Urushiol

Originally from China, Rhus vernicefera has been under cultivation in Japan since the sixth century AD. The latex is collected in the same way as the rubber plant Hevea brasiliensis. The product is known as urushiol, which consists mostly of dihydric phenols of structures (Fig. 6) and is used as lacquers. 

A crude process of extraction of urushiol from the tree Rhus vernicifera was used by the Chinese during the Chou dynasty of 1122-249 BC, and the process was systematised by the Japanese. The tree is tapped at about the 10th year of cultivation by a lateral sloping incision into the bark during June to September. The sap is white to grayish in color, but on exposure to air turns yellow-brown and then black. The crude sap contains approximately 70% urushiol, 4% gum, 2% albuminous materials, and 24% water. It is stirred and filtered and heated to reduce the moisture level [138] and finally stored in air-tight containers. 

As is true in the case of other phenolic lipids, urushiol is also a mixture of components varying mostly in the degree of unsaturation. Thus, the urushiol from Rhus vernicefera has structures shown in Fig. 6 [139]. Rhus toxicodendron is also known to give urushiol, but its... 

Rhus vernicefera Japan lac, Chinese lac Urushiol Japan, China, Korea... 

Although urushiol possesses an interesting structure for transformation into speciality polymers, no attempt has been reported. Notwithstanding its applications in a specified area, it appears that it is not properly put to use as it can be converted to polymers with better properties. The possibilities for such conversions into high-performance polymers are illustrated by cardanol, a phenolic lipid of related structure obtained from Ana-cardium occidentale. 

Urushiol Rhus vernicefera, Rhus toxicodendron 0-orsellinic acid Chaetomium-cochliodes... 

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. 

Uridine, biosynthesis of, 1124 Uronic acid, 994 from aldoses, 994 Urushiols, structure of, 600 UV, see Ultraviolet... 

Urushiol is the liq secretion of Rhus vemicifera used in Japan lacquer. It contains an unbranched, OH unsaturated side chain in the... 

Urushioldimethyletherdiozonide (Diozonid des Urushiol-dunethylathers in Ger), C22H3402(03)2, oily liq explds on heating or by flame, but not as strongly as the tri- or tetraozonides, described below. Prepd by Majima (Ref 2) by passing 6% ozone thru a chloroform soln of dimethylurushiol, cooled in ice, for 6 hours... 

The reason why synthesis of natural urushiols involves multistep, tedious procedures is that the reactive unsaturated group cannot be directly introduced on the catechol moiety protection and deprotection of the catechol moiety are... 

Kalergis, A.M., et al., Modulation of fatty acid oxidation alters contact hypersensitivity to urushiols Role of aliphatic chain B-oxidation in processing and activation of urushiols. Journal of Investigative Dermatology, 108, 57, 1997. 

Mast cells influence the long-term consequences and the resolution of CHS beginning 3 days after challenge of sensitized animals with DNFB or urushiol. Production of the immunosuppressive cytokine lL-10 by mast cells strongly contributed to these late anti-inflammatory effects of mast cells. Thus, this example demonstrates for the first time that mast cells are able to truly modulate - and not only to promote - allergic responses. 

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). 

Mechanism of Action An organoclay subslance lhal absorbs and binds lo urushiol, Ihe aclive principle in poison oak, ivy, and sumac. Therapeutic Effect Blocks urushiol skin conlacl and absorplion. 

Rhus vemiciflua Stokes Gan Qi (Lacquer tree) (exudation of the bark) Resinous oil urushiol.49 This herb may be toxic. As hemolytic, emmenagogue, vermifuge. 

N.A. Rhus radicans L. R. glabra L. R. toxicodendron L. Toxicodendrol, urushiol, 3-n-pentadecylcatechol.102 Sympathetic stimulant, restore nerve function, facial neuritis, ulcerated sores on the bps, mouth, and nasal membrane. 

Resin albaspidin Resinous oil urushiol Reticuline Retinol... 

Tropane alkaloids Turmerone Tyramine Tyrosine Umbelliferone Uric acid Ursolic acid Urushiol Valepotriates Valerianic acid Valeric acid Valtrate Vanillic acid... 

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

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