Composition of three essential oils, and their mammalian cell toxicity and antimycobacterial activity against drug resistant-tuberculosis and nontuberculous mycobacteria strains

Abstract

Tuberculosis (TB) is the most ancient epidemic disease in the world and a serious opportunistic disease in HIV/AIDS patients. The increase in multidrug resistant Mycobacterium tuberculosis (MDR-TB, XDR-TB) demands the search for novel antimycobacterial drugs. Essential oils (EOs) have been widely used in medicine and some EOs and their major components have been shown to be active against M. tuberculosis. The aim of this work was to evaluate the antimycobacterial and cell toxicity activities of three EOs derived from Salvia aratocensis, Turnera diffusa and Lippia americana, aromatics plants collected in Colombia. The EOs were isolated by hydrodistillation and analyzed by GC/MS techniques. The EOs were tested against 15 Mycobacterium spp using a colorimetric macrodilution method and against mammalian Vero and THP-1 cells by MTT. The activity was expressed as minimal concentration in μg/mL that inhibits growth, and the concentration that is cytotoxic for 50 or 90% of the cells (CC50 and CC90). The major components were epi-α-cadinol (20.1%) and 1,10-diepi- cubenol (14.2%) for Salvia aratocensis; drima-7,9(11)-diene (22.9%) and viridiflorene (6.6%) for Turnera diffusa; and germacrene D (15.4%) and trans-β- caryophyllene (11.3%) for Lippia americana. The most active EO was obtained from S. aratocensis, with MIC values below 125 μg mL-1 for M. tuberculosis Beijing genotype strains, and 200 to 500 μg mL-1 for nontuberculous mycobacterial strains. The EOs were either partially or non toxic to Vero and THP-1 mammalian cells with CC50 values from 30 to >100 μg mL-1, and a CC90 >100 μg mL-1. The EOs obtained from the three aromatic Colombian plants are an important source of potential compounds against TB. Future studies using the major EO components are recommended.