CRYPTIC AND FREE SKIN IRRITANTS OF THE DAPHNANE AND TIGLIANE TYPES IN LATEX OF EXCOECARIA-AGALLOCHA

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, C-22- C-30) 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.