RESUMO

This study evaluated the safety of Lafoensia pacari A. St.-Hil. (Lythraceae) stem bark hydroalcoholic extract (LPE) through acute and subchronic toxicological assessments in mice. In the acute toxicity evaluation, a single 2000 mg/kg oral dose of LPE was administered to mice and clinical observations were conducted for 14 days. For subchronic toxicity, LPE doses (6.25-1000 mg/kg) were administered orally for 28 days and biochemical, hematological, histopathological analyses and renal and liver expression of Ki-67 were carried out. The acute oral toxicity evaluation of LPE showed no toxicity in mice and it was was classified as category 5 (LD50>2000-5000 mg/kg). In a repeated dose 28-day toxicity study, LPE (100-1000 mg/kg) led to an increase in reticulocytes, which suggests a possible proliferative effect on blood cells. In addition, LPE (400-1000 mg/kg) of produced alterations in biochemical parameters, although no microscopic changes were found in the organs analyzed. A normal expression of the Ki-67 cell proliferation indicator was observed in the kidney and liver tissues, which suggests that LPE does not bring about changes in the proliferative activity of these organs. In conclusion, LPE should be used with caution, particularly in larger doses over longer periods and also in combination with other medication.

RESUMO

Stem-bark extracts, fractions and the isolated constituent, ellagic acid of Lafoensia pacari St. Hil. (Lythraceae) were in vitro assayed for antifungal activity against a panel of yeasts, hialohyphomycetes as well as dermatophytes with the microbroth dilution method. The EtOH extract and its fractions and ellagic acid exhibited activity against Candida spp and Saccharomyces cerevisiae with MIC values between 250-1000 µg/mL, but they showed no action against filamentous fungi and dermatophytes (MIC>1000 µg/mL). Active extracts were evaluated in Neurospora crassa hyphal growth inhibition and sorbitol assays and then the effect of ergosterol on the MIC of ellagic acid was studied. The active extracts and its fractions and ellagic acid showed a blotchy zone around the paper disk and induced malformations of the hypha. Besides, MIC of the ellagic acid against the Saccharomyces cerevisiae was raised from 62 to 250 µg/mL in the presence of sorbitol 0.8 M, suggesting that the ellagic acid would probably exert its action on fungal cell wall. These results indicate that ellagic acid might be the main active antifungal compound of Lafoensia pacari and further suggest that the mode of antifungal action of these extracts and ellagic acid could be associated with the inhibition of fungal cell wall.

Os extratos, frações e ácido elágico, isolados da entrecasca de Lafoensia pacari A. St.-Hil., Lythraceae, foram testados in vitro para atividade antifúngica, frente a um painel de leveduras, hialo-hifomicetos e dermatófitos, utilizando o método de microdiluição. O extrato EtOH, frações e ácido elágico exibiram atividade contra Candida spp. e Saccharomyces cerevisiae com valores de CIM entre 250-1000 µg/mL, porιm não mostraram ação contra fungos filamentosos e dermatófitos (CIM>1000 µg/mL). Os extratos ativos foram avaliados nos ensaios de inibição do crescimento das hifas de Neurospora crassa, no teste do sorbitol, e pelo estudo do efeito do ergosterol na CIM do ácido elágico. Os extratos ativos, frações e ácido elágico mostraram zonas manchadas ao redor dos discos de papel e induziram malformações nas hifas. Além disso, a CIM do ácido elágico contra Saccharomyces cerevisiae passou de 62 para 250 µg/mL na presença do sorbitol 0,8 M, sugerindo que o ácido elágico provavelmente poderia exercer ação na parede celular fúngica. Esses resultados indicam que o ácido elágico pode ser o principal composto antifúngico de Lafoensia pacari, sugerindo que o modo de ação antifúngico desses extratos e ácido elágico poderia estar associado à inibição da parede celular fúngica.