RESUMO
Five new megastigmanes (1-5) were isolated from a decoction of Uncaria rhynchophylla by separation techniques of column chromatography using a combination of multiple stationary phases, including macroporous adsorbent resin, MCI resin, silica gel, Sephadex LH-20, and Toyopearl HW-40F, and reversed phase HPLC. Their structures were characterized by spectroscopic data analysis of HR-ESI-MS, NMR, and CD, in combination with Mosher's mothed as well as ECD and NMR calculations. The new compounds were named uncarphyllonone A (1), uncarphyllonols A (2) and B (3), and uncarphabscisic acids A (4) and B (5). Although the structures of 3 and 4 were previously reported, the reported NMR spectroscopic data were incorrect or do not support the assigned structures in literatures. This is also the first report of discovery of new megastigmane natural products from the Uncaria genus.
RESUMO
Nor-ursane triterpenes are formed by the reduction of one or several methyl groups on the ursane triterpene carbon skeleton. According to the position of vacant methyl, they can be divided into eight types, including 23-nor, 24-nor, 28-nor, 29-nor, 30-nor, 2-nor, 3-nor, and 3,24-nor. Moreover, nor-ursane triterpenes have several pharmacological effects such as anti-cancer, anti-inflammatory, anti-bacterial, inhibition of acyl cholesterol acyl transferase (ACAT) and so on. In this study, more than 30 relevant literatures of nor-ursane triterpenoid compounds at home and abroad were reviewed. The plant distribution, pharmacological activity and structural characteristics of nor-ursane triterpenes were studied. Therefore, this review may provide the basis for further study of this type of compound.