Phenylpyropenes A, B, and C, isolated from Penicillium griseofulvum F1959, inhibited DGAT in rat liver microsomes with $IC_{50}$ values of $78.7{pm}1.6$, $21.7{pm}0.2$, and $11.04{pm}0.2{mu}M$, respectively. In addition, a kinetic analysis using a Lineweaver-Burk plot revealed that phenylpyropene C was a noncompetitive inhibitor of DGAT. The apparent Michaelis constant ($K_m$) value and inhibition constant ($K_i$) value were calculated to be $8{mu}M$ and $10.48{mu}M$, respectively. Moreover, phenylpyropene C inhibited triglyceride formation in HepG2 cells.