title: Cryptic and free skin irritants of the daphnane and tigliane types in latex of Excoecaria agallocha.
abstract: In the extremely skin irritant and caustic latex of Excoecaria agallocha the major part of the polyfunctional diterpene esters (DTE) (group I) are aliphatic polyunsaturated 9,13,14-orthoesters of the daphnane-type parent alcohol 5 beta-hydroxyresiniferonol-6 alpha, 7 alpha-epoxide, esterified simultaneously in their 20-positions with aliphatic saturated homologous n-carboxylic acids (even numbered, C22-C30). The minor part of DTE is composed of analogous structures of 5 beta, 12 beta-dihydroxyresiniferonol-6 alpha, 7 alpha-epoxide (group II) and of aliphatic 13-polyunsaturated, 20-saturated diesters of the tigliane-type parent alcohol 12-deoxyphorbol (group III). All three groups of DTE exhibit practically no irritant activity on the mouse ear. By alkaline transesterification of groups I-III, the corresponding highly irritant multicomponent mixtures of Excoecaria factors A (OH-20 deacylated) are released. They comprise a mixture of the known Excoecaria factors A1/A2/A3 and three mixtures of hitherto unknown Excoecaria factors A4/A5, A6/A7 and A8/A9. The groups I-III are typical structures of "cryptic irritants". By an alternative, extremely mild separation procedure the highly irritant mixture A1/A2/A3 was obtained directly. It represents the "free" Excoecaria factors, the natural constituents of the latex responsible for its bioactivity.
authors.affiliation: Department of Chemistry, Faculty of Science, Prince of Songkla University, Hat-Yai, Thailand.
authors.forename: C
authors.initials: C
authors.lastname: Karalai
authors.forename: P
authors.initials: P
authors.lastname: Wiriyachitra
authors.forename: H J
authors.initials: HJ
authors.lastname: Opferkuch
authors.forename: E
authors.initials: E
authors.lastname: Hecker
mesh_terms: D000818:Animals; D004951:Esterification; D007509:Irritants / Q000737:chemistry / Q000633:toxicity*; D007840:Latex / Q000737:chemistry / Q000633:toxicity*; D051379:Mice; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry / Q000633:toxicity*; D012867:Skin / Q000187:drug effects*
chemical_list: D007509:Irritants; D007840:Latex; D010936:Plant Extracts