[Research advances in drug resistance mechanisms of bacterial biofilm and natural drug intervention].

Drug resistance resulting from bacterial biofilms can invalidate antibacterial agents. Therefore,eradicating bacterial biofilms to reverse drug resistance is a hotspot in the pharmaceutical research. In recent years,numerous studies have revealed the complicated mechanism of bacterial biofilm formation and strong drug resistance with multiple influential factors involved. This paper gives a comprehensive review on the process of biofilm formation and intervention by natural drugs,which can provide some reference and evidence for the following studies.

Neoflavonoids from the heartwood of Dalbergia melanoxylon.

Three new neoflavonoids, named (1S,8R,9S)-1,5-dihydroxy-4,12-dimethoxy-8-vinyl-tricyclo[7.3.1.02,7]trideca-2,4,6,11-tetraen-10-one (1), 2,5,2',5'-tetrahydroxy-4-methoxybenzophenone (2) and 2,5,3'-trihydroxy-4-methoxybenzophenone (3), were isolated from the heartwood of Dalbergia melanoxylon. Their structures were established by spectroscopic methods, including UV, IR, HRMS, 1 D and 2 D-NMR. Compounds 1-3 were evaluated for inhibitory activity against three fungal strains Candida albicans, Mucor ramosissimus, Saccharomycopsis fermentans and seven bacterial strains Shigella dysenteriae, Salmonella enteri, Bacillus cereus, Staphylococcus epidermidis, Bacillus sphaericus, Staphylococcus aureus, Escherichia coli using the broth dilution method. However, none of compounds 1-3 showed potential antimicrobial activities in vitro.

An electrochemical Hg2+ sensor based on signal amplification strategy of target recycling.

In this work, an unmodified homogeneous electrochemical sensor based on electrochemical bonding and catalytic hairpin assembly (CHA) was first constructed for the high sensitivity detection of Hg2+. Herein, tetraferrocene, a synthesized compound, was used as a signal marker that modified both ends of the hairpin probe to amplify the electrochemical signal. The interaction of T-Hg2+-T could induce the catalytic self-assembly of hairpins by means of auxiliary DNA. The rigid DNA triangle that was formed easily reaches the electrode and induced Au-S self-assembly assisted by potential, allowing tetraferrocene to reach the electrode surface and generate a sensitive electrochemical signal. CHA and tetraferrocene signal markers accomplished dual signal amplification, and the limit of detection was 0.12 pM. Differential pulse voltammetry experiments in the presence of tetraferrocene redox indicator show that the linear response range of electrochemical biosensors to mercury ions is 0.2-2000 pM, This technology offers good selectivity and high recognition efficiency for the detection of mercury ions and has broad application prospects in actual sample detection.

Two new compounds from the heartwood of Dalbergia melanoxylon.

A new neoflavonoid, named S(+)-3'-hydroxy-4',2,4,5-tetramethoxydalbergiquinol (1), and a new benzofuran, named (2S,3S)-5-hydroxy-6-methoxy-3-methyl-2-(4'-hydroxyphenyl)-2,3dihydrobenzofuran (4), together with two known neoflavonoids, were isolated from the heartwood of Dalbergia melanoxylon. Their structures were elucidated by a combination of spectroscopic methods and comparison with the literature. Compounds 1-4 were evaluated for inhibitory activity against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 6538, Salmonella enteri CMCC 50041 and Candida albicans ATCC 289065, which all exhibited inactive or weak activity.

