Studies On Chemical Constituents And Pharmacological Activities Of Saprosma Hainanense

The genus Saprosma, which belongs to the family of Rubiaccous, has about50speciesall over the world. Saprosma hainanense Merr. is an endemic plant in Hainan island. S.merrillii is employed in a traditional Chinese medicine preparation to treat cancer in China.Iridoid glucosides and anthraquinones were isolated from S. scortechinii and S. fragrans..Alkaloids, which exhibited cytotoxic activities, were firstly isolated from S. hainanense inour previous study. In order to take comprehensive utilization, it is very useful to furtherexplore the chemical constituents and biological activities of S. hainanense.The air dried Saprosma hainanense Merr. are crushed, and then extracted by85%ethanol (in volume fraction). After evaporation under reduced pressure a dark ethanol extractwas obtained. The extract was mixed with water, extracted by petroleum ether, chloroform,ethyl acetate and n-BuOH, respectively. The four fractions were respectively subjected tocolumn chromatography over macroporous resin, normal and reversed-phase silica gel,sephadex LH-20, preparation thin-layer chromatography and recrystallization repeatedly toobtain pure compounds. The chemical structures were established on the basis of extensivespectroscopic (IR,1D-NMR,2D-NMR, MS) data analysis and by the comparison withspectroscopic data reported in the literature. Then a test on cytotoxic activities of differentfractions and some compounds had been taken.The main research results are as follows:Bioassay-guided isolation on the extract of S. hainanense led to the isolation of32compounds. They were identified as:7-hydroxy-1,2-dimethoxy-6-methylanthraquinone (1),1-hydroxy-3,6-dimethoxyanthraquinone (2),10,10’-bianthrone (3),9,10-anthraquinone (4),rubiadin(5), damnacanthol(6),2-hydroxy-3-methyl-9,10-anthraquinone (7),3-hydroxy-1,2-dimethoxyanthraquinone (8),3-hydroxy-1-methoxy-2-carbomethoxy-9,10-anthraquinone(9),2-hydroxymethyl-anthraquinone (10), cleistopholine(11),michelalbin(12), michelalbin(13),1H-imidazole-4-carboxylate(14),1H-indole-3-carboxaldehyde(15), lupeol(16),21-H-Hop-22(29)-ene-3,30-diol(17), ursolicacid(18), betulinic acid(19),30-hydroxylupeol(20), stigmasterol(21),3-O-acetyl oleanolicaldehyd(22), ampelopsin A(23),5-hydroxyl-3,4-dimethy-5-penty-12(5H)-furanone(24), scopoletin (25), tyrosol(26), vanillic acid (27), syringic acid(28), p-hydroxybenzoic acid(29),p-hydroxy-benzaldehyde(30), trans-p-hydroxycinnamic acid(31),3,4,5-trimethoxy-benzaldehyde(32). Compounds1and2were new natural products.Compounds1~10,14,15,18,23,24,26,30,31were firstly isolated from this plant. All thecompounds were firstly isolated from this genus, except for compounds11,12,13,25,28,29,32. Among them,1~10were anthraquinones,11~15were alkaloids,16~22were triterpenoid,23was a resveratrol, and25was a coumarin.The chemical ecology effects including cytotoxic activity antibacterial activity andbrine shrimp lethality were used to find active compounds. The tests showed that compound2exhibited moderate activity against A549, with IC50values of13.64μM; And compound1,2,4exhibited the similar activities against Staphylococcus aureus, compared with ciprofloxacin,with MIC value of0.156μg/mL; Compounds4exhibited stronger activity against Bacilluscereus than ciprofloxacin, with MIC values of0.313μg/mL; Compounds1,2and4exhibitedstronger lethality effect to the artemia in the concentration of10μg/mL, with the fatality rateexceeded fifty percent.