Structural Optimization Of Moracin M And Their Inhibitory Activities Towards Phosphodiesterase 4

Phosphodiesterase 4(PDE4)inhibitors as new drugs for asthma treatment received extensive attention.Previous studies found that the ingredient Moracin M from the roots of anti-asthma medicine Morus alba has targeted inhibitory activity of phosphodiesterase 4.In this dissertation,we firstly summary the mechanism of asthma and the drug development of phosphodiesterase 4 inhibitors,and select Moracin M(IC50 2.9pM)as a leading compound to optimize the targeted compounds by Computer Aided Design(CAD),using SYBYL package Surflex Dock module to conduct a molecular docking between part of Moracin M derivative and PDE4 protein crystal structure(PDB code:1XOQ).Then use the phenol compounds as raw materials,to design and synthesis ether derivatives,halogenated derivatives,isopropyl phenyl derivatives,acetylation and other types derivatives of Moracin M and catechol ether analogs,furo[2,3-c]pyridine analogs.2-or 3-naphthyl substituted analogs and so on.Take advantage of the nuclear magnetic resonance spectroscopy to determine the structure of each compound,use[3H]labeled liquid scintillation counting to study in vitro PDE4 inhibition activity of the resulting compounds and further study on their structure-activity relationship(SAR).Forty-six compounds were synthesized,including thirteen intermediate compounds and thirty-three targeted compounds(derivatives or analogs of Moracin M).Their structures were indentified by 1H NMR and 13C NMR spectrum analysis.24 of the targeted compounds are new compounds.We used[3H]labeled liquid scintillation counting to evaluate in vitro PDE4 inhibitory activities of twenty-eight compounds among the targeted compounds.The results of pharmacological activity showed that 6-chloro-2-(3,4-dimethoxy-phenyl)-benzo furan(20)?2-(3,4-dimethoxy-phenyl)-6-fluoro-benzofuran(21)?2-(3,4-dimethoxy-phenyl)-6-methoxy-benzofuran(23)and 2-(3,4-dimethoxy-phenyl)-furan[2,3-c]pyridine(27)significantly inhibited PDE4D2 at 10?M concentration,with inhibitory rate of 91.36%,106.38%,90.45%,98.29%,respectively.Futhermore,2-{3,5-Bis-[2-(4-methoxy-phenyl)-ethoxy]-phenyl}-benzo furan-6-ol(15)?Acetic acid 3-acetoxy-5-(6-acetoxy-benzofuran-2-yl)-phenyl ester(17)?2-(3.4-dimethoxy-phenyl)-6-methyl-benzofuran(22)and 3-naphthalene-2-yl-benzofuran-6-ol(34)also show more than 50%of PDE4 inhibition rate at 10?M concentration,with inhibitory rate of 74.75%?50.69%?66.13%and 50.06%,respectively.The other compounds effect is not obvious,but except for compound 11 and 16,others have shown inhibition of PDE4.In addition,in vitro activity test results showed that the inhibitory activity of compound 20,21 and 27 were stronger than Moracin M(ICso 2.9?M),with IC50 value of 1.29±0.31 pM,1.61 ±0.17?M,1.68±0.20?M,respectively,prompting that they may deserve further optimization on their structure.The compounds with inhibitory rate reach to 60%at 10?M concentration were all catechol ether compounds,wherein the halogen-containing compounds(20,21)were most active,and the N-containing compound(27)was weaker.Specific aspects of the current structure-activity relationships for the active compounds 20,21 and 27 was unclear and deserves further study.By analyze the structural activity relationship of the twenty-eight compounds,we preliminary found that:(1)Substituent position B ring(2-phenyl)greatly affect the activity of the compounds that 3',4'-ortho-substituted compounds were more activity than the compounds with meta-substituted(3',5'? 2',4')on B ring.(2)In the case of the same substituents on B ring,the C-6 substituents type less affected the activity,but overall,the introduction of a strong electronegative group(F?Cl?N?O)were more active than the introduction of an alkyl group.(3)For C-6,C-3',C-5' hydroxyl group to be etherified compounds,O-acetyl substituted compounds were more active than O-alkyl substituted compounds.(4)The type of 3-aryl benzo[b]-furans derivatives were less active.