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 bacterium, SANK 71896. Kinetic study revealed that B-5354c inhibits sphingosine kinase with a Ki value of 12/microM. The inhibition is noncompetitive with respect to sphingosine. The compound also inhibits sphingosine-1-phosphate formation in human platelets. Experiments using synthetic derivatives of B-5354c indicate that all the three functional groups, i.e., the long unsaturated aliphatic chain, 4-amino and 3-hydroxyl groups are necessary to inhibit sphingosine kinase.