- Conversion of the mycotoxin patulin to the less toxic desoxypatulinic acid by the biocontrol yeast Rhodosporidium kratochvilovae strain LS11
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The infection of stored apples by the fungus Penicillium expansum causes the contamination of fruits and fruit-derived products with the mycotoxin patulin, which is a major issue in food safety. Fungal attack can be prevented by beneficial microorganisms, so-called biocontrol agents. Previous time-course thin layer chromatography analyses showed that the aerobic incubation of patulin with the biocontrol yeast Rhodosporidium kratochvilovae strain LS11 leads to the disappearance of the mycotoxin spot and the parallel emergence of two new spots, one of which disappears over time. In this work, we analyzed the biodegradation of patulin effected by LS11 through HPLC. The more stable of the two compounds was purified and characterized by nuclear magnetic resonance as desoxypatulinic acid, whose formation was also quantitated in patulin degradation experiments. After R. kratochvilovae LS11 had been incubated in the presence of 13C-labeled patulin, label was traced to desoxypatulinic acid, thus proving that this compound derives from the metabolization of patulin by the yeast. Desoxypatulinic acid was much less toxic than patulin to human lymphocytes and, in contrast to patulin, did not react in vitro with the thiol-bearing tripeptide glutathione. The lower toxicity of desoxypatulinic acid is proposed to be a consequence of the hydrolysis of the lactone ring and the loss of functional groups that react with thiol groups. The formation of desoxypatulinic acid from patulin represents a novel biodegradation pathway that is also a detoxification process.
- Castoria, Raffaello,Mannina, Luisa,Duran-Patron, Rosa,Maffei, Francesca,Sobolev, Anatoly P.,De Felice, Dario V.,Pinedo-Rivilla, Cristina,Ritieni, Alberto,Ferracane, Rosalia,Wright, Sandra A. I.
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- Isotopic Labeling Studies Reveal the Patulin Detoxification Pathway by the Biocontrol Yeast Rhodotorula kratochvilovae LS11
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Patulin (1) is a mycotoxin contaminant in fruit and vegetable products worldwide. Biocontrol agents, such as the yeast Rhodotorula kratochvilovae strain LS11, can reduce patulin (1) contamination in food. R. kratochvilovae LS11 converts patulin (1) into desoxypatulinic acid (DPA) (5), which is less cytotoxic than the mycotoxin (1) to in vitro human lymphocytes. In the present study, we report our investigations into the pathway of degradation of patulin (1) to DPA (5) by R. kratochvilovae. Isotopic labeling experiments revealed that 5 derives from patulin (1) through the hydrolysis of the ?-lactone ring and subsequent enzymatic modifications. The ability of patulin (1) and DPA (5) to cause genetic damage was also investigated by the cytokinesis-block micronucleus cytome assay on in vitro human lymphocytes. Patulin (1) was demonstrated to cause much higher chromosomal damage than DPA (5).
- Pinedo, Cristina,Wright, Sandra A. I.,Collado, Isidro G.,Goss, Rebecca J. M.,Castoria, Raffaello,Hrelia, Patrizia,Maffei, Francesca,Durán-Patrón, Rosa
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- Bioactivity studies of oxysporone and several derivatives
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Recently oxysporone, a phytotoxic dihydrofuropyranone, was isolated along with two closely related compounds, afritoxinones A and B, from liquid cultures of Diplodia africana, an invasive fungal pathogen of Phoenicean juniper. In this study, eight derivatives were hemisynthesized and assayed for their phytotoxic and antifungal activities in comparison to the parent compound. Each compound was tested on non-host plants and on four destructive plant pathogens such as Athelia rolfsii, Diplodia corticola, Phytophthora cinnamomi and P. plurivora. The results on the phytotoxic activity showed that the dihydrofuropyranone carbon skeleton and both the double bond the hydroxy group of dihydropyran ring appeared to be structural features important in conferring activity. Although the data concerning the antifungal activity did not allow to extract any structure-activity relationships, it should be underlined that the conversion of oxysporone into the corresponding 4-O-benzoyl derivative led to a compound showing a good antifungal activity towards three out of the four organisms tested.
- Andolfi, Anna,Maddau, Lucia,Linaldeddu, Benedetto T.,Scanu, Bruno,Cimmino, Alessio,Basso, Sara,Evidente, Antonio
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- Bioactivity studies of oxysporone and several derivatives
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Recently oxysporone, a phytotoxic dihydrofuropyranone, was isolated along with two closely related compounds, afritoxinones A and B, from liquid cultures of Diplodia africana, an invasive fungal pathogen of Phoenicean juniper. In this study, eight derivatives were hemisynthesized and assayed for their phytotoxic and antifungal activities in comparison to the parent compound. Each compound was tested on non-host plants and on four destructive plant pathogens such as Athelia rolfsii, Diplodia corticola, Phytophthora cinnamomi and P. plurivora. The results on the phytotoxic activity showed that the dihydrofuropyranone carbon skeleton and both the double bond the hydroxy group of dihydropyran ring appeared to be structural features important in conferring activity. Although the data concerning the antifungal activity did not allow to extract any structure-activity relationships, it should be underlined that the conversion of oxysporone into the corresponding 4-O-benzoyl derivative led to a compound showing a good antifungal activity towards three out of the four organisms tested.
- Andolfi, Anna,Maddau, Lucia,Linaldeddu, Benedetto T.,Scanu, Bruno,Cimmino, Alessio,Basso, Sara,Evidente, Antonio
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