Uptake of Cardenolides from Oleander Leaves by Daphnis nerii

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A Sphingidous moss, Daphnis nerii L., has settled in Okinawa Islands. Although the larvae of D.nerii feed on oleander leaves and seem to be able to take in cardenolides from oleander, the larvae appear to retain cryptic color. In order to know the pass way of the cardenolides in the worms of D.nerii, comparative analysis of the cardenolides in the final-instar larvae and their frass, and those of the original oleander leaves was attempted.Most of the cardenolide triosides in the leaves were detected as their corresponding monosides in the worm-homogenate and the frass-extract. From the frass, adynerin was obtained in the unusual high yield, along with nine cardenolide monosides, deacetyloleandrin, odoroside A,DELTA^<16>-adynerin, oleaside A,nerigoside, neriaside, 8beta-hydroxyodoroside A and 5alpha-adynerin. Showing similar HPLC patterns, slight difference between the worm-homogenate and the frass-exract was observed, e.g.the absence of DELTA^<16>-adynerin in the worms and the peak hight of oleandrin in the two sources, suggested that a small amount of cardenolides was taken and accumulated in the worms. The toxicity of the cardenolides in the worms, however, may be insufficient to prevent attack from predators, since the worms retain cryptic color. Excretion of a large amount of adynerin in the frass and roles of adynerin and ursolic acid, two major ingredients in the worms originated from oleander leaves, are to be investigated, furthermore.