Myrcene

β-Myrcene (7-methyl-3-methylene-1,6-octadiene; C₁₀H₁₆) is an acyclic monoterpene with an earthy, musky, slightly fruity aroma, also found in hops, mangoes, lemongrass, and thyme. It is frequently the most abundant terpene in indica-leaning cannabis cultivars, sometimes exceeding 60% of the terpene fraction. Myrcene is widely credited in popular literature with sedative and muscle-relaxant effects — a claim traced principally to rodent studies (do Vale et al., 2002; Rao et al., 1990) showing motor suppression at high parenteral doses. In realistic human inhaled exposures, however, plasma myrcene concentrations are orders of magnitude below those used in rodent models, and no placebo-controlled human trials confirm sedative efficacy (Russo, 2011, British Journal of Pharmacology 163:1344 reviewed the preclinical claims). The popular claim that eating a mango before cannabis potentiates THC is folk lore, not evidence. → See also: Terpene, Entourage effect.