Design, Synthesis and Structural Confirmation of a Series of 2-(Thiophen-2-yl)- 4H-chromen-3-yl-sulfonate Derivatives and Preliminary Investigation of Their Antioxidant and Anticancer Potentials

A series of novel 2-(thiophen-2-yl)-4H-chromen-3-yl-sulfonate derivatives (4a-4n) were synthesized and investigated for their in vitro free radical scavenging potential as well as cytotoxic efficacies against selected cancer cell lines. The cytotoxicity of the 4H-chromene derivatives (4a-4n) was evaluated according to three human cancer cell lines (HepG2, A549, HeLa) by utilizing a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Accordingly, part of the results exhibited better cytotoxic activities than that of the positive controls (4H-chromen-4-one and apigenin). Among them, compounds 4c-4g exhibited better training to the positive control against the three human cancer cell lines (half maximal inhibitory concentration (IC50) = 3.87 ± 0.12 to 21.38 ± 0.52 μM). Moreover, the extract of the 4H-chromene derivatives (4a-4n) showed better activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) in antioxidant assays compared to that of the positive control ascorbic acid (IC50 = 12.72 ± 0.27, 5.09 ± 0.21 μg mL−1). Thus, it can be confirmed from the bioassay results that the overall structural design, as well as proper substitution, is crucial in delivering anticipated biological effects. In this regard, spectroscopic techniques such as 1H nuclear magnetic resonance (NMR), 13C NMR, and high-resolution mass spectrometry (HRMS) were also carried out to confirm the final structures.