Synthesis And Biological Evaluation Of4,4-dimethyl Stimgasterol Derivatives As Novel Inhibitors Of PTP1B And Synthesis Of Some FBP Enzymes Inhibitors

This thesis includes two parts:(1) design and synthesis of series of4,4-dimethyl stimgasterol derivatives and study their structure-activity relationship in order to develop novel small molecule PTP1B inhibitors and preliminary evaluate the effect of mitochondrial membrane potential;(2) synthesis of diaryl oxadiazole NC83813derivatives and evaluation of their FBP inhibitory activity;1. Design and synthesis of series of4,4-dimethyl stimgasterol derivatives and discuss their structure-activity relationship in order to develop novel small molecule PTP1B inhibitorsIn order to develope novel small molecule PTPIB inhibitors, our research group synthesize series of lithocholic acid derivatives which exhibite dramatic improve in inhibitory potency and selectivity. In this paper, Another steroids-stigmasterol as a basic skeleton, we synthesize series of stimgasterol derivatives by modification of stimgasterol's A ring, C ring and side-chain respectively.We also study their structure-activity relationship in attempted to get some more effective small molecular PTP1B inhibitors which have higher PTP1B inhibitory activity and selectivity on other PTPs.1).4,4-Dimethyl stigmasterol-3-one was prepared by oxidation and methylation. Series of new five and six member heterocycles are introduced in the C-2and C-3position of stigmasterol-3-one. The target compounds in25%-55%overall yield are obtained with need three to six steps from stigmasterol. Seven compounds have been designed and synthesized. We characterize the structure of these compounds by NMR and HRMS spectra. Unfortunately, the solubility of these compounds in DMSO/H2O is poor, it does not show inhibitory activity on PTP1B.2).In order to improve the solubility of the compounds, hydrophilic groups(carbonyl, hydroxyl, epoxy ets) is introduced to A ring, B ring and side chain of the stigmasterol. Nine compounds have been designed and synthesized. The evaluation of inhibition on PTP1B shows that the hydrophilic groups can improve the solubility of the compounds. Pyrazole ring modified compound B-6has good PTP1B inhibitory activity. Moreover, introducing some substituents in pyrazole can increase the inhibitory activity.3).Based on the above results, we further introduct hydroxylamine functional groups at C-3and C-7position to improve solubility and examine its impact on PTP1B inhibitory activity of the compounds, eight compounds are synthesized by modification of A ring and B ring of4.4-dimethyl stigmasterol-3-one.The evaluation of inhibition on PTP1B show that C-3with hydroxylamine groups, the compounds showe a certain amount of PTP1B inhibitory activity; when the A-ring was with pyrazole ring, PTP1B inhibitory activity increase nearly2times compared7-hydroxylamine to7β-hydroxyl in B ring; The most potent inhibitor in all compounds is compound B-7with pyrimidine and7-hydroxylamine (IC50=3.53±0.46μM).4). Lowering mitochondrial membrane potential of4,4-dimethyl stimgasterol derivatives are initially investigated. Tests showe that all compound are almost non-toxic;4,4-dimethy-3-hydroxy stigmasterol(B-3),4,4-dimethyl stigmasterol-3,7-dione(B-4),4,4-dimethyl-3,7-dihydroxy stigmasterol (B-5) show that increased with the concentration, they can mild reduce mitochondrial membrane potential (Due to the limited solubility of the compounds, B-3, B-4and B-5lowering mitochondrial membrane potential rebound in the concentration of80μM); Fouthermore, compounds C-1could reduce mitochondrial membrane potential, and mitochondrial membrane potential remaine almost constant increased with the concentration; C-7was with hydroxylamine could improve the solubility of the compounds; In all heterocyclic compounds, The capacity of falling membrane potential is no obvious except the compound C-7. 2. Synthesis of diary1oxadiazole NC83813derivatives and their inhibitory activity on FBPSix Diaryl oxadiazole NC83813derivatives are synthesized for developing novel small molecule FBP inhibitors.Nitrobenzoic acid and a-bromo-acetophenone as the main starting material by esterification, cyclization, catalytic hydrogenation, and amide condensation, six new compounds have been designed and synthesized. We characterize the structure of these compounds by NMR and HRMS spectra. FBP inhibitory activity tests show that these new compounds have no inhibitory activity, which indicate that the part of oxadiazole heterocyclic is an important active site. Further molecular design, synthesis and investigation on their structure-activity relationship is still in progress.