Comments on Chemical Constituents of Virola and Related Genera: Fifty-three voucher collections of Virola and related genera made by various botanists over a time span of several decades have been analyzed for alkaloids. Of the total number of collections, 18 proved negative when analyzed for alkaloids in various parts of the plant. Occasionally, different collections representing the same species have proven to be alkaloidpositive in some cases and negative in others. Four analyses of different collections of Virola surinamensis, however, all proved to be negative. To our knowledge, only the bark and/or constituents of bark are used in the preparation of the intoxicating snuffs employed by the Indians. The alkaloid content of bark specimens is listed in Table 1, which also gives the species used in the manufacture of snuffs and the approximate alkaloidal content. From this table, it is apparent that the species used are usually rich in alkaloids. Virola rufula is not known to be employed and, if it is not utilized, it would appear that the Indians have missed an alkaloid-rich species. In addition to the bark, the leaves and flowering shoots seem to be usually rich in alkaloids. The simple alkaloids MMT, DMT, 5-MeO-MMT and 5-MeO-DMT abound in the species used; they are also present in other species. The nyakwana snuff analyzed by Agurell et al. (1969) proved to be extraordinarily rich in base content (11%). This might explain why the resin of Virola theiodora is also employed as an arrow poison. As has been pointed out by Gottlieb (1979) and as is evident from Table 1, there exist appreciable differences in the base composition of different parts of a single plant (Agurell et al., 1969); this is true also of different species and even in analyses of different specimens representing the same species. When examining the data of Table 1 with respect to use, it must be kept in mind that the preparation of snuffs, pellets and arrow poison involves concentration of the resinous bark exudate to a thick syrup which is subsequently dried, powdered or rolled into pellets which are then coated with the residue of leachings from ashes. Such treatment, not to speak of storage, would be expected to alter the original base composition. The hallucinogenic myristicaceous snuffs of the South American Indians owe their biological activity to the simple methylated indoles mentioned above (Holmstedt and Lindgren 1967; Agurell et al. 1969). Bufotenine, a component of the snuff made from Anadenanthera peregrina (Chagnon et al. 1971) is not present in the species of Virola investigated; neither is it present in the snuff made from them. When analyzing Indian snuffs in 1967, Holmstedt and Lindgren noted the presence of harmala alkaloids in several preparations of uncertain botanical origin. In one case, both the simple indoles and harmine were present in the same preparation. This observation led to the following conclusion: "In South American botany, beta-carbolines (harmine, harmaline and tetrahydroharmine) are usually associated with the species of Banisteriopsis, wherefore it is very likely that this is their origin in the snuffs. Very likely this is an admixture to the snuff, although definite botanical proof for it is lacking at the moment. To the knowledge of the authors, simple indoles and beta-carbolines have not yet been isolated from the same plant. "The occurrence of both tryptamines and beta-carbolines in the South American snuffs is pharmacologically interesting. The beta-carbolines such as harmine and harmaline (Fig. 1) are monoamineoxidase inhibitors (Udenfriend et al. 1958) and could potentiate the action of the simple indoles. The combination of beta-carbolines and tryptamines would thus be advantageous. However, pharmacological action of the beta-carbolines unrelated to monoamineoxidase inhibition has also been proven to exist (Schievelben et al. 1966). Further botanical and chemical studies are obviously needed to see if the two groups of compounds in the snuff are derived from one plant or a mixture of plants" (Holmstedt and Lindgren 1967). This observation has been often quoted and even misquoted. Additional phytochemical and enzymatic evidence is now available. Trace amounts of beta-carbolines have been found to be present in Virola calophylla, V. theiodora and V. elongata (Fig. 2). In one species, which is not known to be used hallucinogenically, Virola cuspidata, harman bases have been found to be the main alkaloids (Fig. 3) (Cassady et al. 1971). Their existence has been unequivocally proven by isolation, spectroscopy and mass spectrometry, as compared to synthetic reference compounds. Interestingly, these authors have also observed aromatization due to heat treatment such as that practiced by the Indians when preparing snuff from other species. They also point out the possibility of increased potency of enzyme inhibition due to the aromatization. Although the monoamineoxidase (MAO) inhibiting properties of harmine were observed indirectly before the enzyme was known to exist (Marinesco et al. 1930), it was only through Udenfriend and co-workers (1958) that these properties of the harmala alkaloids could be quantitated. Recently, the structureactivity relationship has been worked out for a large number of beta-carbolines (Buckholtz and Boggan 1977). From this work, it is clear that the beta-carbolines contained in Banisteriopsis Caapi and Peganum Harmala are far superior MAO-inhibitors than the compounds contained in usually trace amounts in Virola (Figs.2-3). Table 2 (from Buckholtz and Boggan) gives a comparison of enzyme inhibitory power. The occurrence of trace amounts of 6-methoxy-beta-carbolines in some species of Virola (Table 1 and Fig. 2) is not surprising. It might be expected from the point of view of biosynthesis and workup procedure and is pharmacologically of no importance. The occurrence of a mixture of simple methylated indoles and harmine in one Indian snuff of unknown origin, or of harmine and related compounds alone in other snuffs, justifies, however, the statement made in 1967 and quoted above and should encourage further research on this interesting group of indigenous drugs and the plants from which they are derived.