“Euphorbium: Modern Research on Its Active Principle, Resiniferatoxin, Revives an Ancient Medicine”, 1997-01-31 (; backlinks; similar):
Resiniferatoxin, an ultrapotent capsaicin analog present in the latex of Euphorbia resinifera, interacts at a specific membrane recognition site (referred to as the vanilloid receptor), expressed by primary sensory neurons mediating pain perception as well as neurogenic inflammation. Desensitization to resiniferatoxin is a promising approach to mitigate neuropathic pain and other pathological conditions in which sensory neuropeptides released from capsaicin-sensitive neurons play a crucial role. Clinical trials to evaluate the potential of topical resiniferatoxin treatment to relieve pain associated with diabetic polyneuropathy and postherpetic neuralgia are in progress. Though resiniferatoxin was isolated only two decades ago, the dried latex of Euphorbia resinifera, called Euphorbium, has been in medicinal use since the time of recorded history. This review highlights the most important events in the history of this ancient medicine, from the first written record of the therapeutic potential of Euphorbium (at the time of the reign of the Roman Emperor Augustus) to the identification of its active principle as resiniferatoxin in 1975. A brief overview of the enormous contribution of resiniferatoxin to our current understanding of the anatomical localization, function, and pharmacology of vanilloid receptors is provided. Lastly, the mechanisms are summarized by which capsaicin and resiniferatoxin, despite sharing receptors, may have dissimilar biological actions.
[Keywords: euphorbium, resiniferatoxin, capsaicin, vanilloid receptors]
…Only a few fragments of King Juba’s treatise are left6, thus information on the medicinal use of Euphorbium in this period is rather scanty. Subsequently, Euphorbium is mentioned both in the Greek (eg. Dioscorides) and Latin (eg. Pliny the Elder) medical literature as a stemutative (nose irritation) as well as vesicant (skin irritation) agent9. It was also used in the treatment of lethargy: patients could be awakened by “touching their nostrils with a solution of Euphorbium in vinegar”10, with dramatic results, no doubt about it. Other uses of Euphorbium, mentioned by Pliny7, are, however, puzzling, such as the instillation of Euphorbium solutions into the eyes to sharpen sight, or its generalized use against poisons and snake bites. In this case the cure sounds almost worse than the disease: according to Pliny7, no matter where the bite is, an incision is to be made on the skull and the medicament should be inserted there!…During the Renaissance, Euphorbium was widely used as a stemutatory (to provoke sneezing), until its popularity was overshadowed by tobacco5.
…The irritancy of Euphorbium was legendary. Matthiolus in his above mentioned Pedacio Dioscorides reports that pharmacists refused to pulverize it, leaving this task to “facchini o altre persone vili et mecaniche” (that is, to blue collar workers, in today’s lingo)15. Two hundred years later, powdering Euphorbium was still left to “paysans ou gens de basse condition” (ie. to peasants and other folks of low social standing)18. No wonder that Euphorbium soon enjoyed a sinister fame among the makers of practical jokes. For example, balls were disrupted by the general sneezing that followed the spreading of Euphorbium powder on the floor23. Such (mis)use of Euphorbium even found its way into the dramatic literature: Panurge, the merry and cowardly companion of Pantagruel in Rabelais’ play, entitled “Gargantua et Pantagruel”, makes fun of a young girl by giving her a beautiful handkerchief sprinkled with Euphorbium powder. The effect is quite dramatic, to Panurge’s highest delight, the poor victim sneezes “quatre heures sans repos” (ie. four hours without rest).
…In 1975 Hecker’s group in Germany isolated the active principle in Euphorbium and named it resiniferatoxin (RTX)28. During the drying process, the concentration of RTX in the latex diminishes due to oxidation29, which might explain why “young” samples of Euphorbium were not considered suitable for medicinal purposes. As noted by Matthiolus, “Quello che non passa un anno, per la sua molta attivita non e da usare” (ie. samples less than one year old should not be used because they are too powerful)15.