The algal excretion product geranylacetone was proved to be an effective and novel inhibitor of carotene synthesis in Synechoccus 6911. The application of geranylacetone resulted in an ac­ cumulation of phytofluene, indicating an inhibition of the conversion of this compound into fcarotene. The cts-isomer of geranylacetone was as effective as the natural irans-isomer. The chloro­ phyll synthesi...

Studies on models synthesized by stereochemically controlled routes show that the central triene chromophore in the common cis isomer of phytoene has the irans,cis,trans configuration, and that the phytoene from Flavobacterium dehydrogenans consists mainly of the all-trans isomer. Capsorubin, with the natural configuration at all four chiral centres, has been synthesized from (+)-camphor. Sever...