Aspertaichunol A, an Immunomodulatory Polyketide with an Uncommon Scaffold from the Insect-Derived Endophytic Aspergillus taichungensis SMU01

Aspertaichunol A (b1/b), a polyketide with a novel scaffold, was isolated from the medicinal insect (iPeriplaneta americana/i)-derived endophyticiAspergillus taichungensis/iSMU01. Its structure was assigned on the basis of spectroscopic data and quantum chemical computational methods. Notably,b1/bpossesses an uncommon tricyclo[6.2.0.0sup2,6/sup]decane motif and an unusual bridgehead double bond (anti-Bredt system). A plausible biosynthetic pathway, involving a key intramolecular [2+2] cycloaddition and a reductive cyclization, is postulated. Finally, the immunomodulatory activity ofb1/bat 20 nM was evaluated by promoting Th9 cell differentiation from naive CD4sup+/supCD62Lsup+/supT cells.