We have screened toyocamycin as an inhibitor of phosphatidylinositol kinase. It inhibited the enzyme of A431 cell membrane with an IC50 of 3.3 μg/ml. Adenosine and formycin A also inhibited the enzyme, but other 6 related nucleosides did not. Although orobol and 2, 3-dihydroxybenzaldehyde that inhibit phosphatidylinositol kinase inhibited in situ phosphatidylinositol turnover, toyocamycin did not.
Japan Antibiotics Research Association