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Further secondary metabolites produced by the fungus Pyricularia grisea isolated from buffelgrass ( Cenchrus ciliaris )
Author(s) -
Masi Marco,
Santoro Ernesto,
Clement Suzette,
Meyer Susan,
Scafato Patrizia,
Superchi Stefano,
Evidente Antonio
Publication year - 2020
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.23270
Subject(s) - chemistry , cenchrus ciliaris , fungus , phytotoxicity , magnaporthe grisea , circular dichroism , phytotoxin , botany , stereochemistry , biochemistry , toxin , biology , oryza sativa , gene
The fungal pathogen Pyricularia grisea has been studied to evaluate its production of phytotoxins for the biocontrol of the buffelgrass ( Cenchrus ciliaris L.) weed. A first investigation allowed to isolate several new and known phytotoxic metabolites. However, the further investigation on the organic extract obtained from the fungus liquid culture showed the presence of other metabolites possibly contributing to its phytotoxicity. Thus, four known metabolites were isolated and identified by spectroscopic (nuclear magnetic resonance [NMR] and high‐resolution electrospray ionization mass spectrometry [HRESIMS]) methods as dihydropyriculol ( 1 ), epi ‐dihydropyriculol ( 2 ), 3‐methoxy‐6,8‐dihydroxy‐3‐methyl‐3,4‐dihydroisocoumarin ( 3 ), and ( R )‐mevalonolactone ( 4 ). The absolute configuration of 1 – 3 was determined for the first time by a computational analysis of their electronic circular dichroism (ECD) spectra. When the isolated compounds were bioassayed at a concentration of 5 × 10 –3 M in a buffelgrass coleoptile and radicle elongation test no toxicity was detected. On the contrary, compounds 1 and 3 showed a significant stimulating effect of radical elongation. Furthermore, the difference in growth stimulation between 1 and its epimer 2 highlights the tight relationship between absolute configuration and biological activity of these fungal metabolites.