Magnolol is a bioactive compound isolated from the bark of M. officinalis that has been used in Asian traditional medicine for the treatment of anxiety, sleep disorders, and allergic diseases. It can activate cannabinoid (CB) receptors, behaving as a partial agonist with selectivity for the peripheral CB2 subtype (EC50 = 3.28 μM; Ki = 1.44 μM). Tetrahydromagnolol is a major metabolite of magnolol that is 19-fold more potent than magnolol as a peripheral CB2 receptor agonist (EC50 = 0.17 μM; Ki = 0.42 μM). It also behaves as an antagonist at GPR55, a CB-related orphan receptor (KB = 13.3 μM).
