Screening for metabolites from Penicillium novae-zeelandiae displaying radical-scavenging activity and oxidative mutagenicity: isolation of gentisyl alcohol.
In the search for new natural products with anti-oxidant activity, we have combined the cell-free assay based on the scavenging of the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH), with a bioassay that detects oxidative mutagens. This bioassay uses a new Escherichia coli tester strain, IC203, specifically sensitive to oxidative stress due to a deficiency in the OxyR function. OxyR is a redox-sensitive transcriptional activator of genes encoding anti-oxidant enzymes such as catalase and peroxiredoxin alkyl hydroperoxide reductase. The positive response observed in E. coli IC203 with several known anti-oxidants, including cysteine, catechol and ascorbic acid, suggested to us the usefulness of the mutagenicity assay for a rapid screening of anti-oxidant compounds. The extract from Penicillium novae-zeelandiae was found to scavenge the DPPH radical. Subsequently, guided by the DPPH-scavenging assay and the oxidative mutagenesis assay, we isolated and identified three compounds in fractions from that active extract: patulin (1). 3-hydroxybenzyl alcohol (2). and gentisyl alcohol (2,5-dihydroxybenzyl alcohol) (3). Of these, gentisyl alcohol showed both DPPH-scavenging activity and oxidative mutagenicity. This compound also gave rise to intracellular formation of superoxide, evaluated by monitoring the oxidation of dihydroethidium, and was able to inhibit mutagenesis induced by the model oxidant t-butyl hydroperoxide (t-BuOOH).
Alfaro
Cristina
C
Centro de Ecología Química Agrícola, Universidad Politécnica de Valencia, Edificio 9B (Lab 111), Campus de Vera, 46022 Valencia, Spain.
Urios
Amparo
A
González
M Carmen
MC
Moya
Pilar
P
Blanco
Manuel
M
D016587:Antimutagenic Agents; D001592:Benzyl Alcohols / Q000302:isolation & purification*; D001713:Biphenyl Compounds / Q000032:analysis*; D004926:Escherichia coli / Q000187:drug effects; D006834:Hydrazines / Q000032:analysis*; D009152:Mutagenicity Tests; D009153:Mutagens; D010365:Patulin / Q000302:isolation & purification*; D010407:Penicillium / Q000737:chemistry*; D010851:Picrates; D013481:Superoxides / Q000032:analysis
D016587:Antimutagenic Agents; D001592:Benzyl Alcohols; D001713:Biphenyl Compounds; D006834:Hydrazines; D009153:Mutagens; D010851:Picrates; D013481:Superoxides; C011276:3-hydroxybenzyl alcohol; D010365:Patulin; C004931:1,1-diphenyl-2-picrylhydrazyl; C004771:2,5-dihydroxybenzyl alcohol