Four new compounds from Imperata cylindrica.

Four new compounds, impecylone (1), deacetylimpecyloside (2), seguinoside K 4-methylether (3) and impecylenolide (4), were isolated from Imperata cylindrica along with two known compounds, impecyloside (5) and seguinoside K (6). Their structures were elucidated mainly by spectroscopic analyses including 1D- and 2D-NMR techniques, and the absolute configuration of 1 was confirmed by X-ray diffraction analysis. In calcium assay, the result indicated that compounds 1, 2, 4 and 5 cannot obviously inhibit the calcium peak value compared with the negative control, and suggested that the four compounds could not have anti-inflammatory activity.

Metabolic pathways of the psychotropic-carboline alkaloids, harmaline and harmine, by liquid chromatography/mass spectrometry and NMR spectroscopy.

The ß-carboline alkaloids, harmaline and harmine, are present in hallucinogenic plants Ayahuasca and Peganum harmala, and in a variety of foods. In order to establish the metabolic pathway and bioactivities of endogenous and xenobiotic bioactive ß-carbolines, high-performance liquid chromatography, coupled with mass spectrometry, was used to identify these metabolites in human liver microsomes (HLMs) in vitro and in rat urine and bile samples after oral administration of the alkaloids. Three metabolites of harmaline and two of harmine were found in the HLMs. Nine metabolites for harmaline and seven metabolites for harmine, from the rat urine and bile samples, were identified. Among them, four in vivo metabolites were isolated and fully characterised by NMR analysis. For the first time, harmaline is shown transforming to harmine by oxidative dehydrogenation in rat. Five metabolic pathways were therefore proposed, namely, oxidative dehydrogenation, 7-O-demethylation, hydroxylation, O-glucuronide conjugation and O-sulphate conjugation.

Protective effect of Danning tablet on acute livery injury with cholestasis induced by α-naphthylisothiocyanate in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Danning tablet, as a composite prescription of traditional Chinese medicine, has been used clinically to relieve liver and gallbladder diseases in China. However, the mechanisms involved are still unclear. AIM OF THE STUDY: The present investigation was designed to assess the effects and possible mechanisms of Danning tablet on α-naphthylisothiocyanate (ANIT)-induced liver injury with cholestasis. MATERIALS AND METHODS: Danning tablet (3, 1.5 or 0.75g/kg body weight/day) was intragastrically (i.g.) given to experimental rats for seven days before they were treated with ANIT (60mg/kg daily via i.g.) which caused liver injury. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), γ-glutamyltranspeptidase (γ-GTP), total bilirubin (T-Bil), direct bilirubin (D-Bil), total bile acid (TBA) and bile flow were measured to evaluate the protective effect of Danning tablet at 48h after ANIT treatment. Furthermore, protective mechanisms of Danning tablet against ANIT-induced liver injury were elucidated by assays of liver enzyme activities and component contents including myeloperoxidase (MPO), superoxide dismutase (SOD), glutathione peroxidase (Gpx), catalase (CAT) and glutathione S-transferase (GST), as well as liver lipid peroxide (LPO) and glutathione (GSH). The biochemical observations were supplemented by histopathological examination. Phytochemical analysis of Danning tablet was performed by UPLC-MASS. RESULTS: Obtained results demonstrated that high dose (3g/kg) of Danning tablet significantly prevented ANIT-induced changes in bile flow (P<0.01), and serum levels of ALT, AST, ALP, γ-GTP, T-Bil, D-Bil (P<0.01) and TBA (P<0.05). In addition, ANIT-induced increases in hepatic MPO, GST activities and GSH, LPO contents were significantly (P<0.01) reduced, while SOD, Gpx, CAT activities in the liver tissue which were suppressed by ANIT were significantly (P<0.01) elevated in the groups pretreated with Danning tablet at the dose of 3g/kg B.W. Histopathology of the liver tissue showed that pathological injuries were relieved after Danning tablet (3g/kg) pretreatment. The results also showed that medium dose (1.5g/kg) of Danning tablet exhibited partially protective effect on ANIT-induced liver injury with cholestasis by reversing part of biochemical parameters and histopathological changes. Low dose (0.75g/kg) of Danning tablet did not show any protective effect on ANIT-induced liver injury with cholestasis. Phytochemical analyses revealed the presence of anthraquinones, flavonoids and stilbene in the Danning tablet. CONCLUSION: These findings indicate that Danning tablet exerts a dose-dependently protective effect on ANIT-induced liver injury with cholestasis in rats, and the possible mechanism of this activity is likely due to its attenuation of oxidative stress in the liver tissue and neutrophil infiltration.

Iridoids from leaves of Gelsemium elegans.

Six iridoids, geleganoids, designated A-F, and five iridoid glycosides, geleganosides A and B together with three previously reported compounds, were isolated from leaves of Gelsemium elegans. Their structures were elucidated by spectroscopic and chemical analyses. The relative configuration of geleganoid A was confirmed by X-ray crystallographic diffraction analysis, and the absolute configuration of geleganoid B was determined by a modified Mosher's method. Selected compounds were evaluated for PC12 cell neurite outgrowth activity, but they were inactive.

Identification of the UDP-glucuronosyltransferase isozyme involved in senecionine glucuronidation in human liver microsomes.

Senecionine (SEN) is a representative of the hepatotoxic pyrrolizidine alkaloids. Although phase I metabolism for cytochrome P450-mediated metabolic activation of SEN was investigated extensively, phase II metabolism for glucuronidation of this compound has not been investigated until now. In our present study, one unique glucuronidation product of SEN in human liver microsomes (HLMs) was identified as SEN N-glucuronide using an authentically synthesized product for which the structure was identified via (1)H and (13)C NMR analysis. Subsequently, kinetics indicated that SEN N-glucuronidation followed the typical Michaelis-Menten model and only one major isozyme participated in it. Finally, this isozyme was demonstrated to be UDP-glucuronosyltransferase (UGT) 1A4, with the direct evidence that recombinant UGT1A4 exhibited predominant and exclusive activity on SEN N-glucuronidation. This result was confirmed by other experiments including chemical inhibition by selective inhibitors and a correlation study between activities of SEN N-glucuronidation and various UGT isozymes. The exclusive role of UGT1A4 on SEN N-glucuronidation was strengthened additionally by its inhibitory kinetic study in which the selective inhibitor of UGT1A4 showed a similar inhibition pattern and K(i) values in both HLM and recombinant UGT1A4 systems. Because UGT2B10 activity failed to correlate with SEN N-glucuronidation in HLMs from 10 individuals, it was impossible for UGT2B10 to play an important role in this metabolism.