Dear Colleagues,

Exogenous antioxidants, such as polyphenols, often suffer from low bioavailability due to their extensive metabolism in the human body. This leads, among other things, to considerable discrepancies between the results of in vitro antioxidant assays and in vivo biological activity. The metabolites of antioxidants present in blood plasma of humans, after their consumption, often have different biological properties compared with the parent compounds. Inactivation or modulation of their activities, as well as toxication, can occur. Metabolites of bioactive antioxidants are usually not commercially available and, therefore, their preparation is crucial to detailed studies of their properties. They are also required as authentic standards for metabolic studies both ex vivo and in vivo. Due to the complexity of antioxidant molecules, both chemical and enzymatic methods might be useful in the preparation of their (tentative) metabolites in amounts allowing for the determination of their biophysical and biological properties.

This Special Issue focuses on this aspect of antioxidants, which to date has been neglected. Potential topics for this Special Issue include the preparation of metabolites of antioxidants using both chemical and enzymatic methods, the identification and isolation of metabolites from biological material, advanced analytical methods for the characterization of metabolites of antioxidants, and studies of the biological activity of these metabolites in vitro and in cellulo. Comparisons with parent compounds are highly recommended. In case the metabolites are not available, their probable formation should be at least discussed. Studies determining the metabolic profile of natural or synthetic antioxidants in the human or animal body together with e.g. plasma antioxidant capacity are also welcome.

We welcome original research articles or reviews dealing with the biological activity of mammalian metabolites of natural and synthetic antioxidants. The major requirements are: (i) clear novelty; (ii) reproducibility; and (iii) defined structures. Papers dealing with poorly defined mixtures, extracts, or “principles” will be returned without further review.

Dr. Kateřina Valentová
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Antioxidants is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• metabolites
• antioxidants
• enzymatic synthesis
• bioavailability
• biological activity
• toxicity
• metabolic studies