Science Cannabis

The Pharmacology of THC 37and nuclear magnetic resonance to identify the chemicals that they hadseparated by chromatography. In this way they were able to identify alarge number of new cannabinoids in extracts of Lebanese hashish —wenow know that as many as 60 different naturally occurring cannabinoidsexist. Although this complexity might appear daunting, it turned out thatmost of the naturally occurring cannabinoids were present in relativelysmall amounts, or that they lacked biological activity. In fact Gaoni andMechoulam reported in 1964 that virtually all of the pharmacologicalactivity in hashish extracts could be attributed to a single compounddelta-9-tetrahydrocannabinol (THC). 1Among other chemicals in the hashish extracts Gaoni and Mechaloumidentified cannabidiol (Fig. 2.1). They found a variety of othernaturally occurring cannabinoids, but delta-9-THC was the most important.Cannabidiol is present in significant quantities but lacks psychoactiveproperties, although it may have other pharmacological effects (seeChapter 2). Cannabis grown in tropical parts of the world (Africa, SoutheastAsia, Brazil, Colombia, Mexico) usually has much more THC thancannabidiol, with ratios of THC/cannabidiol of 10:1 or higher. Plantsgrown outdoors in more northern latitudes, however, (Europe, Canada,northern United States) usually have a much higher content of cannabidiol,often exceeding the THC content by 2:1 (Clarke, 1981, p. 159).Cannabis also contains variable amounts of carboxylic acid derivatives ofdelta-9-THC, and this is potentially important. Although themselves inactive,the carboxylic acid derivatives readily lose their carboxylate groupas carbon dioxide on heating to form active THC. This occurs, for example,when the plant material is heated during smoking, or heated in thecooking processes used to form various cannabis-containing foods anddrinks. This can in some instances more than double the active THCcontent of the original starting plant material. On the other hand, whencannabis resin or other preparations are stored, pharmacological activity1. In some publications, including those from the Israeli group, this is referred to asdelta-1-tetrahydrocannabinol, but this is because there are two different conventions fornumbering the chemical ring systems of which the substances are composed; the delta-9terminology is the most commonly used.