Design And Synthesis Of Cryptotanshinone Derivatives And Their Effects On The Transcriptional Activity Of STAT3

Salvia miltiorrhiza Bunge,a salvia plant in the Lamiaceae family,is a traditional Chinese medicine.It has a wide range of medicinal effects such as promoting blood circulation,removing blood stasis,easing menstruation and relieving pain,and has always been a hot spot in natural medicine research.TanshinoneⅡA Sodium Sulfonate Injection,the main substances from Salvia miltiorrhiza Bunge,has been used as a first-line anti-cardiovascular medicine since the 1970s.It has good efficacy and low side effects,and has been widely favored by patients.Cryptotanshinone is a fat-soluble active ingredient of Salvia miltiorrhiza,its chemical structure is very similar to that of tanshinoneⅡA and has good medicinal potential.However,it is currently mainly used in the beauty industry（removing acne）and as a secondary component of Tanshinone Injection.The medicinal value of cryptotanshinone needs to be explored in depth.In recent years,researchers have discovered that cryptotanshinone has a good effect on anti-STAT3 protein transcription.STAT3 protein is a member of the STAT protein family,as a transcription factor in the JAK-STAT3 signaling pathway,it has important effects on cell proliferation,differentiation,apoptosis,and canceration.Inhibition of STAT3 protein can effectively reduce the activity of cancer cells and inflammatory cells,promote their apoptosis process,and provide a promising method for anti-tumor and anti-inflammatory treatments.Currently,there are no STAT3 inhibitor drugs approved for clinical treatment.Compared with the FDA-approved inhibitors targeting JAK kinase,STAT3 inhibitors are difficult to control its specificity,meanwhile,clinical trials have found that it has many side effects,so it is extremely difficult to become a medicine,but the prospect of small-molecule STAT3inhibitors is still broad.Cryptotanshinone,which comes from natural medicine,has the advantages of low toxicity and wide indications.However,it has the disadvantages of difficulty obtaining raw materials,together with poor water solubility,and low bioavailability.Based on the previous literature research,we will modify the structure of cryptotanshinone and its skeleton analogs,62compounds were designed and synthesized,46 of which were new compounds.Through the luciferase reporter gene detection method,we found that 27 new compounds had better inhibitory effects on the transcription of STAT3 protein than cryptotanshinone,with the lowest IC50 value of 0.5976μM.All compounds’structures were proved.(¹H、¹³C-NMR,HRMS).Since cryptotanshinone does not have good activity when at low doses and is more toxic to cells at high doses,our structural modification direction is mainly to reduce toxicity and improve the dose-effect relationship.First,we modified the raw materials of cryptotanshinone by using the methods of A ring 1-position substitution,C ring o-dicarbonyl ring formation,and D ring carbon-oxygen bond breaking.Through the detection of the luciferase reporter gene,the activity of the modified compound did not increase significantly,and some compounds acted as a stimulator of STAT3.We obtained cryptotanshinone skeleton analogues by total synthesis,reacted the hydroxyl groups of the skeleton analogues with benzyls,substituted benzoic acid,cinnamic acid and sulfonic acid compounds,and screened the anti-STAT3 transcription activity in vitro,and found that the skeleton analogues of the benzyl and sulfonic acid groups have better activity after being connected.The activity of the benzyl-type benzene ring with electron-withdrawing substituents is weakened,and the activity of the electron-donating substituents is enhanced.The para-substituted and ortho-substituted derivatives have better activity than the meta-substituted derivatives.The IC₅₀ values of benzyl derivatives are in the range of 0.5976-4.238μM,the IC₅₀ values of sulfonate derivatives are in the range of 1.019-6.220μM,and the IC₅₀ value of the most active compound YDST-62 is 0.5976μM.The structure modification of cryptotanshinone’s skeleton analog with A-ring removed,and in vitro anti-STAT3 transcriptional activity screening,obtained good results.We obtained the skeleton analogs with the A ring removed in a fully synthetic manner and derivatized them with benzyl,benzoic acid,cinnamic acid,and sulfonic acid compounds.Among them,the benzyl and sulfonic acid ester derivatives were derivatized with benzyl,benzoic acid,cinnamic acid,and sulfonic acid compounds.The inhibitory activity is good,the IC50 value of benzyl derivatives is in the range of 0.5976-4.238μM,and the IC50 value of sulfonate derivatives is in the range of 1.019-6.220μM.Through the pharmacological experiments of the luciferase reporter gene,we have initially grasped the effects of cryptotanshinone and its derivatives on the transcription activity of STAT3,and clarified the structure-activity relationship of the inhibitors,providing ideas and methods for the development of small-molecule STAT3 inhibitors.