| Systematic study on the chemical constituents of traditional Chinese herbs is one of the important routes to discover bioactive compounds. There are about6species belong to the genus Brucea, family Simaroubaceae. These evergreen shrubs distribute in an altitude of950～1000m between lime mountain thin forests mainly in the eastern hemisphere tropics.There are only two species of Brucea distributed in China, Brucea javanica (L.) Merr and Brucea moll wall.Var.tonkinensis, which are grown in southeast, south and southwest including Fujian, Taiwan, Guangdong, Hainan, Guizhou and Yunnan etc..The seeds of Brucea javanica (L.) Merr,named as Ya-dan-zi in traditional Chinese medicine, are listed in Chinese Pharmacopoeia for the treatment of dysentery, malaria, warts and corns.We systematically studied the chemical constituents of Brucea javanica, and evaluated the activity of inhibiting tumor cell proliferation of some compounds in this paper. By using silica gel chromatography, Sephadex LH-20chromatography, RP-18chromatography and semi-preparative HPLC,30compounds were isolated from the ethanol extract of this plant. The structures were elucidated by spectroscopic methods as follows:brusatol (1), bruceanic acid E (2), dehydrobruceine B (3), dehydrobrusatol (4), dehydrobruceantinol (5), dehydrobruceine A (6), bruceine B (7), bruceine D (8), bruceoside A (9), yadanzioside M (10), yadanzioside G (11), yadanzioside A (12), cleomiscosin A (13), cleomiscosin B (14), cleomiscosin C (15), spicatolignan B (16), luteolin (17), aurantiamide acetate (18),11-hydroxycanthin-6-one (19),(3-sitosterol (20), daucosterol (21), stigmasterol-β-D-glycoside (22),7-oxositosteryl-β-D-glucopyranoside (23),2,3-Dihydroxy-1-(4-hydroxy-3-methoxyphenyl)-propan-1-one (24), vanillin (25), vanillic acid (26), hydroxybenzoic acid (27), laportoside A (28),1-oleoyl-glycerol (29) and9,10-dihydroxystearic acid (30).Among them, compoundsl6,18,22,23,24,28,29and30wereobtained from the seeds of Brucea javanica for the first time.The cytotoxic activity was screened by using MTT assay, the results showed that quassin compounds1-8were toxic to A549, NCI-H292and MSTO-211H cells on different levels. Compound1has a strong cytotoxic activity in A549cells (IC50value is2.83μM).Compounds2-8and15showed strong activity on NCI-H292and MSTO-211H cells with IC50values ranging from0.3to19.1μM.dehydrobruceine B (DHB) was chosen for further evaluation. The compound induced apoptosis of A549and NCI-H292cells in a dose-dependent manner by using AnnexinV/FITC-PI staining and flow cytometry detection.The ROS level in cancer cells incresed after treatment by the compound. The decrease of mitochondrial membrane potential (MMP) suggested that the compound may indcue apoptosis through mitochondrial pathway.The expression levels of cytochrome c, Bax, Bcl-2, Bcl-xL and caspase-3were measured by western blotting. In addition, the synergistic effect of DHB on cytotoxicity with cisplatin was observed by using real-time cellular assaysystem.The results showed that DHB significantly enhanced the effects of cisplatin on A549cells proliferation in sub-toxic concentration.In conclusion, dehydrobruceine B could induce lung cancer cells apoptosis through a mitochondrial-related pathway and could combine with cisplatin to combat lung cancer cells. |
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