Study On The Diterpenoids Of The Stems Of Tripterygium Wilfordii And Their Anti-inflammatory Activities

Tripterygium wilfordii is a traditional Chinese medicine and has been used to treat rheumatoid arthritis and lupus erythematosus for several hundred years.Modern pharmacological studies have showed that T.wilfordii possessed significant anti-tumor activity.The roots of T.wilfordii were generally used as the medicine resources.The studies on the chemical constituents and biological activity in T.wilfordii have also focused on the roots.Therefore,the stem of T.wilfordii was selected as the research objects in the current study.42 diterpenes and 6 triterpenes were isolated and identified from T.wilfordii by various of chromatograph methods（silica gel,medium pressure liquid chromatography,Sephadex LH-20,and HPLC）and detailed spectral studies（1D and 2D NMR,HR-ESI-MS,UV,etc.）.Among of the 48 compounds,8 new ones（1-8）were included,named wilkaunoids A-D（1-4）,wiltriptobenzene（5）,and wilabinoids A-C（6-8）.Compounds 1 and 2 were a pair of C-19 epimers of the kaurane diterpenoid,both of which possessed the rare 19,20-epoxy-19,20-dimethoxy-kaurane.Compound 3 featured a rare naturally occurring 1,3-dioxacyclohexane moiety.Compounds 6 and 8 represented the first example of abietane diterpenoids with an isovalerate substitution from the genus of Tripterygium.The known compounds were identified to be triregelin F（9）,triptohairic acid（10）,triregelin H（11）,triptobenzene R（12）,triptonoterpene（13）,triptonediol（14）,triptobenzene A（15）,wilforol F（16）,hinokione（17）,triptophenolide（18）,neotriptophenolide（19）,abietatrien-3β-ol（20）,triptobenzene B（21）,triptobenzene L（22）,triptobenzene S（23）,hypoglicin B（24）,hypoglicin H（25）,triptoquinone A（26）,triptoquinonide（27）,triptoquinone B（28）,triptoquinone H（29）,triregelin E（30）,triptoquinondiol（31）,hypoglicin I（32）,ent-16β,19-dihydroxykaurane（33）,fischericin D（34）,tripterifordin（35）,16α-hydroxy-19,20-epoxy-19R^*-ethoxy-kaurane（36）,16α-hydroxy-19,20-epoxy-19R^*-methoxy-kaurane（37）,16α-hydroxy-19,20-epoxy-20-methoxy-kaurane（38）,16α-hydroxy-19,20-epoxy-20R^*-ethoxy-kaurane（39）,ent-pimara-8（14）,15-diene-19-ol（40）,13-epi-19-nor-manoyloxide-18-oic acid（41）,and manoyl oxide acid（42）,regelin（43）,triptocalline A（44）,3-oxofriedelan-28-oic acid（45）,tripterfrielanon A（46）,regelin D（47）,and oleanonic acid（48）.The separated compounds were evaluated for anti-tumor,anti-inflammatory and anti-glioma stem cell activities in vitro.As a result,compounds 5-6,25-32 and 40 were found to significantly inhibit the of NO production in LPS-induced RAW 264.7 cells with IC₅₀values of 4.12,7.33,4.43,4.59,1.89,1.70,2.01,10.09,7.94,3.46 and 1.77μmol/L.Compounds 5-6 and 25-32 are all the abietane diterpenes with p-quinone structure of C-ring.The p-quinone structure of C-ring may be the key active group for the anti-inflammatory activity.Compound 23 exhibited weak anti-tumor activity(IC₅₀=18.41μmol/L).Moreover,compounds 27 and 31-32 could inhibit the growth of human glioma stem cells GSC-3#EGFP,with IC₅₀values of 7.99,10.76 and 14.2μg/mL.This study enriched the chemical constituents of T.wilfordii stem and provided a new clue to the understanding of the anti-inflammatory active substances of T.wilfordii.The results also provided a basis for the application and development of T.wilfordii stem in the treatment of inflammatory diseases（such as rheumatoid arthritis）.