Poison ivy, urushiols

Plants Barley dust, lichens (o-usnic acid), hops (colophony), hetzil, sawdust, sesquiterpene lactones compositae, frullania spp.), tulips (tulipalin A), poison ivy (urushiol)... 

Rhus toxicodendron Poison ivy Urushiol As for Japanese lac except (27) absent 26 N. America... 

The removal of urushiol, when regarded as an offensive chemical, can be simply effected by the use of hypochlorites (ref. 329). In a rather more subtle way the induction of tolerance to poison ivy urushiol has been established by epicutaneous applications of the analogue 5-methyl-3-n-pentadecylcatechol (1,2-dihydroxy-4-methylpentadecylbenzene) (ref. 330). 

Toxicodendrons contain varying amounts of alk(en)yl catechols which are highly antigenic [18]. Poison-ivy urushiol has mostly pentadec(en)yl catechols, while poison oak urushiol has mostly heptadec(en)yl catechols. The two-carbon difference in the two side chains is of relatively minor importance. However, the... 

Johnson RA, Baer H, Kirkpatrick CH, et al. (1972) Comparison of the contact allergenicity of the four pentadecyl catechols derived from poison ivy urushiol in human subjects. J Allergy Clin Immunol 49 27-35... 

Phenols occur widely throughout nature and also serve as intermediates in the industrial synthesis of products as diverse as adhesives and antiseptics. Phenol itself is a general disinfectant found in coal tar methyl salicylate is a flavoring agent found in oil of wintergreen and the urushiols are the allergenic constituents of poison oak and poison ivy. Note that the word phenol is the name both of the specific compound hydroxybenzene and of a class of compounds. 

Other significant phenolic resin compounds include the mixture of urushiol variants, immunogenic compounds causing severe dermatitis from the Rhus spp. (poison ivy, poison oak and poison sumac). 

This is an "antibiotic" against you/ one of the components of urushiol of poison ivy... 

Poison oak Rhus toxicodendron or Toxicodendron toxicaria Anacardiaceae) is nearly always found as a low-growing shrub, and has lobed leaflets similar to those of oak. It is also common throughout North America. There appears considerable confusion over nomenclature, and Rhus radicans may also be termed poison oak, and R. toxicodendron oakleaf poison ivy. Poison oak contains similar urushiol structures in its sap as poison ivy, though heptadecylcatechols (i.e. C17 side-chains) predominate over pentadecylcatechols (C15 side-chains). 

Cashew shells contain urushiol, the same irritating oil that is in poison ivy heating inactivates urushiol, so toasted cashews are safe to eat the raw nuts, however, should never be eaten... 

Problem 19.19 Substituted phenols show substituent effects similiar to substituted benzoic acids. Should the pKa of phenol A, one of the naturally occurring phenols called urushiols isolated from poison ivy, be higher or lower than the pfCg of phenol (CeHsOH, pKg = 10) Explain. 

Kalish RS, Wood JA, LaPorte A. Processing of urushiol (poison ivy) hapten by both endogenous and exogenous pathways for presentation to T cells in vitro. / Clin Invest. 1994 93 2039-2047. 

Markiewitz and Dawson separated oleflnic components of the poison ivy principle urushiol in active phenolic form by benzylation, chromatography, and debenzyla-tion with a dispersion of sodium-potassium alloy in ligroin. With this reagent debenzylation was effected without alteration in the position or geometrical configuration of mutliple olefinic bonds separated from one another by only one methylene group (sodium isomerizes such compounds to conjugated systems, which are then reduced by the metal). 

Rhus Radicans Common Names Poison Ivy, Poison Oak Poison Urushiol Dosage ioz(28G)Oil... 

Dihydric phenolic lipids are the most abundant phenolic lipids. They are of the cardol-or urushio 1-type, i.e. with hydroxyl groups in the metha position (1,3-dihydroxy) or in the ortho (1,2-dihydroxy) position respectively. Urushiol-type, dihydroxy phenolic lipids, are practically restricted to the Anacardiaceae family (Rhus genus) of poisonous plants. The most well-known are poison ivy, poison oak and the Indian marking nut. The sap from various plants belonging to Anacardiaceae from which Japanese, Chinese, Burmese, Formosan and Vietnamese lacs is one of the richest source of these phenols. The occurrence of dihydric phenolic lipid of the urushiol type is depicted in Table 3. 

A component of urushiol, the active constituent of the irritating oil of poison ivy, is 3-pentadecyl-l,2-dihydroxy-benzene. Synthesize this compound from catechol. 

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