Essential Oil Composition and Antibacterial Activity of Trixis michuacana Lex. var. michuacana and Trixis michuacana var. longifolia

The Trixis genus (Asteraceae) is involved in traditional medicine from Latinoamerica. In Mexico, Trixis michuacana Lex. var. michoacana and T. michuacana var. longifolia are used in the P'urhepecha ethnomedicine. The analysis of their volatile compounds by gas chromatography/mass spectrometry (GC-MS) is described herein. The sesquiterpene compounds were the main constituents. beta-Caryophyllene (10.80%), germacrene D (7.93%), beta-elemene (7.42%), and gamma-elemene (7.37%) highlighted from var. michuacana, while beta-elemene (10.02%), alpha-copaene (9.91%), beta-caryophyllene (8.97%), germacrene D (7.40%), and gamma-elemene (6.89%) were the major constituents from var. longifolia. A systematic analysis of the chemical components provided an approach to the biosynthetic pathway for volatile metabolite production. Antimicrobial assays provided scientific support for the traditional use of the plants. In- vitro assays using Escherichia coli (ATCC 25922), E. coli (82MR), Klebsiella pneumoniae (ATCC 13883), Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 29213), S. aureus (23MR), S. epidermidis (ATCC 12228), S. epidermidis, Candida albicans (17MR), C. glabrata, and C. tropicalis were achieved. These assays revealed MIC values >2 mg/mL when observed bacterial inhibition for both Trixis species, except for var. michuacana against S. epidermidis ATCC 12228, which was 0.5 mg/mL. These results could partially justify the use of the studied plants in ethnomedicine.