Kratom (Mitragyna speciosa) has been examined for its opioid activity, especially for the treatment of opioid withdrawal and pain. Mitragynine, the most abundant alkaloid in kratom, is thought to be the major psychoactive alkaloid. An HPLC method was developed for the quantification of mitragynine in kratom leaf extracts. In addition, a multiple reaction mode based UPLC-MS/MS method was developed and validated for the quantification of mitragynine in rat plasma. Pharmacokinetic studies were performed by comparing a single intravenous dose of mitragynine (5 mg/kg, mitragynine hydrochloride) to a single oral dose of mitragynine (20 mg/kg, mitragynine hydrochloride), lyophilized kratom tea, and the organic fraction of the lyophilized kratom tea at an equivalent mitragynine dose of 20 mg/kg in rats. After intravenous administration, mitragynine exhibited a biexponential decrease in the concentration-time profile, indicating the fast distribution of mitragynine from the systemic circulation or central compartment to the peripheral compartments. Mitragynine hydrochloride, lyophilized kratom tea, and the lyophilized kratom tea organic fraction were dosed orally and the absolute oral bioavailability of mitragynine in rats was found to be 1.5- and 1.8-fold higher than that of mitragynine dosed alone. The results provide evidence that an equivalent oral dose of the traditional preparation (lyophilized kratom tea) and formulated/manufactured products (organic fraction) of kratom leaves provide better systemic exposure of mitragynine than that of mitragynine dosed alone.

A simple, sensitive and rapid ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) method was developed and validated for the quantification of mitragynine in rat plasma using amitriptyline hydrochloride as an internal standard. Sample preparation involved a one-step liquid-liquid extraction using methyl t-butyl ether. Mitragynine was separated on an Acquity UPLC TM BEH HILIC column using isocratic elution with a mobile phase of 10 mM ammonium formate buffer containing 0.1% formic acid:acetonitrile (15:85, v/v). At a flow rate of 0.2 mL min -1 , the retention time of mitragynine was found to be 1.3 min. Ionization was performed in the positive ion electrospray mode. The selected mass-tocharge (m/z) ratio transition of mitragynine ion [M ? H] ? used in the selected ion recording (SIR) was 399.1. The calibration curve was found to be linear over a concentration range of 1-5,000 ng mL -1 (r = 0.999) with a lower limit of quantification (LLOQ) of 1 ng mL -1 . Intra-and inter-day assay variations were found to be less than 15%. The extraction recoveries ranged from 85-93% at the three concentrations (2, 400 and 4,000 ng mL -1 ) in rat plasma.This method was successfully used to quantify mitragynine in rat plasma following intravenous administration of the compound.

Type-2 diabetes is growing at epidemic proportions world-wide. This report describes the effect of a novel, synthetic, small molecule 2-(3, 4-dihydro-2H-pyrrolium-1-yl)-3oxoindan-1-olate (DHPO), on metabolic abnormalities in genetic and dietary mouse models of type-2 diabetes. DHPO (20mg/kg/d i.p. for 21d) attenuated fasting blood glucose, improved glucose disposal and corrected dyslipidemia in genetic (leptin deficient, ob/ob) and dietary (high-fat-fed) mouse models of insulin resistance. In addition, DHPO augmented 2-deoxy-D-glucose (2DG) uptake in gastrocnemius muscles of wild-type mice and in cultured myotubes. The increase in 2DG-uptake was associated with an increase in the phosphorylation of AMPK (Thr-172) and its downstream effector acetyl-CoA carboxylase without any changes in the phosphorylation of Akt of insulin receptor. The AMPK inhibitor, compound C attenuated DHPO-induced glucose uptake whereas the PI3-kinase inhibitor Wortmannin was less effective. In addition, DHPO failed to augment glucose up-take in the gastrocnemius muscle from AMPK-α2-transgenic (kinase-dead) mice. Taken together, these results suggest that DHPO is a novel small molecule that alleviates impaired glucose tolerance and lipid abnormalities associated with type 2 diabetes.