+<unk>  alkaloids at opioid receptors Compound Affinities () Ratio Ref MOR:DOR:KOR 7-Hydroxymitragynine 13.5 155 123 1:11:9<unk> ne 7.24 60.3 1,100 1:8:152<unk> ne pseudoindoxyl 0.087 3.02 79.4 1:35:913 Kratom contains at least 54 alkaloids. These include<unk> ne, 7-hydroxymitragynine (7-HMG), speciociliatine, corynantheidine, speciogynine, paynantheine, mitraphylline, rhynchophylline, mitralactonal, raubasine, and<unk> line. The alkaloids<unk> ne and 7-hydroxymitragynine are responsible for many of the complex effects of kratom, but other alkaloids may also contribute synergistically. Both<unk> ne and 7-HMG are partial agonists of the μ-opioid receptor and competitive antagonists of the δ-opioid receptor with low affinity for the κ-opioid receptor. 7-HMG appears to have higher affinity at the μ-opioid receptor than<unk> ne. These compounds display functional selectivity and do not activate the β-arrestin pathway partly responsible for the respiratory depression, constipation, and sedation associated with traditional opioids. Both<unk> ne and 7-HMG readily cross the blood-brain barrier.<unk> ne also appears to inhibit COX-2, block L-type and T-type calcium channels, and interact with other receptors in the brain including 5-HT2C and 5-HT7 serotonin receptors, D2 dopamine receptors, and A2A adenosine receptors.<unk> ne stimulates α2-adrenergic receptors, inhibiting the release of norepinephrine (noradrenaline); other compounds in this class include dexmedetomidine, which is used for sedation, and clonidine, which is used to manage anxiety and some symptoms of opioid withdrawal. This activity might explain why kratom can be dangerous when used in combination with other sedatives. Kratom also contains rhynchophylline, a non-competitive NMDA receptor antagonist.<unk> ne is metabolized in humans via phase I and phase II mechanisms with the resulting metabolites excreted in urine. In in vitro experiments, kratom extracts inhibited CYP3A4, CYP2D6, and CYP1A2 enzymes, which results in significant potential for drug interactions.
Mitragyna speciosa
Craniopagus parasiticus
Piedraia hortae
Cedecea davisae
Ephedra distachya
Arcanum joviale
Gongylonema pulchrum
Cerbera odollam