Antitubercular Constituents ofValeriana laxiflora

Abstract

Antitubercular bioassay-guided fractionation of the n-hexane- and CH (2)Cl (2)-soluble extracts of the above-ground biomass and roots of Valeriana laxiflora led to the isolation of a new iridolactone, (4R,5R,7S,8S,9S)-7-hydroxy-8-hydroxymethyl-4-methyl-perhydrocyclopenta[ c]pyran-1-one ( 1), and a new lignan, (+)-1-hydroxy-2,6-bis- epi-pinoresinol ( 2), along with eleven known compounds, betulin ( 3), betulinic acid ( 4), 5,7-dihydroxy-3,6,4'-trimethoxyflavone ( 5), 23-hydroxyursolic acid ( 6), oleanolic acid ( 7), tricin ( 8), ursolic acid ( 9), ferulic acid, (+)-1-hydroxypinoresinol, prinsepiol, and 5,7,3'-trihydroxy-4'-methoxyflavone. The structures of compounds 1 and 2 were elucidated on the basis of spectroscopic evidence. The absolute stereochemistry of 1 was determined by chemical transformations and Mosher ester procedures. In a microplate alamar blue assay against Mycobacterium tuberculosis, compounds 2 - 9 exhibited minimum inhibitory concentrations (MIC) of 15.5 - 127 microg/mL, while the other isolates were regarded as inactive (MIC > 128 microg/mL). In addition, all the isolates were tested for cytotoxicity against African green monkey Vero cells in order to evaluate their selectivity potential.

In vitro anti-Mycobacterium tuberculosis activity of some Brazilian "Cerrado" plants

“…Tosun (2004) considered inactive the plant extracts that could not prevent growth of M.tuberculosis up to concentration of 200 µg/mL and according to Gu (2004) the MIC value of ≤128 mg/mL is defined as active against M. tuberculosis. From analyzed extracts, 12 chloroform extracts were considered promising and the MIC was ranged within 62.5 to 125 µg/mL.…”

Avaliação da atividade antimicobacteriana da lignana diidrocubebina extraída da Piper cubeba e de seus derivados semissintéticos

“…Os demais compostos apresentaram CIM de 250 ou 125 µg/mL para essas duas cepas. Existem muitos trabalhos na literatura sobre a avaliação antimicobacteriana de compostos naturais ou sintético, entretanto, os valores de CIM que definem o grau de atividade desses compostos divergem entre as publicações (Cantrell et al, 2001;Gu et al, 2004;Garcí et al, 2012).…”

“…Segundo Gu et al (2004) CIM ≤128 µg/mL definem uma substância como ativa contra M. tuberculosis. Garcí et al (2012) relataram substâncias como ativas com CIM ≤128 µg/mL, sendo que quanto menor o valor de CIM mais ativa é a substância.…”

“…Portanto, de acordo com os dados de Gu et al (2004) e Garcí et al (2012 a lignana 1 que apresentou CIM=125 µg/mL contra as duas cepas e a lignana 6 com CIM=125 µg/mL contra M. tuberculosis podem também ser consideradas ativas. No entanto, apesar de manter o mesmo CIM do composto 1 a modificação estrutural para a obtenção de 6 não contribuiu para o aumento de atividade.…”

Antimycobacterial activity ofIndigofera suffruticosawith activation potential of the innate immune system

“…The antimycobacterial activities of METH and DCM are presented in Table 2. Gu et al (2004) considered plant extracts with an MIC value ≤ 128 µg/mL to be active. Thus, we considered the result of MIC 125 µg/mL found for the METH crude extract to be promising.…”