Bio-Preservative Efficacy of Some Synthetic Hydroxy Chalcones Against Pathogens and Oxidants

In tropical and subtropical regions specially in Bangladesh and neighborhood countries foodborne diseases are more ubiquitous. Climate change, prolong sunray, high ambient temperatures, humidity etc. might be the root cause of food contamination by bacterial agents. All these factors are also very auspicious for food spoilage by autooxidation. The potential of phytochemicals specially secondary metabolites like flavonoids are known to be used as treatment against food borne pathogens and oxidative radical scavengers, prevention of food contamination to reduce the threat of food illness as well. Biosynthetic plant pigment chalcones were attempted to modify by Claisen-Schmidt condensation process aiming to enhance bio efficacy. Chalcones with ring substituents, 2′ – hydroxy – 2, 4, 6 – trimethoxy, 3a, 2′ – hydroxy – 4′– benzyloxy – 2, 4, 5 – trimethoxy, 3b, 2′ – hydroxy – 2, 4, 5 – trimethoxy, 3c, 2ʹ, 4′, 3 – trihydroxy – 4 – methoxy, 3d, 4 – hydroxy – 3ʹ, 4′, 5′ – trimethoxy, 3e were prepared and structurally confirmed by spectral techniques (UV, IR, 1H, 13C NMR). All the compounds, specially 3a and 3b manifest pretty good in vitro microbial activity against Bacillus cereus, G+, B1 (26, 25), Staphylococcus aureus G+, B2, (32, 08), Escherichia coli G−, B3, (25,15), Shigella dysenteriae G−, B4 (25, 26) as compared to the standard ciprofloxacin (35-40) at 200 μg disc-1 by disk diffusion method measured in mm scale. Least IC50 value was obtained for compound 3b (7.25 μg/mL), at DPPH conc. 0.032% compared to the standard ascorbic acid IC50 (0.081 μg/mL) indicating high potency of antioxidant activity.