[Diterpenoids as PPARγ agonists from Siegesbeckia pubescens and their anti-inflammatory effects in vitro].

This study aims to investigate the PPARγ agonists isolated from the aqueous extract of Siegesbeckia pubescens( SPA) and their anti-inflammatory activities in vitro. The 293 T cells transfected transiently with PPARγ recombinant plasmid were used as a screening model to guide the isolation of PPARγ activitating components,and then PPARγ activities were measured by double luciferase reporter gene assay. The chemical structures were identified by chromatography or spectroscopic techniques. Furthermore,a UC inflammatory model in vitro was established on HT-29 cells by stimulating with TNF-α． The mRNA levels and secretion of proinflammatory cytokines on HT-29 cells,such as IL-1ß,TNF-α,IL-8,were detected by RT-PCR and ELISA. The results showed that five diterpenoids were obtained from the fraction D_(50) with the strongest PPARγ activity among others in SPA,and determined as kirenol( 1),darutigenol( 2),enantiomeric-2-ketone-15,16,19-three hydroxypinomane-8( 14)-ene-19-O-ß-D-glucoside( 3),darutoside( 4),enantiomeric-2-ß,15,16,19-four hydroxypinomane-8( 14)-ene-19-O-ß-D-glucoside( 5),respectively. All the compounds exhibited active effects on PPARγ in a concentration-dependent manner( P<0. 01). In addition,compound 1 significantly inhibited the expression of IL-1ß mRNA and secretion of IL-8 on HT-29 cells inflammation model( P<0. 001); both compounds 2 and 3 effectively inhibited the expression of IL-1ß,TNF-α,IL-8 mRNA and secretion of IL-8( P<0. 01 or P<0. 001),although at different extent; compound 4 significantly inhibited the expression of IL-1ß and TNF-α mRNA( P<0. 01 or P<0. 001),while compound 5 inhibited the expression of IL-1ß mRNA obviously( P<0. 001). In conclusion,the diterpenoids 1-5 isolated from S. pubescens have the PPARγ activation activities and potential effects of anti-UC in vitro.

Stephanthraniline A suppressed CD4(+) T cell-mediated immunological hepatitis through impairing PKCθ function.

Stephanthraniline A (STA), a C21 steroid isolated from Stephanotis mucronata (Blanco) Merr., was previously shown to inhibit T cells activation and proliferation in vitro and in vivo. The purpose of this study was to further evaluate the in vivo immunosuppressive activity of STA and to elucidate its potential mechanisms. The results showed that pretreatment with STA significantly attenuated concanavalin A (Con A)-induced hepatitis and reduced CD4(+) T cells activation and aggregation in hepatic tissue in mice. STA directly suppressed the activation and proliferation of Con A-induced CD4(+) T cells, and inhibited NFAT, NFκB and MAPK signaling cascades in activated CD4(+) T cells in vitro. Moreover, it was proved that STA inhibited T cells activation and proliferation through proximal T cell-receptor (TCR) signaling- and Ca(2+) signaling-independent way. The molecular docking studies predicted that STA could tight bind to PKCθ via five hydrogen. The further findings indicated STA directly inhibited PKCθ kinase activity, and its phosphorylation in activated CD4(+) T cells in vitro. Collectively, the present study indicated that STA could protect against CD4(+) T cell-mediated immunological hepatitis in mice through PKCθ and its downstream NFAT, NFκB and MAPK signaling cascades. These results highlight the potential of STA as an effective leading compound for use in the treatment of CD4(+) T cell-mediated inflammatory and autoimmune diseases.

Two New 8, 14-seco-pregnane Steroidal Aglycones froni Roots of Cynanchum bungei.

Two new 8, 14-seco skeleton C(21) steroidal aglycones, cynanbungeigenin A (1) and cynanbungeigenin B (2), were isolated from the hydrolyzed extract of the EtOAc soluble extract of the roots of Cynanchum bungei. Their structures were determined on the basis of chemical evidence and extensive spectroscopic methods, including 1D and 2D NMR spectroscopy.