Daldipyrenones A–C: Caged [6,6,6,6,6] Polyketides Derived from an Endolichenic Fungus <i>Daldinia pyrenaica</i> 047188
Seungjin Lee, In Guk Park, Jin Won Choi, Jin Young Son, Jin Woo Lee, Jae–Seoun Hur, Youngmee Kim, Sang‐Jip Nam, Hahk‐Soo Kang, Stephen T. Deyrup, Minsoo Noh, Sang Hee Shim
Abstract
Daldipyrenones A–C ( 1 – 3 ), three unprecedented caged xanthone [6,6,6,6,6] polyketides featuring a spiro-azaphilone unit, were discovered from an endolichenic fungus, Daldinia pyrenaica 047188. The structures of 1 – 3 were determined by using spectroscopic analysis and chemical derivatization. Daldipyrenones are likely derived by combining a chromane biosynthesis intermediate, 1-(2,6-dihydroxyphenyl)but-2-en-2-one, and a spiro-azaphilone, pestafolide A, via radical coupling or Michael addition to form a bicyclo[2.2.2]octane ring. Genome sequencing of the strain revealed two separate biosynthetic gene clusters responsible for forming two biosynthetic intermediates, suggesting a proposed biosynthetic pathway. Daldipyrenone A ( 1 ) exhibited significant antimelanogenic activity with lower EC 50 ’s than positive controls and moderate adiponectin-secretion promoting activity.