Anti-arthritis Effect Of A Dibenzylbutane Lignan From Litsea Cubeba(Lour.)Pers Root And Its Synthetic Analogue

Rheumatoid arthritis(RA)is a systemic,chronic disease that is mainly mediated by autoimmunity and is characterized by persistent chronic inflammation and synovial hyperplasia,which destroy cartilage and bone,resulting in reduced physical function and quality of life.Diverse cell populations,such as macrophages,T-cells,osteoclasts and synovial fibroblasts(FLSs),are present in the inflamed synovium and contribute to the destructive in the joint.They produce a deluge of inflammatory cytokines and mediators which may be closely associated with RA pathogenesis.The inflammatory milieu,including TNF-α,NO,MMPs,interleukin(e.g.IL-6,IL-8)and interferon,can also make the articular homeostasis severely disturbed.Morever,the inflammatory microenvironment accelerates the recruitment of bone marrow precursors,and speeds up their differentiation into mature osteoclasts to cause the damage of bone,even osteoporosis.Litsea cubeba(Lour.)Pers.belongs to the Lauraceae family and has been commonly used as folk prescription in Traditional Chinese Medicine and Dai Ethnopharmacy.A lot of diseases,for example,rheumatic diseases,common cold and stomachache can be treated with it in southwestern China.It is also clinically used to treat rheumatoid diseases.But its mechanism is not clear.A previous study from our laboratory has confirmed that Litsea cubeba exerted apparent anti-arthritic activity in a Freund’s adjuvant-induced arthritis model in rats.Moreover,a dibenzylbutane lignan(LCA)from Litsea cubeba has been found to have dual pharmacological effects of anti-inflammation and anti-bone destruction through acting on the targets of MEK and Cathepsin K with molecular docking assay.From these we speculate is there any relationship between the stucture of dibenzylbutane lignan and the activity.Therefore,the structure of LCA was modified to obtain the other synthetic analogues,new monomers that have not been reported yet.Besides,we also synthesize a large number of LCA to do some experiments in vitro and in vivo.In this paper,the in vitro and in vivo activity of these compounds are compared and evaluated.Therefore,this article is aimed to evaluate the influence and mechanism of these dibenzylbutane lignans in vitro and in vivo,and briefly discuss the possible relationship between the structures and efficacy,which will provide a reference for further researchon these kind of compounds in the future and also provide a basis for future development of such compounds as antirheumatic drugs.1 In vitro anti-rheumatoid evaluation of the dibenzylbutane lignansDibenzylbutane lignans were evaluated for the anti-RA effects on LPS-induced inflammation in RAW264.7 cells and TNF-α stimulated Fibroblast-Like Synoviocytes(FLSs).In addition,the effect related bones destruction was detected with Osteoblast(OB)and Osteoclasts(OC).Both LCA and LCA1 showed significant anti-RA effect and activity of inhibiting bone destruction.For example,the ligands(LCA,LCA1 and LCA2)can inhibit the expression of NO in LPS-induced RAW264.7.What’s more,both LCA and LCA1 can inhibit the expression of TNF-α in LPS-induced RAW264.7.They also showed great inhibition in the growth of FLSs and the secretion of inflammatory milieu in TNF-α-stimulated FLSs.In addition,the dibenzylbutane lignans promoted the proliferation of OB,the activity of ALP and the formation of mineralized nodes.Meanwhile,the activity of TRAP in OC colud be prevented by them.2 In vivo anti-rheumatic evaluation of the dibenzylbutane lignans LCA and LCA1Three animal models were used to analyze the effect of LCA and LCA1(20,40mg/kg)in vivo in this part,including xylene-induced ear edema in mice,carrageenan-induced,cotton-ball granuloma in rats and Freund’s adjuvant induced arthritis in rats(AA).The results showed that LCA and LCA1 can significantly inhibit the extent of the ear edema on xylal induced ear-swelling in mice.What’s more,the dibenzylbutane lignans reduce the number of cells and the content of protein in the exudate of acute air-pouch synovitis mouse induced carrageenan.In addition,LCA and LCA1 decreased the level of MPO and IL-1β in a concentration-dependent manner.In the model of cotton-ball granuloma in rats and AA rats,LCA showed remarkably inhibition of the weight of granuloma at doses of 40 mg/kg and development of arthritis in AA rats.In summary,the dibenzylbutane lignans might be developed as therapeutic agents for the treatment of human arthritis in future.3 The mechanism of the dibenzylbutane lignans LCA and LCA1The possible anti-rheumatoid mechanisms of the dibenzylbutane lignans LCA and LCA1 were explored at the protein level with Western Blot in this chapter.The resultsshowed that LCA and LCA1 could significantly inhibit the activation of MEK / ERK signaling pathway in FLSs.Compared with the TNF-α group,the levels of p-MEK,p-MSK1,p-C-Raf,p-ERK,p-90 RSK was prevented in FLSs pretreated with LCA and LCA1.Meanwhile,LCA and LCA1 could inhibit the expression of COX-2,MMP-9 and Bcl-2 at high concentration.But they had no significant effect on the expression of Bax in FLSs and Cathepsin K in osteoclasts.