title: p-Hydroxybenzoylformic acid and (R)-(-)-p-hydroxymandelic acid, two antifungal compounds isolated from the liquid culture of the ectomycorrhizal fungus Pisolithus arhizus.
abstract: Two antifungal compounds isolated from the liquid culture medium of Pisolithus arhizus were identified as p-hydroxybenzoylformic acid and (R)-(-)-p-hydroxymandelic acid and given the trivial names pisolithin A and pisolithin B, respectively. The efficacy of the compounds to inhibit the germination of conidia of Truncatella hartigii was compared with that of commercially available structural analogues, and a comparable range of effectiveness for 50% germination inhibition (GI50) of conidia was recorded. The commercially available synthetic compounds (R)-mandelic acid, benzoylformic acid, and racemic p-hydroxymandelic acid, had GI50 values of 82, 72, and 59 micrograms/mL, respectively, as compared with the natural compounds pisolithin A, 67 micrograms/mL, and pisolithin B, 71 micrograms/mL. Two synthetic S enantiomers of mandelic acid, (S)-mandelic acid and (S)-(+)-p-hydroxymandelic acid, were the most effective compounds, with GI50 values of 31 and 33 micrograms/mL, respectively. A sodium salt of mandelic acid had no activity below 500 micrograms/mL. Pisolithin A and pisolithin B were compared with polyoxin D for inhibition of hyphal growth, as measured by protein estimation. Both pisolithin A and B measured higher levels of putative extractable protein than polyoxin D, but less mycelial wet weight was measured. It is suggested that the pisolithins caused a disruption of cell turgor. A measurement of mycelial dry weights of phytopathogens, incubated with the commercially available analogues, benzoylformic acid and racemic p-hydroxymandelic acid, indicated that benzoylformic acid was either more effective than, or as effective as, racemic p-hydroxymandelic acid or nystatin in arresting fungal growth.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Centre de recherche en biologie forestière, Faculté de foresterie et de géomatique, Université Laval, Sainte-Foy (Qué.), Canada.
authors.forename: H H
authors.initials: HH
authors.lastname: Kope
authors.forename: Y S
authors.initials: YS
authors.lastname: Tsantrizos
authors.forename: J A
authors.initials: JA
authors.lastname: Fortin
authors.forename: K K
authors.initials: KK
authors.lastname: Ogilvie
mesh_terms: D000935:Antifungal Agents / Q000302:isolation & purification* / Q000494:pharmacology; D001487:Basidiomycota / Q000378:metabolism*; D006038:Glyoxylates / Q000302:isolation & purification* / Q000494:pharmacology; D008333:Mandelic Acids / Q000302:isolation & purification* / Q000494:pharmacology; D003904:Mitosporic Fungi / Q000187:drug effects*
chemical_list: D000935:Antifungal Agents; D006038:Glyoxylates; D008333:Mandelic Acids; C014600:4-hydroxymandelic acid; C030921:4-hydroxyphenylglyoxylic acid