Chilocorus cacti

We have recently characterized the heptacyclic alkaloid chilocorine from the ladybird (coccinellid) beetle Chilocorus cacti (23). In spite of its superficial complexity, this structure is easily dissected into two tricyclic moieties, A and B, each of which can be regarded as an acetogenin which has been elaborated from a straight chain of 13 carbon atoms stitched together at three points by a trivalent nitrogen atom. 

The second Chilocorini species studied, Chilocorus cacti, contained several alkaloids closely related to the former. The structure of the heptacyclic chilo-corine A (19) was deduced from a series of NMR experiment (DEPT, HMQC, DQ-COSY, TOCSY) and from a comparison of its spectral properties with those of exochomine (18) from which it differ by having two C-C linkages between the two tricyclic partners. However, the configuration at the asymmetric center in the azaacenaphthylene ring was not established [33]. 

Alkaloid from the coccinellid beetle Chilocorus cacti. 

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