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Articles by O.S. Folorunso
Total Records ( 4 ) for O.S. Folorunso
  S.A. Adeola , O.S. Folorunso , O.O. Okedeyi , B.F. Ogungbe , O.B. Babatimehin and O.Z. Thanni
  The emergence of antibiotic resistant bacteria has made the treatments of pathogenic infections difficult. The discovery that some analytes of plant extracts are active against multi-drug resistant bacteria has opened ways to researching into the antimicrobial activity of these phytocomponents. Studies are designed to determine the antimicrobial and antioxidant potentials of the volatile oil of Ocimum gratissimum and its inhibition on partially purified and characterized extracellular protease of Salmonella enteritidis. The oil was extracted by hydrodistillation. Its antimicrobial effect was carried out using microdilution method while antioxidant effect was tested against 1,1-diphenyl-2-picrylhydrazyl (DPPH). The caseinolytic activity of the enzyme was studied with oil as inhibitor. The enzyme was partially purified with dialysis and gel filtration. The oil has scavenging activity of 66.98±1.78% compared to butylated hydroxyltoluene (positive control), 53.29±2.51% (sig. p<0.0001) against DPPH. Salmonella enteritidis was inhibited by this oil with IC50 of 3.98% (v/v). The enzyme had optimal activities at 45°C and pH 7.5. None of the metallic chloride tested produced any significant increase in the activity of the enzyme. Hg2+ and Pb2+ were inhibitors of this enzyme. The oil showed a non-competitive inhibition with Km = 0.33 mg mL-1, Vmax = 1.25x103 μmol min-1 (oil absent) and V’max = 2.50x102 μmol min-1 (oil present). The highest purification fold = 1.88 and the highest percentage yield = 51.74 as compared to the crude enzyme extract. Therefore, the volatile oil of Ocimum gratissimum possessed antimicrobial and antioxidant activities, its inhibition against this protease may be one of the ways of its antimicrobial effect.
  S.A. Adeola , O.S. Folorunso , G.O. Raimi and A.B. Akinsiku
  The recent development in the antimicrobial therapy to meet the challenges of resistant pathogenic bacteria has called for rapid growth in exploring natural products as alternative. The antimicrobial activity of the oils from the leaf and stem of Chromolaena odorata against nine enteric pathogenic bacteria was assessed and compared with commonly used antibiotics. Specifically, we examined the mode of inhibition of these oils on the extracellular protease of Pseudomonas aeruginosa. The inhibition zones of the oils range from 13.0±1.0-43.5±2.5 mm in Salmonella paratyphimurium and Shigella dysenteriae, respectively. Ceftriaxone has the highest inhibition of 26.0±2.0 mm against Salmonella paratyphimurium. There was a significant difference (p<0.05) between the average inhibition of the antibiotics, 5.0±0.82 mm and the volatile oils, 18.0±4.0 mm. Each of the microbes was sensitive to at least one of the oils. The extracellular protease of Pseudomonas aeruginosa had optimal activities at pH 7.5 and 35°C. The volatile oils competitively inhibited the extracellular protease of Pseudomonas aeruginosa with Vmax = 0.91 μmol min-1 and Km = 0.48 mg mL-1 (oil absent) but the K'm increased to 0.93 and 1.25 mg mL-1 in the presence of the volatile oils of the leaf and stem of this plant, respectively. The highest purification fold of 2.35 (6.92 μmol min-1 mg-1 protein) was achieved from the crude enzyme with DEAE anion exchange chromatography. The chromatographic peaks may be an evidence of multiple subunits of this enzyme. Therefore, the oil of Chromolaena odorata possessed antimicrobial activity and its ability to inhibit extracellular protease of Pseudomonas aeruginosa will be a possible source of nutraceuticals for clinical purpose.
  O.S. Folorunso , S. Adeola and A.O. Giwa Ajeniya
  Background and Objective: Medicinal plants are fast becoming essential pharmaceuticals for disease and infection management. The vast antimicrobial properties of these plants reside in the inhibitory properties of their endogenous secondary metabolites. Therefore, this study aimed to assess if the volatile oil of Syzygium samarangense inhibits enteric bacteria growth and its effect against the caseinolytic activity of the extracellular protease of Salmonella typhimurium. Materials and Methods: The volatile oil was extracted by hydrodistillation, while the antimicrobial assay was assessed with the microdilution method. The extracellular protease was partially purified by salting out, followed by size-exclusion chromatography. The mode of inhibition of this enzyme was deduced from the enzyme-substrate kinetics using a line-weaver burke plot. Results: The antimicrobial properties of the oil were reported against ten enteric bacteria. Proteus vulgaris has the highest IC50 value of 0.75±0.004% v/v, while S. typhimurium, the most sensitive bacterium, showed the lowest IC50 value of 0.17±0.005% v/v. The extracellular protease of S. typhimurium was partially purified to achieve 3.73 purification fold and 314.2 μmol min1 mg1 protein. The optimal caseinolytic activity of this enzyme was found at pH 7.5 and 40 °C. The protease showed significantly higher activity in the presence of Zn2+ (9.3±0.33 U min1) as compared to the control (7.0±0.58 U min1) (p<0.05), however, K+, Ca2+, Co2+, Ba2+, Pb2+ and Hg2+ considerably reduced the enzyme activity. The activity of this enzyme was competitively inhibited by the volatile oil as an inhibitor. Conclusion: The volatile oil of S. samarangense inhibited a wide range of enteric bacteria and, therefore proposed as a potential antimicrobial agent. Inhibiting the extracellular protease of S. typhimurium may be one of its modes of action against these pathogens.
  O.S. Folorunso , K.O. Amisu and B.F. Ogungbe
  The ability of microbial cell membrane to bind organic dye is an age long protocol that preludes the identification and characterization of bacteria cells and its components. We employed formation of keratoconjunctivitis, pigmentations and Congo red binding assay to assess the virulence of eight enteric pathogenic bacteria. Staphylococcus aureus and Salmonella typhimurium, at 3.0×108 CFU mL-1, was sufficient to cause keratoconjunctivitis in the eyes of Albino rat (Sereny test), while observing traces in Streptococcus faecalis, Klebsiella pneumoniae, Pseudomonas aeruginosa and Bacillus subtilis. Pigmentation (PCr+) occurred in Staphylococcus aureus, Streptococcus faecalis and Klebsiella pneumoniae. Highest protein secretion was found in Escherichia coli. Hydrophobicity of the microbial cell membrane increased in the order of chemical pre-treatments (0.9% w/v physiological saline, 50 mM Tris HCl, pH 7.8, 50 mM Tris HCl, pH 7.8+50 mM EDTA). Thus, Tris-EDTA adjunct increased hydrophobicity of the membrane to bind more Congo red than other treatments. Virulence strains of Gram-positive bacteria may likely cause a more severe keratoconjunctivitis. Pigmentations favoured Gram-positive than negative probably because of the membrane differentiation. The effect of multiple subculturing on the Congo red binding ability of these bacteria remained inconclusive as less than half of the tested bacteria complied with our hypothesis though, all were expectedly affected, when pre-treated. The virulence of bacteria is pre-determined by the inherent plasmid factors but their expression is a function of the bacteria cells to bind organic dye. Therefore, physico-chemical treatments that promote hydrophobicity of the bacteria cell membrane are likely to reduce their virulence.
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