Browsing by Author "Abdulhakeem Olarewaju Sulyman"

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    Antidiabetic Screening of Phenolic-rich Extracts of Selected Medicinal Spices
    (2018) Jubril Olayinka Akolade; Asiat Na’Allah; Abdulhakeem Olarewaju Sulyman; Azeemat Titilola Abdulazeez; Asiata Opeyemi Atoti; Mardiya Bawa Isiaku
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    Bioprospection of Selected Plant Secondary Metabolites as Modulators of the Proteolytic Activity of Plasmodium falciparum Plasmepsin V
    (2023) Abdulhakeem Olarewaju Sulyman; Oluwapelumi Oluwaseun Aje; Emmanuel Oladipo Ajani; Rukayat Abiola Abdulsalam; Fatai Oladunni Balogun; Saheed Sabiu; Nikhil Agrawal
    Malaria is a devastating disease, and its management is only achieved through chemotherapy. However, resistance to available medication is still a challenge; therefore, there is an urgent need for the discovery and development of therapeutics with a novel mechanism of action to counter the resistance scourge consistent with the currently available antimalarials. Recently, plasmepsin V was validated as a therapeutic target for the treatment of malaria. The pepsin-like aspartic protease anchored in the endoplasmic reticulum is responsible for the trafficking of parasite-derived proteins to the erythrocytic surface of the host cells. In this study, a small library of compounds was preliminarily screened in vitro to identify novel modulators of Plasmodium falciparum plasmepsin V (PfPMV). The results obtained revealed kaempferol, quercetin, and shikonin as possible PfPMV inhibitors, and these compounds were subsequently probed for their inhibitory potentials using in vitro and in silico methods. Kaempferol and shikonin noncompetitively and competitively inhibited the specific activity of PfPMV in vitro with IC50 values of 22.4 and 43.34 μM, respectively, relative to 62.6 μM obtained for pepstatin, a known aspartic protease inhibitor. Further insight into the structure-activity relationship of the compounds through a 100 ns molecular dynamic (MD) simulation showed that all the test compounds had a significant affinity for PfPMV, with quercetin (-36.56 kcal/mol) being the most prominent metabolite displaying comparable activity to pepstatin (-35.72 kcal/mol). This observation was further supported by the compactness and flexibility of the resulting complexes where the compounds do not compromise the structural integrity of PfPMV but rather stabilized and interacted with the active site amino acid residues critical to PfPMV modulation. Considering the findings in this study, quercetin, kaempferol, and shikonin could be proposed as novel aspartic protease inhibitors worthy of further investigation in the treatment of malaria.
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    Purification and Partial Characterization of Cellulase Produced by Aspergillus niger Cultured on Vitellaria paradoxa shells
    (2017) Abdulhakeem Olarewaju Sulyman; Yusuf A Iyanda; Afolabi Olaniyi Opasola; OtunOla Adedayo; Raliat Abimbola Aladodo
    This research investigated the purification and partial characterization of cellulase produced by Aspergillus niger cultured on Vitellaria paradoxa shells. Cellulase (endoglucanase) from A. niger was produced under optimum fermentation conditions at 35 °C, pH 4.7, V. paradoxa, 4 g/L, inoculum size of 10 mm and the fermentation media incubated for 120 hours. The crude endoglucanase obtained were partially purified by subjecting to ammonium sulphate precipitation, dialysis and gel filtration chromatography for further purification. The effect of temperature and pH on the activity of purified endoglucanase was determined. Cellulase was purified to 734.33 folds by Sephadex G-100 column chromatography with a specific activity and yield of 4.406 U/mg and 63.03% respectively. Fractions 4 and 7 contained the highest endoglucanase activity out of 18 fractions collected and the two fractions were pooled for further analysis. The activity of purified endoglucanase was optimum at a temperature of 40 °C and pH 5. Therefore, the purified endoglucanase produced may be explored in detergent industry.