Design,Synthesis And Bioactivity Of Novel Inhibitor For ?-N-acetyl-D-hexosaminidases Based On Glycosyl Thiazoline

Chitin,acts as the major component to constitute fungi cell wall and arthropod exoskeleton,but it's cann't be found in plant?hunman or other higher organisms,thus,the enzymes releated to the metabolism of chitin have became specific fungicidal and pesticidal targets.the design and synthesis of novel inhibitors for thses enzymes have been an active area of chemical,biological and pharmaceutical research.In nature,chitin is catalyzed by the glycosyl hydrolase(GH)family 18 chitinases and family 20 ?-N-acetyl-D-hexosaminindases.Chitinases cut polymeric chitin into shorter(GlcNAc)2 and(G1cNAc)3,then ?-N-acetyl-D-hexosaminidases hydrolyze these oligosaccharides into GlcNAc.Over the past few decades,?-N-acetyl-D-hexosaminidases has been widely studied and many potent small molecule inhibitors have been found,among them,NAG-thiazoline base on glycosyl thiazoline has been proved as a good transition state(TS)analogue inhibitor and exhibite high inhibitory activity.In this paper,novel inhibitors was designed,synthesised base on the specific structure,and the bioactivities was also studied.Part ?:Design,synthesis of glucopyransoyl thiazoline derivatives.1.NAG-thiazoline were synthesized from commercially available D-Glucosamine hydrochloride as the starting materials,modification at 3,6-OH was also studied to finding the binding mechanism in +1 site.2.A novel series of NAG-thiazoline derivatives were synthesized by introducing substituted aromatic phenyl into the thiazoline ring,The structures of 8 target compounds 2 and 16 unkown intermediates were characterized by 1H NMR,13C NMR and HRMS.3.Azido group was introduced into the thiazoline ring,and a series of substituted 1,2,3-triazoles were synthesized by 'click chemistry',The structures of 6 target compounds 3 and 6 unkown intermediates were characterized by 1H NMR,13C NMR and HRMS.4.Several route was studied for synthesis of trans NAG-thiazoline,and the cyclization reaction precursor was synthesizedPart ?:Design,synthesis of mannopyransoyl thiazoline derivatives.1.We keep the structureof a glycosylated thiazoline base of NGT but change the configuration and present a new type of ?-N-acetyl-D-hexosaminidases inhibitor called NAM-thiazoline 4.2.19 NNMT derivatives 5 were synthesized for the first time to study the Structure-activity relationshipbetween the inhibitory activity and the size of the groups linked to the thiazoline ring.,The structures of target compounds and 38 unkown intermediates were characterized by 1H NMR,13C NMR and HRMS.Part ?:Bioactivity studies1.Enzyme inhibitory activity:A preliminary bioassay was studied by using several enzymes from two ?-N-acetyl-D-hexosaminidase families.All compounds show a poor potency for family 20 and several compounds exhibited good activity for family 84.Among them,NGT-B-1(IC50=12.6 ?M,hOGA)and NGT-B-5(IC50=12.5 ?M,OfOGA)with good inhibitory activity reveals that the substituent group could influence the interactions with residues bychanging the electron distribution on the aromatic group;The inhibiton ratio of 6-indoleacetyl NGT for ofOGA reach to 93%,82%at 25uM?5 uM which is closed to the potency of NGT,the substituted group may extends out from the active site to the +1 site,further modification of the derivatives are in progress;Mannopyransoyl thiazoline derivatives Analysis of the Inhibition constants and selectivities of inhibitors for hOGA and hHex reveals a significant correlation between the potency of the inhibitors and the size of the groups linked to the thiazoline ring.Compounds have substituents with straight-chain alkanes less than 3 carbons show a good inhibition,moreover,compounds which have substituent groups of more than 4 carbons or the substituents were branched-chain alkanes had a very poor potency,revealing that there is a size dependence to the interaction between inhibitor and enzyme and the active pocket in hOGA could tolerate a larger group than the pocket of hHex,which lead the significant selectivity for the O-GlcNAcase over ?-hexosaminidase.2.The insecticidal activity was detected firstly,NGT-B-1?NGT-B-2?NNMT-4?NNMT-12 and NNMT-15 show good acticity to diamond back moth at the concentration of 600 mg/L,and most compounds exhibited obviously growth inhibitory activity.3.The original fungicidal activities results showed that some of the compounds exhibited good fungicidal activities to 8 kinds of pathogenic germs at the concentration of 50 ?g/mL.