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

Lasiodiplodiapyrones A and B ( 1 and 2 ), two new preussomerin derivatives, possessing an unexpected 6-methyl-4 H -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 IC 50 values of 4.8 ± 0.3, 8.5 ± 1.1, 5.9 ± 0.8, and 12.8 ± 1.3 μM, respectively.