title: Isolation and identification of nematode-antagonistic compounds from the fungus Aspergillus candidus.
abstract: Culture medium from an isolate of the fungus Aspergillus candidus was extracted, fractionated and examined to discover compounds antagonistic to plant-parasitic nematodes that are important pathogens of agricultural crops. Column, thin layer and preparative chromatographies and spectral and elemental analyses, were used to isolate and identify two major constituents of an active fraction (Fraction F) obtained from the medium. Compound 1 was identified as 2-hydroxypropane-1, 2, 3-tricarboxylic acid (citric acid). Compound 2 was identified as 3-hydroxy-5-methoxy-3-(methoxycarbonyl)-5-oxopentanoic acid, an isomer of 1, 2-dimethyl citrate. Compound 1 and a citric acid standard, each tested at 50 mg mL(-1) in water, decreased hatch from eggs of the plant-parasitic nematode Meloidogyne incognita by more than 94%, and completely immobilized second-stage juveniles after 4-6 days exposure. Fraction F and Compounds 1 and 2 decreased the mobility of adults of the plant-parasitic nematode Ditylenchus destructor in vitro. Fraction F (25 mg mL(-1)) inhibited mobility >99% at 72 hrs. Compounds 1 and 2 (50 mg mL(-1)) each inhibited mobility more than 25% at 24 hr and more than 50% at 72 hr. This is the first assignment of nematode-antagonistic properties to specifically identified A. candidus metabolites.
authors: Institute of Microbiology and Virology, Ministry of Education and Science of the Republic of Kazakhstan, Bogenbai Batyr Street 103, Almaty 050510, Kazakhstan.
authors: Olga N
authors: ON
authors: Shemshura
authors: Institute of Microbiology and Virology, Ministry of Education and Science of the Republic of Kazakhstan, Bogenbai Batyr Street 103, Almaty 050510, Kazakhstan.
authors: Nadiya E
authors: NE
authors: Bekmakhanova
authors: Institute of Microbiology and Virology, Ministry of Education and Science of the Republic of Kazakhstan, Bogenbai Batyr Street 103, Almaty 050510, Kazakhstan.
authors: Mariya N
authors: MN
authors: Mazunina
authors: Nematology Laboratory, Beltsville Agricultural Research Center, USDA, ARS, 10300 Baltimore Ave., Beltsville, MD 20705-2350, USA.
authors: Susan L F
authors: SL
authors: Meyer
authors: Sustainable Agricultural Systems Laboratory, Beltsville Agricultural Research Center, USDA, ARS, 10300 Baltimore Ave., Beltsville, MD 20705-2350, USA.
authors: Clifford P
authors: CP
authors: Rice
authors: Nematology Laboratory, Beltsville Agricultural Research Center, USDA, ARS, 10300 Baltimore Ave., Beltsville, MD 20705-2350, USA edward.masler@ars.usda.gov.
authors: Edward P
authors: EP
authors: Masler
mesh_terms: D000383:Agriculture; D000818:Animals; D001230:Aspergillus / Q000378:metabolism* / Q000472:pathogenicity; D002951:Citrates / Q000494:pharmacology; D019343:Citric Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D017077:Culture Media, Conditioned / Q000494:pharmacology; D010575:Pesticides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D010935:Plant Diseases / Q000469:parasitology; D014431:Tylenchoidea / Q000187:drug effects*
chemical_list: D002951:Citrates; D017077:Culture Media, Conditioned; D010575:Pesticides; C478839:dimethyl citrate; D019343:Citric Acid
keywords: bio-based compounds; dimethyl citrate isomer; fungal toxins; natural products; nematotoxicity; spectral identification