Quinoline based furanones and their nitrogen analogues: Docking, synthesis and biological evaluation

A small library of twenty-four quinoline based butenolides also known as furanones and their nitrogen analogues was prepared by using two different aroylpropionic acids, viz. 3-(2-naphthoyl)propionic acid (3) and 3-(biphenyl-4-yl)propionic acid (4), as starting materials. The 3-aroylpropionic acids were reacted with different 6-substituted-2-chloroquinolin-3-carbaldehydes (2a-d) to obtain the corresponding furan-2(3H)-ones (5a-h). The purified and characterized furanones were then converted into their corresponding 2(3H)-pyrrolones (6a-h) and N-benzyl-pyrrol-2(3H)-ones (7a-h). The antimicrobial activities of the title compounds were evaluated against two strains of each Gram +ve (Staphylococcus aureus and Bacillus subtilis), Gram -ve bacteria (Escherichia coli and Pseudomonas aeruginosa) and against fungal strains of Aspergillus niger and Aspergillus flavus. In vivo anti-inflammatory potential of the title compounds was investigated by standard method. Majority of the compounds showed significant antibacterial activity against both the Gram +ve strains. Eight most potent anti-inflammatory compounds (5b, 5d, 5h, 6b, 7b, 7d, 7f, 7h) which exhibited >53% inhibition in edema, were also screened for their in vivo analgesic activity. All the tested compounds were found to have significant reduction in ulcerogenic action but only three compounds (5d, 5h and 7h) showed comparable analgesic activity to standard drug, diclofenac. The results were also validated using in silico approach and maximum mol doc score was obtained for compounds 7a-h. On comparing the in vivo and in silico anti-inflammatory results of synthesized compounds, N-benzyl pyrrolones (7a-h) emerged as the potent anti-inflammatory agents. It was also observed that compounds that possess electron withdrawing group such as -Cl or NO₂ are more biologically active.