Lasiodiplodiapyrones A and B, Pyrone-Preussomerin Adducts with Highly Strained Polycyclic Ring Systems from Lasiodiplodia pseudotheobromae .

Lasiodiplodiapyrones A and B ( and ), two new preussomerin derivatives, possessing an unexpected 6-methyl-4-furo[3,2-]pyran-4-one moiety and a highly functionalized conjoint and complicated polycyclic ring system, along with two known congeners ( and ), were isolated from the fungus . 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 - showed suppressive effects on the production of NO with IC values of 4.8 ± 0.3, 8.5 ± 1.1, 5.9 ± 0.8, and 12.8 ± 1.3 μM, respectively.