Enrichment of bioactives from Mimosa pudica Linn. using conventional, super and subcritical (CO2-Soxhlet) fluid extraction for inhibition of a α-amylase and α-glucosidase enzymes

Abstract

Mimosa pudica L. is a common neglected weed with traditional diabetic usages. The current study embarks on isolating bioactive compounds that will be effective against digestive enzymes α-amylase and α-glucosidase inhibition that is connected to postprandial rise in blood glucose level. Subsequently green technology viz. supercritical fluid exyraction and CO2-Soxhlet have been employed for enrichment of the isolated targeted compounds. In the 1st objective the sample had undergone conventional organic solvent extraction and polarity based solvent fractionation followed by α-amylase and α-glucosidase enzyme inhibitory analysis. The activity against the enzyme was as follows, MeOHi> EtOAcf> Acetonef> MeOHf> Hexanef. Ethyl acetate fraction was chosen for isolation in the second stage of the study. For the 2nd objective, the best activity showing fraction was then subjected to bioactivity guided isolation to obtain the antidiabetic compounds. After purification the isolated compounds were subjected to UV, IR, Proton and Carbon-13 NMR, Mass Spectrum, and TLC for structure elucidation. Five compounds were isolated of which three showed antidiabetic activity against α-glucosidase enzyme. The compounds were stigmasterol, quercetin and avicularin. Their IC50 values as compared to Acarbose standard were as follows: 91.08 ±1.54, 75.16 ± 0.92, 481.7 ± 0.703, 351.02 ± 1.46 respectively. The 3rd objective was to obtain enriched extracts using supercritical fluid extraction (SFE) and subcritical CO2-Soxhlet (CO2-Soxhlet) extraction to get the 3 compounds. Various parameters were tested in this study. Box Behnken Design (BBD) was used for experimental design and optimisation of the extraction process. Results showed that SFE was the better enrichment method as compared to CO2-Soxhlet. HPLC and LCMS were used to analyse the level of enrichment by ascertaining the amount of each of the compounds in the extracts. All three compounds were found to be present in the SFE runs at various concentrations but the presence of all three compounds together were not seen in CO2-Soxhlet. Based on enrichment analysis it can be concluded that supercritical fluid extraction (SFE) was the better method. SFE and CO2-Soxhlet can be utilised to collect fraction enriched with antidiabetic compounds stigmasterol, quercetin and avicularin for antidiabetic therapeutics in future.