One important feature of the major opportunistic human pathogen Staphylococcus aureus is its extraordinary ability to rapidly acquire resistance to antibiotics. Genomic studies reveal that S. aureus carries many virulence and resistance genes located in mobile genetic elements, suggesting that horizontal gene transfer (HGT) plays a critical role in S. aureus evolution. However, a full and detailed description of the methodology used to study HGT in S. aureus is still lacking, especially regarding natural transformation, which has been recently reported in this bacterium. This work describes three protocols that are useful for the in vitro investigation of HGT in S. aureus: conjugation, phage transduction, and natural transformation. To this aim, the cfr gene (chloramphenicol/florfenicol resistance), which confers the Phenicols, Lincosamides, Oxazolidinones, Pleuromutilins, and Streptogramin A (PhLOPSA)-resistance phenotype, was used. Understanding the mechanisms through which S. aureus transfers genetic materials to other strains is essential to comprehending the rapid acquisition of resistance and helps to clarify the modes of dissemination reported in surveillance programs or to further predict the spreading mode in the future.
From Lumnitzera racemosa Willd., a new glycoside, 2-O-galloyl-α-L-rhamnopyranosyl-(34)-3-O-galloyl-α-L-rhamnopyranose (1), as well as nine known compounds were isolated. Their chemical structures were elucidated by spectroscopic data analysis as well as comparison with the ones in the literature. The evaluation of α-glucosidase inhibitory activity of the extracts and some isolated compounds was measured.
A new flavone glycoside, lumnitzerone (1), was isolated from leaves of Lumnitzera littorea, together with 9 known flavonoids. Their structures were elucidated by spectroscopic (one-dimensional, two-dimensional nuclear magnetic resonance) and high-resolution mass spectrometry analysis, and comparison with literature data. Extracts and all isolated compounds were evaluated for α-glucosidase inhibitory activity; all the extracts and most of the isolated compounds exhibited better activities than the positive control acarbose.
A new benzofuran derivative, pumiloside (1), together with seven known flavonoid glycosides, afzelin (2), astragalin (3), quercitrin (4), isoquercitrin (5), kaempferol 3-O-rutinoside (6), rutin (7) and kaempferol 3-O-sophoroside (8) were isolated from the leaves of Ficus pumila. Their structures were established by spectroscopic data and comparison with the literature values.
Caryota mitis L., a flowering plant, belongs to the family Arecaceae. In Vietnam, its fruits were used to treat joint pain. The present study was designed to investigate the phytochemicals and chondrocyte proliferation activity of C. mitis L. fruits on young human chondrocyte. The results showed that all of extracts (crude extract as well as n-hexane, chloroform, ethyl acetate and methanol fractions) were stimulated the growth of chondrocyte at 0.1 μg/mL; 0.01 μg/mL concentrations, of which the n-hexane and methanol fractions significantly increased the proliferation of chondrocyte by 30.75 and 24.42% at concentrations of 0.01 μg/mL, respectively. Repeated chromatography of the methanol fraction on silica gel, Sephadex LH-20 and ODS columns afforded a new cerebroside and eight known ones. Their structures were elucidated by analysis of spectral data and in comparison with the published reports.
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