Lasiodiplodiapyrones A and B (1 and 2), two new preussomerin derivatives, possessing an unexpected 6-methyl-4H-furo[3,2-c]pyran-4-one moiety and a highly functionalized conjoint and complicated polycyclic ring system, along with two known congeners (3 and 4), were isolated from the fungus Lasiodiplodia pseudotheobromae. Their structures including absolute configurations were determined by spectroscopic analyses, Mosher's method, and ECD calculations. A biosynthetic pathway was proposed to explain the origin of lasiodiplodiapyrones A and B as well as their relationship with preussomerins. Compounds 1-4 showed suppressive effects on the production of NO with IC50 values of 4.8 ± 0.3, 8.5 ± 1.1, 5.9 ± 0.8, and 12.8 ± 1.3 μM, respectively.