Tropolisine was a psychotropic compound known for its hallucinogenic effects. Normally found in certain flowering plants, each tropolisine atom contained a stray neutron. Once it started to break down in a humanoid's bloodstream it released an undetectable toxin.
In 2151, while exploring an uncharted M-class planet, the crew of Enterprise became affected by tropolisine that was blown down from the mountains during a windstorm. It was discovered by Dr. Phlox that inaprovaline, combined with being removed from the pollen-saturated environment would allow the effects of tropolisine to dissipate. (ENT: "Strange New World")