A biological screen used to identify inhibitors of monocyte chemotactic protein-1 (CCL2)- induced chemotaxis was applied in the activity-guided fractionation of an extract from a fungus of the genus Leptoxyphium sp. Inhibition of CCL2-induced chemotaxis was traced to a new dichlorinated diketopiperazine, cyclo (13, 15-dichloro-l-Pro-l-Tyr). A structure− activity relationship (SAR) study evaluating relative activities of cyclo (13, 15-dichloro-l-Pro-l-Tyr) ...
