Anti-melanogenic effects of glucosylceramides and elasticamide derived from rice oil by-products in melanoma cells, melanocytes, and human skin.

Glucosylceramides (GlcCer), which are present in many edible plants, suppress melanin production in mouse melanocytes. Rice GlcCer consist of multiple molecules that comprise different types of sphingoid bases as well as diverse lengths and stereotypes of free fatty acids. Adjacent to the GlcCer fraction, there are free ceramides (Cer) as minor constituents. However, the anti-melanogenic activities of individual GlcCer and Cer remain unknown. Therefore, we herein isolated 13 GlcCer and elasticamide, a Cer [AP] from the gummy by-products of rice bran oil, and examined their anti-melanogenic activities. In theophylline-induced melanogenesis in B16 melanoma cells, GlcCer [d18:2(4E,8Z)/18:0], GlcCer [d18:2(4E,8Z)/20:0], and elasticamide significantly suppressed melanin production with IC50 values of 6.6, 5.2, and 3.9 µM, respectively. Elasticamide, but not GlcCer [d18:2 (4E,8Z)/20:0], suppressed melanogenesis in human 3D-cultured melanocytes and the expression of tyrosinase-related protein 1 in normal human melanocytes. Based on these results, we conducted a clinical trial on the effects of rice ceramide extract (Oryza ceramide®), containing 1.2 mg/day of GlcCer and 56 µg/day of elasticamide, on UV-B-induced skin pigmentation. The ingestion of Oryza ceramide® for 8 weeks significantly suppressed the accumulation of melanin 7 days after UV irradiation (1288 and 1546 mJ/cm2 ·S). Rice-derived GlcCer and elasticamide, which exhibited anti-melanogenic activities, were suggested to contribute to the suppressive effects of Oryza ceramide® on UV-induced skin pigmentation. Although the mechanisms underlying the anti-melanogenic activities of GlcCer remain unclear, elasticamide was identified as a promising Cer that exhibits anti-melanogenic activity. PRACTICAL APPLICATIONS: The anti-melanogenic activities of rice-derived GlcCer and elasticamide currently remain unclear. We herein demonstrated the inhibitory effects of individual GlcCer and elasticamide on melanogenesis in melanoma cells, melanocytes, and human skin.

Urinary caffeine and caffeine metabolites, asthma, and lung function in a nationwide study of U.S. adults.

OBJECTIVE: Coffee intake has been inversely associated with asthma in adults. We examined the relation between urinary levels of caffeine or caffeine metabolites and asthma, lung function, and fractional exhaled nitric oxide (FeNO) in adults. METHODS: Cross-sectional study of 2,832 adults aged 18-79 years in the US National Health and Nutrition Examination Survey (NHANES). Multivariable logistic or linear regression was used for the analysis of urinary levels of caffeine or each of its three major metabolites (paraxanthine, theobromine, and theophylline) and current asthma, lung function, and FeNO. RESULTS: Subjects with urinary paraxanthine levels in the fourth quartile (Q4) had 53% lower odds of current asthma than those whose urinary paraxanthine levels were in the first quartile (Q1; 95% confidence = 0.22 to 1.00). Among never and former smokers, subjects with urinary theophylline levels above Q1 had 49% lower odds of current asthma than those whose urinary theophylline level was in Q1 (95% CI = 0.31 to 0.85). Among subjects without current asthma, each log10-unit increment in paraxanthine level was associated with a 0.83% increment in percent predicted (%pred) FEV1 and a 1.27% increment in %pred FVC, while each log10-unit in theophylline was associated with a 1.24% increment in %pred FVC. Neither urinary caffeine nor any urinary caffeine metabolite was associated with bronchodilator response or FeNO. CONCLUSIONS: Our findings suggest that two caffeine metabolites (theophylline and paraxanthine) may contribute to the previously reported inverse association between coffee intake and asthma in adults.

Finger sweat analysis enables short interval metabolic biomonitoring in humans.

