Natural Products of Picea Endophytes from the Acadian Forest

Endophytes of healthy needles were collected from Picea rubens (red spruce) and P. mariana (black spruce) in a survey of southeastern New Brunswick, Canada. Four endophyte strains were selected for further investigation based on the production of biologically active extracts from culture filtrates during screening as well as phylogenetic relationship to species known to produce natural products or taxonomic novelty. A novel endophyte within the family Rhytismataceae produced two new dihydropyrones (1 and 2) as major metabolites together with phthalides (3 and 4), isocoumarins (5 and 6), and tyrosol (7). Lachnum cf. pygmaeum synthesized a new chlorinated para-quinone, chloromycorrhizinone A (8), and the nematicidal compounds (1'Z)-dechloromycorrhizin A (9), mycorrhizin A (10), and chloromycorrhizin A (11). A new isocoumarin (12) and four related structures (13-16) were isolated from an undescribed taxon in the Mycosphaerellaceae. The known antifungal metabolites cryptosporiopsin (17), 5-hydroxycryptosporiopsin (18), (+)-cryptosporiopsinol (19), and mellein (20) were produced by Pezicula sporulosa. Phylogenetically diverse conifer endophytes from the Acadian forest continue to be a productive source of new biologically active natural products.