Pharmaceutical Microbiology

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Start date: 2020Subject: search.filters.subject.Antimicrobial activity

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    Characterization, antimicrobial and catalytic activities of silver nanoparticles biosynthesized using aqueous extract of Euphorbia graminea
    (Istanbul Medipol University, Turkey, 2023) Thomas, O. E.; Alabi, O. S.; Osharode, P. E.
    Phytosynthesis of silver nanoparticles (AgNPs) is not only affordable and ecofriendly but provides a means of synthesizing phytochemical capped AgNPs with predefined characteristics. The objective of this study was the green synthesis of AgNPs that possess antimicrobial and catalytic activities using aqueous extract of Euphorbia graminea. Reactions parameters critical to the yield, size and morphology of the biosynthesized AgNPs were optimized using UV spectroscopy. The UV-visible spectra analysis of the biosynthesized AgNPs showed surface plasmon resonance occurred at 462 nm. Scanning Electron Microscopy with Energy dispersive X-ray analysis revealed the characteristic absorption band of AgNPs at 3 KeV and confirmed 73.66% composition of particles as metallic silver. The AgNPs appeared as well-separated, quasi-spherical particles with narrow size distribution of 6.77±0.89 nm when examined with Transmission electron microscopy. X-ray diffraction confirmed the crystallinity of the AgNPs with mean crystallite size of 7.65 nm. The biosynthesized AgNPs showed broad-spectrum antimicrobial activity against bacteria and fungi. The rate constant of the degradation of methylene blue in the presence of as-synthesized AgNPs was increased several folds to sec-1 from sec-1 in its absence. The prepared AgNPs could find applications as therapeutic coats in medical devices and in effluent treatment of chemical industries.
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    Preliminary phytochemical screening, antimicrobial potentials and GC-MS analysis of Secamone afzelli Rhoem (asclepiadaceae) leaves extracts
    (Faculty of Physical Sciences and Faculty of Life Sciences, Univ. of Ilorin, Nigeria, 2020) Oyinloye, O. E.; Alabi, O. S.
    Secamone afzelli is used ethno-medicinally as remedies for stomach, colic and gastro-intestinal tract infections. This study screened the hexane, ethyl acetate and ethanol extracts of S. afzelli leaves for phytocompounds, antimicrobial activity and identified bioactive compounds in the most active extract using Gas Chromatography Mass Spectrometry (GC-MS) analysis. S. afzelli (200mg) leave was extracted by soxhlet apparatus using three solvents (hexane, ethyl acetate and ethanol) and the phytochemicals determined. Antimicrobial susceptibility and minimum inhibitory concentrations (MICs) was determined by agar-diffusion and agar-dilution methods respectively against selected resistant bacterial and fungal clinical isolates. The most active of the three crude extracts was analysed by GC-MS for bioactive compounds identification. Presence of carbohydrates, anthraquinone, glycosides, proteins, tannin, phenolic compounds and steroids were determined. The three extracts (hexane, ethyl acetate, and ethanol extracts) had antibacterial (Range of inhibition zone = 10 to 18 mm and MICs 12.5 to 200 mg/mL) but no antifungal activity. The ethanol extract was the most active with 29 bioactive compounds including piperazine, phytol, leucine methyl ester, N-methyl-N-(1-methylethyl)- 1Pentanamine, 7-propyl-pyrrolizin-1-thione and 4,5-dimethylnonane. The antibacterial activity and arrays of bioactive compounds detected in S. afzelli leaves suggest that the plant may be a good source of novel antimicrobial compounds.