Metabolic biomonitoring in humans is typically based on the sampling of blood, plasma or urine. Although established in the clinical routine, these sampling procedures are often associated with a variety of compliance issues, which are impeding time-course studies. Here, we show that the metabolic profiling of the minute amounts of sweat sampled from fingertips addresses this challenge. Sweat sampling from fingertips is non-invasive, robust and can be accomplished repeatedly by untrained personnel. The sweat matrix represents a rich source for metabolic phenotyping. We confirm the feasibility of short interval sampling of sweat from the fingertips in time-course studies involving the consumption of coffee or the ingestion of a caffeine capsule after a fasting interval, in which we successfully monitor all known caffeine metabolites as well as endogenous metabolic responses. Fluctuations in the rate of sweat production are accounted for by mathematical modelling to reveal individual rates of caffeine uptake, metabolism and clearance. To conclude, metabotyping using sweat from fingertips combined with mathematical network modelling shows promise for broad applications in precision medicine by enabling the assessment of dynamic metabolic patterns, which may overcome the limitations of purely compositional biomarkers.

Trapping Acrolein by Theophylline/Caffeine and Their Metabolites from Green Tea and Coffee in Mice and Humans.

Acrolein (ACR) is found exogenously as a widespread environmental pollutant and endogenously, where it is thought to be involved as a pathogenic factor in the progression of many pathological conditions. Eliminating ACR by dietary-active substances has been found to be one potential strategy to prevent ACR-associated chronic diseases. This study first compared the scavenging ACR efficacy of four purine alkaloids, theophylline (TP), paraxanthine (PXT), theobromine (TB), and caffeine (CAF), and then, TP, CAF, and their metabolites were investigated for their ability to trap ACR in vivo. Our results indicated that TP, which possesses an -NH moiety at the N-7 position, exhibits the best ACR-trapping capacity in vitro, while CAF has a slight ability to trap ACR due to the substitutions by -CH3 at the N-1, N-3, and N-7 positions. After oral administration of TP or CAF, the ACR adducts of TP and the metabolites of TP or CAF (e.g., mono- and di-ACR-TP, mono-ACR-1,3-DMU, and mono-ACR-1-MU) were detected in urinary samples obtained from both TP- and CAF-treated mouse groups by using ultra-performance liquid chromatography-tandem mass spectrometry. The quantification studies demonstrated that TP and its metabolites significantly trapped ACR in a dose-dependent manner in vivo. Furthermore, we also detected those ACR adducts of TP and TP/CAF's metabolites in human urine after four cups of green tea (2 g tea leaf/cup) or two cups of coffee (4 g coffee/cup) were consumed per day. Those results indicated that dietary TP or CAF has the potential capacity to scavenge ACR in vivo.

In Vitro Selection of RNA Aptamers Binding to Nanosized DNA for Constructing Artificial Riboswitches.

We here designed an in vitro selection scheme for obtaining an aptamer with which to rationally construct an artificial riboswitch as its component part. In fact, a nanosized DNA-binding aptamer obtained through this scheme allowed us to easily and successfully create eukaryotic riboswitches that upregulate internal ribosome entry site-mediated translation in response to the ligand (nanosized DNA) in wheat germ extract, a eukaryotic cell-free expression system. The induction ratio of the best riboswitch ligand-dose-dependently increased to 21 at 300 µM ligand. This switching efficiency is much higher than that of the same type of riboswitch with a widely used theophylline-binding aptamer, which was in vitro selected without considering its utility for constructing riboswitches. The selection scheme described here would facilitate obtaining various ligand/aptamer pairs suitable for constructing artificial riboswitches, which could serve as elements of synthetic gene circuits in synthetic biology.

Production of theophylline via aerobic fermentation of pu-erh tea using tea-derived fungi.

