UnizikSpace Collection: Scholarly Works

Antimicrobial Activities of the Endophytic Fungus, Fusarium equiseti, Isolated from The leaves of Ocimum gratissimum

2022-08-01T00:00:00Z

Title: Antimicrobial Activities of the Endophytic Fungus, Fusarium equiseti, Isolated from The leaves of Ocimum gratissimum Authors: Adione, Nnamdi Markben; Onyeka, Ifeanyi Peter; Abba, Chika Christiana; Okoye, Nkeoma Nkasi; Eze, Peter Maduabuchi; Umeokoli, Blessing Ogechukwu; Anyanwu, OgechI Ozioma; Okoye, Festus Basden Chiedu Abstract: Introduction: Fungal endophytes of medicinal plants origin are gaining increasing interest as sources of novel bioactive agents with therapeutic capacity. This study was designed to identify and evaluate secondary metabolites isolated from Fusarium equiseti; an endophytic fungus isolated from leaves of Ocimum gratissimum for their antimicrobial potentials. Methods: The isolation and molecular identification of the endophytic fungus, as well as fermentation, and extraction of secondary metabolites were carried out following standard laboratory procedures. The crude extract was partially purified by partitioning into different fractions using column chromatographic techniques and the fractions were tested for antimicrobial activity. The phytoconstituents in the bioactive fractions were detected by dereplication using High-Performance Liquid Chromatography linked with Diode Array Detection (HPLC-DAD).Results: Our findings showed that fraction 4 (DCM/ Methanol fraction 95:5) exhibited moderate to strong inhibition against the test micro-organisms namely, Bacillus subtilis, Staphylococcus aureus,Escherichia coli, and Candida albicans with MIC values in the range of 0.03 to 1 mg/mL but had no inhibition against Aspergillus niger and Salmonella typhi. The compounds detected in the HPLCassay include Phomoxanthone A, Scalarolide, equisetin, epi-equisetin an episomer of equisetin, Naamine A, Carbonarone A, destruxin B, cytosporin G, and WLIP (β-hydroxydecanoyl-Leu1-D Glu-De-Thr-Dval-DLeu3 DSer-Leu-Dser-Ile). These compounds have been reported to possess antimicrobial activity. Conclusion: The detection of these metabolites further confirms the potential of the endophytic fungus, Fusarium equiseti isolated from leaves of Ocimum gratissimum as a potential source of bioactive molecules for treatment of infectious diseases. Description: scholarly work

Spectrophotometric determination of some cephalosporin antibiotics using Prussian blue reaction

2007-07-05T00:00:00Z

Title: Spectrophotometric determination of some cephalosporin antibiotics using Prussian blue reaction Authors: Okoye, Nkeoma N; Nwokedi, Godwin I. C; Ukwueze, Nkechinyere N; Okoye, Festus B. C Abstract: A simple, sensitive and accurate spectrophotometric method of analysis of ceftriaxone, cefotaxime and cefuroxime in pharmaceutical dosage forms has been developed and validated. The method is based on the formation of Prussian Blue (PB) complex. The reaction between the acidic hydrolysis product of the antibiotics (T = 70C) with the mixture of Fe3+and hexacyanoferate (III) ions was evaluated for the spec- trophotometric determination of the antibiotics. The maximum absorbance of the coloured complex occurred at = 700 nm and the molar absorptivity is 3.0 x 104l.mol-1cm-1. Reaction conditions have been optimized to obtain PB complex of high sensitivity and longer stability. Under optimum conditions the absorbance of the PB complex were found to increase linearly with increase in concentrations of ceftriaxone, cefotaxime and cefuroxime, which corroborated with the correlation coefficient values. The linear range of the calibration graph was 2 - 20 g/ml for ceftriaxone and cefotaxime and 2 - 18 g/ml for cefuroxine. The proposed method was successfully applied to the determination of the selected antibiotics in bulk drugs and pharmaceutical formulations and the results obtained agree well with the labeled contents. Description: scholarly work

Evaluation of the antioxidant potentials of extract and fractions of Vitex doniana fruit and identification of the bioactive metabolites using HPLC-DAD-MS analysis

