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Title: Comparison of three chromatographic techniques for the detection of mitragynine and other indole and oxindole alkaloids in mitragyna speciosa (Kratom) plants

Author
item WANG, MEI - University Of Mississippi
item CARRELL, EMILY - University Of Mississippi
item ALI, ZULFIQAR - University Of Mississippi
item AVONTO, CRISTINA - University Of Mississippi
item PARCHER, JON - University Of Mississippi
item KHAN, IKHLAS - University Of Mississippi

Submitted to: Journal of Separation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2014
Publication Date: 4/1/2014
Citation: Wang, M., Carrell, E., Ali, Z., Avonto, C., Parcher, J., Khan, I. 2014. Comparison of three chromatographic techniques for the detection of mitragynine and other indole and oxindole alkaloids in mitragyna speciosa (Kratom) plants. Journal of Separation Science. 37(12):1411-1418.

Interpretive Summary: The research was carried out in an attempt to provide new analytical methods for the determination the principal psychoactive components, viz., mitragynine and 7-hydroxymitragynine, of the herbal plant M. speciosa, also known as kratom. The results showed that the technique of supercritical fluid chromatography was superior to the other chromatographic techniques. The results show clearly that any chromatographic technique for the quantitative analysis of mitragynine and other indole alkaloids must address the issue of interference by diastereoisomers of the alkaloids such as speciogynine, mitraciliatine, and speciociliatine.

Technical Abstract: Leaves of the Southeast Asian plant Mitragyna speciosa (kratom) are used to suppress pain and mitigate opioid withdrawal syndromes. The potential threat of abuse and ready availability of this uncontrolled psychoactive plant material in the U.S. have led to the need for improved analytical techniques for the detection of the major, active components of this plant, viz., mitragynine and 7-hydroxymitragynine. Three independent chromatographic methods coupled with two detection systems, GC/MS, SFC/DAD, and HPLC/MS/DAD, were compared for the analysis of mitragynine and other indole and oxindole alkaloids in speciosa plant extracts. The indole alkaloids included two sets of diastereoisomers, viz., i) paynantheine and 3-isopaynantheine, and ii) mitragynine, speciogynine, and speciociliatine. In addition, two oxindole alkaloid diastereoisomers, viz., corynoxine and corynoxine B, were also studied. It was determined that the resolution and sensitivity of the HPLC and SFC methods were further enhanced by the addition of ammonium acetate to the eluent. This is in contrast to the more common use of an acidic additive for liquid eluents. The HPLC and SFC methods successfully resolved the major components, mitragynine, paynantheine, speciogynine and speciociliatine, with slightly different elution orders. The GC method used in this study was less satisfactory because it was unable to resolve the diastereoisomers, mitragynine and speciociliatine. This separation was difficult by gas chromatography with a liquid stationary phase because these diastereoisomers differ only in the orientation of an interior hydrogen. The observed lack of resolution of the indole alkaloid diastereoisomers coupled with the likeness of the MS and MS2 spectra, calls into question proposed GC methods for the analysis of mitragynine based on solely GC/MS separation and identification.