Cytotoxic Fractions from the Leaves ofTachia grandiflora.

Abstract

This work is part of a larger screening program, which seeks to discover new antitumor plants and compounds from the Brazilian Amazon. In a prescreen of stem and leaf extracts of Tachia grandiflora Maguire & Weaver (Gentianaceae) based on the SRB method, leaf methanol and ethanol extracts showed appreciable cytotoxicity in human breast (MCF-7) and colon (HCT-8) tumor cell lines. Liquid-liquid partitioning of the leaf ethanol extract yielded hexane, chloroform, butanol, and water-methanol fractions. Only the hexane and chloroform fractions were active, inhibiting murine melanoma (B-16) and HCT-8 cells. The chloroform fraction suffered sequential column chromatography on silica gel using different eluent systems and yielded a number of very active subfractions. In all, 25 fractions and subfractions were tested, and 10 exhibited high growth inhibition of HCT-8, and two of these presented strong inhibition of murine melanoma (B-16) cells. The most active subfractions were tested against five tumor cell lines (leukemia CEM and HL-60, as well as the three used previously) using the MTT assay, and four fractions demonstrated significant cytotoxicity based on IC 50 . Cell lysis was discarded as a possible mechanism for in vitro cytotoxicity given that these fractions did not exhibit hemolytic activity. The greatest antiproliferative potential was found in the second (two samples) and third generation (two samples) chromatographic subfractions of the chloroform fraction (obtained from partitioning of the ethanol extract). These subfractions proved to be complex mixtures from which no pure substance could be isolated after further chromatographic separations.

In vitro and in vivo antimalarial activity and cytotoxicity of extracts, fractions and a substance isolated from the Amazonian plant Tachia grandiflora (Gentianaceae)

“…The extracts and fractions of roots and leaves of T. grandiflora were not toxic to human fibroblasts in vitro (IC 50 > 50 µg/mL). Interestingly, Pohlit et al (2007) found that fractions of leaf extracts of T. grandiflora were cytotoxic in vitro to five tumour cell lines (IC 50 = 4.1-25.4 µg/mL). Thus, there is a selective in vitro cytotoxic effect of the leaf extracts and fractions against the faster growing tumour cells than against normal (human fibroblast) cells.…”

“…In another study, extracts of T. grandiflora at 500 µg/mL exhibited moderate toxicity (7-64% lethality) to larvae of Aedes aegypti (Pohlit et al 2004). Also, extracts of T. grandiflora were highly active inhibitors of the growth of cancer tumour cell lines (Pohlit et al 2007). …”

Endophytic fungi found in association with Smallanthus sonchifolius (Asteraceae) as resourceful producers of cytotoxic bioactive natural products

“…Cultures were maintained in a humidified incubator at 37 °C and 5% CO 2 atmosphere. The cytotoxic effect was assessed using the MTT-dye reduction assay for cell viability described by Mosmann [16] according to an established protocol [17]. Briefly, tumor cells were placed in 96-well plates at the following densities: 0.7 × 10 5 (HCT-8), 0.6 × 10 5 (SF295), 0.3 × 10 6 (HL-60) and 0.1 × 10 6 (MDA-MB435) cells/ml.…”

Propagação de Tachia grandiflora por Estaquia de Galhos

“…A T. grandiflora (Figura 1) também é arbusto esporádico, sendo encontrado no Peru (MISSOURI BOTANICAL GARDENS, 2003), Guiana Francesa (COBB; MAAS, 1998) e no Brasil, nos Estados do Amazonas, Pará e Roraima (MAGUIRE; WEAVER, 1975;COBB;MAAS, 1998). Em estudo recente, foi possível mostrar que extratos e frações cromatográficas da folha de T. grandiflora apresentam significativa atividade citotóxica in vitro em linhagens de células tumorais (POHLIT et al, 2006). Das folhas de T. grandiflora, também foram isolados um seco-iridoide citotóxico raro (SANTOS, 2003) : destaque da flor característica : destaque da flor característica : destaque da flor característica : destaque da flor característica e à direita, em baixo: destaque de galho com flor e à direita, em baixo: destaque de galho com flor e à direita, em baixo: destaque de galho com flor e à direita, em baixo: destaque de galho com flor e à direita, em baixo: destaque de galho com flor Dada a pouca disponibilidade natural da caferana para fins de estudos e uso medicinal, bem como o potencial farmacológico de espécies de Tachia, faz-se necessário desenvolver métodos para a propagação dessa gentiana, família de difícil domesticação.…”