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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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American foulbrood (AFB) is a serious worldwide spreading disease in bees caused by Paenibacillus larvae. Plants extracts are known to decrease or inhibit the growth of these bacteria. The purpose of this study was to evaluate the antimicrobial activity of Calendula. officinalis, Cariniana domestica, and Nasturtium officinale extracts against the P. larvae and to evaluate the toxicity of the extracts in bees. In vitro activity against P. larvae of the extracts was evaluated by micro dilution method and the minimal inhibitory concentrations (MICs) were also determined. The concentrations used in the toxicity test were established based on the MIC values and by the spraying application method. The P. larvae was susceptible to the evaluated crude extract of C. officinalis and N. officinale. To C. domestica, only the ethyl acetate (EtAc) fraction and n-butanol (BuOH) fractions had activity against P. larvae. Toxicity analysis in bees showed no toxicity for N. officinale crude extract and for C. domestica BuOH fraction during 15 days of treatment, however, some deaths of bees occurred during the first three days of treatment with C. officinalis and C. domestica EtAc fraction. The results with these species were firstly described and showed that N. officinale crude extract and C. domestica BuOH fraction both presented not toxic effects in the concentration tested by the spraying application method, and can be a useful alternative for treatment or prevention of AFB.

The total phenolic content (Folin-Ciocalteu) of the leaves of Ficus benjamina and Ficus luschnathiana was evaluated and screened by HPLC-DAD. Ficus luschnathiana crude extract (CE) presented phenolic content higher than that of F. benjamina (149.92 ± 3.65 versus 122.63 ± 2.79 mg of GAE). Kaempferol (1.63 ± 0.16 mg g(-1) dry weight of CE) and chlorogenic acid (17.77 ± 0.57 mg g(-1) of butanolic fraction) were identified and quantified in F. benjamina, whereas rutin (1.39 ± 0.20 mg g(-1)), caffeic (1.14 ± 0.13 mg g(-1)) and chlorogenic (3.73 ± 0.29 mg g(-1)) acids were quantified in the CE of F. luschnathiana. Additionaly, rutin (15.55 ± 1.92 mg g(-1)) and quercetin (3.53 ± 0.12 mg g(-1)) were quantified in ethyl acetate and butanolic fractions, respectively. Antimycobacterial activity of CEs and fractions was evaluated against Mycobacterium smegmatis by broth microdilution method. Ethyl acetate fraction from F. benjamina and n-butanol fraction from F. luschnathiana displayed the highest inhibitory activity (MIC = 312.50 µg mL(-1) and 156.25 µg mL(-1), respectively). Further studies are required to identify the compounds directly related to antimycobacterial activity.

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