1. Metal-free and regiospecific synthesis of 3-arylindoles
Chuangchuang Xu, Wenlai Xie, Jiaxi Xu Org Biomol Chem. 2020 Apr 8;18(14):2661-2671. doi: 10.1039/d0ob00317d.
A convenient, metal-free, and organic acid-base promoted synthetic method to prepare 3-arylindoles from 3-aryloxirane-2-carbonitriles and arylhydrazine hydrochlorides has been developed. In the reaction, the organic acid catalyzes a tandem nucleophilic ring-opening reaction of aryloxiranecarbonitriles and arylhydrazine hydrochlorides and Fischer indolization. The organic base triethylamine plays a crucial role in the final elimination step in the Fischer indole synthesis, affording 3-arylindoles regiospecifically. The reaction features advantages of microwave acceleration, non-metal participation, short reaction time, organic acid-base co-catalysis, and broad substrate scope.
2. Antifungal effect of high- and low-molecular-weight chitosan hydrochloride, carboxymethyl chitosan, chitosan oligosaccharide and N-acetyl-D-glucosamine against Candida albicans, Candida krusei and Candida glabrata
F Seyfarth, S Schliemann, P Elsner, U-C Hipler Int J Pharm. 2008 Apr 2;353(1-2):139-48. doi: 10.1016/j.ijpharm.2007.11.029. Epub 2007 Nov 23.
Objectives: Generally, chitosan is a water-insoluble polyaminosaccharide with antimicrobial activity. The antifungal activity of water-soluble low- and high-molecular-weight chitosan hydrochloride, carboxymethyl chitosan, chitosan oligosaccharide and N-acetyl-d-glucosamine against Candida albicans, Candida krusei and Candida glabrata was investigated. Methods: Solutions of the tested substances in different concentrations (1, 0.5, 0.25, 0.1, 0.05, 0.025, 0.01, 0.005, and 0.0025%) were prepared and the influence on C. albicans DSM 11225, C. krusei ATCC 6258 and C. glabrata DSM 11226 was investigated. Yeasts (3 x 10(5) cells/mL) were incubated with Sabouraud liquid medium at 30 degrees C. Measurements were done with a microplate nephelometer (NEPHELOstar Galaxy, BMG LABTECH Ltd.) for 24 h. High values of light scattering correlate with strong cultural growth. Results were shown as growth curves and histograms displaying 24 h end points. These were compared with control by Mann-Whitney test. Furthermore, MIC(50%), MIC(80%) and Spearman correlation coefficients were calculated. Results: C. albicans and C. krusei were the most sensitive species. C. glabrata was also inhibited, whereas 1% of tested substances could not prevent its growth completely. However, only both chitosan hydrochlorides showed a definite antifungal effect with high correlation between inhibition and test concentration. Carboxymethyl chitosan, chitosan oligosaccharide and N-acetyl-D-glucosamine showed only a weak or no antifungal activity, respectively. Conclusions: Antifungal activity decreases with declining molecular mass (chitosan oligosaccharide and N-acetyl-D-glucosamine) and increasing masking of the protonated amino groups with functional groups (carboxymethyl chitosan).