BACKGROUND: Caffeine is one of the most abundant methylxanthines in tea, and it remains stable in processing of general teas. In the secondary metabolism of microorganism, theophylline is the main conversion product in caffeine catabolism through demethylation. Microorganisms, involved in the solid-state fermentation of pu-erh tea, have a certain impact on caffeine level. Inoculating an appropriate starter strain that is able to convert caffeine to theophylline would be an alternative way to obtain theophylline in tea. The purpose of this study was to isolate and identify the effective strain converting caffeine to theophylline in pu-erh tea, and discuss the optimal conditions for theophylline production. RESULTS: Caffeine content was decreased significantly (p < 0.05) and theophylline content was increased significantly (p < 0.05) during the aerobic fermentation of pu-erh tea. Five dominant fungi were isolated from the aerobic fermentation and identified as Aspergillus niger, Aspergillus sydowii, Aspergillus pallidofulvus, Aspergillus sesamicola and Penicillium mangini, respectively. Especially, A. pallidofulvus, A. sesamicola and P. mangini were detected in pu-erh tea for the first time. All isolates except A. sydowii TET-2, enhanced caffeine content and had no significant influence on theophylline content. In the aerobic fermentation of A. sydowii TET-2, 28.8 mg/g of caffeine was degraded, 93.18% of degraded caffeine was converted to theophylline, and 24.60 mg/g of theophylline was produced. A. sydowii PET-2 could convert caffeine to theophylline significantly, and had application potential in the production of theophylline. The optimum conditions of theophylline production in the aerobic fermentation were 1) initial moisture content of 35% (w/w), 2) inoculation quantity of 8%, and 3) incubation temperature at 35 °C. CONCLUSIONS: For the first time, we find that A. sydowii PET-2 could convert caffeine to theophylline, and has the potential value in theophylline production through aerobic fermentation.

Biodegradation of caffeine by whole cells of tea-derived fungi Aspergillus sydowii, Aspergillus niger and optimization for caffeine degradation.

BACKGROUND: Pu-erh tea is a traditional Chinese tea and produced by natural solid-state fermentation. Several studies show that the natural microbiota influence caffeine level in pu-erh tea. Our previous research also found that the caffeine declined significantly (p < 0.05) in the fermentation, which suggested that the caffeine level could be influenced by specific strains. The purpose of this study was to isolate and identify microorganisms for caffeine degradation, and this research explored the degradation products from caffeine and optimal condition for caffeine degradation. RESULTS: 11 Fungi were isolated from pu-erh tea fermentation and 7 strains could survive in caffeine solid medium. Two superior strains were identified as Aspergillus niger NCBT110A and Aspergillus sydowii NRRL250 by molecular identification. In the substrate tests with caffeine, A. niger NCBT110A could use caffeine as a potential carbon source while glucose is absent, A. sydowii NRRL250 could degrade 600 mg/L caffeine completely in a liquid medium. During the degradation product analysis of A. sydowii NRRL250, theophylline and 3-methlxanthine were detected, and the level of theophylline and 3-methlxanthine increased significantly (p < 0.05) with the degradation of caffeine. The single factor analysis showed that the optimum conditions of caffeine degradation were 1) substrate concentration of 1200 mg/L, 2) reaction temperature at 30 °C, and 3) pH of 6. In the submerged fermentation of tea infusion by A. sydowii NRRL250, 985.1 mg/L of caffeine was degraded, and 501.2 mg/L of theophylline was produced. CONCLUSIONS: Results from this research indicate that Aspergillus sydowii NRRL250 was an effective strain to degrade caffeine. And theophylline and 3-methlxanthine were the main caffeine degradation products.

Different Catabolism Pathways Triggered by Various Methylxanthines in Caffeine-Tolerant Bacterium Pseudomonas putida CT25 Isolated from Tea Garden Soil.

