Browsing by Author "Ahmadu, Augustine A."

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    Novel cholinesterase inhibitory effect of α-spinasterol isolated from the leaves of Acacia auriculiformis A. CUNN Ex. Benth (Fabaceae)
    (Tropical Journal of Pharmaceutical Research, 2020-07) Lawal, Bilqis A.; Udobre, Aniefiok; Elufioye, Taiwo O.; Ahmadu, Augustine A.; Olanipekun, Bolatito
    Purpose: To investigate the in vitro anticholinesterase, α-glucosidase and antioxidant activities of α- spinasterol isolated from Acacia auriculiformis leaves. Methods: The powdered leaves of Acacia auriculiformis were extracted with 70 % ethanol and the dried hydroalcoholic extract was suspended in water and partitioned with ethyl acetate and n-butanol to give their soluble fractions. The in vitro inhibitory activities of α-spinasterol were determined against cholinesterase and, α-glucosidase enzymes, and free radical scavenging potentials using (1,1-diphenyl- 2-picrylhydarzyl (DPPH) and 2,2-azino-bis (3-Ethylbenzothiazoline-6-sulphonic acid (ABTS) antioxidant assays. Results: The compound, α-spinasterol, exhibited moderate anticholinesterase activity (IC50 value of 44.19±2.59 μg/mL which was significantly different at (p < 0.05) when compared to the standard galanthamine (IC50 value of 1.73 ± 1.10 μg/mL). It also displayed a good α-glucosidase inhibitory activity with IC50 value of 8.65 ± 1.71μg/mL which was not significantly different when compared to the standard, acarbose with IC50 value of 2.79±0.81 μg/mL. This compound, however, exhibited weak free radical scavenging activities at 26.93 ± 0.00 and 35.16 ±.0.26 % inhibition of DPPH+ and ABTS+ radicals as compared to ascorbic acid and Trolox (73.88 ± 0.04 and 99.82 ± 0.00%) respectively. Conclusion: The results show that α-spinasterol isolated from Acacia auriculiformis exerts potent inhibitory effect against cholinesterase enzyme which might serve as a lead in the search for drugs against Alzheimer disease and diabetes mellitus.
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    Tetrahydroxy Flavone from Acacia auriculiformis A. Cunn Ex Benth. (Fabaceae) with Novel Kinase Activity.
    (Pharmacognosy Journal, 2019-04) Ahmadu, Augustine A.; Lawal, Bilqis A.; Haruna, Anas; Mustapha, Lukman
    Background: The decoctions of the bark of Acacia auriculiformis are used in folkloric medicine to relieve pain and inflammation and as remedy for cancer. Objective: The aim of this work is to screen the extract and fractions of Acacia auriculiformis for protein kinase inhibitory activity and also to isolate and characterize chemical entities from this plant and evaluate their protein kinase inhibitory activity. Materials and Methods: Kinase inhibitory activity were assayed in appropriate buffer, with either protein or peptide as substrate in the presence of 15μM (33-P) ATP (3,000Ci/mmol; 10mCi/ml) in a final volume of 30μL. Controls were performed with appropriate dilutions of dimethyl sulphoxide. A portion of the Chloroform extract, ethylacetate and n-butanol soluble fractions of the stem bark of Acacia auriculiformis were screened against a panel of disease-related protein kinases and the active fractions was tested over a wide range of concentrations from 0.016 to 50μg/ml and the IC50 values were determined from the dose response curve. The most active fraction was subjected to chromatographic separation using Silica gel G column chromatography and sephadex LH-20 to give compound I. The structure of the isolated compound was elucidated using NMR and LCMS. Results: The Primary screening of the extract and fractions showed that the chloroform extract was inactive against all the protein kinases investigated, while the ethylacetate and n-butanol soluble fractions inhibited all the protein kinases tested. Compound I also inhibited all the kinases tested. The IC50 of the active fractions and compound were also evaluated. Ethylacetate fraction inhibited all the kinases tested with the highest activity against Haspine kinase with IC50 of 1.0 μg/ml, while n-butanol also gave the highest activity against Haspine kinase with 1C50 of 1.3 μg/ml. From the active ethylacetate fractions 3, 4’, 7, 8- tetrahydroxy flavone was isolated. The Compound exhibited the maximal activity against DYRK1A kinase with an IC50 of 2.05 μg/ml followed by CDK9 with an IC50 of 2.28 μg/ml. Conclusion: 3, 4’,7, 8- tetrahydroxy flavone was isolated was found to be a DYRK1A and CDK9 inhibitor which might justify the anticancer potential of this plant.