Identification and quantification of secondary metabolites of Pterocarpus marsupium by LC–MS techniques and its in-vitro lipid lowering activity

Pterocarpus marsupium (Vijaysar) is a deciduous tree, considered to have high insulinogenic properties. Since ancient times Ayurveda practitioners believed that heartwood of vijaysar significantly reduced blood sugar levels in diabetes. Marsupsin, pterosupin and pterostilbene are the three important phenolic constituents of the heartwood of this plant reported to significantly lower the blood glucose level. For the dereplication of bioactive phytochemicals present in heartwood of Pterocarpus marsupium a method was developed to identify and elucidate the main fragmentation pathways of phytoconstituents in positive electrospray ionization mode using HPLC-ESI-QTOF-MS/MS. Further, an UPLC-ESI-QqQ_LIT-MS/MS method was developed to determine the contents of bioactive compounds, namely 2,6-dihydroxyphenyl glucopyranoside, pterosupol, vijyoside, marsuposide, pteroside, pterocarposide, epicatechin, vanillic acid, quercetin, formononetin and naringenin in heartwood of this plant. Twenty seven compounds were tentatively identified based on their retention time, accurate mass and MS/MS patterns. In-vitro assessment of compounds in 3T3-L1 adipocytes revealed significant attenuation of lipid accumulation in extract from Pterocarpus marsupium, hence it may have certain phytochemicals which are responsible for reducing obesity. The analytical method for quantitation was validated and successfully applied for the simultaneous determination of eleven bioactive compounds. In conclusion, rapid and accurate HPLC-ESI-QTOF-MS/MS and UPLC-ESI-QqQ_LIT-MS/MS methods developed in positive ionization mode were successfully applied for identification and quantitation of bioactive phytochemicals present in heartwood of Pterocarpus marsupium.