Studies on the synthesis and opioid agonistic activities of mitragynine-related indole alkaloids: discovery of opioid agonists structurally different from other opioid ligands
Takayama H, Ishikawa H, Kurihara M, Kitajima M,
Aimi N, Ponglux D, Koyama F, Matsumoto K,
Moriyama T, Yamamoto LT, Watanabe K, Murayama T, Horie S.
Laboratory of Molecular Structure and Biological Function,
Graduate School of Pharmaceutical Sciences,
Chiba University, Yayoi-cho, 1-33,
Inage-ku, Chiba 263-8522, Japan.
J Med Chem. 2002 Apr 25;45(9):1949-56


Mitragynine (1) is a major alkaloidal component in the Thai traditional medicinal herb, Mitragyna speciosa, and has been proven to exhibit analgesic activity mediated by opioid receptors. By utilizing this natural product as a lead compound, synthesis of some derivatives, evaluations of the structure-activity relationship, and surveys of the intrinsic activities and potencies on opioid receptors were performed with guinea pig ileum. The affinities of some compounds for mu-, delta-, and kappa-receptors were determined in a receptor binding assay. The essential structural moieties in the Corynanthe type indole alkaloids for inducing the opioid agonistic activity were also clarified. The oxidative derivatives of mitragynine, i.e., mitragynine pseudoindoxyl (2) and 7-hydroxymitragynine (12), were found as opioid agonists with higher potency than morphine in the experiment with guinea pig ileum. In addition, 2 induced an analgesic activity in the tail flick test in mice,
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The Pleasures of Opium
Opioids and anaesthesia
Mitragyna speciosa (Kratom)
Mitragynine and the mu opioid receptors
Opium substitute Kratom (Mitragyna speciosa) and mitragynine

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