Synthesis And Biological Activity Of Derivatives Of 5-nitro-1,3-indandione

Apoptosis, or programmed cell death, plays an important role in organisms to maintain normal immune system and tissue homeostasis stability. Caspase family plays a central role in the process of apoptosis, and caspase-3 is the ultimate performer. Many diseases are closely related to apoptosis, and apoptosis is closely related to caspase-3, so the effective inhibition of caspase-3 can inhibit the abnormal apoptosis and then treat diseases induced by abnormal apoptosis. So far, scientists have been trying to find an efficient inhibitor of caspase-3.So far, most of the caspase-3 inhibitors are still peptide inhibitors or peptidomimetics. Although they have effective inhibition to the activity of caspase-3 in in-vitro essay, peptide inhibitors commonly are poor cell membrane permeable, expensive, metabolic instable and of poor specificity and so on. Therefore, we set study target on small molecule. non-peptide-based inhibitors of caspase-3 having simple and stable structure. These small molecule compounds, are commerdially available or easy to be synthesized, not only have highly inhibitory activity, but also have the potential treatment of cell-related diseases induced by abnormal apoptosis. A large number of compounds containing indanone skeleton showed good biological activity.1,3-indanedione containing (3-carbonyl skeleton, belong toβ-diketone compounds, having the ability to react with anhydrides in the presence of ammonia, andβ-diketone compound is a very important organic intermediate, they can participate in various of important organic reactions. In this thesis, according to the interaction of caspase-3 with substrate (or inhibitor), we screened a series of small molecule organic compounds with the characteristic groups, and obtained the IC50 of ninhydrin (Nin) was 1.2μM. So we determined ninhydrin as a molecular skeleton to study the inhibition. Modifing the structure and introducing polar groups into ninhydrin to improve their polarity, we designed and synthesized 5-nitro ninhydrin derivatives as a new type of caspase-3 inhibitors.In order to obtain 5-nitro ninhydrin, we first synthesised 5-nitro-1,3-indandione and then through a series of reaction to obtain 5-nitro ninhydrin. Roughly as follows:starting from phthalimide to give nitro-phthalic anhydride, phthalic anhydride reacts with acetic anhydride and triethylamine to give 5-nitro-1,3-indandione-2-carboxylic acid ethyl ester, and then proceed decarboxylation by hydrochloric acid to obtain 5-nitro-1,3-indandione. On the synthetic step of 5-nitro ninhydrin from 5-nitro-indane dione, the current internationally method is using the substitution of 2-position chlorides, but we found this method was a failure, so we tried a variety of methods, and ultimately we synthesized 5-nitro ninhydrin, through the method of oximation and de-oximation.We studied 5-nitro ninhydrin by measuring their inhibitory activity in vitro and obtained the value of IC50 was 714nM. In order to get more and better caspase-3 inhibitors, according to the specific conjugation of caspase-3 and substrate.we optimized the structure of 5-nitro ninhydrin and synthesized a series of non-peptide-based inhibitors of caspase-3. By the assay of caspase-3 inhibition in vitro, we found that different modification of structural analogues showed different activities, and some showed better inhibitory effects. Because of their relatively simple structure, easy optimization, there must be still much room for modification of the inhibitors. In the future, based on inhibitor molecules what we haved,our research focus on enhancing the inhibitory activity by changing the nitro with other active groups on the benzene to get better non-peptide caspase-3 inhibitors. It may have a potential in the study of caspase-3 inhibitor.