Aim and Objective: Mitragynine, a major active alkaloid of Mitragyna speciosa, acts as
an agonist on µ-opioid receptors, producing effects similar to morphine and other opioids. It has been
traditionally utilized to alleviate opiate withdrawal symptoms. Besides consideration about potency
and selectivity, a good drug must possess a suitable pharmacokinetic profile, with suitable
absorption, distribution, metabolism, excretion and toxicity (ADME-Tox) profile, in order to have a
high chance of success in clinical trials.
Material and Method: The purity of mitragynine in a Mitragyna speciosa alkaloid extract (MSAE)
was determined using Ultra-Fast Liquid Chromatography (UFLC). In vitro high throughput ADMETox
studies such as aqueous solubility, plasma protein binding, metabolic stability, permeability and
cytotoxicity tests were carried out to analyze the physicochemical properties of MSAE and
mitragynine. The UFLC quantification revealed that the purity of mitragynine in the MSAE was
Results: MSAE and mitragynine are highly soluble in aqueous solution at pH 4.0 but less soluble at
pH 7.4. A parallel artificial membrane permeability assay demonstrated that it is extensively
absorbed through the semi-permeable membrane at pH 7.4 but very poorly at pH 4.0. Both are
relatively highly bound to plasma proteins (> 85 % bound) and are metabolically stable to liver
microsomes (> 84 % remained unchanged). In comparison to MSAE, mitragynine showed higher
cytotoxicity against WRL 68, HepG2 and Clone 9 hepatocytes after 72 h treatment.
Conclusion: The obtained ADME and cytotoxicity data demonstrated that both MSAE and
mitragynine have poor bioavailability and have the potential to be significantly cytotoxic.