Title:A Study on Identification of Nutraceutical Value of New Imidazolone Schiff Base Analogues
VOLUME: 14 ISSUE: 12
Author(s):Subbulakshmi N. Karanth, Badiadka Narayana*, Balladka K. Sarojini, Saleemulla Khan and Shashidhara S. Kenkere
Affiliation:Department of Studies in Chemistry, Mangalore University, Mangalagangothri-574 199, Karnataka, Department of Studies in Chemistry, Mangalore University, Mangalagangothri-574 199, Karnataka, Department of Industrial Chemistry, Mangalore University, Mangalagangothri-574 199, Karnataka, Department of Pharmacognosy, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal-576104, Karnataka, Department of Genetics and Plant Breeding, College of Agriculture, University of Agricultural Sciences, Bangalore, Karekere, Hassan-573225, Karnataka
Keywords:Imidazolone, schiff base, antioxidant, structure-activity, molecular docking, glycine.
Abstract:Background: Imidazolones as well as Schiff base are extensively used as building blocks
for the synthesis of various pharmaceutically active agents. The use of synthetic antioxidant for use
in the diet and therapy demands a great deal of research attention for synthetic antioxidants. It was
observed that the π-excessive ring systems are responsible for antioxidant activity of the compounds.
Objective: The primary objective of this study was to develop a new method to synthesize
imidazalone derivatives which are evaluated for in vitro antioxidant activity in order to check their
nutraceutical value.
Methods: Novel method for the synthesis of imidazalone derivatives is developed starting from
simple easily accessible glycine, thiophene aldehyde and benzoyl chloride. The synthesis of target
molecules is achieved in four steps via formation of an intermediate oxazolone which undergoes
ring opening on reaction with hydrazine hydrate and subsequent cyclization with aldehydes in presence
of acid catalyst.
Results: All Imidazolone compounds were evaluated for their in vitro antioxidant activity using
2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Almost all the tested imidazalone
compounds showed moderate to excellent activity, the substitution on arylidene group substantially
influenced their overall activity. The compound 3-{[(E)-(4-chlorophenyl)methylidene]amino}-2-
phenyl-5- (thiophen-2-ylmethylidene)-3,5-dihydro-4H-imidazol-4-one (9) showed very high radical
scavenging capacity with IC50 value 2.886 µg/ml in comparison with the standard ascorbic
acid (1.439 µg/ml). The antioxidant activities of the synthesized compounds appeared in the
following order 6 >5> 13> 8>7>20>11>12>10>19>15>14>18>16 and 17. Further in silico studies
complement the in vitro antioxidant studies.
Conclusion: Compound, 3-{(4-chlorophenyl)methylidene]amino}-2-phenyl-5-(thiophen-2-ylmethylidene)-
3,5-dihydro-4H-imidazol-4-one (9) displayed best antioxidant activity due to the presence of active
chloro group. Compounds bearing hydroxyl group at para and ortho position (16 and 18) showed
very low activity. This anomalous result could be explained on the basis of intramolecular hydrogen
bonding. These results were complement the in silico antioxidant studies.
