The Synthesis Of Bleomycin Disaccharide, DP-b99 And Their Derivatives

The bleomycins (BLMs) are a family of glycopeptide-derived antitumor antibiotics used clinically for the treatment of squamous cell carcinomas and malignantlymphomas et al. Their antitumor activity is thought to result from selective oxidative cleavage of 5’-GC-3’and 5’-GT-3’sequences in DNA and possibly also from oxidative degradation of RNA. Recent study showed that bleomycin disaccharide could selectively target a variety of cultured tumor cells except normal cells. This suggests that bleomycin disaccharide plays an important role in the identification of tumor cells. But its mechanism is unclear now.In this dissertation, the synthetic strategy of bleomycin disaccharide was explored for the efficient synthesis of bleomycin disaccharide and its derivatives for future biological evaluation.DP-b99 is a first-in-class, membrane-activated ion chelator of zinc which is associated with cell signaling and, if overloaded, can result cell death and subsequent brain degeneration following a stroke. But phase III clinical trial of DP-b99 was failed as its curative effect is not enough. Therefore, recent study has been focused on enhancing the DP-b99’s curative effect.Hydrogen sulfide (H2S) is another gasotransmitter except NO and CO. At physiologically relevant concentrations, H2S can relax vascular tissues and serve as a neuroprotectant in the nervous system. As hydrogen sulfide can dilate blood vessels and protect nerve cells, in this paper, we introduce sulfur groups which can generate hydrogen sulfide gasotransmitter in DP-b99 to improve the anti-stroke and neuroprotective effects. In this dissertation, DP-b99 sulfur derivatives were prepared by the structural modification of benzene and side chain section of DP-b99.Part 1:synthesis of bleomycin disaccharide and its derivativesBleomycin disaccharide moiety consists of a a 1,2 linked 3-O-carbamoyl-D-mannopyranose with L-gulopyranose. Mannose donor and gulonic acceptor were prepared respectively, then coupled to afford the bleomycin disaccharide.Synthesis of mannose donors:2,4,6-Tri-O-acetyl-3-O-carbamoyl-a-D-manno-pyranosyl diphenyl phosphate (9-1) and 2,4,6-Tri-O-acetyl-3-O-carbamoyl-a-D-mannopyranosyl trichloroacetimidate (9-2) are synthesized from methyl mannoside by eight-step reactions in total yield 25.3% and 33.5%, respectively.Synthesis of gulonic acceptor:The new gulonic acceptor of p-Methyl Phenyl 4,6-O-benzylidene-3-O-acetyl-l-thio-β-L-gulopyranoside (G-7) is obtained from L-gulonic acid gamma-lactone by seven-step reactions in total yield 29.6%. In addition, the new gulonic acceptor G-7 (X-8) is also obtained from D-galactose through SN2 reaction by eight-step reactions in total yield 47%. This method is simple, and suitable for large-scale preparation with easy separation and purification.Synthesis of bleomycin disaccharide and its derivatives:The glycosylation of mannose donor 9-2 with gulonic acceptor G-7 produced the disaccharide F-1 successfully in yield 77%, which then coupled with different connecting with functional groups (such as chlorine, azido group, amino group) to afford the bleomycin disaccharide derivatives. These disaccharide derivatives serve as a basis for the study of biological activity of bleomycin disaccharide and can also be coupled with anti-tumor agents to increase their targeting ability.Part 2:synthesis of DP-b99 and its derivativesUsing DP-b99 as lead compound, its sulfur derivatives were synthesized by the structural modification of benzene and side chain section of DP-b99.Synthesis of anhydride intermediates:BAPTA-Anhydride (A-5) is synthesized from 2-Nitrophenol by five-step reactions in total yield 19.8%; 5,5-Dinitro-BAPTA-Anhydride (B-3) is synthesized from 2-Nitrophenol by six-step reactions in total yield 15.3%; 5,5’-dimethyl BAPTA-Anhydride (C-5) is synthesized from 5-Methyl-2-nitrophenol by five-step reactions in total yield 27.6%.Synthesis of glycol monoalkyl ether:Ethylene glycol monooctyl ether (CL-a) is synthesized from 1-bromooctane in total yield 60%; Ethylene glycol monoprotogen ether (CL-c) is synthesized from lipoic acid in total yield 86.8%.Synthesis of DP-b99 and its sulfur derivatives:The esterification of anhydride intermediates with glycol monoalkyl ether produced DP-b99 and its sulfur derivatives A-b (ethyl thioglycolate thioester of BAPTA) successfully.In the synthesis bleomycin disaccharide and its derivatives, a strategy for the efficient synthesis of bleomycin disaccharide was constructed, which served as a basis for the study of biological activity of bleomycin disaccharide. The synthesis of DP-b99 and its sulfur derivatives provided a basis for the study of structure-activity relationships of DP-b99.