A Comparative Tissue-specific Metabolite Analysis and Determination of Protodioscin Content in Asparagus Species used in Traditional Chinese Medicine and Ayurveda by use of Laser Microdissection, UHPLC-QTOF/MS and LC-MS/MS

IntroductionAsparagus is esteemed in Traditional Chinese Medicine and Ayurveda, and it is commercially one of the most important drugs in the global herbal market. Comparative metabolite profiling of different species would help in determining the similarities and ascertain their validity for being used as substitutes for each other. Laser microdissection (LMD) facilitates identification of metabolites in specific tissues, and thus it can aid in exploration of metabolic pathways in target tissues. ObjectiveTo compare tissue-specific metabolites and protodioscin content of Asparagus cochinchinensis (Lour.) Merr. and Asparagus racemosus Willd. used in China and India. MethodsMetabolite analysis of laser-dissected tissues was carried out using UHPLC-QTOF/MS and LC-MS/MS. The protodioscin contents were determined and the method was validated as per the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines. ResultsMetabolite analysis reveals that the velamen tissue, among other tissues such as cortex, vascular bundles and pith, contained maximum components, specifically those belonging to the steroidal saponin class. Although the metabolite profiles were similar, the content of protodioscin was found to be higher in Chinese than Indian species. ConclusionThe study provided a suitable methodology for metabolite profiling and protodioscin content determination of Asparagus by use of LMD, UHPLC-QTOF/MS and LC-MS/MS. The similarities in metabolite profiles indicate that Asparagus species from India and China can serve as substitute for each other in various therapeutic and pharmaceutical applications. Copyright (c) 2014 John Wiley & Sons, Ltd. The present study compares the tissue-specific metabolites and protodioscin content of Asparagus cochinchinensis (Lour.) Merr. and A. racemosus Willd. Tissues were Laser micro-dissected and UHPLC-QTOF/MS and LC-MS/MS were used for metabolite analysis. Results indicate that the velamen tissue contained maximum number of steroidal constituents compared to the other dissected tissues and A. cochinchinensis had higher content of protodioscin. Similarities in metabolite profiles of tubers of selected Asparagus species suggest that they can be qualitatively substituted for each other.