Guanidinyl benzothiazole derivatives: Synthesis and structure activity relationship studies of a novel series of potential antimicrobial and antioxidants

A series of N-phenyl-substituted and disubstituted guanidinyl benzothiazole derivatives 4a-4m were synthesized and characterized as novel antimicrobial and antioxidant agents. The in-vitro antioxidant activities of these compounds were evaluated and compared with commercial antioxidants, using ascorbic acid (AA) and employing 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and 2,2'-azino-bis (3-ethylbenzthiazoline- 6-sulphonic acid (ABTS) assay. The results showed that IC50 values of compounds 4a and 4m were similar to the IC50 values of the standard. This assay indicates the good activities of these compounds. In addition, the in-vitro antimicrobial activities of these compounds were evaluated and the results demonstrated that the compounds 4i and 4l exhibited excellent antimicrobial activities. Compounds 4c and 4i having electron withdrawing groups at p-position and compound 4l and 4m having electron donating groups at o-position showed better antimicrobial activities compared to the standard.