Studies On The Chemical Constituents Of Tibetan Medicine Hypecoum Leptocarpum Hook.f.et Thoms

Hypecoum leptocarpum Hook.f.et Thoms.is a herbaceous plant from the genus Hypecoum,which belongs to the Papaveraceae family,mainly distributed in south-and northwest China.It is commonly used in Tibetan medicine.According to traditional Chinese medicine records,Hypecoum leptocarpum has long been used in clearing away heat and detoxification,relieving pain,anti-inflammatory and relieving cough.It is often used in clinical treatment of a variety of heat syndrome,venom,influenza and other diseases.A total of 28 monomer compounds were isolated from the ethanol extract of Hypecoum leptocarpum by a variety of separation methods and purification methods.The structures of all the compounds were identified by physicochemical properties,modern spectral techniques and data reported in relevant literatures,including 17 alkaloids:leptocarpinine B（S-1）、corydamine acid（S-2）、leptocaramine（S-3）、corydamine（S-4）、norsanguinarine（S-5）、coptisine（S-6）、coryximine（S-7）、hendersine B（S-8）、leptopidine（S-9）、cryptopine（S-10）、protopine（S-11）、torulosine（S-12）、N-methyldemethyltorulosine（S-13）、N-methylcorydaldine（S-14）、oxohydrastinine（S-15）、protopinium（S-16）、zarzissine（S-17）,and eleven non-alkaloid compounds:adenosine（S-18）、3-isopropyl-2,5-piperazinedione（S-19）、17³-ehoxyphaeophytin b（S-20）、13²S-hydroxypheophytin a（S-21）、stigmasterol（S-22）、sitosterol（S-23）、isoimperatorin（S-24）、betulin（S-25）、2,2’-oxybis[2,5-bis（1,4-dimethylethyl）]-benzene（S-26）、n-tetratriacont-20,23-dienoic acid（S-27）、14-methyl-1-octadecene（S-28）.Among them,20compounds except S-3,S-4,S-9,S-10,S-11,S-13,S-15 and S-16 were isolated from this plant for the first time,and S-1 and S-2 were new compounds,which belong to benzazepine and isoquinoline alkaloids,respectively.The antioxidant and antitumor activities of sixteen alkaloids were also tested.The antioxidant activity showed that compound S-13 showed the most significant antioxidant activity with an IC₅₀value of 20.58μM compared with the positive control vitamin C against DPPH.Compounds S-1 and S-15 had higher scavenging rates for superoxide anions,with IC₅₀values of 48.16μM and 46.67μM,respectively.The antitumor activities of sixteen compounds were screened by MTT assay.The results showed that compound S-3 exhibited moderate cytotoxicity against HepG2 cell line with IC₅₀ value of 22.16μM.Compound S-6 exhibited good cytotoxic activity against A2780,HeLa and HepG2 tumor cell lines,with IC₅₀ values of31.49μM,30.72μM and 28.53μM,respectively.