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Cao M.-M.,CAS Kunming Institute of Botany | Cao M.-M.,University of Chinese Academy of Sciences | Huang S.-D.,CAS Kunming Institute of Botany | Di Y.-T.,CAS Kunming Institute of Botany | And 5 more authors.
Organic Letters | Year: 2014

One Myrioneuron alkaloid, myrifabine (1), the first example of a dimer with 12 chiral centers embraced in a decacyclic novel skeleton, was isolated from Myrioneuron faberi. Its structure was elucidated by spectroscopic data and single-crystal X-ray diffraction. The antimicrobial and cytotoxic activities of 1 were evaluated in vitro. © 2013 American Chemical Society.

Fu P.,Ocean University of China | Kong F.,Ocean University of China | Wang Y.,Research Center for Natural Medicines | Wang Y.,Yunnan Traditional Chinese Medical College | And 4 more authors.
Chinese Journal of Chemistry | Year: 2013

From the oligotrophic culture of a soft coral-associated actinomycetes strain, Streptomyces sp. OUCMDZ-1703, we isolated and identified two new chlorinated polyketides that we named strepchloritides A and B (1 and 2), three thiazole derivatives known as watasemycin A (3), pulicatin G (4) and aerugine (5), along with pyrrole-2-carboxamide, furan-2-carboxamide and 1-(3,5-dihydroxyphenyl)ethanone. The new structures of 1 and 2 were determined by spectroscopic studies such as 1D- and 2D-NMR and MS analyses, while the known compounds were identified by comparison of the NMR data with those in literatures. The results showed that actinomycete strain OUCMDZ-1703 could use the relative high ratio of chlorine in the oligotrophic medium to synthesize chlorinated natural products. New compounds 1 and 2 displayed cytotoxicity against the MCF-7 cells with IC50 values of 9.9 and 20.2 μmol·L-1, respectively. Thiazole derivatives 3 and 5 were first found to be active against three clinical strains of methicillin-resistant Staphylococcus aureus (MRSA082, MRSA111 and MRSA234) with the same MIC/MBC values of 7.81/7.81 μg·mL-1. Copyright © 2013 SIOC, CAS, Shanghai & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An J.,Research Center for Natural Medicines | An J.,Guiyang Medical University | Zuo G.Y.,Research Center for Natural Medicines | Hao X.Y.,Guiyang Medical University | And 2 more authors.
Phytomedicine | Year: 2011

The in vitro antibacterial activity of taxifolin-7-O-α-l- rhamnopyranoside (TR) and its synergy with four conventional antibiotics (ampicillin (AMP), levofloxacin (LEV), ceftazidime (CAZ) and azithromycin (AZM)) against ten clinical isolates of methicillin-resistant staphylococcus aureus (MRSA) were evaluated, respectively. Individual MICs and MBCs were determined by microdilution methods following the CLSI guidelines. Anti-MRSA synergy effects were measured using the chequerboard and time-kill curve tests. MICs/MBCs (μg/ml) ranges were 32-64/64-128 for TR alone against all 10 MRSA isolates. Chequerboard method showed that significant synergies were observed for the TR/CAZ and TR/LEV combinations with FICI ranged 0.187-0.375 and 0.25-0.5, respectively. Some synergy and additivity effects were also observed for TR/AMP and TR/AZM combinations. In the time-kill dynamic confirmation test, synergy results kept by the TR/CAZ combination (2.186 log 10 cfu/ml increase in killing), but the TR/LEV combination changed to additivity (1.839 log 10 cfu/ml increase in killing). These results demonstrated that TR enhanced the efficacy of CAZ and LEV in vitro, which had potential for combinatory therapy of patients infected with MRSA. © 2011 Elsevier GmbH. All rights reserved.

Zuo G.-Y.,Research Center for Natural Medicines | Li Y.,Research Center for Natural Medicines | Li Y.,Kunming Medical College | Han J.,Yunnan Traditional Chinese Medical College | And 3 more authors.
Molecules | Year: 2012

Antibacterial activity of berberine (Ber) and 8-acetonyl-dihydroberberine (A-Ber) alone and combined uses with antibacterial agents ampicillin (AMP), azithromycin (AZM), cefazolin (CFZ) and levofloxacin (LEV) was studied on 10 clinical isolates of SCCmec III type methicillin-resistant Staphylococcus aureus (MRSA). Susceptibility to each agent alone was tested using a broth microdilution method and the chequerboard and time-kill tests for the combined evaluations, respectively. The alone MICs/MBCs (μg/mL) ranges were 32-128/64-256 (Ber) and 32-128/128-512 (A-Ber). Significant synergies were observed for the Ber (A-Ber)/AZM and Ber (A-Ber)/LEV combinations against 90% of the tested MRSA strains, with fractional inhibitory concentration indices (FICIs) values ranged from 0.188 to 0.500. An additivity result was also observed for the Ber/AZM combination by time-kill curves. These results demonstrated for the first time that Ber and A-Ber enhanced the in vitro inhibitory efficacy of AZM and LEV to a same extent, which had potential for further investigation in combinatory therapeutic applications of patients infected with MRSA. © 2012 by the authors.

Zuo G.Y.,Research Center for Natural Medicines | Han Z.Q.,Research Center for Natural Medicines | Han Z.Q.,Guiyang Medical University | Hao X.Y.,Guiyang Medical University | And 3 more authors.
Phytomedicine | Year: 2014

The in vitro antimicrobial activities of three 3-Benzylchroman derivatives, i.e. Brazilin (1), Brazilein (2) and Sappanone B (3) from Caesalpinia sappan L. (Leguminosae) were assayed, which mainly dealt with synergistic evaluation of aminoglycoside and other type of antibiotics against methicillin-resistant Staphylococcus aureus (MRSA) by the three compounds through the Chequerboard and Time-kill curve methods. The results showed that Compounds 1-3 alone exhibited moderate to weak activity against methicillin-susceptible S. aureus (MSSA) and other standard strains by MICs/MBCs ranged from 32/64 to >1024/>1024 μg/ml, with the order of activity as 1 > 2 > 3. Chequerboard method showed significant anti-MRSA synergy of 1/Aminoglycosides (Gentamicin, Amikacin, Etimicin and Streptomycin) combinations with (FICIs)50 at 0.375-0.5. The combined (MICs)50 values (μg/ml) reduced from 32-128/16-64 to 4-8/4-16, respectively. The percent of reduction by MICs ranged from 50% to 87.5%, with a maximum of 93.8% (1/16 of the alone MIC). Combinations of 2 and 3 with Aminoglycosides and the other antibiotics showed less potency of synergy. The dynamic Time-killing experiment further demonstrated that the combinations of 1/aminoglycoside were synergistically bactericidal against MRSA. The anti-MRSA synergy results of the bacteriostatic (Chequerboard method) and bactericidal (time-kill method) efficiencies of 1/Aminoglycoside combinations was in good consistency, which made the resistance reversed by CLSI guidelines. We concluded that the 3-Benzylchroman derivative Brazilin (1) showed in vitro synergy of bactericidal activities against MRSA when combined with Aminoglycosides, which might be beneficial for combinatory therapy of MRSA infection. © 2014 Published by Elsevier GmbH.

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