2021-10-17T00:00:00Z

Title: Evaluation of the antioxidant potentials of extract and fractions of Vitex doniana fruit and identification of the bioactive metabolites using HPLC-DAD-MS analysis Authors: Ajah, Keziah Uchechi; Asomugha, Ozioma Anne; Ifedigbo, Chinazom Perpetua; Umeh, Kosoluchukwu Chidubem; Obidiegwu, Onyeka Chinwuba; Ajaghaku, Amara Anwuchaepe; Okoye, Nkeoma Nkasi; Omoriri, Moses Aziakpono; Okoye, Festus Basden Chiedu Abstract: Isoflavones and flavonoids in general found in fruits and vegetable act as natural antioxidants. This study was aimed at screening the isoflavone-rich fractions of Vitex doniana fruit extract for antioxidant activity using in vitro and in vivo models. The ethyl acetate and butanol fractions were screened for in vitro antioxidant activity by DPPH free radical scavenging and FRAP (Fe3+ Reducing Antioxidant Power) assays using ascorbic acid as standard. In vivo antioxidant activity was also tested against carbon tetrachloride-induced toxicity in mice using carbon tetrachloride (4 mL/kg) and silymarin (100 mg/kg) as standard. The ethyl acetate fraction and butanol Vacuum Liquid Chromatography (VLC) sub-fractions were subjected to High Performance Liquid Chromatography–Diode Array Detector (HPLC-DAD) and Liquid Chromatography-Mass Spectrometry (LC-MS) analyses. The ethyl acetate and butanol fractions inhibited DPPH radicals with an IC50 of 897 μg/mL and 2809.38 μg/mL respectively. Both fractions also showed mild FRAP result with EC50 of 1401 μg/mL and 7051 μg/mL respectively. The fractions produced significant decrease (P < 0.05) in ALP levels only while ethyl acetate fraction caused a significant reduction in the value of only malondialdehyde. Both fractions also increased levels of superoxide dismutase (SOD). HPLC-DAD analysis led to the detection of cinnamic acid, protocatechuic acid and two isoflavones daidzein and genistein. Further LC-MS analysis confirmed the presence of the isoflavones tectorigenin, 5-O-methylgenistein, and 5-O-methyltectorigenin, among other flavonoids, peonidin, 5-methylpeonidin, methylmalvidin and kaempferol-3-O-(2''galloyl)-glucopyranoside. The detected isoflavones and other flavonoids may contribute to the observed mild in vitro and good in vivo antioxidant activity of V. doniana fruit extract and fractions. Description: scholarly work

Antimicrobial Screening and HPLC-DAD-MS Characterization of the Flavonoid–Rich Fractions of the Methanol Leaf-Extract of Lawsonia inermis Linn

2021-09-02T00:00:00Z

Title: Antimicrobial Screening and HPLC-DAD-MS Characterization of the Flavonoid–Rich Fractions of the Methanol Leaf-Extract of Lawsonia inermis Linn Authors: Okeke, Vivian O; Okoye, Nkeoma N; Ngwoke, Kenneth G; Okoye, , Festus B. Chiedu Abstract: Flavonoids are known for their wide biological activities, including antimicrobial activity. This study was aimed at investigating the antimicrobial potential of the flavonoid-rich fractions of Lawsonia inermis leaf extract. The ethylacetate fraction from the methanol extract of L. inermis leaves was subjected to Vacuum Liquid Chromatography (VLC) using binary combinations of Hexane: Ethylacetate and Dichloromethane:Methanol to obtain fractions F1-F14. Fractions F11 and F12 which contain flavonoids were further subjected to High Performance Liquid Chromatography–Diode Array Detector (HPLC-DAD) and Liquid Chromatography-Mass Spectrometry (LC-MS) analysis, and subsequently subjected to in vitro test for antimicrobial activity against laboratory strains of Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger, Candida albicans using Agar well diffusion method at concentrations of 0.0625-1 mg/mL. Erythromycin (50 μg/mL) and Miconazole (50μg/mL) were used as positive controls for bacteria and fungi, respectively. HPLC-DAD and LC-MS analysis of the flavonoid-rich fraction (F12) led to the detection and identification of four flavone pigments namely; vitexin, luteolin 4-glucoside, apigenin monoglycoside and isoorientin (luteolin 6C-β-glucoside). Fraction F11 (constituents not identified) and fraction F12 (the flavone- rich fraction) showed moderate antibacterial activity, with E. coli being the most susceptible bacteria with Minimum Inhibition Concentrations (MIC) of 62.5 μg/mL for F11 and 500 μg/mL for F12. Very mild anti-fungal activity was only observed against C. albicans but not against A. niger. The unidentified polar compounds (the major components of F11) and luteolin 6C-β-glucoside (the major flavones detected in F12) may contribute to the observed antimicrobial activity of L. inermis leaf extract. Description: scholarly work