7-OH (7-hydroxymitragynine): chemistry

7-OH is short for 7-hydroxymitragynine, a terpenoid indole alkaloid found in the kratom plant, Mitragyna speciosa [1]. Its formula is C23H30N2O5, molecular weight 414.5 g/mol [2]. It is a psychoactive alkaloid and an oxidative derivative of mitragynine, found in extracts of dried kratom leaves [3]. In the plant, it's a trace constituent, making up less than 2% of total alkaloid content in natural leaf [4]. In the human body, it's also produced independently: the liver oxidizes ingested mitragynine into 7-OH, and this metabolite does much of the work behind mitragynine's pain-relieving effects [5][1].

Both mitragynine and 7-OH act as partial agonists at the human mu-opioid receptor [5]. 7-OH shows an EC50 of 34.5 nM and Emax of 47%, compared with mitragynine's EC50 of 339 nM and Emax of 34% [5]. Net effect: roughly tenfold greater potency at this receptor [5]. In rodent studies, this translates into opioid-typical respiratory depression, fully reversible with naloxone [6].

One structural quirk shapes real-world exposure: 7-OH ingested orally is poorly absorbed, only about 2.7% bioavailable in a rodent pharmacokinetic study [6]. Toxicologists note that limited absorption doesn't mean limited risk — high doses, or routes like sublingual or buccal absorption that bypass first-pass metabolism, could still produce clinically meaningful exposure [6]. This is part of why concentrated 7-OH products, which are synthetic rather than extracted at natural ratios, can deliver far more 7-OH per dose than kratom itself [7].

References

1. 7-Hydroxymitragynine — Wikipedia
2. Monographs: 7-Hydroxy mitragynine — Center for Forensic Science Research and Education (CFSRE)
3. Chemistry and toxicity of 7-hydroxymitragynine (7-OHMG): an updated review on the oxidized derivative of mitragynine — ResearchGate
4. 7-Hydroxymitragynin (7-OH): An Assessment of the Scientific Data and Toxicological Concerns Around an Emerging Opioid Threat — U.S. Food and Drug Administration (FDA)
5. 7‑hydroxymitragynine is an active metabolite of mitragynine and a key mediator of its analgesic effects — Washington University in St. Louis
6. ACMT Position Statement: 7-Hydroxymitragynine — American College of Medical Toxicology
7. 7-OH: What is it? Why do people use it? What medical approaches can help? — University of Washington Addictions, Drug & Alcohol Institute