Study On Chemical Constituents From The Petroleum Ether Fraction Of The Leaves Of Rhododendron Dauricum L.with Inhibiton Of No Profuction

The chemical constituents from the petroleum ether fraction of the leaves of Rhododendron dauricum L.and their inhibition of NO production in LPS-induced RAW 264.7 cells were investigated in this study.Rhododendron dauricum L.is belonging to the family Ericaceae,it is distributed mainly in northeast China and Mongolia,Japan,North Korea and Russia.The leaves of R.dauricum have been traditionally used for the treatment of acute and chronic bronchitis,cough,headache and asthma.A new pentacyclic triterpenoid,3-oxo-urs-11,13(18)-dien-28-oic acid(1),along with twenty-four known compounds,a-amyrin(2),19a-hydroxy-a-amyrin(3),triptohypol E(4),uvaol(5),2a,3a-dihydroxyurs-11-en-13?,28-olide(6),ehretiolide(7),ursolic acid(8),asiatic acid(9),oleanolic acid(10),aegiceradienol(11),obtusalin(12),betulinic acid(13),,grifolin(14),daurichromene A(15),confluentin(16),rel-(1R,1aS,33aR,8bR,8cR)-1a,2,3,3a,8b,8c-hexahydro-1,3a,6-trimethyl-1-(4-methyl-3-penten-1-yl)-1H-4-oxabenzo[f]cyclobut[ce]inden-8-ol(17),6?,7,8,9,10,10?-hexahydro-3,6,9-trimethyl-6-(4-methylpent-3-en-1-yl)-1,9-epoxy-6H-dibenzo[b,d)pyran(18),9a-hydroxy-1?-methoxycaryolanol(19),cassipourol(20),?-sitosterol(21),daucosterol(22),?-sitosterol-3-O-(6'-O-13"-octadecenoyl)-?-D-glucoside(23),gingerglycolipid A(24),1-O-(9Z,12Z,15Z-octadecatrienoyl)-2-O-hexadecanoyl-3-O-a-(6-sulfoquino vopyrano syl)glycerol(25)were isolated from the petroleum ether fraction of the leaves of R.dauricum by using various column chromatographic methods.Their structures were established from spectroscopic data and comparison with reported values.Among of them,compounds 3,4,6,7,11,17-20 and 25 were reported from the family Ericaceae for the first time.Compounds 2,5,9,12,13,15,16,22 and 24 were obtained from this plant for the first time.In the present work,thirteen triterpenoids,one prenylphenol,two chromene derivatives,two chromane derivatives,one sesquiterpene,one diterpene,three steroids and two glycolipids from the petroleum ether fraction of leaves of R.dauricum.The triterpenoids(1-13)as characteristic constituents were selected to investigate the inhibitory effects on the production of NO in LPS-induced RAW 264.7 cells.Compounds 2-7 and 10-11 showed NO inhibitory activity at 3,10 and 30 ?M concentrations with a dose-dependent manner.Compounds 6 and 10-11 significantly inhibited the levels of NO production in LPS-stimulated RAW 264.7 cells at 3 ?M.The research provides scientific basis for the further research of the petroleum ether fraction of leaves of R dauricum.