Design, Synthesis And Activity Study Of The Prodrug Of 5-Fluorouracil And Tamibarotene

5-Fluorouracil(5-FU) is an antimetabolite drug which is widely applied in anti-tumor treatment. Owing to its excellent antineoplastic activity,5-FU is preferred for the treatment of cancers such as gastric cancer, colorectal cancer and breast cancer. Although its clinical success domonstrates the excellent anticancer activity of 5-FU, various adverse effects such as severe myelosuppression and gastrointestinal side effects have been reported in some patients during clinical evaluation. Moreover, short half-life and poor selectivity also limit its application in anticancer treatments.Tamibarotene (AM80), a retinoic acid receptor alpha (RARa) subtype-selective agonist, was developed to treat against relapsed and refractory acute promyelocytic leukemia (APL) and has been marketed in Japan in June,2005. Additionally, earlier trials have validated that it tends to be more potent and tolerated than all-trans retinoic acid (ATRA). Unfortunately, a wide variety of side effects such as triglyceride, hypercholesterolemia, rash, ostealgia, retinoic acid syndrome and teratogenesis has been reported during clinical evaluation and consequently restrict its clinical application.Herein, with the aim of reducing side effects and prolonging the drug action time, and based on the structure of 5-fluorouracil and tamibarotene, we designed and synthesized the prodrug T-5FU, which was formed by ester linkages between 5-FU and AM80.5-FU firstly reacted with 37% formaldehyde solution to introduce a hydroxyl group. Then the intermediate reacted with AM80 directly under the condition of DCC and DMAP to finally afford T-5FU. The structure was confirmed by 'H-NMR and ESI-MS. Subsequently, a series of in vitro metabolic stability tests were carried out in stimulated gastric fluid, stimulated intestinal fluid, human plasma, mouse fresh plasma and liver homogenate to evaluate the stability of the prodrug T-5FU. In addition, MTT assay was applied to evaluate the antiproliferative activity of T-5FU against three cell lines (HL60, K562 and U937). Besides, we conducted in vivo antitumor activity study in nude mice for further evaluation.In vitro metabolic stability tests indicated that T-5FU is stable in stimulated gastric fluid without degradation.8 h later, there is a degradation but with low degradation rate in stimulated intestinal fluid. In human plasma, there is a degradation after 4 h, and the degradation rate reaches 62% after 10 h. In addition, T-5FU is found to be easy to degrade in mouse plasma and liver homogenate. In vitro antiproliferative assay demonstrated that T-5FU exhibits better antiproliferative activity than AM80 and 5-FU. However, in vivo antitumor activity study revealed that T-5FU possessed poorer tumor suppression than AM-80 and 5-FU. More importantly, T-5FU shows no obvious side effects and can prolong the drug acition time, which provide a strong foundation for preclinical studies of T-5FU including the dosage and route of administration.