Objective:To isolate,purify,characterize,elucidate structure and evaluate bioactive compounds from the sponge-derived Salinispora sp.FS-0034.Methods:The symbiotic actinomycete strain FS-0034 with an interesting bioact...Objective:To isolate,purify,characterize,elucidate structure and evaluate bioactive compounds from the sponge-derived Salinispora sp.FS-0034.Methods:The symbiotic actinomycete strain FS-0034 with an interesting bioactivity profile was isolated from the Fijian marine sponge Theonella sp.Based on colony morphology and obligatory requirement of seawater for growth,and mycelia morphological characteristics the isolate FS-0034 was identified as a Salinispora sp.The bioactive compound was identified by using various spectral analysis of ultraviolet,high resolution electrospray ionization mass spectroscopy,H nuclear magnetic resonance,correlated spectroscopy and heteronuclear multiple bond coherence spectral data.A minimum inhibitory concentration assay were performed to evaluate the biological properties of the pure compound against multi-drug resistant pathogens.Results:Bioassay guided fractionation of the ethyl acetate extract of the culture of Salinispora sp.FS-0034 by different chromatographic methods yielded the isolation of an antibacterial compound,which was identified as rifamycin W(compound 1).Rifamycin W was reported for its potent antibacterial activity against methicillin-resistant Staphylococcus aureus,wild type Staphylococcus aureus and vancomycin-resistant Enterococcus faecium and displayed minimum inhibitory concentrations of 15.62,7.80 and 250.00 μg/mL,respectively.Conclusions:The present study reported the rifamycin W from sponge-associated Salinispora sp.and it exhibited appreciable antibacterial activity against multi-drug resistant human pathogens which indicated that sponge-associated Actinobacteria are significant sources of bioactive metabolites.展开更多
Nowadays,it is concern for researchers that due to high recombination rate of photogenerated charge carriers in tungsten trioxide(WO_(3)) nanoparticles,the future applications are limited in the field of photocatalysi...Nowadays,it is concern for researchers that due to high recombination rate of photogenerated charge carriers in tungsten trioxide(WO_(3)) nanoparticles,the future applications are limited in the field of photocatalysis.Herein we attempt to synthesize tungsten trioxide nanoparticles with different doping concentrations of lanthanum i.e.2 wt%,4 wt%,6 wt% and 8 wt%.The synthesized samples were characterized by using various characterization techniques:X-ray diffraction(XRD),Raman spectroscopy,Fourier transform infrared spectroscopy(FTIR),photoluminescence spectra(PL),transmission electron microscopy(TEM),energy dispersive X-ray(EDX) and UV-Vis spectroscopy.WO_(3) retains its monoclinic structure even after doping which was confirmed by XRD analysis.FTIR helps to descry functional groups present in the samples.The size of nanoparticles was calculated by using TEM.EDX confirms the absence of any impurity in the synthesized samples.Raman spectroscopy confirms the presence of a large number of imperfections induced in the lattice of WO_(3).The rate of recombination was analyzed by photoluminescence(PL) spectroscopy and is minimum in 4 wt% doping of lanthanum.The optical bandgap was calculated using UV-Vis spectroscopy and becomes narrow along with the doping concentrations.Intriguingly,it is found that doping of La in WO_(3) has considerably ameliorate the photocatalytic activity by reducing rate of recombination due to the trapping of electrons by defects introduced in the lattice.Photocatalytic decolorization of Rhodamine B(RhB) dye was performed and the values of c/c_0 and rate constant(k) confirm that the 4 wt% doping shows maximum degradation efficiency.The kinetic study for photodegradation of Rhodamine B was done by using various kinetic models and results show that the reaction follows first order kinetics very well.Therefore,optimum doping of lanthanum increases the decolorization ability of WO_(3) towards RhB dye.展开更多
基金Support from the U.S.National Institutes of Health's International Cooperative Biodiversity Groups Program(Grant NO.NIH ICBG U01-TW007401)
文摘Objective:To isolate,purify,characterize,elucidate structure and evaluate bioactive compounds from the sponge-derived Salinispora sp.FS-0034.Methods:The symbiotic actinomycete strain FS-0034 with an interesting bioactivity profile was isolated from the Fijian marine sponge Theonella sp.Based on colony morphology and obligatory requirement of seawater for growth,and mycelia morphological characteristics the isolate FS-0034 was identified as a Salinispora sp.The bioactive compound was identified by using various spectral analysis of ultraviolet,high resolution electrospray ionization mass spectroscopy,H nuclear magnetic resonance,correlated spectroscopy and heteronuclear multiple bond coherence spectral data.A minimum inhibitory concentration assay were performed to evaluate the biological properties of the pure compound against multi-drug resistant pathogens.Results:Bioassay guided fractionation of the ethyl acetate extract of the culture of Salinispora sp.FS-0034 by different chromatographic methods yielded the isolation of an antibacterial compound,which was identified as rifamycin W(compound 1).Rifamycin W was reported for its potent antibacterial activity against methicillin-resistant Staphylococcus aureus,wild type Staphylococcus aureus and vancomycin-resistant Enterococcus faecium and displayed minimum inhibitory concentrations of 15.62,7.80 and 250.00 μg/mL,respectively.Conclusions:The present study reported the rifamycin W from sponge-associated Salinispora sp.and it exhibited appreciable antibacterial activity against multi-drug resistant human pathogens which indicated that sponge-associated Actinobacteria are significant sources of bioactive metabolites.
基金supported by the National Project Implementation Unit (NPIU),a unit of Ministry of Human Resource Development (MHRD),Government of India,for the financial assistantship TEQIP-Ⅲ Project at Deenbandhu Chhotu Ram University of Science and Technology,Murthal,Haryana,the DST,India for sanctioning the DST-FIST project (SR/FST/PS-I/2012/32)。
文摘Nowadays,it is concern for researchers that due to high recombination rate of photogenerated charge carriers in tungsten trioxide(WO_(3)) nanoparticles,the future applications are limited in the field of photocatalysis.Herein we attempt to synthesize tungsten trioxide nanoparticles with different doping concentrations of lanthanum i.e.2 wt%,4 wt%,6 wt% and 8 wt%.The synthesized samples were characterized by using various characterization techniques:X-ray diffraction(XRD),Raman spectroscopy,Fourier transform infrared spectroscopy(FTIR),photoluminescence spectra(PL),transmission electron microscopy(TEM),energy dispersive X-ray(EDX) and UV-Vis spectroscopy.WO_(3) retains its monoclinic structure even after doping which was confirmed by XRD analysis.FTIR helps to descry functional groups present in the samples.The size of nanoparticles was calculated by using TEM.EDX confirms the absence of any impurity in the synthesized samples.Raman spectroscopy confirms the presence of a large number of imperfections induced in the lattice of WO_(3).The rate of recombination was analyzed by photoluminescence(PL) spectroscopy and is minimum in 4 wt% doping of lanthanum.The optical bandgap was calculated using UV-Vis spectroscopy and becomes narrow along with the doping concentrations.Intriguingly,it is found that doping of La in WO_(3) has considerably ameliorate the photocatalytic activity by reducing rate of recombination due to the trapping of electrons by defects introduced in the lattice.Photocatalytic decolorization of Rhodamine B(RhB) dye was performed and the values of c/c_0 and rate constant(k) confirm that the 4 wt% doping shows maximum degradation efficiency.The kinetic study for photodegradation of Rhodamine B was done by using various kinetic models and results show that the reaction follows first order kinetics very well.Therefore,optimum doping of lanthanum increases the decolorization ability of WO_(3) towards RhB dye.