Pinofuranoxins A and B, Bioactive Trisubstituted Furanones Produced by the Invasive Pathogen Diplodia sapinea

Abstract

Two new bioactive trisubstituted furanones, named pinofuranoxins A and B ( 1 and 2 ), were isolated from Diplodia sapinea , a worldwide conifer pathogen causing severe disease. Pinofuranoxins A and B were characterized essentially by NMR and HRESIMS spectra, and their relative and absolute configurations were assigned by NOESY experiments and computational analyses of electronic circular dichroism spectra. They induced necrotic lesions on Hedera helix L., Phaseolus vulgaris L., and Quercus ilex L. Compound 1 completely inhibited the growth of Athelia rolfsii and Phytophthora cambivora , while 2 showed antioomycetes activity against P. cambivora . In the Artemia salina assay both toxins showed activity inducing larval mortality.

(4Z)-Lachnophyllum Lactone, an Acetylenic Furanone from Conyza bonariensis, Identified for the First Time with Allelopathic Activity against Cuscuta campestris

“…The configuration of the double bond was deduced from the presence of coupling between H-5 with H-3 and H-2 in the NOESY spectrum (Figure S1). In addition, the chemical shifts of H-5 (δ = 5.33) and C-5 (δ = 94.5) were very similar to those previously reported for lachnophyllum lactone and other natural furanones, with an α Z-disubstituted vinyl group, substantially differing from those having a E-vinyl group [38][39][40][41]. This structure was confirmed by the data of its ESI-MS spectrum which showed the sodiated adduct [2M + Na] + and protonated [2M + H] + dimers, and protonated [M + H] + ions at m/z 347, 325 and 163, respectively.…”

“…In addition, a repellent activity against Monotonda neritoides was identified in lachnophyllum lactone with unspecified configuration isolated from Erigeron sumatrensis [37]. These biological activities could be related to the presence in the structure of (4Z)-lachnophyllum lactone of an α,β-unsaturated carbonyl group, a known structural feature involved in nucleophilic Michael addition reaction mechanism frequently reported for bioactive natural compounds [40,45]. However, further studies are needed to elucidate the specific mode of action of this acetylenic furanone on Cuscuta development identified in this work.…”

Secondary Metabolites, including a New 5,6-Dihydropyran-2-One, Produced by the Fungus Diplodia corticola. Aphicidal Activity of the Main Metabolite, Sphaeropsidin A

“…Its structure was determined by spectroscopic methods, essentially 1D and 2D NMR, IR, and UV combined with mass spectrometry, as reported below ( Figures S1–S8 ). Moreover, ten known metabolites were identified by comparison of their proton spectra ( Figures S9–S18 ), and eventually optical rotation, with those reported in the literature for: sphaeropsidins A and B ( 2 and 3 , [ 19 ]), sphaeropsidin C ( 4 ) [ 20 ], ( R )-mellein, (3 R ,4 R )- and (3 R ,4 S )-4-hydroxymelleins ( 5 – 7 ) [ 21 ], sapinofuranone B ( 8 ) [ 22 ], pinofuranoxin A ( 9 ) [ 23 ], diplobifuranylone B ( 10 ) [ 24 ], and tyrosol ( 11 ) [ 25 ] ( Figure 1 ).…”

A Diels–Alder probe for discovery of natural products containing furan moieties

“…One well-studied example is the antifungal flufuran, which was isolated from Aspergillus flavus [ 2 ]. Another example is plakorsin D, an anticancer polyketide natural product which was isolated from a sea sponge, Plakortis simplex [ 3 – 4 ].…”