Identification of benzo[c]phenanthridine metabolites in human hepatocytes by liquid chromatography with electrospray ion-trap and quadrupole time-of-flight mass spectrometry.

The metabolism of the benzo[c]phenanthridine alkaloids was studied using human hepatocytes which are an excellent model system for biotransformation studies. For analysis of the alkaloids and their metabolites, an electrospray quadrupole ion-trap mass spectrometry (ESI ion-trap MS) connected to a reversed phase chromatographic system based on cyanopropyl modified silica was used. The optimized experimental protocol allowed simultaneous analysis of the alkaloids and their metabolites and enabled study of their uptake into and interconversion in human hepatocytes. The results show that formation of the dihydro metabolite which may be followed by specific O-demethylenation/O-demethylation processes, is probably the main route of biotransformation (detoxification) of the benzo[c]phenanthridines in human hepatocytes. The structure of the main O-demethyl metabolite (2-methoxy-12-methyl-12,13-dihydro-[1,3]dioxolo[4',5':4,5]benzo[1,2-c]phenanthridin-1-ol; 336.1 m/z,) was proposed by the multi-stage MS and quadrupole time-of-flight MS methods using chemically synthesized standard.

Protopine and allocryptopine increase mRNA levels of cytochromes P450 1A in human hepatocytes and HepG2 cells independently of AhR.

The isoquinoline alkaloids protopine and allocryptopine are present in phytopreparations from medicinal plants, such as Fumaria officinalis. Since nothing is known about effects of the alkaloids on the expression of xenobiotic-metabolizing enzymes, we examined whether protopine or allocryptopine affect the expression of cytochromes P450 (CYPs) 1A1 and 1A2 in primary cultures of human hepatocytes and human hepatoma HepG2 cells. In HepG2 cells, protopine and allocryptopine significantly increased CYP1A1 mRNA levels after 24h exposure at concentrations from 25 and 10 µM, respectively, as shown by real-time PCR. Both protopine and allocryptopine also dose-dependently increased CYP1A1 and CYP1A2 mRNA levels in human hepatocytes. However, the effects of the tested alkaloids on both cell models were much lower than the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a prototypical CYP1A inducer. Using gene reporter assays performed in transiently transfected HepG2 cells, we demonstrated that the induction of CYP1A1 expression by either protopine or allocryptopine was associated with mild or negligible activation of the aryl hydrocarbon receptor. In contrast to TCDD, CYP1A mRNA levels induced by protopine or allocryptopine in both HepG2 cells and human hepatocytes did not result in elevated CYP1A protein or activity levels as shown by western blotting and EROD assays, respectively. We conclude that the use of products containing protopine and/or allocryptopine may be considered safe in terms of possible induction of CYP1A enzymes.

Gastric submucosal microdialysis in the detection of rat stomach ischemia--a comparison of the 3H2O efflux technique with metabolic monitoring.

Microdialysis has been utilized for nutritive blood flow measurements, but both the advantages and disadvantages of various approaches have not been evaluated in parallel in the stomach yet. Our aim was to compare the (3)H(2)O efflux technique with biochemical monitoring during temporary celiac artery occlusion in anesthetized rats. Microdialysis probes were implanted in the gastric submucosa and perfused with (3)H(2)O; samples were analyzed for ß-activity, glucose, lactate, pyruvate and glycerol. Gastric mucosa and plasma were subjected to morphometry and analysis of myeloperoxidase, total thiols and lactatdehydrogenase. The most dramatic responses to ischemia were observed in lactate/pyruvate and lactate/glucose (%) ratios (6.1-9.3×, p < 0.0001); the changes in (3)H(2)O efflux and glycerol were less pronounced (1.1-1.7×, p < 0.0001 and < 0.01, respectively). (3)H(2)O efflux correlated best with the lactate/glucose ratio and glucose alone (r = 0.693 and -0.681, respectively, p < 0.0001). A correlation was also found between plasma lactatdehydrogenase and relative glycerol release (r = 0.600, p < 0.05). Myeloperoxidase, lactatdehydrogenase and histology score were increased by ischemia/reperfusion (0.06-0.12 nkat g(-1), p < 0.05, 0.26-0.44 nkat g(-1), p < 0.05 and 1.79-2.33, p < 0.05, respectively), macroscopy and plasma thiols remained unchanged. Microdialysis is useful in monitoring gastric ischemia, metabolic monitoring being superior to the (3)H(2)O efflux technique. The results question the efficacy of the utilized model to produce standardized major gastric damage.

Identification of new phase II metabolites of xanthohumol in rat in vivo biotransformation of hop extracts using high-performance liquid chromatography electrospray ionization tandem mass spectrometry.

