Luna-Herrera J, Costa M C, González H G, Rodrigues A I, Castilho P C
Departamento de Inmunología, Escuela Nacional de Ciencias Biológicas, IPN, Prolongacion de Carpio y Plan de Ayala S/N, 11430, México City, Mexico.
J Antimicrob Chemother. 2007 Mar;59(3):548-52. doi: 10.1093/jac/dkl523. Epub 2007 Jan 11.
The aim of this study was to determine the antimycobacterial potential of laurel oil, its fractions and its two sesquiterpene lactones against several mycobacterial strains and clinical isolates, and to establish the possibility of occurrence of some synergistic effects between those lactones using a modification of the fluorometric Alamar Blue microassay (FMABA).
The in vitro antimycobacterial activity of whole oil and its fractions and pure active compounds were determined by FMABA. A bioassay-guided fractionation of the traditional preparation of laurel oil from Madeira Islands was performed, yielding pure compounds chemically identified by standard procedures. Synergism of pure compounds was established by X/Y quotient analysis adapted to FMABA.
Sesquiterpene lactones, costunolide and dehydrocostuslactone, were the compounds responsible for the antimycobacterial activity against Mycobacterium tuberculosis H37Rv with MICs of 6.25 and 12.5 mg/L, respectively. Antimycobacterial activity against drug-resistant M. tuberculosis clinical isolates was better for the mixture than for pure compounds.
Both lactones presented synergistic activity, i.e. analysis of relative fluorescence units presented an X/Y value <0.5 at a concentration of 1/8 MIC of each compound in the combination. Establishment of synergism by FMABA represents another application of the microplate Alamar Blue assay.
本研究旨在确定月桂油及其馏分和两种倍半萜内酯对几种分枝杆菌菌株和临床分离株的抗分枝杆菌潜力，并使用荧光Alamar蓝微量法（FMABA）的改良方法确定这些内酯之间产生某些协同效应的可能性。
通过FMABA测定全油及其馏分和纯活性化合物的体外抗分枝杆菌活性。对来自马德拉群岛的月桂油传统制剂进行生物测定指导的分级分离，得到通过标准程序化学鉴定的纯化合物。通过适用于FMABA的X/Y商数分析确定纯化合物的协同作用。
倍半萜内酯、木香烯内酯和脱氢木香内酯是对结核分枝杆菌H37Rv具有抗分枝杆菌活性的化合物，其最低抑菌浓度分别为6.25和12.5mg/L。混合物对耐多药结核分枝杆菌临床分离株的抗分枝杆菌活性优于纯化合物。
两种内酯均具有协同活性，即在组合中每种化合物的1/8最低抑菌浓度下，相对荧光单位分析显示X/Y值<0.5。通过FMABA确定协同作用代表了微孔板Alamar蓝测定的另一种应用。
