Studies On The Chemical Constituents And Bioactivities Of Alisma Orientale And Rheum Nobile

In order to take advantage of resources of medicinal plant,and discover more structurally unique and bioactive compounds from natural resource,the chemical constituents and biological activities of Alisma orientale and Rheum nobile were carried out in this paper.By means of various chromatographic methods(such as silica gel,MCI,RP-18,ODS,Sephadex LH-20,preparative TLC and preparative HPLC,etc)and spectroscopic techniques(including NMR,MS and X-ray),in combination with calculated ECD and 13C-NMR,56 compounds were isolated and identified from the above two medicinal materials,including protostane-type triterpenoids,guaiane-type sesquiterpenoids,anthraquinones,and so on.Among them,19 compounds were new ones and 2 compounds were new natural products.Furthermore,the biological activities,including vasorelaxant effect,inhibition of NO production,inhibitition on 11β-HSD1 and anti-HCV activity of the isolates were evaluated.Alismatis Rhizoma("Zexie" in Chinese),a Chinese crude drug prepared from dried rhizome of Alisma orientale(Sam.)Juzep.(Alismataceae)widely cultivated in China and Japan,has been used as a diuretic agent.Thirty-one protostane triterpenoids(1-31),fourteen guaiane-type sesquiterpenoids(32-45)and two aliphatic compounds(46 and 47)were isolated from the EtOAc extract of A.orientale.Among them,compounds 1-13 were new protostane triterpenoids,compounds 14 and 15 were new natural protostane triterpenoids,and compounds 32-37 were new guaiane-type sesquiterpenoids.New compounds and new natural products were named as alisol R(1),25-methoxyalisol F(2),16β-hydroperoxyalisol B 23-acetate(3),alisol S 23-acetate(4),16β-hydroperoxyalisol B(5),16β-methoxyalisol B(6),16β-methoxyalisol E(7),16β,25-dimethoxyalisol E(8),16β-hydroperoxyalisol E(9),alisol T(10),alisol U(11),16α-hydroperoxyalisol B 23-monoacetate(12),16a-methoxyalisol B 23-monoacetate(13),alisol V(14),alisol W(15),10-O-methyl-orientalol A(32),10-O-ethyl-alismoxide(33),3β,4β-expoxy-chrysothol(34)and orientalols G-I(35-37),respectively.Compound 1 was the first octanorprostane triterpenoid,and its proposed biosynthetic pathway was discussed.Compounds 3,5,9 and 12 were the first examples of protostane triterpenoids with a hydroperoxy group at C-16,which was confirmed by X-ray diffraction experiment.Compound 11 was the first protostane triterpenoid with oxetane ring in the side-chain,and the absolute configuration at C-23 and C-24 was established by calculated ECD and 13C-NMR methods.Furthermore,compounds 31 and 33 had significant vasorelaxant effect on the endothelium-intact thoracic aorta rings precontracted with KCl,the maximum relaxant values were 31.58± 3.08,26.78 ± 7.25 at 30 min and 53.04 ±7.27,51.42 ± 8.55 at 60 min,respectively.Compounds 38 and 44 showed moderate inhibition of NO production with IC50 values of 36.997 and 48.602 μM,respectively.Rheum nobile Hook.f.et Thoms,a famous Tibetan medicine,was used to the treatment of Huang Water disease.Nine known compounds,piceatannol glucoside(1),emodin(2),chrysophanol(3),chrysophanol-emodin bianthrones(4A and B),emodin bianthrones(5 and 6)?β-sitosterol(7)and daucosterol(8)were isolated from the fresh herb of R.nobile.Among them,compounds 1 and 4-6 were isolated from this plant for the first time.Furthermore,compound 2 showed potent inhibition of NO production with an IC50 value of 18.528 μM.Meanwhile,compound 3 exhibited significant anti-HCV activity with a selective index(SI)of 21.19,which was higher than that of ribavirin(SI = 10.05).