| Summary: | The tree species P. indica (Lauraceae) is an important endemism in the Canary Islands laurel forest and can readily be distinguished by its defoliated appearance due to the seasonal action of wild rats (Rattus rattus), which eat the plant and become intoxicated. These observations and the phytochemical interest of this plant species led us to study the potentially toxic chemicals responsible for such action. We found that an ethanolic extract of P. indica and its water fraction were toxic when injected into laboratory mice. The mice also died after ingestion of the stems and showed a significant preference for those extracted and rehydrated with an 8% aqueos extract solution when compared with the water control. Two compounds that have beer isolated from the toxic fraction and identified by sprectoscopic methods are the plyhydroxy pentacyclic diterpenes ryanodol and cinnceylanol. Possible ecological implications are discussed. We thank M. Fernández Galván (ICIA, Tenerife) for his advice on plant collection and classification. Stephen Carlin and Juan M. de León for their technical assistance, and the I.C.O.N.A. staff in Tenerife for their support and logistical assistance A.G.C. thanks to the Ministry of Education and Science (Madrid) for a research associate grant. Peer reviewed
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