| Resumo: |
Fatty acids, especially those from phospholipids (PLFA), are essential membrane components, present in a relatively constant proportion in the biological membranes under natural conditions. However, under harmful growth conditions such as diseases, environmental changes and chemical exposure, the proportion of lipids may vary. Once these changes could be identified and revel to be specific for such adverse situation, it could be used as a biomarker. Thus, the biomarkers can help, for example, to identify a virulence and resistance mechanism to a particular chemotherapeutic agent. Therefore, to make treatment more effective, a specific biomarker could lead to a better therapeutic decision, regarding candidate drugs and their indications. The objective of this study was to compare the fatty acid profiles of L. chagasi and L. amazonesis isolates resistant and sensitive to antimony (Glucantime ®) and to nitric oxide (NO). We studied 2 isolates of L. amazonensis and 8 of L. chagasi. Total lipids were extracted from lyophilized promastigotes forms in late logarithmic growth phase (50 mL; 5x108/mL cells). Fatty acid methyl esters (FAMEs) were obtained from total lipids, ester-linked lipids and ester-linked phospholipids by MIDI, ELFA and PLFA techniques respectively. FAMEs were analyzed by chromatography and mass spectrometry. Differences in FAME profiles associated with species or resistance were assessed by non-metric multidimensional scaling, multiresponse permutation procedures and indicator species analyses using PC-ORD 6.0. Previously to these analyses, molar masses of individual FAMEs were relativized by FAMEs totals within each sample. Isolates resistant and sensitive to NO and antimony had different MIDI-FAME profiles, regardless the species. However, neither ELFA nor PLFA profiles differed between sensitive and resistant isolates. The fatty acid 18:1 δ9c was increased in sensitive isolates (p<0,001), whereas an yet unidentified peak showed the opposite trend (p<0,01). We can conclude that these two fatty acids are potential biomarkers for NO and antimony resistance in L. chagasi and L. amazonesis and they can be helpful for therapeutical diagnosis. |
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