Characterization of Polyketide Metabolites from Foliar Endophytes of Picea glauca

Abstract

A collection of 250 foliar endophytes of Picea glauca (white spruce) yielded several isolates that produced metabolites toxic to Choristoneura fumiferana (spruce budworm). Three of these strains were selected for further study based on their ability to be cultured and produce secondary metabolites under laboratory conditions. The culture filtrate of each was extracted and analyzed by LC-MS and LC-NMR, and the major metabolites were isolated and characterized. Structures were elucidated by spectroscopic analyses including 2D NMR and HRMS and by comparison to literature data. In some cases the extract was methylated in order to facilitate separation, but the original natural structure was determined by comparing the NMR data of the isolated methylated product with that of the stop-flow NMR of the underivatized extract (i.e., 2a, 2b, and 4). Two of these metabolites, 1 and 2a, are new structures, 3 and 4 are reported here for the first time as fungal metabolites, and 5- 10 as known fungal metabolites from other species. Tyrosol (10) was the only common metabolite found in all three extracts but did not account for the observed toxicity to C. fumiferana.

Metabolic analysis of elicited cell suspension cultures of Cannabis sativa L. by 1H-NMR spectroscopy

“…It has an antioxidant activity (Giovannini et al 1999). Tyrosol occurs in plants of the Rhodiola species (Li and Zhang 2008) and in foliar fungal endophytes of Picea glauca (Sumarah et al 2008 Table 2). Apparently, the excretion of these aromatic compounds was not affected by JA or pectin treatment in the GC cell line and it could be an inherent part of the metabolism of this cell line.…”

Four new glucosides from the aerial parts of Mediasia macrophylla

“…go.jp/sdbs/cgi-bin/direct_frame_top.cgi), p-hydroxybenzaldehyde (Sigma-Aldrich, http://www.sigmaaldrich.com/spectra/ fnmr/FNMR001261.PDF), 3,4,5-trimethoxybenzaldehyde (SDBS, http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_ frame_top.cgi), tachioside [35], viridoside [36], salidroside [37], icariside D [38], 2-methoxy-2-(4 0 -hydroxyphenyl) ethanol [39], tyrosol [40], quercetin [41], hyperin [42], scopolin [43], (? )-syringaresinol [44], lariciresinol-4-O-b-D-glucopyranoside [45].…”

Antimicrobial dihydrobenzofurans and xanthenes from a foliar endophyte of Pinus strobus

“…Metabolites in this chemical class have been identified as by-products of griseofulvin biosynthesis in liquid culture (Harris et al, 1976). Related xanthones have been previously isolated from fungal endophytes of white spruce (Picea glauca; Sumarah et al, 2008) and from a Xylaria endophyte of a shrub found in Australia (Glochidion ferdinandi; Davis and Pierens, 2006). To the best of our knowledge, compounds 5 and 6 represent the first examples of natural product xanthenes having an unmodified 9H-xanthene skeleton.…”

“…Initial screening for the antifungal activity of the crude extracts, 50 mg L À1 , was achieved by disk diffusion assay; see Sumarah et al, 2008Sumarah et al, , 2011 Compounds 1-6 were tested for in vitro antimicrobial activity against M. violaceum, S. cerevisiae, B. subtilis (ATCC 23857) and Pseudomonas fluorescens (F9-10). M. violaceum was grown in 20 g L À1 malt extract (Difco), 2.5 g L À1 peptone (Difco) and 2.5 g L À1 yeast extract (Sigma) whereas S. cerevisiae was inoculated and grown in 1 g L À1 yeast extract supplemented with 10 g L À1 glucose.…”