Phenolic C-glycoside synthesis using microbial systems

Plants produce different types of phenolic compounds. The majority of these compounds are glycosylated. Phenolic O-glycosides are also common. Recently, C-glycosylation of phenolic compounds has received attention because of the biological importance of phenolic C-glycosides. To date, three classes of C-glycosyltransferases (CGTs) have been characterized based on the type of sugar acceptor: flavonoid CGT, coumarin CGT, and xanthone CGT. Phylogenetic analysis of glycosyltransferases has revealed that CGTs form a distinct class that is clearly different from that of O-glycosyltransferases. The characterized CGTs have been introduced into microbial systems to synthesize phenolic C-glycosides. Here, we review recent progress in the development of CGTs and their application in the synthesis of phenolic C-glycosides using microbial systems.

Two new compounds from the leaves of Indocalamus latifolius

Two new compounds, erythro-syringylglycerol-9-O-trans-4-hydroxycinnamate 7-O-β-d-glucopyranoside (1) and indocalatin A (2), together with three known ones, 5,7,3'-trihydroxy-6-C-β-d-digitoxopyranosyl-4'-O-β-d-glucopyranosyl flavonoid (3), 5,4'-dihydroxy-3',5'-dimethoxy-7-O-[β-d-apiose-(1→2)]-β-d-glucopyranosyl flavonoid (4), and tricin-6-C-β-boivinopyranosyl-8-C-β-glucopyranoside (5), were isolated from the 95% EtOH extract of Indocalamus latifolius leaves. Their molecular structures were determined by UV, IR, HRESIMS, CD, and 1D and 2D NMR data analyses.

Chemical Constituents and Antibacterial Properties of Indocalamus latifolius McClure Leaves, the Packaging Material for "Zongzi"

The glutinous rice dumpling named "Zongzi" in Chinese is a type of traditional food that is popular in East Asian countries. "Zongzi" is made of glutinous rice and wrapped in the leaves of Indocalamus latifolius McClure as the packaging material. Four new compounds, latifoliusine A (2), (7S,8R) syringylglycerol-8-O-4'-sinapyl ether 4-O-β-d-glucopyranoside (7), (7S,8S) syringylglycerol-8-O-4'-sinapyl ether 7-O-β-d-glucopyranoside (8), and (7R,8S) syringylglycerol-8-O-4'-sinapyl ether 7-O-β-d-glucopyranoside (10), along with six known compounds (1, 3-6 and 9) were isolated from I. latifolius McClure leaves. The structures and relative configurations of the compounds were determined by detailed spectroscopic analysis, high-resolution electrospray ionization mass spectroscopy (HRESIMS), heteronuclear single quantum correlation (HSQC), heteronuclear multiple bond correlation (HMBC), nuclear overhauser enhancement (NOE) and circular dichroism (CD). All of the isolated compounds were screened for their antibacterial activities in vitro. The results indicated that apigenin 6-C-α-l-arabinopyranosyl-8-C-β-d-glucopyranoside (5) and apigenin 7-O,8-C-di-glucopyranoside (6) have antibacterial activities against four bacterial strains (Staphylococcus aureus, Bacillus thuringiensis, Escherichia coli and Pseudomonas solanacearum).

In vitro antioxidant activities of polysaccharides extracted from Moso Bamboo-Leaf

The objective of this study was to evaluate in vitro antioxidant capacities of polysaccharides extracted from Moso Bamboo-Leaf (BLP). The molecular weight of the polysaccharides were obtained by SEC-LLS and their molecular masses were 13.4×10(4)Da, 2.8×10(4)Da and 1.9×10(4)Da, respectively. Available data obtained with in vitro models suggested WB1 (precipitated by 30% ethanol) showed significant inhibitory effects on superoxide radical, hydroxyl radical, DPPH radical and ferrous metal-chelating capacities. These results clearly establish the possibility that polysaccharides extracted from Moso Bamboo-Leaf could be effectively employed as ingredient in health or functional food, to alleviate oxidative stress.