Tetrahydroxy Flavone from Acacia auriculiformis A. Cunn Ex Benth. (Fabaceae) with Novel Kinase Activity.
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Date
2019-04
Journal Title
Journal ISSN
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Publisher
Pharmacognosy Journal
Abstract
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.
Description
Keywords
Tetrahydroxyflavone, Protein kinases, CDK9, DYRK1A