Análise da atividade antimicrobiana de extratos e frações purificadas da planta arrabidaea chica verl

Abstract

This study describes the therapeutic potential of extracts and standardized fractions of Arrabidaea chica leaves. A. chica is a Bignoniaceae popularly known as “crajiru”. The genus Arrabidaea occurs in Tropical America, from the Southern Mexico to the Southern Brazil. The red color of its dried leaves is attributed to two flavonoidal pigments: carajurina (main pigment) and carajurona. Chemical studies described the isolation of saponins and flavonoids from the plant leaves; purified 3- desoxyanthocyanidins were reported as anti-inflammatory. The infusion or decoction of the plant leaves is used in the folk medicine to treat anemia, inflammation and in skin wound-healing. In this work, the antimicrobial activity of the standardized extracts and fractions of A. chica cultivated at Embrapa Amazônia Ocidental, Manaus, were evaluated against fungal and bacterial microorganisms grown either from local domestic dogs and cats, or from human samples supplied by the Microorganism Collection of FIOCRUZ, in Manaus, Brazil. The plant dried leaves were extracted with increasing polarity solvents and progressively purified in preparative thin layer chromatography (TLC) and silica-gel column; the semi-purified extracts were standardized in TLC. The agar diffusion method; bioautography; minimum inhibitory concentrations tested against Staphylococcus epidermidis (CBAM 293), Staphylococcus aureus (CBAM 324), Pseudomonas aeruginosa (CBAM 232), Escherichia coli (CBAM 002), Trichophyton mentagrophytes (CFAM 1288), Microsporum canis (CFAM 1289), Malassezia pachydermatis (CFAM 1290) e Candida albicans (CFAM 1285). The standardized fractions were effective against all these microorganisms, but more intensively against Microsporum canis and Staphylococcus epidermidis. The results might favour the use of the standardized sub-fractions of A. chica as topic phytotherapic agent to treat canine external otitis. So far oleanolic and ursolic acids were identified as the main compounds in the active semi-purified fraction but other compounds of the leaves extract were not discarded. Later studies will consider the veterinarian use of the standardized extract, of the active pure entities and the convenience of the natural active antibiotic mix.