The degradation efficiency and catabolism pathways of the different methylxanthines (MXs) in isolated caffeine-tolerant strain Pseudomonas putida CT25 were comprehensively studied. The results showed that the degradation efficiency of various MXs varied with the number and position of the methyl groups on the molecule (i.e., xanthine > 7-methylxanthine ≈ theobromine > caffeine > theophylline > 1-methylxanthine). Multiple MX catabolism pathways coexisted in strain CT25, and a different pathway would be triggered by various MXs. Demethylation dominated in the degradation of N-7-methylated MXs (such as 7-methylxanthine, theobromine, and caffeine), where C-8 oxidation was the major pathway in the catabolism of 1-methylxanthine, whereas demethylation and C-8 oxidation are likely both involved in the degradation of theophylline. Enzymes responsible for MX degradation were located inside the cell. Both cell culture and cell-free enzyme assays revealed that N-1 demethylation might be a rate-limiting step for the catabolism of the MXs. Surprisingly, accumulation of uric acid was observed in a cell-free reaction system, which might be attributed to the lack of activity of uricase, a cytochrome c-coupled membrane integral enzyme.

The Role of Uric Acid and Methyl Derivatives in the Prevention of Age-Related Neurodegenerative Disorders.

High uric acid (UA levels have been correlated with a reduced risk of many neurodegenerative diseases through mechanisms involving chelating Fenton reaction transitional metals, antioxidant quenching of superoxide and hydroxyl free radicals, and as an electron donor that increases antioxidant enzyme activity (e.g. SOD. However, the clinical usefulness of UA is limited by its' low water solubility and propensity to form inflammatory crystals at hyperuricemic levels. This review focuses on the role of UA in neuroprotection, as well as potential strategies aimed at increasing UA levels in the soluble range, and the potential therapeutic use of more water-soluble methyl-UA derivatives from the natural catabolic end-products of dietary caffeine, theophylline, and theobromine.

Effect of decursinol angelate on the pharmacokinetics of theophylline and its metabolites in rats.

Herb-drug interactions represent a serious problem as herbal medicine is used extensively in the modern world. This study investigated the effects of decursinol angelate on the pharmacokinetics of theophylline, a typical substrate of the cytochrome P450 1A2 enzyme, in rats. After 3 days of decursinol angelate pretreatment, on the fourth day, rats were administered decursinol angelate and theophylline concomitantly. Blood theophylline and its major metabolite [1-methylxanthine (1-MX), 3-methylxanthine (3-MX), 1-methyluric acid (1-MU), and 1,3-dimethyluric acid (1,3-DMU)] levels were monitored by liquid chromatography-tandem mass spectroscopy. The results indicated that theophylline clearance significantly decreased and the area under the concentration-time curve (AUC) increased in decursinol angelate (25 mg/kg)-pretreated rats administered theophylline (10 mg/kg). The elimination half-life (t1/2) of theophylline was increased by 20%. In the presence of decursinol angelate (25 mg/kg), the pharmacokinetic parameters of three metabolites (1-MX, 1,3-DMU, and 1-MU) were significantly altered (half-life for 1-MU, and AUC24 h for 1-MX, 1,3-DMU, and 1-MU). Our results suggest that patients receiving CYP1A2-metabolized drugs, such as caffeine and theophylline, should be advised of the potential herb-drug interaction to reduce the risk of therapeutic failure or increased toxicity of conventional drug therapy.

Influence of cross-linking agent type and chitosan content on the performance of pectinate-chitosan beads aimed for colon-specific drug delivery.

Pectinate-chitosan-beads aimed for colon theophylline delivery have been developed. The effect of zinc or calcium ions as cross-linking agent, and of chitosan concentration on the properties and colon-targeting performance of beads was investigated. Beads were characterized for morphology, entrapment efficiency and mucoadhesion properties. Zn-pectinate-chitosan beads formed a stronger gel network than the Ca-containing ones, enabling a greater entrapment efficiency, which further increased with chitosan content, probably due to polyelectrolyte complexes formation. Transport studies across Caco-2 cells evidenced a significant (p > 0.05) drug permeation increase from all beads with respect to drug alone, attributable to the enhancer and/or mucoadhesion properties of the polymers, and Ca-pectinate-chitosan beads were more effective than the Zn-containing ones. Beads formulated as enteric-coated tablets demonstrated good colon-targeting properties, and no differences were observed in drug-release profiles from Zn- or Ca-pectinate-chitosan beads. Therefore, Ca-pectinate-chitosan beads emerged as the choice formulation, joining colon-targeting specificity with better permeation enhancer power.

