Gynostemma pentaphyllum (Thunb.) Makino has signifcant whole herb medicinal applications including its demonstrated anti-obesity effects. Patented heat and steam processing of the natural extract has increased the levels of gypenosides L & LI and damulins A & B, the latter two causing, at least in vitro, a significant increase in AMP-activated protein kinase activity. Such a patent-protected, refined extract is at odds with published monographs (1,2) of the whole herb. Insight into the identity of key marker compounds in the natural extract, especially saponins and flavonoids, are required to ensure quality and efficacy of any subsequent processed natural product.
The work undertaken and presented here encompasses identification of all major flavonoids and key saponins by UPLC-MS and NMR, in an authenticated voucher specimen (Medicinal Plant Herbarium, Southern Cross University (Accession No: PHARM160054). Plant materials surveyed include a range of retail Jiaogulan teas as well as various trade herb and extracts available in Australia. The identified saponins include the gypenosides XLVI and LVI and two novel acetylated derivatives and new damulin analogues. Eleven fully identified glycosylated flavonoids of kaempferol, quercetin and isorhamnetin provide a definitive fingerprint profile. Previously reported constituents (3) including ginsenosides Rb1 and Rd, with the flavonoids vitexin and ombuoside are not present in the authenticated specimen. Given the wide geographic distribution of this plant species, it is likely that chemotypic variation is at play here and more detailed survey data is needed to define this variation for future quality control to be rigorously implemented.
[1]. Herba Gynostemmatis – Jiaogulan. H. Wagner et al (eds) Chromatographic Fingerprint Analysis of herbal Medicines, Vol 3, DOI 10.1007/978-3-319-06047-7_6, Springer International Publishing Switzerland 2015.
[2]. Gynostemmatis Herba, Hong Kong Chinese Materia Medica Standards (HKCMMS), ( http://www.cmd.gov.hk/hkcmms/vol5/Vol5_pdf_English/D_Monographs/14-Gynostemmatis%20Herba.pdf ).
[3]. Xie, Z, Shi, H and Yu L (2013). HPLC/MS Fingerprinting Techniques for Quality Control of Gynostemma pentaphyllum (Thunb.) Makino samples. DOI: 10.1021/bk-2013-1138.ch003.