Synthesis and in Vitro Biological Evaluation of Hybrids from Tetrahydro-[beta]-carboline and Hydroxylcinnamic Acid as Antitumor Carcinoma Agents

Novel hybrids 8a-j and 9a-j were designed and synthesized by coupling the carboxyl group of hydroxylcinnamic acids with tetrahydro-β-carboline alkaloids which were linked with different substituted nitrogen-containing heterocycles at the positions-N9, and their in vitro biological activities were evaluated. It was found that most hybrids showed good to moderate anti-tumor activities. Especially, compound 9j had a great potency superior to 5-fluorouracil (5-FU) and comparable to adriamycin in human cancer cells, and could selectively inhibit tumor cells, but not inhibit non-tumor cell proliferation in vitro. More importantly, apoptosis assay indicated that 9j could significantly induce tumor cell apoptosis in a dose-dependent manner. Therefore, our novel findings may provide a new framework for the design of new hybrids for the intervention of human cancers.