Artemisinin drugs are of utmost importance in the treatment of malaria, because they represent the sole class of therapeutically used antimalarial drugs to which malaria parasites have not yet developed resistance. The major disadvantage of these medicines is the comparatively high recrudescence rate, which has been attributed to the remarkable decrease of artemisinin plasma concentrations during multiple dosing. Autoinduction of CYP2B6-mediated metabolism has been implicated as the underlying mechanism. So far, the molecular mechanism of induction by artemisinin has not been resolved. Because the xenosensors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) have been shown to mediate induction of drug-metabolizing enzymes and drug transporters, we investigated the hypothesis that artemisinin induces cytochrome P450 expression by activating PXR and/or CAR. By combining in vitro transfection methods and quantitative analyses of gene expression in cell lines and primary human hepatocytes, we here show that artemisinin drugs activate human PXR as well as human and mouse CAR and induce the expression of CYP2B6, CYP3A4, and MDR1 in primary human hepatocytes and in the human intestinal cell line LS174T. Furthermore, we demonstrate that artemisinin acts as a ligand of both nuclear receptors, because it modulates the interaction of the receptors with coregulators. In conclusion, activation of PXR and CAR and especially the resulting induction of CYP3A4 and MDR1 demonstrate that artemisinin has a higher risk of potential drug interactions than anticipated previously.Malaria, a parasitic infection by protozoans, is one of the most threatening human infections worldwide. Among the four human malaria parasites, Plasmodium falciparum causes the majority of all severe cases and deaths. Because of the extensive use of monotherapy in the past, this parasite has rapidly developed resistance to several commonly used and cost-effective antimalarial drugs, including chloroquine, sulfadoxine-pyrimethamine, and mefloquine, in many malaria-affected areas (White, 2004). Spread of resistant parasites is regarded to be a major contributor to the global resurgence of malaria in the last decades. Today, artemisinin drugs represent the only therapeutically used antimalarial drug class to which resistance has not yet been developed. Therefore, these drugs are increasingly used in the treatment of drug-resistant falciparum malaria, especially in combination therapy with a second antimalarial drug (White, 2004).Artemisinin, a sesquiterpene lactone endoperoxide, wasThis work was supported by Deutsche Forschungsgemeinschaft Grant Bu 1249/1-2, 3, and the Robert Bosch Foundation (Germany).Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org. doi:10.1124/mol.104.009019.ABBREVIATIONS: P450, cytochrome P450; PXR, pregnane X receptor; CAR, constitutive androstane receptor; MDR, multidrug resistance; CITCO,

Selected indole-based kratom alkaloids were evaluated for their opioid and adrenergic receptor binding and functional effects, in vivo antinociceptive effects, plasma protein binding, and metabolic stability. Mitragynine, the major alkaloid in Mitragyna speciosa (kratom), had higher affinity at opioid receptors than at adrenergic receptors while the vice versa was observed for corynantheidine. The observed polypharmacology of kratom alkaloids may support its utilization to treat opioid use disorder and withdrawal.

Sigma-1 receptor (S1R) radioligands have the potential to detect and monitor various neurological diseases. Herein we report the synthesis, radiofluorination and evaluation of a new S1R ligand 6-(3-fluoropropyl)-3-(2-(azepan-1-yl)ethyl)benzo[d]thiazol-2(3H)-one ([18F]FTC-146, [18F]13). [18F]13 was synthesized by nucleophilic fluorination, affording a product with >99% radiochemical purity (RCP) and specific activity (SA) of 2.6 ± 1.2 Ci/Amol (n = 13) at end of synthesis (EOS). Positron emission tomography (PET) and ex vivo autoradiography studies of [18F]13 in mice showed high uptake of the radioligand in S1R rich regions of the brain. Pre treatment with 1 mg/kg haloperidol (2), non radioactive 13, or BD1047 (18) reduced the binding of [18F]13 in the brain at 60 min by 80%, 82% and 81% respectively, suggesting that [18F]13 accumulation in mouse brain represents specific binding to S1Rs. These results indicate that [18F]13 is a promising candidate radiotracer for further evaluation as a tool for studying S1Rs in living subjects.

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Introduction Kratom (Mitragyna speciosa), a plant native to Southeast Asia, has been used for centuries for its stimulant and opium-like effects. Mitragynine and 7-hydroxymitragynine, exclusive to M. speciosa, are the alkaloids primary responsible for Kratom's biologic and psychoactive profile, and likely contribute to its problematic use. We purchased several commercially available Kratom analogs for analysis and through our results, present evidence of probable adulteration with the highly potent and addictive plant alkaloid, 7-hydroxymitragynine. Methods A simple and sensitive LC-MS/MS method was developed for simultaneous quantification of mitragynine and 7-hydroxymitragynine in methanol extract of marketed Kratom supplements. Results We found multiple commercial Kratom products to have concentrations of 7-hydroxymitragynine that are substantially higher than those found in raw M. speciosa leaves. Conclusions We have found multiple packaged commercial Kratom products likely to contain artificially elevated concentrations of 7-hydroxymitragynine, the alkaloid responsible for M. speciosa's concerning mechanistic and side effect profile. This study describes a unique form of product adulteration, which stresses the importance of increased dietary supplement oversight of Kratom-containing supplements.

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Kratom (Mitragyna speciosa) is a psychoactive plant popular in the United States for the self‐treatment of pain and opioid addiction. For standardization and quality control of raw and commercial kratom products, an ultra‐performance liquid chromatography−tandem mass spectrometry (UPLC−MS/MS) method was developed and validated for the quantification of ten key alkaloids, namely: corynantheidine, corynoxine, corynoxine B, 7‐hydroxymitragynine, isocorynantheidine, mitragynine, mitraphylline, paynantheine, speciociliatine, and speciogynine. Chromatographic separation of diastereomers, or alkaloids sharing same ion transitions, was achieved on an Acquity BEH C18 column with a gradient elution using a mobile phase containing acetonitrile and aqueous ammonium acetate buffer (10mM, pH 3.5). The developed method was linear over a concentration range of 1–200 ng/mL for each alkaloid. The total analysis time per sample was 22.5 minutes. The analytical method was validated for accuracy, precision, robustness, and stability. After successful validation, the method was applied for the quantification of kratom alkaloids in alkaloid‐rich fractions, ethanolic extracts, lyophilized teas, and commercial products. Mitragynine (0.7%–38.7% w/w), paynantheine (0.3%–12.8% w/w), speciociliatine (0.4%–12.3% w/w), and speciogynine (0.1%–5.3% w/w) were the major alkaloids in the analyzed kratom products/extracts. Minor kratom alkaloids (corynantheidine, corynoxine, corynoxine B, 7‐hydroxymitragynine, isocorynantheidine) were also quantified (0.01%–2.8% w/w) in the analyzed products; however mitraphylline was below the lower limit of quantification in all analyses.

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