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OBJECTIVE@#To evaluate antimicrobial potential of the fractions partitioned from Euclea crispa leaf extract and determination of their impact on cell membrane disruption.@*METHODS@#Antimicrobial potentials were evaluated via susceptibility test, determination of minimum inhibitory concentrations (MICs) and time-kill kinetics of the potent fractions. Degree of membrane disruption was determined by the amount of proteins and nucleotides released from within the cells and SEM images of the membrane after 120 min of treatment.@*RESULTS@#The largest inhibition zone (25.5 ± 0.50 mm) was obtained by ethylacetate fraction against Aeromonas hydrophilla at 10 mg/mL. The lowest MIC (0.16 mg/mL) was exhibited by n-butanol and ethylacetate fractions against test bacteria while all fractions exhibited MIC values between 0.31 and 1.25 mg/mL against susceptible yeast. n-Butanol fraction achieved absolute mortality against Bacillus pumulis (B. pumulis) and Klebsiella pneumoniae (K. pneumoniae) after 90 and 120 min contact time respectively at 1 × MIC. Total mortality also achieved by n-hexane fraction against B. pumulis and K. pneumoniae after 90 and 120 min respectively at 2 × MIC. Ethylacetate fraction achieved absolute mortality against both bacteria after 120 min at 2 × MIC. n-Hexane fraction achieved total mortality against Candida albicans after 120 min at 1 × MIC. Maximum amount of proteins (0.566 μg/mL) was released from K. pneumoniae by n-butanol fraction at 2 × MIC after 120 min of treatment while the maximum amount of nucleotides released (4.575 μg) was from B. pumulis by n-hexane fraction under similar condition.@*CONCLUSION@#This study suggests the leaf of Euclea crispa a source of bioactive compound with membrane attack as one of the mechanisms of its biocidal action.
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Objective To evaluate antimicrobial potential of the fractions partitioned from Euclea crispa leaf extract and determination of their impact on cell membrane disruption. Methods Antimicrobial potentials were evaluated via susceptibility test, determination of minimum inhibitory concentrations (MICs) and time-kill kinetics of the potent fractions. Degree of membrane disruption was determined by the amount of proteins and nucleotides released from within the cells and SEM images of the membrane after 120 min of treatment. Results The largest inhibition zone (25.5 ± 0.50 mm) was obtained by ethylacetate fraction against Aeromonas hydrophilla at 10 mg/mL. The lowest MIC (0.16 mg/mL) was exhibited by n-butanol and ethylacetate fractions against test bacteria while all fractions exhibited MIC values between 0.31 and 1.25 mg/mL against susceptible yeast. n-Butanol fraction achieved absolute mortality against Bacillus pumulis (B. pumulis) and Klebsiella pneumoniae (K. pneumoniae) after 90 and 120 min contact time respectively at 1 × MIC. Total mortality also achieved by n-hexane fraction against B. pumulis and K. pneumoniae after 90 and 120 min respectively at 2 × MIC. Ethylacetate fraction achieved absolute mortality against both bacteria after 120 min at 2 × MIC. n-Hexane fraction achieved total mortality against Candida albicans after 120 min at 1 × MIC. Maximum amount of proteins (0.566 μg/mL) was released from K. pneumoniae by n-butanol fraction at 2 × MIC after 120 min of treatment while the maximum amount of nucleotides released (4.575 μg) was from B. pumulis by n-hexane fraction under similar condition. Conclusion This study suggests the leaf of Euclea crispa a source of bioactive compound with membrane attack as one of the mechanisms of its biocidal action.
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Four - day cyclic female rats were ovariectomized in the morning of day 1 of diestrus and injected on this and the following two days at 09.00 h either with constant or with increasing doses of estradiol benzoate [EB]. The serum concentrations of LH and estradiol - 17 beta were determined 4 h after the last injection. Significant inhibition of LH secretion resulting from three injections of 0. 25 micro g EB/100g b. w. was completely prevented when 0.75 micro g EB/100g b. w. were administered at increasing dosage. Markedly higher serum concentrations of estradiol were found after the administration of 0.05, 0.10 and 0.25 than after three injections of 0.13 micro micro g EB/100 g b. w; but the circulating LH level did not differ between both groups. Even the total amount of 4.0 micro g EB/100 g b. w. did not inhibit LH secretion when increasing dosage was applied. Although preliminary, the data indicate a hitherto unknown action of estrogens in the control of LH secretion which may be of importance for the therapeutic use of these hormones