Identificação de cromenos, naftoquinonas e outros constituintes de Sinningia allagophylla (Gesneriaceae) e avaliação de suas atividades citotóxica, anti-inflamatória, analgésica e larvicida

Abstract

Resumo: A familia Gesneriaceae compreende cerca de 150 generos e 3000 especies, distribuidas nas regioes tropicais e subtropicais do mundo inteiro. No Brasil esta representada por 28 generos e 215 especies. O genero Sinningia compreende 68 especies, das quais 67 sao encontradas em territorio brasileiro. Os estudos quimicos ja realizados revelam que as especies de Sinningia contem principalmente antraquinonas e terpenos. Sinningia allagophylla (Martius) Wiehler, e uma erva anual, com tuberculo perene, encontrada nas regioes Centro-Oeste, Sul e Sudeste do Brasil, e tambem na Argentina e no Paraguai. E considerada medicinal, sendo usada na medicina popular como tonico, febrifugo, depurativo e diuretico. O presente trabalho descreve, pela primeira vez, o isolamento e identificacao de seus constituintes quimicos e a avaliacao das atividades citotoxica, analgesica, anti-inflamatoria e larvicida de extratos e substancias isoladas. Os tuberculos secos de S. allagophylla foram extraidos com etanol. O extrato etanolico foi fracionado por particao com solventes e, posteriormente por cromatografia. As substancias puras obtidas foram identificadas por tecnicas espectrometricas (massas, RMN). Desse modo foram identificadas 23 substancias: lapachenol (1), 8-metoxilapachenol (2), 8- metoxi-12-hidroxilapachenol (3), allagophyllolideo (4), allagophyllina A (5), allagophyllina B (6), allagophyllina C (7), tectoquinona (8), dunniol (9), -dunniona (10), 8-hidroxidunniona (11), dunniona (12), allagophyllona (13), aggregatina E (14), 6-metoxiaggregatina E (15) halleridona (16), cedrol (17), -muurolol (18), 8-cedren-13-ol (19), oleato de sitosterila (20), linoleato de sitosterila (21), oleato de estigmasterila (22) e linoleato de estigmasterila (23). As substancias 2-7 e 13-15 sao ineditas. O extrato etanolico apresentou atividade citotoxica, analgesica e anti-inflamatoria. A atividade citotoxica foi avaliada in vitro contra varias linhagens de celulas tumorais humanas, sendo 9 identificada como a substancia mais ativa. Esta naftoquinona inibiu totalmente o crescimento das linhagens de celulas tumorais de leucemia (K562), glioma (U251), mama (MCF-7), ovario (OVCAR-3) e ovario resistente a multiplos farmacos (NCI-ADR/RES) em concentracoes de 1,14-6,88 ƒÊg mL-1 (4,5-28 ƒÊM). As atividades analgesica e anti-inflamatoria foram avaliadas in vivo, em camundongos. A substancia 2 foi ativa na concentracao de 1,8 mg kg-1 (6,7 ƒÊmol kg-1), quando administrada por via oral. Essa substancia tambem apresentou atividade larvicida contra larvas de Aedes aegypti, com um valor de CL50 = 7,41 ƒÊg mL-1 (27,4 ƒÊM) apos 24 h.

Abstract: The family Gesneriaceae comprises about 150 genus and 3000 species, distributed in the tropics and subtropics around the world. In Brazil the family is represented by 28 genera and 215 species. The genus Sinningia comprises 68 species, of which 67 are found in Brazil. Previous chemical studies reveal that Sinningia species produce mainly anthraquinones and terpenes. Sinningia allagophylla (Martius) Wiehler is an annual herb, with perennial tubers, growing in the Mid-Western, Southeastern and Southern regions of Brazil, besides Argentine and Paraguay. This plant is considered medicinal, being used in the folk medicine as tonic, febrifuge, depurative and diuretic. This work describes, for the first time, the isolation and identification of chemical constituents and evaluation of cytotoxic, analgesic, antiinflammatory and larvicidal activities of extracts and pure compounds of S. allagophylla. Dried tubers were extracted with ethanol. The extract was fractionated by partition with solvents and chromatographic techniques. Pure compounds were identified by spectrometric techniques (mass, NMR). This procedure resulted in the identification of 23 compounds: lapachenol (1), 8-methoxylapachenol (2), 8-methoxy-12-hydroxylapachenol (3), allagophyllolide (4), allagophyllin A (5), allagophyllin B (6), allagophyllin C (7), tectoquinone (8), dunniol (9), -dunnione (10), 8-hydroxydunnione (11), dunnione (12), allagophyllone (13), aggregatin E (14), 6-methoxyaggregatin E (15), halleridone (16), cedrol (17), -muurolol (18), 8-cedren-13-ol (19), sitosteryl oleate (20), sitosteryl linoleate (21), stigmasteryl oleate (22) and stigmasteryl linoleate (23). Compounds 2-7 and 13-15 are new. The ethanol extract showed cytotoxic, analgesic and anti-inflammatory activities. The cytotoxic activity was evaluated in vitro against several human tumor cell lines, and 9 was identified as the most active compound. This naphtoquinone inhibited totally the growth of leukemia (K562), gliome (U251), mama (MCF-7), ovarian (OVCAR-3), and drug-resistant ovarian cell lines with concentrations of 1.14-6.88 ìg mL-1 (4.5-28 ìM). The analgesic and anti-inflammatory activities were evaluated in vivo, using mice. Compound 2 showed activity in the concentration of 1.8 mg kg-1 (6.7 ìmol kg-1), by via oral. This compound also exhibited larvicidal activity against Aedes aegypti larvae, with LC50 = 7.41 ìg mL-1 (27.4 ìM) after 24 h.