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.