Potent inhibition of macrophomate synthase by reaction intermediate analogs

Potent inhibitors for macrophomate synthase, which has recently been found to catalyze a highly unusual five-step chemical transformation, were explored. Among 11 oxalacetate analogs tested, only three analogs had moderate to relatively strong inhibitory activities (I50 1.3-8.1 mM). On the other hand, among 35 bicyclic intermediate analogs synthesized, two diacids were found to be the most potent inhibitors (I50 0.80, 0.84 mM) which had a much higher affinity than that of the natural substrate 2-pyrone. (-)-Enantiomers of the diacids showed 30 times stronger activity (I50 0.34, 0.41 mM) than (+)-ones. The I50/Km values (0.20, 0.24) showed their potent inhibitions. Competitive inhibitions were observed in two representative inhibitors.