PhD Scientific Days 2021

PH_I_P: Pharmaceutical Sciences I. Posters

Blood-brain barrier permeability study of Mitragyna speciosa alkaloids.

Text of the abstract

Introduction: Mitragyna speciosa (kratom) is a tropical plant indigenous to
Southeast Asia. Its leaves have been used for hundreds of years to reduce fatigue
and relieve pain due to their euphoric and sedative effects. Several alkaloids have
been identified in the drug, the most important ones being mitragynine and 7-OH-
mitragynine, that have been proved to be partial agonists at the μ-opioid and
competitive antagonists at the κ- and δ-opioid receptors. Numerous cases indicate
that despite the growing popularity of kratom, excessive consumption of its extracts
can lead to severe side effects, therefore careful pharmacological study of the drug
and its constituents has become urgent.
Aims: Our aim was the screening study of compounds with good blood-brain barrier
penetration ability in kratom extracts by coupling the PAMPA-BBB (Parallel Artificial
Membrane Permeability Assay for the Blood-Brain Barrier) technique to ultra-high
performance liquid chromatography (UHPLC).
Methods: Purchased kratom alkaloid extracts (27% and 45% mitragynine content)
were separated using a pilot-scale Centrifugal Partition Chromatography (CPC)
procedure (solvent system: dichloromethane:methanol:water-8:3:4 v/v/v). For the
phytochemical analyses an UHPLC-DAD-ESI-QTOF-MS method was applied.
Alkaloids were isolated by flash chromatographic and semi-preparative HPLC
techniques and their structures were identified by NMR spectroscopy. The PAMPA-
BBB method was utilised for the investigation of the transcellular passive diffusion of
the compounds across the blood-brain barrier.
Results: Based on the results of the PAMPA-BBB studies, 4 main and 14 minor
compounds were found to be able to penetrate the BBB via passive diffusion (BBB+).
The 4 main and 3 other minor BBB+ alkaloids were isolated and identified by NMR
spectroscopy as mitragynine, speciogynine, speciociliatine, paynatheine and
mitragynine N-oxide isomers. Our future plans include the isolation and identification
of the additional minor BBB+ alkaloids.
Conclusion: Our data suggest that besides the main alkaloids, other minor
constituents in kratom are also able to reach the central nervous system. This
justifies further investigation of the CNS effect of these compounds.
Funding: Supported by ÚNKP-20-3-I-SE-28 New National Excellence Program of the Ministry
for Innovation and Technology.

University and Doctoral School

Semmelweis University, Doctoral School of Pharmaceutical Sciences