Studies on the Genotoxic and Mutagenic Potentials of Mefloquine.

Purpose: The detection of mefloquine mutagenicity has not been achieved by the use of Salmonella typhimurium his TA1535, TA1537 as tester strains. With the introduction of improved and more sensitive strains, it is of interest to evaluate the current mutagenic and genotoxic status of the drug. This study presents data on the in-vitro mutagenic and genotoxic potentials of mefloquine hydrochloride clinically used as an antimalarial agent. Method: The mutagenicity potentials was investigated in the Escherichia coli WP2 trp and WP2 uvrA trp tester strains containing the plasmids, pEB017 and pKM101, and the Salmonella typhimurium TA97 containing pKM101. The genotoxicity potential was determined using the microscreen phage-induction assay. Results: The presence of plasmids pEBO17 and pKM101 enhanced the detection of mutagenicity of mefloquine. Microsomal-activated mefloquine unequivocally elicited base-pair substitution mutagenicity. The genotoxicity test indicated that mefloquine was generally not genotoxic but was of the same potential mutagenicity as chloroquine phosphate. Conclusion: Melfloquine hydrochloride exhibits base pair substitution mutagenesis, but not potentially genotoxic, even though it showed concentration dependent cytotoxicity. Its use as a last line antimalarial agent should still be encouraged. Keywords: Base-pair substitution, genotoxicity, mefloquine hydrochloride, mutagenicity, R-plasmid pEB017 Tropical Journal of Pharmaceutical Research 2002; 1(2):91-9

Prevalence of methicillin-resistant staphylococcus aureus among healthy residents of Ekosodin community in Benin-City, Nigeria

Purpose: To determine the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in apparently healthy residents of Ekosodin community, a peri-urban settlement, in Benin City, Nigeria.Method: Nasal swabs collected from 200 randomly selected individuals, aged between 16 and 38 years, were used in the study. Isolates from the swabs were aseptically collected and characterized using standard and established microbiological methods, which included growth and fermentation on mannitol salt agar (MSA), colonial morphology, Gram-staining reaction and biochemical tests. Antimicrobial susceptibility test was performed on Mueller-Hinton agar (MHA) by modified Kirby-Bauer disc diffusion method.Results: S. aureus was isolated in 49.5 % (n = 99) of the 200 nasal swabs. Among these isolates, 43 % were from male residents and 22.2 % (n = 22) were MRSA. The MRSA isolates indicated relatively high rate of resistance to penicillins, moderate resistance to erythromycin and cefuroxime, and leastresistance to gentamicin, streptomycin, ceftriaxone, ciprofloxacin and co-trimoxazole. There was no significant gender difference in terms of the colonization of S. aureus (p < 0.05).Conclusion: Many apparently healthy residents of Ekosodin community are nasal carriers of MSRA. The need for rational chemotherapy, routine detection and regular surveillance of MRSA to limit its spread and reduce treatment failures is vital

Antimicrobial and time-kill kinetics of the aqueous extract of Citrullus lanatus (Thunb.) seeds

This study evaluated the antimicrobial property of the aqueous extract of Citrullus lanatus (watermelon) seeds and its concentration-effect relationship (time-kill studies) on typed bacterial and fungal strains. Crude powdered seeds of Citrullus lanatus were extracted by maceration with water. Antimicrobial assay of the aqueous extracts was determined against Bacillus subtilis (NCTC 8236), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 10145), Staphylococcus aureus (ATCC 25923), and Candida albicans (ATCC 24433) using standard microbiological methods. A total of 106 CFU/mL of each test strain was used as a baseline to carry out the time-kill studies. Extract concentration at minimum inhibitory concentration (MIC), 2MIC and 4MIC were used over a period of 24 hours. Aqueous extract had an intermediate antibacterial activity with inhibition zone diameters (IZD) of 15 - 18 mm and MIC range of 2.5 - 20 mg/mL. Time-kill studies showed a bacteriostatic, non-concentration dependent mode of antimicrobial activity with characteristic regrowth for all test strains. Citrullus lanatus seeds aqueous extract exhibited antimicrobial activity with a bacteriostatic, non-concentration dependent mode of action against test bacterial strains. Further studies aimed at isolating and purifying the antimicrobial principle in the aqueous extract of C. lanatus seed is warranted as this could serve as a potential new antibiotic for treating microbial infections

A preliminary study on the antimicrobial activities and gas chromatography-mass spectrometry (GC-MS) analysis of the ethyl acetate extract of Dennettia tripetala G. Baker seeds

The study investigated the antimicrobial properties and the chemical composition of ethyl acetate extract of Dennettia tripetala (pepper fruit) seeds. Crude extract obtained by maceration of pulverized seeds in ethyl acetate was evaluated for antimicrobial activity against Escherichia coli, Staphylococcus aureus, Klebsiella aerogenes, Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans and Aspergillus niger using standard agar-well diffusion method. GC-MS method was used to determine the chemical constituents of the extract. The extract was oily, yellowish-brown with a yield of 1.66 % and had activity against most of the test microorganisms, with inhibition zone diameters ranging between 10 to 25 mm. About 41 chemical constituents were present in the extract with formic acid methyl esters and fatty acids accounting for 57.23 and 18.49 % respectively. Ethyl acetate extract of Dennettia tripetala seeds possessed antimicrobial activity against bacteria but not fungi. The observed activity may be due to the presence of formic and fatty acid esters in the seed. The study further established a scientific proof for the traditional use of Dennettia tripetala seed extracts in treating microbial infections. &nbsp

Phytochemical and Antibacterial Evaluations of the Stem Bark of Newbouldia laevis against Isolates from Infected Wounds and Eyes

Purpose: To examine the phytochemical constituents and verify the ethnomedical claim of Newbouldia laevis (P.Beauv.) Seeman ex Bureau Bignoniaceae in treating septic wounds and eye problems. Methods: Applying standard methods, the phytochemical constituents of the stem bark were examined while the antibacterial potentials of the methanol extract of the stem bark and its organic solvent fractions were tested on clinical bacterial isolates from infected wounds and eyes using the agar -well diffusion method. Ciprofloxacin and gentamicin were used as standard controls. The time-kill kinetics of the methanol stem bark extract and ciprofloxacin were determined using isolates of Staphyloccocus aureus . Results: Phytochemical screening of the stem bark revealed the presence of flavonoids, tannins, saponins and alkaloids with no traces of cyanogenic glycosides. The 65 bacterial pathogens isolated included Proteus mirabilis (26.0 %) and Pseudomonas aeurginosa (17.4 %) from non-diabetic patients’ wounds; Staphylococcus aureus (32.0 %) and Escherichia coli (16.0%) from diabetic patients’ wounds; Staphylococcus aureus (35.3%) and Pseudomonas aeruginosa (35.3 %) from infected eyes. The chloroform fraction was observed to be more active on Gram-negative organisms while the aqueous fraction was more active on Gram-positive organisms. Time-kill kinetics of Staphylococcus aureus showed that the extract was bactericidal (99.9 % killing) at MIC and 2 x MIC after 24 and 3 hours, respectively. Conclusion: The study has established that the stem bark of Newbouldia laevis has antibacterial activities against bacterial isolates from infected wounds and eyes as claimed in ethnomedicinal practice