Inhibition of Escherichia coli nitroreductase by the constituents in Syzygium aromaticum / 中国天然药物

Gut bacterial nitroreductases play an important role in reduction of various nitroaromatic compounds to the corresponding N-nitroso compounds, hydroxylamines or aromatic amines, most of which are carcinogenic and mutagenic agents. Inhibition of gut nitroreductases has been recognized as an attractive approach for reducing mutagen metabolites in the colon, so as to prevent colon diseases. In this study, the inhibitory effects of 55 herbal medicines against Escherichia coli(E. coli) nitroreductase (EcNfsA) were examined. Compared with other herbal extracts, Syzygium aromaticum extract showed superior inhibitory potency toward EcNfsA mediated nitrofurazone reduction. Then, the inhibitory effects of 22 major constituents in Syzygium aromaticum against EcNfsA were evaluted. Compared with other tested natural compounds, ellagic acid, corilagin, betulinic acid, oleanic acid, ursolic acid, urolithin M5 and isorhamnetin were found with strong to moderate inhibitory effect against EcNfsA, with IC50 values ranging from 0.67 to 28.98 mol·L-1. Furthermore, the inhibition kinetic analysis and docking simulation demonstrated that ellagic acid and betulinic acid potently inhibited EcNfsA (Ki < 2 μmol·L -1) in a competitively inhibitory manner, which created strong interactions with the catalytic triad of EcNfsA. In summary, our findings provide new scientific basis for explaining the anti-mutagenic activity of Syzygium aromaticum, where some newly identified EcNfsA inhibitors can be used for developing novel agents to reduce the toxicity induced by bacterial nitroreductase.

High protein acetylation/succinylation levels and their correlation with high histone 2AX expression level in breast cancer / 解剖学报

Objective To explore the protein acetylation/succinylation and histone 2AX (H2AX) expression levels in breast cancer, as well as their correlation. Methods By Western blotting and RT-PCR methods to detect the protein modification and H2AX expression levels in 11 breast cancer tissues and cells, as well as to explore the common regulation way of protein acetylation and succinylation by treatment of histone deacetylase inhibitors ; To study the relationship between H2AX expression level and protein modification level through the construction and over-expression of indicated plasmids. Results Compared with the adjacent normal tissues, there existed an increase protein acetylation/succinylation levels in breast cancer tissues, and the protein acetylation and succinylation were both regulated by histone deacetylase (HDAC) members. The H2AX mRNA and protein expression levels were increased both in breast cancer cell and tissues, its expression level and the expression and modification level of represented protein nucleophosmin 1(NPM1) showed a positive correlation. Conclusion The breast cancer possesses a characteristic of high protein acetylation/succinylation levels and high H2AX expression level, the H2AX expression level and the modification level of partial proteins in breast cancer have a positive correlation.

Antioxidant mechanism of gastrodin combined with isorhynchophylline in inhibiting MPP~+-induced apoptosis of PC12 cells / 中国中药杂志

Gastrodiae Rhizoma-Uncariae Ramulus cum Uncis is the most frequently used herbal pair in the treatment of Parkinson's disease(PD). Gastrodin and isorhynchophylline are important components of Gastrodiae Rhizoma-Uncariae Ramulus cum Uncis herb pair with anti-Parkinson mechanism. This study aimed to investigate the effect of gastrodin combined with isorhynchophylline on 1-methyl-4-phenylpyridinium(MPP~+)-induced apoptosis of PC12 cells and their antioxidant mechanism. The leakage of lactate dehydrogenase(LDH) from cells to media was analyzed by spectrophotometry. Apoptotic cells were labeled with Annexin V-fluorescein isothiocyanate(FITC) and propidium iodide(PI) and analyzed by flow cytometry. The cell cycle was analyzed using propidium iodide(PI) staining. Lipid peroxidation(LPO) level was analyzed by spectrophotometry. The mRNA expression of caspase-3 was examined by Real-time RT-PCR. The protein expressions of heme oxygenase 1(HO-1) and NADPH: quinoneoxidore-ductase 1(NQO-1) were determined by Western blot. Gastrodin combined with isorhynchophylline reduced the percentage of Annexin V-positive cells and cell cycle arrest in MPP~+-induced PC12 cells. Gastrodin combined with isorhynchophylline down-regulated the mRNA expression of caspase-3, up-regulated the protein expressions of HO-1 and NQO-1, and reduced LPO content in MPP~+-induced PC12 cells. PD98059, LY294002 or LiCl could partially reverse these changes pretreated with gastrodin combined with isorhynchophylline, suggesting that gastrodin combined with isorhynchophylline inhibited MPP~+-induced apoptosis of PC12 cells and oxidative stress through ERK1/2 and PI3 K/GSK-3β signal pathways. Our experiments showed that gastrodin combined with isorhynchophylline could down-re-gulate the mRNA expression of caspase-3 and up-regulate the protein expressions of HO-1 and NQO-1, so as to reduce oxidative stress and inhibit apoptosis.