Wen-Hong Liu’s research while affiliated with Zhejiang Chinese Medical University and other places

Metallo-β-lactamases (MBLs) are a group of enzymes that can inactivate most commonly used β-lactam-based antibiotics. Among MBLs, New Delhi metallo-β-lactamase-1 (NDM-1) constitutes an urgent threat to public health as evidenced by its success in rapidly disseminating worldwide since its first discovery. Here we report the biochemical and genetic characteristics of a novel MBL, ElBla2, from the marine bacterium Erythrobacter litoralis HTCC 2594. This enzyme has a higher amino acid sequence similarity to NDM-1 (56%) than any previously reported MBL. Enzymatic assays and secondary structure alignment also confirmed the high similarity between these two enzymes. Whole genome comparison of four Erythrobacter species showed that genes located upstream and downstream of elbla2 were highly conserved, which may indicate that elbla2 was lost during evolution. Furthermore, we predicted two prophages, 13 genomic islands and 25 open reading frames related to insertion sequences in the genome of E. litoralis HTCC 2594. However, unlike NDM-1, the chromosome encoded ElBla2 did not locate in or near these mobile genetic elements, indicating that it cannot transfer between strains. Finally, following our phylogenetic analysis, we suggest a reclassification of E. litoralis HTCC 2594 as a novel species: Erythrobacter sp. HTCC 2594.

Background: Abnormal expression of serum TGF-β1 was found in patients with diabetic nephropathy. However, the association of TGF-β1 with the risk of diabetic nephropathy remains unknown. The present study was undertaken to investigate whether such an association exists. Methods: We searched the Chinese VIP, Wangfang, China National Knowledge Infrastructure, PubMed, Embase, and Google Scholar databases for relevant studies and extracted all eligible data. Stata12 software was used for statistical analysis. Results: Nine reports met our criteria and were used for data extraction. There were 264 patients and 227 healthy controls from qualified reports in this meta-analysis. The results suggested that serum TGF-β1 levels were significantly up-regulated in patients with diabetic nephropathy; the instrumental variable was 3.94 (95% confidence interval 3.20-4.68, p<0.01). Conclusions: Meta-analysis suggested that elevated serum TGF-β level in patients with diabetes is associated with a high risk of nephropathy. Further studies are required to validate these observations.

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Two new polyketides, neosarphenols A (I) and B (II), are isolated from Neosartorya glabra together with six known polyketides.

Two new polyketides, neosarphenols A and B (1 and 2, resp.), were isolated from Neosartorya glabra, together with six known polyketides, 3–8, and two meroterpenoids, 9 and 10. The structures of the new compounds were elucidated by comprehensive spectroscopic analysis, especially by HR-ESI-MS and NMR experiments. All compounds were evaluated for their cytotoxic activities against MDA-MB-231, MCF-7, and PANC-1 tumor cell lines; 1 and 6 exhibited selective and moderate cytotoxicities against PANC-1 cell line.

Three new xanthones, namely huperxanthones A–C (1–3, resp.), were obtained from the cultures of Aspergillus versicolor, a fungal endophyte of Huperzia serrata, together with 1,7‐dihydroxy‐8‐(methoxycarbonyl)xanthone‐3‐carboxylic acid (4), β‐diversonolic acid methyl ester (5), 4‐hydroxyvertixanthone (6), and sydowinin B (7). The structures of the new compounds were established by detailed NMR and MS analysis, especially by 2D‐NMR experiments. All xanthones were evaluated for their effects on α‐glucosidase. Compound 4 exhibited a potent inhibitory activity against α‐glucosidase with an IC 50 value of 0.24 mM (vs. 0.38 mM for acarbose). The rest of the compounds showed weak or no activity against α‐glucosidase.

Two new polyhydroxypregnane glycosides, namely cynotophyllosides I–J, were isolated from the roots of Cynanchum otophyllum, together with three known steroids, namely deacetylmetaplexigenin, sarcostin and hemoside. Their structures were established by extensive spectroscopic methods especially 2D NMR techniques) and acidcatalysed hydrolysis.

Novel specific 16S rDNA-targeted primers were successfully designed and applied to the characterization of endophytic diversity in Dendrobium officinale. Using the popular universal bacterial primers 27f/1492r, the fragments of chloroplast and mitochondrion 16S/18S rDNA were amplified from D. officinale. They shared high nucleotide identity with the chloroplast 16S rDNAs (99-100 %) and with the mitochondrion 18S rDNAs (93-100 %) from various plants, respectively, and both shared 73-86 % identities with the bacterial 16S rDNA sequences in GenBank. The current bacterial universal primers, including 27f/1492r, match well with the chloroplast and mitochondrion 16S/18S rDNAs, which accordingly renders these primers not useful for endophytic diversity analysis. Novel 16S rDNA-targeted primers fM1 (5'-CCGCGTGNRBGAHGAAGGYYYT-3') and rC5 (5'-TAATCCTGTTTGCTCC CCAC-3') were designed, which show good specificity compared to the 16S/18S rDNAs of D. officinale, and perfect universality within bacteria except for Cyanobacteria. The primers fM1/rC5, together with 515f-GC/rC5, which overlaps the whole V4 region of 16S rDNA, were subjected to nested polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) to analyze the diversity of endophytic bacteria in D. officinale from three different sources in China. The results showed diversities in roots and stems of the plants from all three locations. Altogether, 29 bands were identified as bacteria, with the dominant group being Proteobacteria and the dominant genus being Burkholderia, some of which commonly has the function of nitrogen fixation and thus may play potentially important roles in D. officinale. Therefore, the nested PCR-DGGE method based on the novel primers provides a good alternative for investigating the communities and roles of endophytes in D. officinale.

Two new polyhydroxypregnane glycosides, namely cynotophyllosides I-J, were isolated from the roots of Cynan-chum otophyllum, together with three known steroids, namely deacetylmetaplexigenin, sarcostin and hemoside. Their structures were established by extensive spectroscopic methods especially 2D NMR techniques) and acid-catalysed hydrolysis.