Department of Microbiology-Journal Articles

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Browsing Department of Microbiology-Journal Articles by Author "Akinpelu, Oluseun F."

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    Biocidal effects of stem bark extract of Chrysophyllum albidium G. Don on vancomycin-resistant Staphylococcus aureus
    (BMC Complementary and Alternative Medicine, 2016-04-14) Akinpelu, David A; Odewade, Joseph O.; Aiyegoro, Olayinka A.; Ashafa, Anofi O. T.; Akinpelu, Oluseun F.; Agunbiade, Mayowa O.
    Background: Staphylococcus aureus causes variety of infections in humans and animals worldwide and predominates in surgical wound infections. This study assessed the antimicrobial potential of the stem bark extract of Chrysophyllum albidum against an array of vancomycin resistant Staphylococcus aureus (VRSA) isolated from clinical samples. Methods: The methanolic crude extract of the plant was preliminary screened for the presence of phytochemicals; after then, the extract was partitioned into n-hexane, chloroform, ethyl acetate and butanol fractions. A range of concentrations of the plant extract fractions was prepared to assess its antimicrobial potency; the minimum inhibitory concentrations (MICs); the minimum bactericidal concentrations (MBCs); the rate of killing; the potassium ion leakage potential and nucleotides leakage ability against the VRSAs. Results: The phytochemical screening revealed the presence of tannins, alkaloids, flavonoids, saponins, steroids, reducing sugars and terpenoids as major phytoconstituents resident in the crude plant extract. The two active fractions (n-hexane and butanol) at a concentration of 10 mg/ml exhibited antibacterial activities with the MIC and MBC values for the fractions ranged between 0.63–10 mg/ml and 1.25–10 mg/ml respectively. The time kill assay revealed that the antibacterial action of the two fractions are time and concentration dependent; the n-hexane and butanol fractions achieved 100 % kill on the test isolates at a concentration of 3×MIC and 2×MIC respectively after 120 min of reaction time. Varying amount of potassium ions as well as nucleotides were leaked from the test cells by n-hexane and butanol fractions. Conclusions: This study has established the possibility of developing antimicrobial agents of natural origin to manage possible infection from vancomycin resistant Staphylococcus aureus that are now developing multi-resistance against many antibiotics.
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    Probable mechanisms of biocidal action of Cocos nucifera Husk extract and fractions on bacteria isolates
    (BMC Complementary and Alternative Medicine, 2015-05-02) Akinpelu, David A; Alayande, Kazeem A; Aiyegoro, Olayinka A.; Akinpelu, Oluseun F.; Okoh, Anthony I
    Background: The incidence of resistance to the existing antibiotics by microorganisms demand increased effort in the development of new antibiotics for the treatment of microbial infections and diseases. Infections due to multidrug resistant pathogens are difficult to manage due to relatively limited choices of antimicrobial agents. This study investigated antimicrobial activities of the husk extract of Cocos nucifera on some bacteria that are associated with human diseases. Methods: Powdered husk of Cocos nucifera was cold extracted using mixture of methanol and distilled water in ration 3:2 (v/v). Extract was partitioned into n-hexane. Chloroform, ethylacetate and n-butanol fractions and thereafter, the minimum inhibitory concentrations (MICs) of the extract and those of the fractions were determined. The ethylacetate fraction was found to be more active and was partially purified by a combination of thin-layer and column chromatography. Finally, the rate of killing, leakages of proteins, potassium ions and nucleotides from the tests bacterial cells were determined. Results: The minimum Inhibitory concentrations (MICs) of the extract ranged between 0.39 and 12.50 mg/ml and those of the fractions ranged between 0.16 and 5.00 mg/ml. The time-kill assay revealed a minimum of 27.8% killed at 1×MIC after 15 min contact time with the fractions and a minimum of 95% killed after 120 min. Varying amount of proteins, potassium ions as well as nucleotides were leaked from selected bacterial isolates by the four active fractions. The amount of proteins leaked from the cells after 15 min contact time ranged between 3.56 and 19.08 μg/ml at 1 × MIC and between 10.97 and 19.54 μg/ml at 2 × MIC. The amount of potassium ions leaked from the cells after 15 min contact time ranged between 0.182 and 0.379 mg/ml at 1 × MIC and between 0.227 and 0.561 mg/ml at 2 × MIC. The nucleotides leaked from the cells after 15 min contact time ranged between 0.609 and 2.446 μg/ml at 1 × MIC and between 0.897 and 2.841 μg/ml at 2 × MIC. Conclusions: This study established the possibility of developing antimicrobial agents of natural origin to combat resistance to antimicrobial compounds by some pathogens currently being experienced in agricultural and health care environments.