Development of a whole-cell screening system for evaluation of the human CYP1A2-mediated metabolism.

Cytochrome P450 1A2 (CYP1A2) is an important member of cytochrome P450 involved in drug metabolism. In this study, a cell line, Huh7-1A2-I-E, with high expression level of CYP1A2 is established based on Huh7 cells. To achieve this, we constructed a recombinant lentiviral vector, pLenti-1A2-I-E, containing a single promoter encoding CYP1A2 followed by an internal ribosome entry site (IRES) to permit the translation of enhanced green fluorescence protein (EGFP). Such a design has greatly facilitated the selection of stable cell lines because the translations of CYP1A2 and EGFP proteins would be based on a single bi-cistronic mRNA. The Huh7-1A2-I-E cells were evaluated as a cell-based model for identification of CYP1A2 inhibitors and for studies of cytotoxicity resulted from CYP-mediated drug metabolism. Treatment of Huh7-1A2-I-E cells and the Huh7-E control cells with aflatoxin B1 showed that cells with CYP1A2 expression are much more sensitive to aflatoxin B1 and the cellular toxicity of aflatoxin B1 in Huh7-1A2-I-E cells could be prevented by furafylline, a CYP1A2 inhibitor. A collection of approximately 200 drugs were screened using this system and results indicate that for most drugs the metabolism by CYP1A2 is unlikely to have made a major contribution to the in vitro cytotoxicity except for thimerosal and evoxine. Several previously unidentified CYP1A2 inhibitors such as evoxine and berberine were also identified in this study.

Ammonium carbamates as highly active transdermal permeation enhancers with a dual mechanism of action.

Transdermal permeation enhancers are compounds that temporarily increase drug flux through the skin by interacting with constituents of the stratum corneum. Transkarbam 12 (T12) is a highly active, broad-spectrum, biodegradable enhancer with low toxicity and low dermal irritation. We show here that T12 acts by a dual mechanism of action. The first part of this activity is associated with its ammonium carbamate polar head as shown by its pH-dependent effects on the permeation of two model drugs. Once this ammonium carbamate penetrates into the stratum corneum intercellular lipids, it rapidly decomposes releasing two molecules of protonated dodecyl 6-aminohexanoate (DDEAC) and carbon dioxide. This was observed by thermogravimetric analysis and infrared spectroscopy. This step of T12 action influences drug permeation through lipidic pathways, not through the aqueous pores (polar pathway) as shown by its effects on various model drugs and electrical impedance. Consequently, protonated DDEAC released in the stratum corneum is also an active enhancer. It broadens the scope of T12 action since it is also able to increase permeation of hydrophilic drugs that prefer the pore pathway. Thus, this dual effect of T12 is likely responsible for its favorable properties, which make it a good candidate for prospective clinical use.

Induction of hepatic cytochrome P450s by the herbal medicine Sophora flavescens extract in rats: impact on the elimination of theophylline.

The roots of Sophora flavescens (Sf) have been widely used as a herbal medicine for the treatment of diarrhea, gastrointestinal hemorrhage, and eczema. Cytochrome P450 (P450) forms including CYP1A2, CYP2B, CYP2E1, and CYP3A participate in the oxidative metabolism of theophylline, which is an important bronchodilation agent with a narrow therapeutic index. To assess the interaction of Sf with theophylline, the effects of Sf extract on theophylline-metabolizing P450s and on the pharmacokinetic profile of theophylline were investigated in male Sprague-Dawley rats. Oral treatment of rats with the Sf extract caused dose-dependent increases of liver microsomal oxidation activities toward 7-ethoxyresorufin, 7-pentoxyresorufin, and nifedipine. However, nitrosodimethylamine N-demethylation activity was not affected. The ingestion of Sf extract stimulated theophylline 8-oxidation and N-demethylation activities. The increases of oxidative activities were in consensus with the elevation of the protein levels of CYP1A2, CYP2B1/2, CYP2C11, and CYP3A. Sf-treatment increased the clearance of theophylline and decreased the area under the concentration-time curve (AUC) and the area under the moment curve (AUMC). These results demonstrate that Sf reduces blood theophylline concentration through facilitating the elimination of theophylline. In patients taking Sf, possible P450 induction-induced drug interaction should be noted to decrease the risk of therapeutic failure or adverse effects resulting from the use of additional therapeutic agents.

