Syntheses, crystal structures, in vitro antitumor and free radical scavenging activity evaluation of a series of 2-substituted thiophenes

A series of thiazole, pyridine and benzylidene derivatives derived from thiophene scaffold have been synthesized. The antitumor evaluation of the newly synthesized products against four cancer cell lines, namely breast carcinoma (MCF-7), liver carcinoma (HepG2), colon carcinoma (HCT-116) and prostate carcinoma (PC3), indicated that the thiazole derivative 11b showed remarkable activity against all cell lines with LC₅₀ values of 18.3, 2.5, 7.5 and 7.6 μM, respectively. Cytotoxicity toward normal cell lines was also investigated and indicated that compound 21c displayed remarkable potency against PC3 with LC₅₀ values of 7.1 μM and showed weak inhibition of normal cell lines at (GI %) of 41.2 % and thus could be considered as an important lead compound for potential application in anticancer chemotherapy. Brine shrimp lethality assay of the most active compounds was carried out to detect possible cytotoxicity effects and indicated that highly active compound, 21c, is not harmful. The X-ray crystallographic analysis of compounds 3 and 11b was obtained thus establishing with certainty the proposed structures in this work. The synthesized compounds were also screened for their free radical scavenging activity. Hydrazino-thiazole derivatives 15 and 16 showed remarkable antioxidant activity with IC₅₀ values of 60.9 and 61.9 μg ml^-1, respectively.