L'azione antiossidante, che consiste in antiossidanti enzimatici e non enzimatici, contrasta lo stress ossidativo che produce danni cellulari. I radicali liberi, i processi infiammatori patologici, le specie reattive dell'azoto e le specie reattive dell'ossigeno sono responsabili del processo di invecchiamento e di molte malattie causate dall'ossidazione.

Componenti che esercitano un'azione antiossidante: qualche esempio. 

• Vitamina C. Un potente antiossidante che protegge le cellule dai danni dei radicali liberi.
• Vitamina E. Aiuta a proteggere le membrane cellulari dallo stress ossidativo.
• Beta-carotene. Un precursore della vitamina A con proprietà antiossidanti.
• Selenio. Un minerale che agisce come cofattore per gli enzimi antiossidanti.
• Polifenoli. Presenti in frutta, verdura, tè e vino, hanno forti proprietà antiossidanti.
• Flavonoidi. Un gruppo di polifenoli noti per la loro attività antiossidante.
• Luteina e zeaxantina. Antiossidanti trovati in verdure a foglia verde che proteggono la salute degli occhi.
• Coenzima Q10. Aiuta a proteggere le cellule dal danno ossidativo e ha un ruolo nella produzione di energia cellulare.

Questi componenti sono essenziali per neutralizzare i radicali liberi e proteggere il corpo dallo stress ossidativo, contribuendo alla prevenzione di malattie croniche.

Diversi componenti possono contribuire o esacerbare le malattie legate all'ossidazione. Questi includono:

• Radicali liberi. Molecole instabili che possono danneggiare le cellule e contribuire allo sviluppo di malattie croniche.
• Fumo. Contiene sostanze chimiche che generano radicali liberi e aumentano lo stress ossidativo.
• Inquinanti ambientali. Come i metalli pesanti e le tossine, possono indurre danni ossidativi alle cellule.
• Alimenti ad alto contenuto di grassi saturi e trans. Possono aumentare i livelli di stress ossidativo nel corpo.

• Alcol. Il suo metabolismo produce radicali liberi che possono danneggiare le cellule.
• Radiazioni UV. Possono causare danni ossidativi alla pelle e aumentare il rischio di cancro della pelle.
• Stress. Può aumentare la produzione di radicali liberi e lo stress ossidativo.
• Dieta povera di antiossidanti. Una dieta con bassi livelli di vitamine e minerali antiossidanti può ridurre la capacità del corpo di combattere lo stress ossidativo.

Questi fattori possono aumentare il rischio di sviluppare malattie legate all'ossidazione, come malattie cardiovascolari, alcuni tipi di cancro e malattie neurodegenerative.

Studi

Melini F, Melini V, Luziatelli F, Ficca AG, Ruzzi M. Health-Promoting Components in Fermented Foods: An Up-to-Date Systematic Review. Nutrients. 2019 May 27;11(5):1189. doi: 10.3390/nu11051189.

Abstract. Fermented foods have long been produced according to knowledge passed down from generation to generation and with no understanding of the potential role of the microorganism(s) involved in the process. However, the scientific and technological revolution in Western countries made fermentation turn from a household to a controlled process suitable for industrial scale production systems intended for the mass marketplace. The aim of this paper is to provide an up-to-date review of the latest studies which investigated the health-promoting components forming upon fermentation of the main food matrices, in order to contribute to understanding their important role in healthy diets and relevance in national dietary recommendations worldwide. Formation of antioxidant, bioactive, anti-hypertensive, anti-diabetic, and FODMAP-reducing components in fermented foods are mainly presented and discussed. Fermentation was found to increase antioxidant activity of milks, cereals, fruit and vegetables, meat and fish. Anti-hypertensive peptides are detected in fermented milk and cereals. Changes in vitamin content are mainly observed in fermented milk and fruits. Fermented milk and fruit juice were found to have probiotic activity. Other effects such as anti-diabetic properties, FODMAP reduction, and changes in fatty acid profile are peculiar of specific food categories.

Giampieri F, Alvarez-Suarez JM, Battino M. Strawberry and human health: effects beyond antioxidant activity. J Agric Food Chem. 2014 May 7;62(18):3867-76. doi: 10.1021/jf405455n.

Abstract. The usefulness of a diet rich in vegetables and fruits on human health has been widely recognized: a high intake of antioxidant and bioactive compounds may in fact play a crucial role in the prevention of several diseases, such as cancer, cardiovascular, neurodegenerative, and other chronic pathologies. The strawberry (Fragaria × ananassa Duch.) possesses a remarkable nutritional composition in terms of micronutrients, such as minerals, vitamin C, and folates, and non-nutrient elements, such as phenolic compounds, that are essential for human health. Although strawberry phenolics are known mainly for their anti-inflammatory and antioxidant actions, recent studies have demonstrated that their biological activities also spread to other pathways involved in cellular metabolism and cellular survival. This paper has the main objective of reviewing current information about the potential mechanisms involved in the effects elicited by strawberry polyphenols on human health, devoting special attention to the latest findings.

