The activity of flavones and oleanolic acid from Lippia lacunosa against susceptible and resistant Mycobacterium tuberculosis strains

Tuberculosis (TB), caused by Mycobacterium tuberculosis, is the world's number one killer among infectious diseases. The search for new naturalproducts that can act as drugs against TB has received increased attention duringthe last years. In this work we describe the isolation and identification of the active antimycobacterial principles of the dichloromethane extract from Lippia lacunosa Mart. & Schauer, Verbenaceae. Compounds were evaluated for their in vitro activity against Mycobacterium tuberculosis (susceptible and rifampicin resistantstrain) using a redox bioassay. From the dichloromethane extract of L. lacunosa leaves, seven methoxy-flavones named cirsimaritin (1), eupatilin (2), eupatorin (3), salvigenin (4), 3'-O-methyl-eupatorin (5), 3',7-dimethoxy-5,6,4'- trihydroxyflavone (6), and 7'-O-methylapigenin (7), and one triterpene, named oleanolic acid (8), were isolated. All compounds were found to display antimycobacterial activity against susceptible strain, with MIC ranging from 25 to 200 µg/mL. None of them was active against rifampicin resistant strain. This is the first report in the antimycobacterial activity of 6-substituted flavones, as well as the first report of the occurrence of these substances in L. lacunosa.

Screening of Central and South American plant extracts for antimycobacterial activity by the Alamar Blue test / Triagem de extratos de plantas das Américas Central e do Sul para atividade antimicobacteriana pelo teste do Alamar Blue

Forty eight ethanolic crude extracts and fractions (hexane, dichloromethane, ethyl acetate and n-butanol) from ten Brazilian plants (Leguminosae, Monimiaceae and Verbenaceae), 1 from Costa Rica (Verbenaceae) and 1 from Argentina (Verbenaceae) were screened for anti-mycobacterium activity against Mycobacterium tuberculosis (ATCC-27294H37Rv), by the Alamar Blue test, at a fixed concentration of 100 µg/mL. Out of the forty eight, seven were active at this concentration, corresponding to Lantana trifolia (hexane and dichloromethane extracts from leaves), Vitex cooperi (methanol:water, 1:1 extract from barks), Lippia lacunosa (hexane and dichloromethane extracts from leaves) and Lippia rotundifolia (hexane and dichloromethane extracts from leaves), all from the Verbenaceae family.

Quarenta e oito extratos brutos etanólicos e frações (em hexano, diclorometano, acetato de etila e n-butanol) de dez plantas brasileiras pertencentes às famílias Leguminosae, Monimiaceae e Verbenaceae; uma da Costa Rica (Verbenaceae) e uma da Argentina (Verbenaceae) foram ensaiados para verificação da atividade anti-micobacteriana contra Mycobacterium tuberculosis (ATCC-27294H37Rv), pelo teste do Alamar Blue, a uma concentração fixa de 100 µg/mL. Dentre os quarenta e oito extratos e frações estudados, sete mostraram-se ativos na concentração ensaiada - frações em hexano e diclorometano de folhas de Lantana trifolia, extrato em metanol:água, 1:1 de cascas de Vitex cooperi, frações em hexano e diclorometano de folhas de Lippia lacunosa e de Lippia rotundifolia, sendoque todas essas plantas pertencem à família Verbenaceae.