The novel spermidine alkaloid inandenine was isolated from Oncinotis inandensis Wood et Evans. It was found to be a mixture of two isomers A and B, which could not be separated hitherto. Chemical and mass‐spectrometric investigations revealed that both alkaloids possess the macrocyclic 21‐ring structure 3a and 3b. These two formulae differ only with respect to the position of the ketogroup. Structural elements of the two bases are 9‐oxo‐ and 10‐oxo‐palmitic acid, respectively, and spermidine. Copyright © 1970 Verlag GmbH & Co. KGaA, Weinheim