Cannabinoids act as necrosis-inducing factors in Cannabis sativa

Cannabis sativa is well known to produce unique secondary metabolites called cannabinoids. We recently discovered that Cannabis leaves induce cell death by secreting tetrahydrocannabinolic acid (THCA) into leaf tissues. Examinations using isolated Cannabis mitochondria demonstrated that THCA causes mitochondrial permeability transition (MPT) though opening of MPT pores, resulting in mitochondrial dysfunction (the important feature of necrosis). Although Ca(2+) is known to cause opening of animal MPT pores, THCA directly opened Cannabis MPT pores in the absence of Ca(2+). Based on these results, we conclude that THCA has the ability to induce necrosis though MPT in Cannabis leaves, independently of Ca(2+). We confirmed that other cannabinoids (cannabidiolic acid and cannabigerolic acid) also have MPT-inducing activity similar to that of THCA. Moreover, mitochondria of plants which do not produce cannabinoids were shown to induce MPT by THCA treatment, thus suggesting that many higher plants may have systems to cause THCA-dependent necrosis.