Enantioselective Total Syntheses of (+)-Gallocatechin, (−)-Epigallocatechin, and 8-C-Ascorbyl-(−)-epigallocatechin

Chemical Constituents with Anti-Lipid Droplet Accumulation and Anti-Inflammatory Activity from Elaeagnus glabra

Non-alcoholic fatty liver disease (NAFLD) is a type of steatosis caused by excess lipids accumulating in the liver. The prevalence of NAFLD has increased annually due to modern lifestyles and a lack of adequate medical treatment. Thus, we were motivated to investigate the bioactive components of Formosan plants that could attenuate lipid droplet (LD) accumulation. In a series of screenings of 3000 methanolic extracts from the Formosan plant extract bank for anti-LD accumulation activity, the methanolic extract of aerial parts of Elaeagnus glabra Thunb. showed excellent anti-LD accumulation activity. E. glabra is an evergreen shrub on which only a few phytochemical and biological studies have been conducted. Here, one new flavonoid (1), two new triterpenoids (2 and 3), and 35 known compounds (4-38) were isolated from the ethyl acetate layer of aerial parts of E. glabra via a bioassay-guided fractionation process. Their structures were characterized by 1D and 2D NMR, UV, IR, and MS data. Among the isolated compounds, methyl pheophorbide a (37) efficiently reduced the normalized LD content to 0.3% with a concentration of 20 μM in AML12 cell lines without significant cytotoxic effects. 3-O-(E)-Caffeoyloleanolic acid (13) and methyl pheophorbide a (37) showed inhibitory effects on superoxide anion generation or elastase release in fMLP/CB-treated human neutrophils (IC50 < 3.0 μM); they displayed effects similar to those of the positive control, namely, LY294002. These findings indicate that E. glabra can be used for developing a new botanical drug for managing LD accumulation and against inflammation-related diseases.

Asymmetric Synthesis of Chiral Flavan-3-Ols

Flavan-3-ols are a series of natural products widely present in plants and show versatile biological activities. The structures of such compounds are characterized by owing two adjacent chiral centers and three rings. Their interesting structures and promising biological activities have driven increasing research developments toward the preparation of enantioenriched flavan-3-ols. This review summarizes the recent approaches for the asymmetric synthesis of chiral flavan-3-ols from two strategies in the construction of chiral centers. The key steps in the synthetic protocol involve Sharpless asymmetric dihydroxylation, Shi asymmetric epoxidation and Sharpless asymmetric epoxidation.