The anti-diabetic activities, gut microbiota composition, the anti-inflammatory effects of Scutellaria-coptis herb couple against insulin resistance-model of diabetes involving the toll-like receptor 4 signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Scutellaria-coptis herb couple (SC) is one of the well-known herb couples in many traditional Chinese compound formulas used for the treatment of diabetes mellitus (DM), which has been used to treat DM for thousands of years in China. AIM OF THE STUDY: Few studies have confirmed in detail the anti-diabetic activities of SC in vivo and in vitro. The present investigations aimed to evaluate the anti-diabetic activity of SC in type 2 diabetic KK-Ay mice and in RAW264.7 macrophages to understand its possible mechanism. MATERIALS AND METHODS: High-performance liquid chromatography with ultraviolet detection (HPLC-UV) and LC-LTQ-Orbitrap Pro mass spectrometry were used to analyze the active ingredients of SC extracts and control the quality. A type 2 diabetic KK-Ay mice model was established by high-fat diet. Body weight, fasting blood glucose levels, fasting blood insulin levels, glycosylated hemoglobin and glycosylated serum protein were measured. The effects of SC on total cholesterol (TC), high-density lipoprotein (HDL) and triglyceride (TG) levels were examined. The lipopolysaccharide (LPS), interleukin-6 (IL-6) and tumour necrosis factor alpha (TNF-α) levels were measured. Gut microbial communities were assayed by polymerase chain reaction (PCR) and PCR-denaturing gradient gel electrophoresis (PCR-DGGE) methods. The expressions of Toll-like receptor 4 (TLR4) and MyD88 protein in the colons were measured by western blot. In RAW264.7 macrophages, IL-6, TNF-α, TLR4 and MyD88 protein levels were measured by enzyme-linked immunosorbent assay (ELISA) kits or western blot, and the mRNA expression of IL-6, TNF-α and TLR4 was examined by the real time PCR. RESULTS: The present results showed that the SC significantly increased blood HDL and significantly reduced fasting blood glucose, fasting blood insulin, glycosylated hemoglobin, glycosylated serum protein, TC, TG, LPS, IL-6 and TNF-α levels (P < 0.05 or P < 0.01) in type-2 diabetic KK-Ay mice. Furthermore, SC could regulate the structure of intestinal flora. Additionally, the expressions of TLR4 and MyD88 protein in the colons were significantly decreased in the model group (P < 0.05 or P < 0.01). However, SC had no significant effect on weight gain. In RAW264.7 macrophages, SC containing serum (SC-CS) (5%, 10% and 20%) significantly decreased IL-6, TNF-α, TLR4 and MyD88 protein levels and the mRNA expression of IL-6, TNF-α and TLR4 (P < 0.05 or P < 0.01). CONCLUSIONS: The anti-diabetic effects of SC were attributed to its regulation of intestinal flora and anti-inflammation involving the TLR4 signaling pathway. These findings provide a new insight into the anti-diabetic application for SC in clinical settings and display the potential of SC in the treatment of DM.

Chemical composition and antioxidant activities of essential oils from different parts of the oregano.

This research was undertaken in order to characterize the chemical compositions and evaluate the antioxidant activities of essential oils obtained from different parts of the Origanum vulgare L. It is a medicinal plant used in traditional Chinese medicine for the treatment of heat stroke, fever, vomiting, acute gastroenteritis, and respiratory disorders. The chemical compositions of the three essential oils from different parts of the oregano (leaves-flowers, stems, and roots) were identified by gas chromatography-mass spectrometry (GC-MS). The antioxidant activity of each essential oil was assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and reducing the power test. Among the essential oils from different parts of the oregano, the leaf-flower oils have the best antioxidant activities, whereas the stem oils are the worst. The results of the DPPH free radical scavenging assay showed that the half maximal inhibitory concentration (IC50) values of the essential oils were (0.332±0.040) mg/ml (leaves-flowers), (0.357±0.031) mg/ml (roots), and (0.501±0.029) mg/ml (stems), respectively. Interestingly, the results of reducing the power test also revealed that when the concentration exceeded 1.25 mg/ml, the leaf-flower oils had the highest reducing power; however, the stem oils were the lowest.

A new pyridine alkaloid from Zingiberis rhizoma.

A new alkaloid, named 2-methoxy-4-(2-(2-pyridine)-ethyl) phenol (1), together with two known compounds, was isolated from Zingiberis rhizoma. Their structures were elucidated on the basis of 1D and 2D NMR spectra and MS spectra. Compound 1 exhibited substantial bioactivity against Canidia albicans ATCC 10231 with a minimum inhibitory concentration of 1.0 mg/mL.