Polyphenolic compounds occurring in hop extracts and their phases I and II metabolites formed during in vivo rat biotransformation have been analyzed using HPLC/MS/MS with electrospray ionization (ESI). Two main groups of polyphenolics are present in the hops, i.e., xanthohumol related compounds and so called alpha- and beta-bitter acids (humulones and lupulones). In our study, hybrid quadrupole-time-of-flight (QqTOF) analyzer is used for the identification of both natural phenolics and their metabolites due to the possibility of accurate mass measurements in full scan and tandem mass spectra supported by MS(n) data obtained with the ion trap analyzer. Both ESI polarity modes are used for the determination of molecular weights based on [M+H](+) and [M-H](-) ions in the full scan spectra and the structural information in subsequent tandem mass spectra. The emphasis is given on the elemental composition determination of individual metabolites based on accurate masses typically better than 5ppm even with the external calibration. Advanced software tools are used for the metabolite identification using the comparison of the blank chromatogram with the real incubation sample together with the software prediction and detection of possible metabolites. Chromatograms of rat incubations are also compared with chromatograms of pure rat feed, rat feed enriched with hop extracts and the placebo experiment. More than ten compounds originating from the hops are identified in rat feces, two of them belong to phase I metabolites and five compounds are phase II metabolites.

Liposomal formulation of alpha-tocopheryl maleamide: in vitro and in vivo toxicological profile and anticancer effect against spontaneous breast carcinomas in mice.

The vitamin E analogue alpha-tocopheryl succinate (alpha-TOS) is an efficient anti-cancer drug. Improved efficacy was achieved through the synthesis of alpha-tocopheryl maleamide (alpha-TAM), an esterase-resistant analogue of alpha-tocopheryl maleate. In vitro tests demonstrated significantly higher cytotoxicity of alpha-TAM towards cancer cells (MCF-7, B16F10) compared to alpha-TOS and other analogues prone to esterase-catalyzed hydrolysis. However, in vitro models demonstrated that alpha-TAM was cytotoxic to non-malignant cells (e.g. lymphocytes and bone marrow progenitors). Thus we developed lyophilized liposomal formulations of both alpha-TOS and alpha-TAM to solve the problem with cytotoxicity of free alpha-TAM (neurotoxicity and anaphylaxis), as well as the low solubility of both drugs. Remarkably, neither acute toxicity nor immunotoxicity implicated by in vitro tests was detected in vivo after application of liposomal alpha-TAM, which significantly reduced the growth of cancer cells in hollow fiber implants. Moreover, liposomal formulation of alpha-TAM and alpha-TOS each prevented the growth of tumours in transgenic FVB/N c-neu mice bearing spontaneous breast carcinomas. Liposomal formulation of alpha-TAM demonstrated anti-cancer activity at levels 10-fold lower than those of alpha-TOS. Thus, the liposomal formulation of alpha-TAM preserved its strong anti-cancer efficacy while eliminating the in vivo toxicity found of the free drug applied in DMSO. Liposome-based targeted delivery systems for analogues of vitamin E are of interest for further development of efficient and safe drug formulations for clinical trials.

Natural feed additive of Macleaya cordata: safety assessment in rats a 90-day feeding experiment.

Macleaya cordata (Willd.) (Papaveraceae) is used as an active component in the natural feed additive Sangrovit. Sangrovit contains mixture of the intact aerial parts and the fraction of quaternary benzo[c]phenanthridine alkaloids from M. cordata (FQBA). In a 90-day pilot toxicity trial, Sangrovit and the FQBA were tested for safety. Male Wistar rats were fed for 90 days with 100, 7000 or 14000mg of Sangrovit or 600mg of FQBA in 1kg of feed. Body and organ weights, clinical chemistry and hematology markers, oxidative stress parameters, morphological structure of tongue, liver, ileum, kidney and heart samples, and total cytochrome P450 in liver were monitored. The results showed no statistically significant alterations in any parameter between control and treated animals, except for the group treated with 14000ppm Sangrovit that resulted in elevation of reduced glutathione level and superoxide dismutase activity in liver.

The toxicity and pharmacokinetics of dihydrosanguinarine in rat: a pilot study.

The quaternary benzo[c]phenanthridine alkaloid sanguinarine (SG) is the main component of Sangrovit, a natural livestock feed additive. Dihydrosanguinarine (DHSG) has recently been identified as a SG metabolite in rat. The conversion of SG to DHSG is a likely elimination pathway of SG in mammals. This study was conducted to evaluate the toxicity of DHSG in male Wistar rats at concentrations of 100 and 500 ppm DHSG in feed for 90 days (average doses of 14 and 58 mg DHSG/kg body weight/day). No significant alterations in body or organ weights, macroscopic details of organs, histopathology of liver, ileum, kidneys, tongue, heart or gingiva, clinical chemistry or hematology markers in blood in the DHSG-treated animals were found compared to controls. No lymphocyte DNA damage by Comet assay, formation of DNA adducts in liver by 32P-postlabeling, modulation of cytochrome P450 1A1/2 or changes in oxidative stress parameters were found. Thus, repeated dosing of DHSG for 90 days at up to 500 ppm in the diet (i.e. approximately 58 mg/kg/day) showed no evidence of toxicity in contrast to results published in the literature. In parallel, DHSG pharmacokinetics was studied in rat after oral doses 9.1 or 91 mg/kg body weight. The results showed that DHSG undergoes enterohepatic cycling with maximum concentration in plasma at the first or second hour following application. DHSG is cleared from the body relatively quickly (its plasma levels drop to zero after 12 or 18 h, respectively).