In vitro transdermal delivery of caffeine, theobromine, theophylline and catechin from extract of Guarana, Paullinia Cupana.

Extracts of guarana (Paullinia cupana) feature as putatively stimulating ingredients in a number of foods, drinks and dietary/herbal supplements. The objective of this work was to investigate in vitro the transdermal delivery of the major pharmacologically active compounds contained in guarana extract. Saturated solutions of guarana were prepared in polyethylene glycol 400 (PEG400), propylene glycol (PG) and H(2)O at 32 degrees C. Guarana extract was also formulated in Duro-tak 2287 transdermal adhesive in a range of concentrations and the diffusional release was determined in addition to adhesive properties. Transdermal delivery across full thickness pig ear skin was investigated in vitro using Franz-type diffusion cells, with reverse-phase HPLC being used for the quantification of the permeation of theobromine (TB), theophylline (TP), (+)-catechin (C) and caffeine (CF). Based upon a combination of release and adhesive property data a patch containing 5.55 mg guarana extract cm(-2) was deemed optimal. The general trend for the delivery of the 4 analytes was: water >5.55 mg cm(-2) patch approximately PG>PEG400. For CF the greatest steady state flux was obtained from the water vehicle: 19 microg cm(-2)h(-1), with approximately 420 microg cm(-2) permeating after 24h. This was some 6x times more than from the drug-in-adhesive patch and 10x greater than PG, a well-known penetration enhancer, and 50x that of the 'regular' excipient PEG400. A water vehicle also provided the greatest delivery of TB (0.45 microg cm(-2) h(-1)), TP (0.022 microg cm(-2) h(-1)), and C (0.10 microg cm(-2) h(-1)). An inverse relationship was noted between lipophilicity and k(p) in each vehicle. The simultaneous transdermal delivery of the major actives of guarana was established, with permeation rates being highly concentration and vehicle dependent.

Development and evaluation of an in vitro method for prediction of human drug absorption II. Demonstration of the method suitability.

The aim of the present work was to assess the actual suitability and general applicability of a new in vitro permeation method based on an appositely developed artificial membrane to evaluate and predict drug absorption potential. The proposed method was employed to evaluate the apparent permeability of a set of 21 structurally diverse drugs having very different solubility and permeability properties, covering the whole range of fraction absorbed in humans (F(a) from 13 to 100%); 13 of the drugs in this study were part of the list suggested by FDA for validation of in vitro permeation methods. An excellent linear correlation (R(2)=0.957) was obtained between artificial membrane apparent permeability and human absorption data in the whole range of F(a) values examined (including all the drugs belonging to the above FDA list), indicating the good predictive ability of the proposed method not only for highly absorbed hydrophobic compounds but also, differently from other in vitro permeation methods, for poorly or middling permeable drugs. The predictive ability of the new method was greater than those obtained for the same set of drugs with PAMPA and Caco-2 permeability literature data, probably due to the poor sensitivity of these methods towards hydrophilic drugs. The better performance of our artificial membrane was attributed to the hydrophilic nature of the support that, differently from the commonly used hydrophobic supports, offers less resistance to permeation of hydrophilic compounds. A comparison of permeation data of theophylline, ketoprofen, aciclovir and furosemide (selected, respectively, as models of I-IV BCS classes) obtained using a Caco-2 cell based dynamic method and the developed artificial membrane and the corresponding F(a) values in humans further confirmed the suitability of the proposed permeation method as predictor of the oral absorption of passively absorbed drugs.

