ANTIMICROBIAL ACTIVITY OF EXTRACTS, ESSENTIAL OIL AND METABOLITES OBTAINED FROM TAGETES MENDOCINA

Extracts from the Argentinean herb Tagetes mendocina Phil. (Asteraceae) were tested for antimicrobial activity against fungi, bacteria and protozoa. The different extracts (PE, DCM, MeOH and EtOAc) and the essential oil displayed activity mainly against dermatophytes, a group of fungi that produces skin infections. The bioassay-guided fractionation of PE, DCM and EtOAc extracts led to the isolation of eight compounds including two thiophenes, two acetophenone derivatives, dihydrorosefuran and three flavonoids. The thiophenes 5-(4-hydroxy-1-butynyl)-2,2 ’ -bithienyl (BBTOH) (1) and its acetate (BBTOAc) (2) proved to be highly active against the dermatophytes Microsporum gypseum, Trichophyton rubrum and T. mentagrophytes with MIC values of 3.12, 3.12 and 6.25 µg/mL for compound 1 and 25, 3.12 and 6.25 µg/mL for compound 2, respectively. In turn, the essential oil displayed a weak to moderate antifungal effect against M. gypseum with MIC = 250 µg/mL. The essential oil was examined by GC and GC-MS and 21 constituents (97.3%) were identified. ( E) β-ocimene, (Z)-tagetone, (E)-tagetone, (Z)-ocimenone, α-pinene and (E)-ocimenone were the major components. In addition, thiophenes 1 and 2 and 2-hydroxyacetophenone 3 showed antiprotozoal activity against Leishmania amazonensis, L. brasiliensis and L. infantum promastigotes with 100% lysis at 100 µg/mL.