[Chemical composition of Brazilian marihuana samples and the importance of several constituents to the pharmacological activity of the plant].

The gas chromatographic analysis of marihuana samples seized by the São Paulo State Police showed high levels of delta9-trans-tetrahydrocannabinol (delta9-THC) the most active of cannabis constituents. The cannabiol (CBN) levels were also high and probably able of interfering with delta9-THC actions in some samples. The cannabidiol (CBD) and delta8-trans-tetrahydrocannabinol (delta8THC) levels were generally low. When compared to marihuanas used in other countries the amount of delta9-THC in our samples was in average higher. When the pharmacological activity of one of those marihuana extracts, called natural extract containing a high delta9-THC to the others cannabinoid ratio (CBD, CBN and delta8-THC) was compared to a synthetic extract with the same proportions of those cannabinoids, the activity was not identical in all animals tests used. The possibility of others substances present in the plant, besides those cannabinoids listed before, of interfering with the plant's pharmacological activity is discussed.