Design, Synthesis, Docking Studies and Antimicrobial Activity of 5-Substituted 4-Phenyl-2-(Phenylamino) Thiophene-3-Carboxylic Acid Ethyl Esters

There is an urgent need to develop new anti-microbials with better therapeutic profiles to combat emerging antimicrobial-resistant microbes. To this end, a series of new 2,3,4,5-tetra substituted thiophene derivatives bearing various scaffolds at 5-position were synthesized and screened for their potential antibacterial and antifungal activities. The tested compounds demonstrated significant antibacterial activity against the Gram-positive strains than to Gram-negative strains. The observed zone fields were 12.3 - 19.5 and 12.7 - 29.8 mm against S. pneumonia and B. subtilis, respectively. The highest inhibition zones against the Gram-positive strains S. pneumoniae and B. were observed with compound 10. Similarly, in observing the activity against the Gram-negative bacterial strains, compound 7 (thiophene moiety coupled with pyridazine) was effective against both the Gram-negative bacterial strains (Pseudomonas aeruginosa and Escherichia coli), giving zone of inhibitions of 18.2 and 15.6 mm, respectively. At the antibacterial activity profile of our blends, it is evident that compounds 7, 11 were potent against a broad range of bacterial strains. In addition, all tested compounds were very active against tested fungal strains. However, the thiophene derivative 4, which structurally extended with amide, exhibited notable antifungal activity in tested fungal strains (A. fumigates and S. racemosum) better than the reference drug Amphotericin B. Docking studies further supported our finding and provided the basis of linkages in terms of conventional hydrogen bonds and pi- bonding patterns. In summary, the present results lay the groundwork for developing lead compounds with improved antimicrobial activities.