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Abstract:The antimycobacterial activity of Scutia buxifolia Reissek, Rhamnaceae, leaves extracts and fractions were evaluated for the first time. Four compounds were identified, flavonoids (quercetin and quercitrin) and phenolic acids (gallic and caffeic acids) and quantified by HPLC-DAD. Promising antiMycobacterium smegmatis activity was observed with ethyl acetate extract (MIC 312.50 μg/mL) and their fractions (MIC values ranging from 78.12 to above 312.50 μg/mL). The fractions III and VI of S. buxifolia leaves showed a high level of activity against M. smegmatis (MIC 78.12 and 156.25 μg/mL, respectively), M. tuberculosis (MIC 156.25 μg/mL) and M. avium (MIC 312.50 μg/mL), whereas to the other fractions the values varied from 312.50 to 1250.00 μg/mL against these strains. The better MIC result was associated with two fractions that contain bigger amounts of quercetin, quercitrin, gallic and caffeic acids. The results provided evidence that the studied plants fractions might be potential sources of new antimicrobial drug.

The antimicrobial and cytotoxic activities of the dichloromethane, ethyl acetate and butanolic fractions from the leaves, twigs and stem bark of Scutia buxifolia were evaluated using the broth microdilution method and the brine shrimp lethality method, respectively. Phytochemical analysis was performed by thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The antimicrobial results demonstrated that the strongest effect occurred with the butanol fraction from the twigs and the ethyl acetate fraction from the stem bark against Saccharomyces cerevisiae (minimal inhibitory concentration; MIC = 62.5 µg mL(-1)), whereas the ethyl acetate and butanolic fractions from the twigs and stem bark were effective against Pseudomonas aeruginosa and Staphylococcus aureus, with MIC values ranging from 125 to 500 µg mL(-1). LD(50) values varied from 50.00 ± 0.22 to 82.23 ± 0.34 µg mL(-1). Quercetin, quercitrin, isoquercitrin and rutin were identified by HPLC and may be partially responsible for the antimicrobial activities observed. This study reports for the first time the antimicrobial and cytotoxic activities of S. buxifolia leaves, twigs and stem bark.

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