Characterization of B-5354c, a new sphingosine kinase inhibitor, produced by a marine bacterium

B-5354c is a new inhibitor of sphingosine kinase from a novel marine bacter ium, SANK 71896. Kinetic study revealed that B-5354c inhibits sphingosine k inase with a Ki value of 12 mu M. The inhibition is noncompetitive with res pect to sphingosine. The compound also inhibits sphingosine-1-phosphate for mation in human platelets. Experiments using synthetic derivatives of B-535 4c indicate that all the three functional groups, i.e., the long unsaturate d aliphatic chain, 4-amino and 3-hydroxyl groups are necessary to inhibit s phingosine kinase.