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Flavonoids are important secondary metabolites that exist in many medicinal plants. Flavonoid glycosyltransferases can transfer sugar moieties to their parent rings, producing various flavonoid glycosides with significant pharmacological activities. Here, we report the molecular cloning of the O-glycosyltransferase TwUGT2 from Tripterygium wilfordii and its catalytic activity was explored by heterologous expression in E. coli . The results showed that TwUGT2 has specific glycosyltransferase activity towards C-3 and 7 hydroxyl groups of flavonoids, thereby converting quercetin and pinocembrin into isoquercitrin and pinocembrin 7-O-beta-D-glucoside, respectively. The identification of TwUGT2 will provide a useful molecular tool for synthetic biology and contribute to drug discovery.[Formula: see text].

Andrographis paniculata is an important traditional medicinal herb in which flavonoids are part of the primary specialized metabolites. A flavonoid glucosyltransferase with broad substrate spectrum (named ApUGT3) was successfully identified by screening homologous glycosyltransferase genes from A. paniculata . The enzyme displayed glycosylation activity toward multiple flavonoids in vitro , and the major products were identified as 7 -O- glucosides. Phylogenetic analysis revealed that ApUGT3 is the first reported glycosyltransferase from the Acanthaceae family that belongs to cluster I, suggesting that ApUGT3 is a new flavonoid glycosyltransferase of this subcluster. This enzyme is potentially useful as powerful glycosylation catalysts to modify flavonoid-like compounds and improve their biological activities. [Formula: see text].

The biosynthetic pathways of phytosterols and steroidal saponins are located in two adjacent branches which share cycloartenol as substrate. The rate-limiting enzyme S-adenosyl-L-methionine-sterol-C24-methyltransferase 1 (SMT1) facilitates the metabolic flux toward phytosterols. It catalyzes the methylation of the cycloartenol in the side chain of the C24-alkyl group, to generate 24(28)-methylene cycloartenol. In this study, we obtained two full-length sequences of SMT1 genes from Pari polyphylla, designated PpSMT1-1 and PpSMT1-2. The full-length cDNA of PpSMT1-1 was 1369 bp long with an open reading frame (ORF) of 1038 bp, while the PpSMT1-2 had a length of 1222 bp, with a 1005 bp ORF. Bioinformatics analysis confirmed that the two cloned SMTs belong to the SMT1 family. The predicted function was further validated by performing in vitro enzymatic reactions, and the results showed that PpSMT1-1 encodes a cycloartenol-C24-methyltransferase, which catalyzes the conversion of cycloartenol to 24-methylene cycloartenol, whereas PpSMT1-2 lacked this catalytic activity. The tissue expression patterns of the two SMTs revealed differential expression in different organs of Paris polyphylla plants of different developmental stage and age. These results lay the foundation for detailed genetic studies of the biosynthetic pathways of steroid compounds, which constitute the main class of active substances found in P. polyphylla.

Celastrol is an important bioactive triterpenoid in traditional Chinese medicinal plant, Tripterygium wilfordii. Methyl Jasmonate (MJ) is a common plant hormone which can regulate the secondary metabolism in higher plants. In this study, the mevalonate (MVA) pathway genes in T. wilfordii were firstly cloned. The suspension cells of T. wilfordii were elicited by MJ, and the expressions of MVA pathway genes were all enhanced in different levels ranging from 2.13 to 22.33 times of that at 0 h. The expressions were also enhanced compared with the CK group separately. The accumulation of celastrol in the suspension cells after the treatment was quantified and co-analyzed with the genes expression levels. The production of celastrol was significantly increased to 0.742 mg g(-1) after MJ treatment in 288 h which is consistent with the genes expressions. The results provide plenty of gene information for the biosynthesis of terpenoids in T. wilfordii and a viable way to improve the accumulation of celastrol in T. wilfordii suspension cells.

Two new compounds 5-[4'-(4″-hydroxybenzyl)-3'-hydroxybenzyloxymethyl]-furan-2-carbaldehyde (1) and 5-[4'-(4″-hydroxybenzyl)-3'-hydroxybenzyl]-furan-2-carbal-dehyde (2), together with two known 5-(4-hydroxbenzyloxymethyl)-furan-2-carbaldehyde] (3) and 5-(hydroxymethyl)-2-furaldehyde (4), were isolated from the rhizome of Gastrodia elata. Their structures were elucidated by spectroscopic analysis and comparison of their spectral data with those reported previously. All compounds exhibited weak or no cytotoxicity against human colon carcinoma cell line (HT-29) and human chronic myelogenous leukemia cell line (K-562).

Two new triterpenoid saponins, named sarcandroside A and B, have been isolated from Sarcandra glabra (Thunb) Nakai. Their structures have been established as 3beta,19alpha,20beta-trihydroxyurs-11,13 (18)-diene-28,20beta-lactone-3-O-beta-D-glucopyranosyl (1 --> 3)-[alpha-L-rhamnopyranosyl(1 --> 2)]-beta-D-xylopyranoside (1) and 3-O-beta-D-glucopyranosyl (1 --> 3)-[alpha-L-rhamnopyranosyl(1 --> 2)]-beta-D-xylopyranosyl-pomolic acid 28-O-beta-D-glucopyranosyl ester (2) by means of spectral and chemical methods.