Synthesis of substituted 3-hydroxy flavones for antioxidant and antimicrobial activity

Flavonoids are phenolic compounds widely distributed in the plant kingdom. They are known to exhibit antioxidant, anti-inflammatory, antimicrobial, antihypertensive, antiplatelet, gastroprotective, antitumor, and antiallergic activies. Many available literatures prompted us to modify the benzopyrone ring present in the flavonoids to explore newer activities associated with this nucleus. The chalcones were prepared by reacting o-hydroxy acetophenone with dimethylamino benzaldehyde. 3-hydroxy flavone was prepared by reacting chalcone with alkaline hydrogen peroxide. 3-methoxy and 3- acetoxy flavone were prepared by reacting 3- hydroxyl flavone with dimethyl sulphate in acetone medium and acetic anhydride respectively. The different esters of 3-hydroxy flavones were prepared by treating the 3-hydroxy flavone with different acid chlorides in the presence of pyridine. The test compounds were characterised by UV, IR, ¹H-NMR and Mass spectral studies. For each test compounds λ _max, ∈ _max and pKa were determined using standard protocol. Two out of twelve test compounds showed antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, comparable to standard antibiotics Amoxicillin and Gentamycin. However, the test compounds found to have poorer DPPH radical scavenging activity.