Research: COVID-19 Virus

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Research that investigated genetic mutation and the clinical significance of possible mutations.

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    Inhibition Characteristics of Peptide Extracts of Four Medicinal Plants on Activities of Bovine Trypsin
    (Elsevier, 2023-07-04) Famutimi, Oladoyin Grace ; Adewale, Isaac Olusanjo; Adegoke,Kehinde Rofiat
    Aqueous extract of leaves of Momordica charantia, Hymenocardia acida, Lawsonia inermis and fruit of Xylopia aethiopica have been used in sub Saharan Africa in the management of many viral diseases. Their medicinal properties had been reported to be due to their high antioxidant activities, but limited information is available whether these properties are also due to inhibition or modulation of proteases important in the pathology of viral infections. We report the inhibitory characteristics of peptides extracted from these medicinal plants against bovine trypsin, a serine protease. Extraction of the peptides was done using standard procedure and their inhibitory activities were measured against bovine trypsin. Aqueous extract of M. charantia, H. acida, L. inermis and X. aethiopica contain 5.7 ± 0.5 mg/ml, 1.0 ± 0.2 mg/ml, 1.8 ± 0.1 mg/ml and 28.3 ± 4.1 mg/ml of peptides, respectively. Using Nα-benzoyl-DL-arginine 4-nitroanilide (BAPNA) as trypsin substrate, a Km and Vmax of 0.34 mM and 0.6 μmole/min/mg protein obtained, were altered in the presence of the peptide extracts suggesting the extracts modulate trypsin activity. The inhibition was either competitive, non-competitive or mixed-type of non-competitive inhibition. Inhibition constant (Ki) ranging from 81 to 831±120 μg/ml were obtained using Dixon plot with the peptide extract from M. charantia being the most potent. We concluded that the medicinal and antiviral properties of the extracts could also be due to inhibition or modulation of proteases involved in the pathology of viral infection.
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    Large-Scale Synthesis of CISe/ZnS Core-Shell Quantum Dots and Its Effects on the Enzymatic Activity of Recombinant Human Furin (an Activator of SARS-CoV-2 S1/S2 Spike Proteins)
    (2023) Vuyelwa Ncapayi; Oladoyin Famutimi; Thabang Calvin Lebepe; Rodney Maluleke; Sam Masha; Nande Mgedle; Sundararajan Parani; Tetsuya Kodama; Isaac Olusanjo Adewale; Oluwatobi Samuel Oluwafemi
    We herein report, for the first time, the activity of copper indium selenide/zinc sulphide core-shell quantum dots (CISe/ZnS QDs) as an inhibitor against recombinant human furin, an enzyme that has been implicated in the aetiology of many diseases, including Covid-19. The cell viability of the as-synthesised CISe/ZnS QDs was tested against mouse colon carcinoma cells (C26), while the Furin activity was measured by hydrolysis of peptide substrate Pyr-RTKR-AMC liberating the fluorogenic 7-amino-4-methyl coumarin. The result showed that the as-synthesised stable near-infrared emitting (840 nm) CISe-ZnS QDs is biocompatible against C26 and can inhibit furin with an inhibition constant, Ki, of 15.66 μM. The IC50 was 11.29 ± 0.54 μM, while the enzymatic activity was abolished at about 23 μM of the inhibitor concentration. The results indicate the chemotherapeutic potential of CISe-ZnS QDs as an enzyme inhibitor, which may find application in managing diseases whose pathogenesis involves hyperactivity of furin.