Elias RJ, Kellerby SS, Decker EA. Antioxidant activity of proteins and peptides. Crit Rev Food Sci Nutr. 2008 May;48(5):430-41. doi: 10.1080/10408390701425615. 

Abstract. Proteins can inhibit lipid oxidation by biologically designed mechanisms (e.g. antioxidant enzymes and iron-binding proteins) or by nonspecific mechanisms. Both of these types of antioxidative proteins contribute to the endogenous antioxidant capacity of foods. Proteins also have excellent potential as antioxidant additives in foods because they can inhibit lipid oxidation through multiple pathways including inactivation of reactive oxygen species, scavenging free radicals, chelation of prooxidative transition metals, reduction of hydroperoxides, and alteration of the physical properties of food systems. A protein's overall antioxidant activity can be increased by disruption of its tertiary structure to increase the solvent accessibility of amino acid residues that can scavenge free radicals and chelate prooxidative metals. The production of peptides through hydrolytic reactions seems to be the most promising technique to form proteinaceous antioxidants since peptides have substantially higher antioxidant activity than intact proteins. While proteins and peptides have excellent potential as food antioxidants, issues such as allergenicity and bitter off-flavors as well as their ability to alter food texture and color need to be addressed.

Huang D, Ou B, Prior RL. The chemistry behind antioxidant capacity assays. J Agric Food Chem. 2005 Mar 23;53(6):1841-56. doi: 10.1021/jf030723c. 

Abstract. This review summarizes the multifaceted aspects of antioxidants and the basic kinetic models of inhibited autoxidation and analyzes the chemical principles of antioxidant capacity assays. Depending upon the reactions involved, these assays can roughly be classified into two types: assays based on hydrogen atom transfer (HAT) reactions and assays based on electron transfer (ET). The majority of HAT-based assays apply a competitive reaction scheme, in which antioxidant and substrate compete for thermally generated peroxyl radicals through the decomposition of azo compounds. These assays include inhibition of induced low-density lipoprotein autoxidation, oxygen radical absorbance capacity (ORAC), total radical trapping antioxidant parameter (TRAP), and crocin bleaching assays. ET-based assays measure the capacity of an antioxidant in the reduction of an oxidant, which changes color when reduced. The degree of color change is correlated with the sample's antioxidant concentrations. ET-based assays include the total phenols assay by Folin-Ciocalteu reagent (FCR), Trolox equivalence antioxidant capacity (TEAC), ferric ion reducing antioxidant power (FRAP), "total antioxidant potential" assay using a Cu(II) complex as an oxidant, and DPPH. In addition, other assays intended to measure a sample's scavenging capacity of biologically relevant oxidants such as singlet oxygen, superoxide anion, peroxynitrite, and hydroxyl radical are also summarized. On the basis of this analysis, it is suggested that the total phenols assay by FCR be used to quantify an antioxidant's reducing capacity and the ORAC assay to quantify peroxyl radical scavenging capacity. To comprehensively study different aspects of antioxidants, validated and specific assays are needed in addition to these two commonly accepted assays.

Ozawa H, Miyazawa T, Burdeos GC, Miyazawa T. Biological Functions of Antioxidant Dipeptides. J Nutr Sci Vitaminol (Tokyo). 2022;68(3):162-171. doi: 10.3177/jnsv.68.162. 

Abstract. In the history of modern nutritional science, understanding antioxidants is one of the major topics. In many cases, food-derived antioxidants have π conjugate or thiol group in their molecular structures because π conjugate stabilizes radical by its delocalization and two thiol groups form a disulfide bond in its antioxidative process. In recent years, antioxidant peptides have received much attention because for their ability to scavenge free radicals, inhibition of lipid peroxidation, chelation of transition metal ions, as well as their additional nutritional value. Among them, dipeptides are attracting much interest as post-amino acids, which have residues in common with amino acids, but also have different physiological properties and functions from those of amino acids. Especially, dipeptides containing moieties of several amino acid (tryptophan, tyrosine, histidine, cysteine, and methionine) possess potent antioxidant activity. This review summarizes previous details of structural property, radical scavenging activity, and biological activity of antioxidant dipeptide. Hopefully, this review will help provide a new insight into the study of the biological functions of antioxidant dipeptides.

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