Investigation Of The Toxic Constituents And Toxicological Mechanism Of Fructus Xanthii

Fructus Xanthii named Cang-Er-Zi is the ripe fruits with involucre of Xanthium sibirium Patr. It is a traditional Chinese medicine that is used in curing nasal diseases and headache according to the Chinese Pharmacopoeia. Fructus Xanthii is in great need in clinic. However, utilization of Fructus Xanthii is limited by its toxicity. Fructus Xanthii is toxicant,and it maybe result in poisoning when used excessively,without preparation or in inappropriate preparation.Recently studies have demonstrated that Fructus Xanthii may have the potential of hepatotoxicity. However, so far there is little studies concening the toxic mechanisms and the toxicologic assessment of its essential components. So, there are no identified conclusions about its toxicity. In this study, in vivo and in vitro experiments have been applied to explore the toxicity and the target organs of Fructus Xanthii, and compared the toxicity of its essential components. After then, the toxic mechanisms are elucidated based on metabonomic technologies in order to offer some toxicological information for its safely clinical usage. The main contents of our study are as following three aspects:1 Study on toxic components of Fructus XanthiiToxicity response of different extractions from Fructus Xanthii was compared using acute toxicity experiment LD50 and MTD in mice. Toxic fraction(D1) was determined. Bioactivity guided isolation of toxic fractions and compounds were undertaken by various chromatographic methods. 7 known compounds were isolated from the toxic fraction. The major types of the isolated compounds were phenolic acids, kaurene glucosides and heterocycles.2 Evaluation of toxic fractions of Fructus XanthiiThe results of level of serum transaminase, biochemical parameters of liver tissue and histopathlogy showed that the main toxic target organ of Fructus Xanthii is liver using acute toxicity experiment. It demonstrated that Fructus Xanthii induce hepatotoxicity in mice by way of its induction of oxidative stress as lipid peroxidation in liver, which merited further studies. Then, the chronic liver toxicity experiment was also determined. It deserves attention that long-term and high-dosage administration of Fructus Xanthii can damage the liver to varied degrees.3 Evaluation of toxic components of Fructus XanthiiComparative toxicity studies of its essential components indicated that atractyloside, carbxyatractyloside and 4'-desulphate-atractyloside are main toxic constituents using cell test. It was found that the three kaurene glycosides can strongly inhibite human normal liver L-02 and rat normal liver BRL cells growth. Then, the toxicity of atractyloside was determined in toxicity experiment in mice. The results demonstrated that the toxic constituents of Fructus Xanthii are kaurene glucosides.4 Investigation of toxic methanism of Fructus Xanthii using integrated metabonomic technologyA integrated metabonomic study with high-resolution 1H NMR spectroscopy has been applied to investigate the biochemical composition of urine and plasma obtained from Fructus Xanthii treated rats. It was found that the level ofβ-HB, lactate, valine, Glutamate, Creatinine, acetone, lactate and allantoin was elevated,and the levels of GPC and glucose were decreased in blood plasma. The level of lactate, hippurate, acetate, TMAO, tryptophane, MA, myoinositol, citrate, N-methy-nicotinamide and tyrosine increased in urine,whileα-ketoglutarate, Creatinine, 2-hydroxy-isovalerate, succinate, histidine, 3-hydroxy butyrate, DMG, NAC, taurine and lysine decreased significantly. The increased level of citrate, N-methy-nicotinamide and tryptophane is the typical biomarker of induction of oxidative stress as lipid peroxidation in liver of Fructus Xanthii.Above all, the main toxic target organ of Fructus Xanthii is liver. Kaurene glycosides are main toxic constituents. From these results, we can infer that Fructus Xanthii induce hepatotoxicity in mice by way of its lipid peroxidation and energy metabolismin. Combination with biochemistry and histological research,we used metabonomic analysis of urines and serum samples to visualize significant alterations in metabolite expression patterns as a result of induced metabolic responses. The study of these metabolite alterations also allowed several major metabolic pathways.Fructus Xanthii is widely and safely used in Chinese medicines usually, while the toxic effects will appear when it was used in large dose and for a long time. There for, when it is used for a long time, the dose will not exceed 3-9 g. When the patients have liver injury, the dose must be modified, and functions of kidney and liver should be monitored. Other herb containing kaurene glycosides may have similar toxic effects. Quality criteria should be established to control the content of toxic substance acordingly. With the development of metabonomics,this novel technology might provide additional discrimination in the toxicological effects of other herb in the future, which will contributes to the modemlization of traditional Chinese medicines.