Characterization of Secondary Metabolites Produced by Foliar Endophytes of Red and Black Spruce

Eastern spruce budworm (Choristoneura fumiferana) is a cyclic pest responsible for widespread defoliation of conifer trees in the Acadian forest. During epidemics, affected forestry areas are vast, making insecticidal protection impractical. Research has shown endophytes produce toxins in planta at effective concentrations that deter spruce budworm herbivory. Red and black spruce endophytes were studied here. Five isocoumarins (1-5) were isolated from Phaeocryptopus cf. gaeumannii, where compound (1) is a new structure. Two new pyrones (6, 7), two phthalides (8, 9), two isocoumarins (10, 11) and tyrosol (12) were isolated from an undescribed Rhytismatales species. Phomopsolides A-C (13-15) were isolated from a newly described fungal endophyte, Diaporthe maritima. Cryptosporiopsin (16), 5-hydroxy cryptosporiopsin (17), cryptosporiopsinol (18) and mellein (19) were produced by Pezicula sporulosa. A majority of these compounds possessed antibacterial (Bacillus subtilis, Escherichia coli) and/or antifungal activity (Saccharomyces cerevisiae, Microbotryum violaceum).