During the screening of microbial fermentation extracts for their ability to inhibit the binding of I-125-peptid YY (PYY) to the neuropeptide Y (NPY) receptor using the scintillation proximity assay (SPA), BMS-192548 was isolated from the extract of Aspergillus niger WB2346 by bioassay-guided fractionation. BMS-192548 showed the inhibitory activity against I-125-PYY binding to SK-N-MC and SMS-KAN cells, which express NPY, and NPY, receptors, respectively, with IC50 values of 24 mu M in Y-1 and 27 mu M in Y-2 receptor binding. BMS-192548 demonstrated weak cytotoxicity against murine tumor cell line M-109 with an IC50 value of 240 mu M.