Synthesis and biological evaluation of nitric oxide-releasing hybrids from gemcitabine and phenylsulfonyl furoxans as anti-tumor agents

A series of novel hybrids 10a–m were designed and synthesized by coupling phenylsulfonyl furoxans with gemcitabine through various diols or alcohol amine linkers, and their biological activities were evaluated in vitro. Most of the hybrids exhibited good to moderate anti-tumor activities, which are associated with NO release. In particular, hybrid 10e showed excellent anticancer activities which were more potent than or comparable to gemcitabine. However, inhibition of nucleoside transport only significantly decreased the inhibitory rates of gemcitabine against HepG2 cells but not 10e, and the inhibitory rates of 10e were partially reduced by pre-treatment with hemoglobin, demonstrating that the anti-tumor activity of 10e might result from the synergic effect of high levels of NO production and gemcitabine fragment. In addition, compound 10ecould apparently induce cell apoptosis by regulating apoptotic relative proteins. Therefore, our novel findings provide a proof of principle in the design of new furoxan/gemcitabine hybrids for the intervention of human cancers.