[Analyses on distribution and structure of blaCARB-2 in Klebsiella pneumoniae].

In order to characterize the structure of the beta-lactamase gene and its corresponding mobile genetic elements in Klebsiella pneumoniae, the beta-lactamase genes from 240 clinical Klebsiella pneumoniae isolates were studied. blaCARB-2, a newly characterized gene, was extensively investigated utilizing next-generation sequencing, PCR, molecular cloning, conjugation, and comparative genomics analysis. We identified 11 beta-lactamase genes among the 240 clinical Klebsiella pneumoniae isolates; the blaCARB-2 gene exists only in one specific isolate (Klebsiella pneumoniae KP1276) (1/240, 0.42%). The blaCARB-2 gene lies on a conjugative plasmid pKP1276-82, a 182,450-bp plasmid, which encodes 222 open reading frames. The plasmid has seven resistance genes, termed blaCARB-2, blaKLUC, aadA1, aadA2, cmlA1, dfrA1, and sul2. Among these genes, blaCARB-2 was identified for the first time in Klebsiella pneumoniae. Four of these resistance genes and an int gene form a class 1 integron (int-blaCARB-2-aadA2-cmlA1-aadA1). Further studies show that the blaCARB-2, aadA2, and cmlA1 genes are resistant to their corresponding antibiotics and the blaCARB-2 exhibits higher resistance activities to penicillin beta-lactams. These results reveal the possibility of horizontal transfer of the resistance genes and dissemination of resistance among bacteria of different genera or species of Enterobacteriaceae.

A new dibenzofuran and other constituents from Ligularia caloxantha, a Chinese medicinal plant.

A new dibenzofuran named 1,2,4-trimethyl-7,8-dimethoxy-dibenzofuran (1), together with seven known compounds, euparin (2), 2,5-diacetyl-6-hydroxy-benzofuran (3), 2-acetyl-5,6-dimethoxy-benzofuran (4), gummosogenin (5), lupeol (6), stigmasterol (7) and (E)-2,5-dihydroxy-cinnamic acid (8), were isolated from the roots of Ligularia caloxantha, a Chinese medicinal plant. The structures of the compounds were elucidated by spectroscopic methods.

Simultaneous determination of three flavonoid aglycones in Elsholtzia blanda by adopting orthogonal test and high-performance liquid chromatography.

A new HCl hydrolysis/HPLC method, by adopting L9(34) orthogonal test to optimize hydrolysis condition, has been developed for simultaneous determination of three flavonoid aglycones in Elsholtzia blanda benth. The HCl concentration, methanol concentration, hydrolysis temperature, hydrolysis time are taking as four inspecting foctors, and the contents of luteolin, apigenin, and 5-hydroxy-6,7-dimethoxyflavone in hydrolytic solution are used as the evaluation indexes. Agilent Zorbax SB-C18 is used as analytical column. The mobile phase is a mixture of methanol-0.2% phosphoric acid (70:30, v/v), and UV detector is set at 350 nm. The flow rate is 1.0 mL/min, the temperature of column is maintained at 30 degrees C. The optimal hydrolysis conditions are 3.0M HCl, 70% methanol, 85 degrees C hydrolytic temperature and 3 h hydrolytic time. Standard curves are linear over the concentration range 8.54-85.4 microg/mL, 1.2-12 microg/mL, 9.2-92 microg/mL, and their average recoveries are 96.8%, 98.0%, and 100.5% for luteolin, apigenin, 5-hydroxy-6, 7-dimethoxyflavone, respectively. Thus, the optimum hydrolysis condition is relatively gentle, and the HPLC method is proved to be simple, accurate, and sensitive, so it will be able be applied to quality control of medicinal plant of Elsholtzia blanda.

[Studies on chemical constituents of green algae Ulva pertusa].

OBJECTIVE: To study the compounds from Ulva pertusa. METHOD: The alga was extracted with ethanol, isolated and purified by column chromatography on silica gel and sephadex LH -20. All the compounds were identified on the basis of spectral analysis (including IR, MS, NMR). RESULT: Seven compounds were elucidated as cis-asarone (1), trans-asarone (2), gamma-asarone (3), trans-phytol (4), phytyl-stearate (5), phytyl-acetate (6), isophytol (7). CONCLUSION: All other compounds were isolated for the first time from U. pertusa, except for the compound 4.

Endothelium-dependent and direct relaxation induced by ethyl acetate extract from Flos Chrysanthemi in rat thoracic aorta.

The aims of the present study were to investigate the vasoactive effects of ethyl acetate extract from Flos Chrysanthemi (FCE) and its mechanisms on the rat thoracic aorta. FCE (9.4-150 mg/L) caused a concentration-dependent relaxation on endothelium-intact rings precontracted with phenylephrine (PE, 10(-6)M) or a high level of K+ (6x10(-2)M). By removal of endothelium, the effect was not abolished but reduced significantly. N(G)-nitro-l-arginine methyl ester (l-NAME) (10(-4) M), methylene blue (10(-5) M) significantly inhibited the effect of FCE. Meanwhile, NO synthase of aorta in FCE group was markedly elevated versus the control. However, indomethacin did not influence FCE effect. SKF-525A combined with l-NAME had the same effect as l-NAME. Tetraethylammonium, BaCl2, 4-aminopyridine, 5-HD and propranolol also did not influence the vascular effect of FCE, but glibenclamide significantly attenuated its vasodilation. FCE did not reduce PE-induced transient contraction in Ca(2+)-free medium, but inhibited PE-induced contraction in K(+)-free solution or Ca2+ caused contraction after PE induced a stable contraction in Ca(2+)-free solution. It is concluded that FCE induced both endothelium-dependent and -independent relaxation. NO and cGMP-mediated pathway are likely involved in the endothelium-dependent relaxation, whereas inhibition of voltage-dependent Ca2+ channel, receptor-operate Ca2+ channel and activation of K(ATP) contribute in part to the endothelium-independent relaxation.