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Download filePhytotoxic Metabolites Produced by Diaporthella cryptica, the Causal Agent of Hazelnut Branch Canker
journal contribution
posted on 2018-03-14, 00:00 authored by Alessio Cimmino, Paola Nocera, Benedetto Teodoro Linaldeddu, Marco Masi, Marcin Gorecki, Gennaro Pescitelli, Lucio Montecchio, Lucia Maddau, Antonio EvidenteFrom the culture filtrates of Diaporthella cryptica, an emerging hazelnut pathogen, 2-hydroxy-3-phenylpropanoate
methyl
ester and its 3-(4-hydroxyphenyl) and 3-(1H-indol-3-yl)
analogues, named crypticins A–C, were isolated together with
the well-known tyrosol. Crypticins A–C were identified by spectroscopic
(essentially nuclear magnetic resonance and high-resolution electrospray
ionization mass spectrometry) methods. The R absolute
configuration (AC) of crypticin A was determined by comparing its
optical rotation and electronic circular dichroism (ECD) spectrum
with those of papuline, the methyl ester of (−)(S)-phenyllactic acid isolated as the main phytotoxin of Pseudomonas
syringae pv. papulans, responsible
for apple blister spot. The ACs of crypticins B and C were determined
by time-dependent density functional theory calculations of their
ECD spectra. Papuline and the new metabolites herein isolated, except
tyrosol, were tested at 1 mg/mL on cork oak, grapevine, hazelnut,
and holm oak leaves using the leaf puncture assay. They were also
tested on tomato cuttings at 0.5 and 0.05 mg/mL. In the leaf puncture
assay, none of the compounds was found to be active. Crypticin C and
papuline were active in the tomato cutting assay. Additionally, crypticin
C displayed moderate inhibitory effect against Phytophthora
cambivora.