Irritant Principles of Mezereon Family (Thymeleaceae), New skin irritants and tumour promoters of the daphnane and 1, 2-alkyldaphnane type from Synaptolepis kirkii and S. Retusa.

Citation:
Adolf W, Seip EH, Dossaji SF, Hecker E. "Irritant Principles of Mezereon Family (Thymeleaceae), New skin irritants and tumour promoters of the daphnane and 1, 2-alkyldaphnane type from Synaptolepis kirkii and S. Retusa." Journal of Natural Products. 1988;51(4):662-674.

Abstract:

—Seventeen mostly new, skin irtitant diterpene esters (DTE) of the daphnane
and la-alkyldaphnane types were isolated from roots of Synaptolepis kirkii and Synaptolepis retusa.
The parent alcohols of the daphnane types are shown to be 5(J-hydroxyresiniferonol-6a,7o:- oxide [ 1 ] and 5p\e [2]. Ten of the daphnane types are 9,13,14-otthoesters and three ate conventional esters involving tertiary or secondary hydroxyl groups at C-13 or C-14, respectively. The latter may be considered immediate precursors of corresponding orthoesters. The four la-alkyldaphnane types are intramolecular 9,13, l4-ortho-(2- hexadecenoic acid)-esters in which, formally, the second to last C atom of the orthoester moiety
is linked covalently to C-lct of the diterpene parent alcohols 1 or 2. Thus, in the new structure,
a macrocyclic ring bridges the ct side of the diterpene moiety in an "ansa" type manner.
The irritancies on the mouse ear of the DTE obtained cover a wide range ( I 2 4 = 0.05-670
nmole- ). Some of them are considerably more irritant than the daphnane type standard simplexin.
Structure/activity investigations reveal that an ester group instead of a free hydroxyl group
at C-20 ("cryptic types"), or presence of a hydroxy or an acetoxy group in position 12 diminishes
the irritancies of the daphnane types isolated, similar to what is known in corresponding tigliane
types. In the standardized initiation/promotion protocol on the back skin of mice, some of the
irritant DTE exhibit tumot-promoting activities higher than that of simplexin

Notes:

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