Synthesis and Biological Activity of New Heterocyclic Compounds Derived from Thiosemicarbazide and Vanillin

Abstract

In this project, the reaction of Vanillin with Thiosemicarbazide give Schiff base (1) which then cyclized by using potassium carbonate, iodine and a solvent 1,4-dioxane to give compound (2), which react with Vanillin afforded the another Schiff base (3). This derivative was then introduced into the cyclization process with Sodium Azide NaN3, amino acid (Glycine, Alanine and Tyrosine), Mercaptoacetic acid (thioglycolic acid), phthalic anhydride, 2-Aminobenzoic acid, hydroxyl acetic acid (Glycolic acid) and Lactic acid to yield new Titrazoles (3a), imidazolidine-4-one (3b), (3c), 4-thiazolidinones (3d), 1,3-Oxazepine-4,7-dione (3e), Hydroquinazoline (3f), Oxazolidines (3g) and (3h), respectively. 1,3-oxazepine-4,7-dione compounds (3e) have been reacted with phenyl hydrazine to produce 1,3-diazepine-4,7-dione compounds (3ee), also, 4-thiazolidinones (3d) have been reacted with p-dimethylaminobenzaldahyde to produce thiazolidinone ring (3dd). Purity and characterization of the synthesized compounds were confirmed by determination of physical properties; melting points & Rf values. The final products were screened for their antimicrobial and antioxidant activities. The synthesized derivatives were evaluated for their antimicrobial activity against Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and K. pneumonia), and their antifungal activity against Candida albicans fungus, the results showed that tested compound (3d) showed the highest and promising antibacterial activity against S. aureus, E. col and K. pneumonia bacteria. Compound (3ee) showed the highest antibacterial activity against S. aureus, and moderate an inhibition against Klebsiella pneumonia, while compounds (3a) and (3g) showed moderate an inhibition against S. aureus. Also, the antioxidant activity of the synthesized compounds was evaluated by Ferric-bipyridine reducing capacity of total antioxidants (FBRC) method. The results showed that the compound (3c) to possess very strong antioxidant activity better than another prepared compounds. Also the compound (3c) possess high activities comparable to the standard BHT.