.