Humantenmine

Development of a validated UPLC-MS/MS method for determination of humantenmine in rat plasma and its application in pharmacokinetics and bioavailability studies.[Pubmed:28557019]

Biomed Chromatogr. 2017 Dec;31(12).

Humantenmine (HMT), the most toxic compound isolated from Gelsemium elegans Benth, is a well-known active herbal compound. A rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to estimate the absolute oral bioavailability of HMT in rats. Quantification was performed by multiple reaction monitoring using electrospray ionization operated in positive ion mode with transitions of m/z 327.14 --> m/z 296.19 for HMT and m/z 323.20 --> m/z 236.23 for gelsemine (internal standard, IS). The linear range of the calibration curve was 1-256 nmol/L, with a lower limit of quantification at 1 nmol/L. The accuracy of HMT ranged from 89.39 to 107.5%, and the precision was within 12.24% (RSD). Excellent recovery and negligible matrix effect were observed. HMT remained stable during storage, preparation and analytical procedures. The pharmacokinetics of HMT in rats showed that HMT reached the concentration peak at 12.50 +/- 2.74 min with a peak concentration of 28.49 +/- 6.65 nmol/L, and the corresponding area under the concentration-time curve (AUC0-t ) was 1142.42 +/- 202.92 nmol/L min after 200 mug/kg HMT was orally administered to rats. The AUC0-t of HMT given at 20 mug/kg by tail vein administration was 1518.46 +/- 192.24 nmol/L min. The calculated absolute bioavailability of HMT was 7.66%.

Ultrasound/microwave-assisted extraction and comparative analysis of bioactive/toxic indole alkaloids in different medicinal parts of Gelsemium elegans Benth by ultra-high performance liquid chromatography with MS/MS.[Pubmed:24375943]

J Sep Sci. 2014 Feb;37(3):308-13.

Indole alkaloids are the main bioactive/toxic components in Gelsemium elegans Benth. To determine the distribution and contents of indole alkaloids in its different medicinal parts, a novel and rapid method using ultra-high performance LC (UPLC) with MS/MS has been established and validated with an optimized ultrasound/microwave-assisted extraction method. Four constituents, namely, humantenidine, Humantenmine, gelsemine, and koumine, were simultaneously determined in 6 min. Chromatographic separation was achieved on an ultra-high performance LC BEH C18 column with a gradient mobile phase consisting of methanol and water (containing 0.1% formic acid both in methanol and water) at a flow rate of 0.3 mL/min. The detection was performed on a triple quadrupole electrospray MS/MS by positive ion multiple-reaction monitoring mode. All the analytes showed good linearity (r >/= 0.9934) within a concentration range from 0.1-25 mug/mL with a LOQ of 25-50 ng/mL. The overall intra- and intervariations of four components were <4.7% with an accuracy of 97.3-101.3%. The analysis results showed that there were remarkable differences in the distribution and contents of four chemical markers in the roots, stems, and leaves of G. elegans Benth. The findings can provide necessary and meaningful information for the rational utilization of its resources.

Inhibitory effects of cytochrome P450 enzymes CYP1A2, CYP2A6, CYP2E1 and CYP3A4 by extracts and alkaloids of Gelsemium elegans roots.[Pubmed:25764964]

J Ethnopharmacol. 2015 May 26;166:66-73.

ETHNOPHARMACOLOGICAL RELEVANCE: Gelsemium elegans (GE), widely distributed in East Asia, South East Asia and Northern America, is a kind of well-known toxic plant throughout the world. Yet it has been used as a Chinese folk medicine for treatment of malignant tumors, pain, rheumatic arthritis, psoriasis and immune function. AIM OF THE STUDY: The present study was to investigate the potential inhibitory effects of G. elegans (GE) roots on four major cytochrome P450 (CYP450) isoforms (CYP1A2, CYP2A6, CYP2E1 and CYP3A4) in vitro. MATERIALS AND METHODS: Four extracts (petroleum ether, dichloromethane, EtOAc and aqueous) of GE and two commercially available alkaloids (koumine and Humantenmine) were screened for their CYP isoforms inhibitory activity. Four enzyme inhibition assays were examined according to the method of the literature. Phenacetin, coumarin, chlorzoxazone and testosterone were used as probe substrates in order to determine CYP1A2, CYP2A6, CYP2E1 and CYP3A4 catalytic activity, respectively. Each probe substrate was incubated with or without each extract and active constituent for corresponding isoform, followed by determination of the kinetics parameters, IC50 and Ki, to characterize inhibitory effects. RESULTS: GE dichloromethane extract selectively inhibited activities of CYP2E1 (IC50=29.04microg/ml) and CYP2A6 (IC50=46.84microg/ml), with Ki of 10.16 and 19.33microg/ml, respectively. In the case of alkaloids, koumine exhibited significant inhibitory effects on CYP2E1 while Humantenmine showed more potent inhibition on CYP2E1 and CYP2A6 (IC50 of 47.44, 18.34 and 45.87microg/ml, Ki of 31.20, 35.06 and 52.06microg/ml, respectively). Because of their relatively high Ki values, the active constituents in GE dichloromethane extract were analyzed. The UPLC-DAD-ESI-MS/MS data showed that GE dichloromethane extract contains 6 kinds of indole alkaloids (koumine, Humantenmine, humantenine, humantenirine, N-methoxytaberpsychine, and sempervirine). As for CYP1A2 and CYP3A4, the negligible inhibitions were observed. CONCLUSION: G. elegans extracts inhibited several CYP450 enzyme activities with varying potency. Strong inhibition was observed in CYP2E1 and CYP2A6 isoforms by GE dichloromethane extract, koumine and Humantenmine, inferring the involvement of alkaloids chemical constituents from GE dichloromethane extract in the effect.