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Heightened awareness of spatial dimensions
Uppers, downers, painkillers, hallucinogens – and the list could go on. Every time we drink a cup of coffee (unless it is ‘decaf’) we experience at first hand the drug synthesizing abilities of plants. However, several of the drugs elaborated by plants have effects that are considerably more dramatic than those of caffeine. Thus, as reported by Daniel Siebert (Malibu, California, USA, pp. 763–771) a Mexican labiate, Salvia divinorum (‘diviners’ sage’) produces a powerful psychoactive diterpene, salvinorin A, which induces altered states of awareness that may include dream-like visions. Salvinorin A is a powerful agonist of kappa-opioid receptors. In addition to traditional cultural and religious uses in Mexico there is interest in developing salvinorin A as an anti-depressant. It is thus important to understand better the processes of synthesis and accumulation of this compound. Anatomical examination of the plant reveals the presence of three types of glandular trichomes, and based on general knowledge of such structures they are thought likely to be involved in the elaboration of salvinorin A. Further, one class of glandular trichome, the peltate glandular trichomes, have a curious sub-cuticular space which is generated by the separation of the outer cell walls of the glands’ head cells from the substantial impervious cuticle that protects them. Any compounds that are secreted by these cells are likely to be trapped in this sub-cuticular space. The author surmised therefore that the peltate glandular trichomes are the sites of accumulation of salvinorin A in S. divinorum. Collection of glandular secretions from various parts of the plant, including peltate glandular trichomes stripped from leaves, followed by thin-layer chromatography, revealed that salvinorins, especially salvinorin A, are indeed secreted, as components of a complex resin, into the sub-cuticular space of these structures. Further, although not specifically demonstrated, it is likely that these compounds are actually synthesized within the trichomes.Professor J. A. Bryant
University of Exeter, UK
j.a.bryant{at}exeter.ac.uk
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