Plants of Abuse

For millennia, humans have exploited the use of psychoactive substances to induce altered states of consciousness. These substances were most often natural products derived from plant or animal sources, examples of which include the bufotoxins excreted from the parotid glands of toads of the genus Bufo, psychedelic mushrooms that contain hallucinogens, and the peyote cactus that contains mescaline. In recent times, with the advance of analytical technologies, the specific compounds responsible for the mind-altering effects have been determined. One result has been the development of synthetic methods that enabled production of highly purified active compounds which, although used medicinally in some cases, are nevertheless abused in others. Thus, many of these drugs have become highly regulated and their sale, possession and ingestion are criminal acts. A case in point is marijuana, where the easily identified plant from which it is derived (cannabis), as well as its psychoactive constituents (tetrahydrocannabinol and related compounds) are scheduled. In response, drug manufacturers have gone back to basics, and are exploiting the fact that the majority of plants known or thought to contain psychoactive substances are not scheduled. These plants of abuse are prepared for inclusion in “herbal blends” that contain other mind-altering ingredients or are extracted with solvents to yield crude residues for ingestion.

Since the world of psychoactive plant and animal derived drugs is vast, it has become increasingly difficult in a forensics context to distinguish between innocuous plant-based food material (e.g. spices or coffee grounds), and a plant that is being abused. Thus, when plant material found at a crime scene cannot be identified through traditional means, its evidentiary value can be greatly reduced. Instead, our work has focused on a method to identify plant material through multivariate statistical analysis of its unique metabolomic signature. By building a comprehensive database that contains information on plant species and their corresponding chemotaxonomic markers, mass spectrometric analysis of plant material “unknowns” can comparison of the results to database information can enable identification of plant material at a crime scene and inform further investigations and conclusions. Our work is demonstrating that mass spectrometry can be a powerful tool for the identification and differentiation of plants of abuse.