Effect of St. John's wort on the pharmacokinetics of theophylline in healthy volunteers.

The objective of this study was to investigate the effect of St. John's wort (SJW, Hypericum perforatum) on the pharmacokinetics of theophylline in healthy volunteers. Twelve healthy Japanese male volunteers participated in this randomized, open-labeled, crossover study. The subjects took an SJW caplet (300 mg) three times a day for 15 days. On day 14, they received a single oral dose of 400 mg of theophylline. They took the same dose of theophylline without SJW treatment on another occasion. Plasma and urine samples were obtained during a 48-hour period after theophylline administration. Theophylline concentrations in plasma and urine, as well as the major metabolites (13U, 1U, 3X) in urine, were measured. SJW caused no significant changes in the pharmacokinetics of theophylline in plasma. SJW administration tended to increase the ratio of 1U/the total amount excreted in urine. However, no changes in the ratio of unchanged theophylline, 13U, and 3X were observed. It is unlikely that the effect of 15 days of treatment with SJW on CYPs is sufficient to cause a change in plasma theophylline concentrations.

Induction of the procarcinogen-activating CYP1A2 by a herbal dietary supplement in rats and humans.

Herbal dietary supplements to promote health may be double-edge swords. A herbal dietary supplement, FastOne, which contains extracts of kola nut, grape, green tea and Ginkgo biloba, and is used as an agent for weight management, was administered to rats to test whether it induced CYP1A2, a procarcinogen-activating enzyme. Western blot analysis indicated that treatments with 0.15, 0.3, 0.5, 1 and 2 g/kg of the supplement for 3 days increased CYP1A2 expression in rat liver microsomes in a dose-dependent manner. The 0.3, 0.5, 1 and 2 g/kg treatments increased rat liver microsomal CYP1A2 activity measures as the conversion of caffeine to paraxanthine to 166, 212, 331 and 473% of normal, respectively. In humans, the intake of 2 and 4 capsules of the supplement for 3 days increased CYP1A2 activity to 194 and 203%, respectively, as assessed by the change in the urinary ratio of 1,7-dimethylxanthine plus paraxanthine to unmetabolized caffeine. Intake of the herbal supplement increased CYP1A2 activity to levels higher than that observed from smoking (179%). This study suggests that the long-term intake of the dietary supplement inducing CYP1A2 may increase the incidence of colorectal cancers caused by procarcinogens activated by CYP1A2 in rapid N-acetyltransferase-2 acetylators and of lung adenocarcinoma in slow acetylators.

St John's wort (Hypericum perforatum): drug interactions and clinical outcomes.

AIMS: The aim of this work is to identify the medicines which interact with the herbal remedy St John's wort (SJW), and the mechanisms responsible. METHODS: A systematic review of all the available evidence, including worldwide published literature and spontaneous case reports provided by healthcare professionals and regulatory authorities within Europe has been undertaken. RESULTS: A number of clinically significant interactions have been identified with prescribed medicines including warfarin, phenprocoumon, cyclosporin, HIV protease inhibitors, theophylline, digoxin and oral contraceptives resulting in a decrease in concentration or effect of the medicines. These interactions are probably due to the induction of cytochrome P450 isoenzymes CYP3A4, CYP2C9, CYP1A2 and the transport protein P-glycoprotein by constituent(s) in SJW. The degree of induction is unpredictable due to factors such as the variable quality and quantity of constituent(s) in SJW preparations. In addition, possible pharmacodynamic interactions with selective serotonin re-uptake inhibitors and serotonin (5-HT(1d)) receptor-agonists such as triptans used to treat migraine were identified. These interactions are associated with an increased risk of adverse reactions. CONCLUSIONS: In Sweden and the UK the potential risks to patients were judged to be significant and therefore information about the interactions was provided to health care professionals and patients. The product information of the licensed medicines involved has been amended to reflect these newly identified interactions and SJW preparations have been voluntarily labelled with appropriate warnings.