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Item 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.Item 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.Item Antimicrobial screening and GC-MS analysis of bioactive compounds from strains of pseudomonas aeruginosa isolated from poultry fecal littered soil in Ibadan, Nigeria.(Faculty of Physical Sciences and Faculty of Life Sciences,University of Ilorin, 2019) Alabi, O. S.; Koleoso, O. B.; Abiala, A. M.The emergence of pathogens exhibiting multiple antibiotic resistance (MDR) is bringing a thwart to available chemotherapeutic agents thus the urgency in the search for bioactive agents that will be effective against the MDR pathogens. This study screened isolates of Pseudomonas aeruginosa from poultry fecal littered soil in two selected locations in northern Ibadan, southwest Nigeria (University of Ibadan Teaching Research Farm and Ayede community) for production of bioactive compounds, evaluated their activities against selected MDR bacteria pathogens and analyzed the crude ethylacetate extract using GC-MS. A total of 178 strains of P. aeruginosa were isolated on cetrimide agar and identified presumptively by standard biochemical test. Primary and secondary screening of the whole cell and cell free supernatant ethylacetate extracts were done by perpendicular streaking and agar-well diffusion methods respectively against selected clinical MDR bacteria pathogens. Five out of the 178 strains of the presumptive P.aeruginosa with excellent antibacterial activity were further confirmed by 16S rRNA amplification and sequencing. Cell free supernatant ethylacetate extracts of two most active strains among the five (denoted with code APC2-1 and APC2-14) were subjected to GC-MS analysis of the metabolites. The five P. aeruginosa strains were identified as P. aeruginosa MR24 strains 1, 2, 3, Pseudomonas sp SD12 and P. aeruginosa Kasamber 1 which were closely related phylogenetically. The bioactive compounds produced by the isolates that were studied had greater activity on Gram positive than Gram negative pathogens. GC-MS analysis revealed a total of 19 different compounds (1-heptadecanamine; 2ethyl-1-hexanamine; 3-butyn-1-ol; Pent-3-enylamine; Pent-4-enylamine; Propane; Acetaldehyde; Ethylene oxide; hydroxyacetonitrile; Bromo-acetonitrile; Azetidine; 2-methyl-Azetidine; Aminocaproic acid; 18nonadecen-1-amine; 5-aminovaleric acid; 2,2-dimethyl-1,3-propanediamine; 1-octadecanamine; 1-octanamine and 2-(3-butynyloxy)tetrahydro-2H-pyran) among which are antibacterial, anticancer, antifibrinolytic, and antimalarial compounds. This study therefore revealed the potentials of Pseudomonas aeruginosa as producers of secondary metabolites of medical and industrial importance. Multidrug resistance is currently on the increase, globally threatening public health and decreasing the efficacy of the antibiotics available currently (WHO, 2017). This therefore, has precipitated the search for novel compounds from natural sources like the environment, beneficial microorganisms, animals and plants from both aquatic and terrestrial habitats with potentials to produce potent antimicrobial agents against the resistant pathogens (Wolfender et al., 2015; Dias et al., 2016). Microbial genome mining is an important tool in the discovery of unculturable organisms and screening of isolates with potential secondary metabolites (Bachmann et al., 2014; Ziemert et al., 2016). With the availability of certain technologies like Ultra-High Performance Liquid Chromatography (UHPLC) and Gas Chromatography and Mass Spectrometry Analysis (GC-MS), an effective separation and identification of different bioactive metabolites from natural products is achievable. Some microorganisms such as bacteria and fungi from ages produce antimicrobials and other bioactive compounds (Butler and Bus, 2006). Pseudomonas spp. are group of Gram-negative bacilli with polar flagella, Gammaproteobacteria and family, Pseudomonadaceae. The species of this genus have a wide array of metabolic diversities capable of colonizing different ecological niches requiring non-specific nutritional requirement for their growth (Meyer et al., 2002). Pseudomonas spp. are known producers of bioactive metabolites such as Phenazine compounds, volatile organic compounds, thioquinolobactin etc. Some of these metabolites have been reported to possess antimicrobial activity, anticancer property, biosurfactant, bio-controlling, bio-pesticide/ bioinsecticide and bioremediation effects, hence its application in pharmaceutical, agricultural, cosmetic, industrial and environmental sector is important (Meyer et al., 2002; Kumar et al., 2016; Gionco et al., 2017). Despite the numerous antibiotics produced from microorganisms most especially the actinomycetes, resistance has taken aItem Comparative antimicrobial activities of extracts of garcinia kola, kola acuminata and kola nitida seeds on isolates of respiratory tract and other infections(West African Postgraduate College of Pharmacists, 2008) Adeleke, O. E.; Alabi, O. S.The methanolic extracts of the powdered seeds of Garcinia kola (Guttilerae), Kola acuminata, and Kola nitida (Sterculiaceae) were tested individually for antimicrobial activity using isolates from respiratory tract infections and other sites of infection such as High vagina swab, wounds, urethra and skin. The isolates included Staphylococus aureus (5strains), Z strains each of Escherichia coli, Proteus mirabilis and Streptococcus pneumoniae; I strain each of Streptococcus viridians Entercoccus faecalis, Streptococcus pyogenes, Bacillus subtilis, Haemophillus influenzae, Candida albicans, Asp. Niger, Ap. Eumigatus and Trichophyton specie, and 3 strains each of Pseudomonas aeruginosa and Klebsiella pneumoniae. The antimicrobial susceptibility test of the extracts showed zones of growth inhibition ranging from 9mm to as large as 35mm, depending on the organism being tested. The minimum inhibitory concentration (MIC) was determined by agar-diffusion method and ranged from 0.23mg/ml to 30mg/ml for the three extracts. The crude extracts of Garcinia Kola showed a stronger antimicrobial against most organisms particularly the Gram-positive bacterial isolates from the respiratory tract, than the other two extracts, while Kola nitida was the least active.