Mitragynine is an indole-based opioid-receptor agonist and the most abundant active alkaloid in the kratom. Mitragynine, otherwise known as kratom. Dry kratom leaf contains roughly 1.2–2.1% mitragynine.
7-Hydroxymitragynine is an agonist at the μ-opioid receptor with a potency, calculated using pD (2) values, that is 30-fold higher than that of mitragynine otherwise known as kratom. It’s 17-fold higher than that of morphine.