Chemical constituents from Gnaphalium affine and their xanthine oxidase inhibitory activity.

Gnaphalium affine D. Don, a medicinal and edible plant, has been used to treat gout in traditional Chinese medicine and popularly consumed in China for a long time. A detailed phytochemical investigation on the aerial part of G. affine led to the isolation of two new esters of caffeoylquinic acid named (-) ethyl 1, 4-di-O-caffeoylquinate (1) and (-) methyl 1, 4-di-O-caffeoylquinate (2), together with 35 known compounds (3-37). Their structures were elucidated by spectroscopic data and first-order multiplet analysis. All the isolated compounds were tested for their xanthine oxidase inhibitory activity with an in vitro enzyme inhibitory screening assay. Among the tested compounds, 1 (IC50 11.94 µmol·L-1) and 2 (IC50 15.04 µmol·L-1) showed a good inhibitory activity. The current results supported the medical use of the plant.

Isoprenylated flavonoids from Morus nigra and their PPAR γ agonistic activities.

A novel dihydroflavonol unprecedentedly with a prenyl group at C-2, nigragenon A (1), four new sanggenon-type flavonones, nigragenons B-E (2-5), along with six known isoprenylated flavonoids (6-11) were isolated from the twigs of Morus nigra. Their structures were elucidated through extensive analysis of spectroscopic data. Interestingly, compound 1 was the first reported biogenetic precursor of sanggenon-type flavanones and the biogenetic pathway from 1 to sanggenol F was proposed. The PPAR γ agonistic activity was investigated in HEK293 cells using dual luciferase reporter assay. Compounds 2, 4, 7, and 9 showed obvious agonistic activities on PPAR γ, and compound 2 was a potential PPAR γ partial agonist. Moreover, the preliminary structure-activity relationships for the tested compounds were discussed.

Anti-proliferative and apoptotic effects of S1, a tetrandrine derivative, in human gastric cancer BGC-823 cells.

The aim of the study was to investigate the anti-proliferation and apoptosis-inducing effects of S1, a novel tetrandrine derivative, in human gastric cancer BGC-823 cells and explore the possible mechanism of action. The anti-proliferative activity was determined by MTT assay; the induction of cell cycle arrest and apoptosis were detected by flow cytometry. Quantitative real time RT-PCR and Western blotting were used to evaluate the mRNA and protein expression levels in mitochondrial pathway. S1 significantly reduced cell viability and induced a G2/M phase arrest and apoptosis in dose- and time-dependent manner. Further studies showed that S1 increased mRNA and protein expression of Bax and the Bax/Bcl-2 ratio. Moreover, S1 decreased the protein expression of procaspase-9 and procaspase-3, suggesting that the induction of apoptosis may be related to the alteration of the ratio of Bax/Bcl-2 and the activation of caspases. These findings suggested that S1 merits further investigation as a novel therapeutic agent for the treatment of human gastric cancer.

Synthesis and antitumor activity of tetrandrine derivatives.

Tetrandrine possesses antitumor activity, however, only a few studies on its structure modification were reported. To improve the antitumor activity of tetrandrine, 20 new tetrandrine derivatives were designed and synthesized by Sonogashira and Suzuki reactions. Their antitumor activities were evaluated against three tumor cell lines including A549, HepG2, and BGC-823 by methyl thiazolyl tetrazolium assay with taxol as a positive control. The results showed that compounds 2c and 2g were highly potent against BGC-823 cell line, and compounds 1i and 1k showed particular activity against HepG2 cells. These results demonstrated that compounds 1i, 1k, 2c, and 2g were promising leads for further investigation.