Seco - Dck Derivatives As Anti-hiv Lead Compounds For Development Research

Suksdorfin, a natural product isolated from the fruit of Lomatium Suksdorfii, has an angular pyranocoumarin skeleton with interesting biological properties, especially its anti-HIV activity (EC50=2.6±2.1μM, TI=30.6±22.4, TI=therapeutic index IC50/EC50). Structural modification of Suksdorfin yielded DCK and 4-methyl-DCK which demonstrated extremely potent inhibitory activity against HIV-1 replication in H9 lymphocytic cells (EC50=4×10-4μM, TI=136719 and EC50=1.57×10-7μM, TI>109, respectively).In the further research of our group, we found the anti-HIV activity of 7-S-DCKs was higher than DCKs. Particularly, the 4-methyl-7-thio-DCK exhibited moderate potency against drug resistant HIV-1TMDR (EC50=2.25μM, TI>12.4),which was not sensitive to DCK derivatives. This suggests that 7-sulfur atom instead of 7-oxygen atom in DCKs may be favorable for improving anti-HIV activity. Moreover, in order to find new analogues with better drug likeness character, a series of Seco-DCK analogs with only dicyclic skeleton were designed and synthesized by our group. Among them, Seco-C ring 4-methyl DCK showed the best anti HIV activity with an EC50 value of 0.058μM and TI of 1000, threefold more potent than 4-me-DCK (EC50:0.126μM, TI: 301.2) in the same against HIV-1ⅢB assay. This information implies the integrity of C ring in DCKs is not essential for maintaining anti-HIV activity.Based on above research results, in this thesis we further designed and synthesized 7-S-Seco-DCK analogues to investigate the effect of bioisosteric replacement at 7-position with sulfur instead of oxygen in Seco-DCKs. Meanwhile, considering the camphonoyl ester unit in DCKs or Seco-DCKs is not benefit to molecule stability and ease to cause the complicacy of metabolism in vivo, a kind of 9-camphonoyl ether analogues of seco-DCK was synthesized to explore their chemical stability and the impact on the anti-HIV activity.In the synthetic research, we use the 7-Hydroxy-4-methy-coumarin as starting material to get target 7-S-seco-DCK via the introduction of 8-formyl with Duff's reaction, followed by the protection with glycol, esterification of 7-hydroxyl with dimethylthiocarbamoyl chloride, Newman-Kwart rearrangement, deprotection, reduction of formyl, hydrolysis of 7-S ester and re-esterification with camphonoyl chloride.Additionally, three 7-0-9-ether-seco-DCKs and one 7-O-ester-seco-DCK were synthesized using 2,6-dihydroxy-toluene as starting material, via the bromination of methyl, esterification, hydrolysis, etherization and so on multi-steps. During the attempt of selective bromination of 8-methy in coumarin skeleton, the complicated behavior of the reaction of 7-O-substituted 8-methyl-coumarins with N-bromosuccinimide in CCI4 were investigated carefully. The effect of different substituents at 7-oxygen on bromination products was explored and the mechanism of forming a series of products were rationaly discussed. Finally, the bromination at 8-methyl was realized by the optimization of reaction condition.In this thesis reaserch, five novel target molecules and other 36 new compounds were synthesized. The structures of them were confirmed by various spectral analyses, including 1H NMR,13C NMR and mass spectra.All target compounds are sent for testing anti-HIV activity. According a part of received preliminary bioassay data, the 9-comphonol ether of seco-DCK showed a considerable anti-HIV activity but much lower than corresponding 9-comphonoyl ester. This indicated ester linkage in 9-position is benificial to anti-HIV activity. The assay of other target molecules is undergoing.The study on chemical stability in vitro revealed that 7-S-seco-DCK is more stable than both of 7-O-seco-DCK and 4-methyl-DCK in acidic solution.