Daldipyrenones A-C: Caged [6,6,6,6,6] Polyketides Derived from an Endolichenic Fungus Daldinia pyrenaica 047188

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 EC50's than positive controls and moderate adiponectin-secretion promoting activity.

Automated summary

Three unprecedented caged xanthone [6,6,6,6,6] polyketides, Daldipyrenones A-C (1-3), were discovered from an endolichenic fungus, Daldinia pyrenaica 047188. The structures of 1-3 were determined using spectroscopic analysis and chemical derivatization. Daldipyrenones are likely formed by the combination of a chromane biosynthesis intermediate and a spiro-azaphilone through radical coupling or Michael addition, resulting in the formation of a bicyclo[2.2.2]octane ring. Genome sequencing revealed two biosynthetic gene clusters responsible for the formation of two biosynthetic intermediates, suggesting a proposed biosynthetic pathway. Daldipyrenone A (1) exhibited significant antimelanogenic activity and moderate adiponectin-secretion promoting activity with lower EC50 values than positive controls.