Synthesis And PTP1B Inhibitory Activity Of Isosteviol Derivatives

Diabetes is a metabolic disorder disease,its main symptom is hyperglycemia.In recent years,the prevalence of diabetes is increasing year by year,showing a trend of younger age,which has a negative impact on human health and quality of life.Among diabetes patients,type II diabetes is the most common type,accounting for about 90%.The cause of the disease is complex and the treatment is difficult.At present,drugs for diabetes are mainly divided into insulin and oral hypoglycemic drugs.However,both drugs have serious side effects.Therefore,it is still an important and difficult task to screen new and efficient diabetes drugs with no side effects.Protein tyrosine phosphatase 1B(PTP1B)is a negative regulator of insulin and leptin signal transduction pathway,which is involved in regulating glucose and lipid metabolism,and is considered as an effective therapeutic target for type II diabetes and obesity.Drug research and development of PTP1 B is mainly focused on small molecule PTP1 B inhibitors.In recent years,a large number of highly active PTP1 B inhibitors have been found.However,due to the large molecular weight,poor bioavailability and low selectivity of these compounds,it is difficult to prepare drugs,so there is no PTP1 B inhibitor for clinical use at present.Isosteviol,a natural product,belongs to tetracyclic diterpenoid compounds and has a wide range of pharmacological activities,such as anti-tumor,hypotension,hypoglycemic,bacteriostatic,anti-inflammatory,antiviral,cardiovascular protection and so on.Isosteviol has been widely concerned by researchers because of its unique structural framework and diverse biological activities.Researchers have carried out a lot of modification and activity evaluation on it.However,the current research on the biological activities of isosteviol and its derivatives is mainly focused on the anti-tumor effect and its molecular mechanism,and there are relatively few reports on the anti-diabetes activity.Therefore,it is of great significance for the research and development of new drugs to strengthen the study of the hypoglycemic activity of the derivatives of isosteviol and determine their target.In this study,isosteviol was used as a lead compound for structural modification,aiming at screening natural product inhibitors.Specifically,we designed and synthesized a series of isosteviol derivatives by modifying the C-15,C-16 and C-19 positions of isosteviol.And their inhibitory activity and structure-activity relationship on PTP1 B enzyme were investigated,in order to find small molecule PTP1 B inhibitors with high activity and high selectivity.In this paper,in chapter one,we first reviewed the research progress of PTP1 B inhibitors and the various biological activities of isosteviol derivatives.On the basis of extensive analysis of literature,we found that isosteviol exhibits good hypoglycemic activity and can serve as a potential PTP1 B active fragment.In the second chapter,a series of derivatives IS-1-13 with different substituents were synthesized by nucleophilic substitution at the C-19 position with isosteviol as the lead compound.The corresponding oxime IS-14-17 was obtained by oximation reaction on the basis of isosteviol and derivative IS-1-3.On the basis of derivatives IS-4 and IS-5,derivatives IS-18-20 are obtained by introducing piperazine or piperidine ring.In order to study the effect of carbonyl on the inhibition activity of PTP1 B,further reduction and acylation reactions were carried out to obtain derivatives IS-21-23.In order to further explore the structure-activity relationship,the derivative IS-24-28 was synthesized through bromination,etherification and esterification.The synthesized compounds were separated and purified by silica gel column chromatography,and the28 pure compounds were characterized by 1H NMR,13 C NMR spectra and high-resolution mass spectrometry to determine the specific structure of the compounds.In chapter three,we further evaluated the in vitro PTP1 B inhibitory activity of isosteviol and all synthesized derivatives through enzyme-linked immunosorbent assay,and summarized their structure-activity relationships according to activity analysis results.The results showed that most of the derivatives showed moderate to good PTP1 B inhibitory activity.Among them,derivatives IS-10、IS-13、IS-24 and IS-27 showed significant inhibitory activity on PTP1 B in vitro,with IC50 value of 0.24μM-0.40 μM range.The structure-activity relationship between isosteviol derivatives and PTP1 B inhibitory activity is summarized as follows:(1)The introduction of bromine atoms at the C-15 position helps to enhance the inhibitory activity;(2)When the carbonyl group changes to oxime,its inhibitory activity decreases slightly,but the inhibitory effect of oxime derivatives increases with the extension of the carbon chain at the C-16 position;(3)The acylation of hydroxyl can improve its inhibitory activity;(4)Ethylation of isosteviol at C-19 is beneficial to the inhibition of PTP1B;(5)The inhibition activity can be improved by introducing alkyl into carboxyl group;(6)Benzene ring ortho-iodine is beneficial to the enhancement of PTP1 B inhibitory activity;(7)Benzene ring para Br is beneficial to inhibitory activity;(8)The introduction of piperazine or piperidine into isosteviol at the C-19 position helps to enhance the inhibitory activity.The selective experiment found that derivatives IS-10、IS-13、IS-24 and IS-27 showed effective inhibitory activity against other PTPs,especially CDC25 B.Compared with isosteviol,derivative IS-24 showed 10-fold enhanced inhibitory activity on PTP1B(IC50 value is 0.24 μM)and good selectivity(7 times higher than TCPTP and 14 times higher than CDC25B).In chapter four,we used molecular docking simulation experiments to predict the specific binding modes of the active derivatives IS-10,IS-13,IS-24,IS-27 with PTP1 B enzyme,and calculated the binding energy of the compounds and PTP1 B,which provided a theoretical basis for further explaining the high inhibitory activity of these derivatives.Therefore,the active derivative IS-24 can be used as a potential new PTP1 B inhibitor.In conclusion,the isosteviol derivatives synthesized and studied in this paper have laid a corresponding foundation for the research and development of related anti diabetes drugs.