Chemistry and Biochemistry of Agri-Food Molecules

Introduction.
Role of the secondary metabolites in the interactions between plants and environment. Allelopatic substances and elicitors. Repellent and attractors

Topics.
The chemistry of flavours and fragrances: sweet, astringent, bitter and hot substances. Natural flavours. Flavor enhancers.
Terpenes and steroids. Linear and cyclic monoterpenes. Outlines on their biosynthesis.
Antioxidants and natural pigments: structure, chemico-physical properties and reactivity of polyphenols and carotenoids. Sulphur containing substances. Natural sources.
Antinutritional factors: saponins, alkaloids. Outlines on alkaloid biosynthesis.
Phototoxic agents: structure, natural sources and mechanism of action.

Laboratory tutorials.
Extraction, purification, chemical and biochemical activity assays of a natural substance discussed in the course. The biochemical activity might eventually be discussed in the second course module.

The meaning of molecular diversity. General aspect of metabolism. Typologies of enzyme reactions. General aspects of secondary metabolism.
Amino acids as precursors of secondary metabolites. Biosynthesis of amino acids (general aspects). Features of aromatic amino acids. Biosynthesis of aromatic amino acids. Bacteria-fungi and plants specificity of the prephenate branch. Biosynthesis of tyrosine from phenylalanine: phenylalanine hydroxylase (phenylketonuria). Shikimate pathway regulation in bacteria and plants (hints).
EPSP synthase, the action site of glyphosate. Mechanism of the glyphosate activity. Key amino acid residues in the interaction glyphosate/EPSP synthase. Glyphosate-tolerant EPSP synthases. Glyphosate-resistant plants. Advantages and disadvantages in the use of glyphosate (hints).
Phenylpropane: basic structure of phenylpropanoids and tyrosine and phenylalanine. Phenylpropanoid pathway. Phenylalanine ammonia lyase and tyrosine ammonia lyase. Cinnamate hydroxylase. The typical reactions of phenilpropanoid biosynthesis. Acetyl-CoA, precursor of the polyketide moiety of flavonoids. Acetyl-CoA carboxylase. Chalcone synthase. From chalcone to the other flavonoids (hints). The other type-III polyketide synthases. The transcriptional regulation and the promoter of the chalcone synthase gene. Natural roles of flavonoids: vicenin-2; involvement in the nodulation process; the anthocyans and the colours.
Metabolic precursors of terpenoids. Mevalonate pathway. Acetoacetyl-CoA thiolase and HMG-CoA synthase: cholesterogenic and ketogenic forms. HMG-CoA reductase: statins sensitivity. The methylerythritol phosphate pathway. The DXP reductoisomerase: the fosmidomycin target. Statins and fosmidomycin in the study of the metabolic source of terpenoids. Subcellular localization and taxonomy specificity of MVA and MEP pathways. The elongation phase of terpenoid biosynthesis: prenyltransferases and their subcellular localization; primary and secondary refinement (hints).
Taxol (paclitaxel): discovering, source, biosynthesis (hints), subcellular localization, cytotoxicity, physiological role, effect of tubulin structure on cytotoxicity. Taxol production and its improvement perspectives.
Strategies of metabolic engineering. Holistic approach of metabolic engineering: the case of catharanthine. Pros and cons in the use of plant cell coltures for the production of molecules of interest. Plant cell coltures for the production of complex recombinant proteins. The case of glucocerebrosidase and the Gaucher illness. Other cell systems for metabolite production: bioreactors and biofuels (hints). The case of biohydrogen (dark fermentation, photofermentation). Potential biotechnological use of lignocellulosic wastes (hints).
Vitamin K, role and biosynthetic origin. The phylloquinone role in the plant. The menaquinone role in bacteria. Functional distinction between ubiquinone and menaquinones. Vitamin D (cholecalciferol, ergocalciferol, calcitriol, ercalcitriol). Metabolic source of cholecalciferol. Vitamin A (retinol and aldehyde and acid derivatives). Retinal role in the vision system (rhodopsin and photopsins). Biosynthetic source of retinal and beta-carotene.
Vitamin A deficit. Food fortification and biofortification. Golden Rice. Golden Rice DNA constructs (GR1 and GR2 prototypes).
Reactive oxygen and other radical species biologically significant. Biological sources of radicals. Mechanism and ROS reactivity. Oxidative damages in the cell. Oxidative stress defence mechanisms. Glutathione and glutathione peroxidase. Reduced glutathione regeneration: glutathione reductase. Glucose 6-phosphate dehydrogenase and the relation with favism and malaria. Isouramil and divicine induced-redox-cycle. Thiolic functional homologues of glutathione. Meaning and evaluation of antioxidant power in biological/experimental and food systems.
Vitamin E (tococromanols). Biosynthetic source of tocopherols. Chloroplasts tocopherols (plastoglobules). Antioxidant activity of tocopherols. Antioxidant triad. Ascorbic acid (vitamin C) and redox activity. Biosynthetic source of ascorbic acid (animals, plants). Ascorbic acid role in plants and animals. Ascorbic acid as co-factor of alpha-chetoglutarate-dependent hydroxylases. The ascorbic acid, the collagen and the scurvy. Essential fatty acids.
Storage seed tissues in dicots and monocots and its molecular macro composition. Osborne's protein fractionation. 2S albumins. 7S and 11S globulins. Prolamines: types and structures. Maize prolamines: zeins. Subcellular protein sorting pathways. Prolamines and protein bodies. Cupin and prolamine protein superfamilies. Functional-technological properties of wheat gluten. Gluten proteins: glutenins and gliadins. Electrophoretic analysis of gliadins. Main chemical and enzyme flour-additives and mechanism of action. Food and biotechnological use of transglutaminase. Flour allergens (hints). General and molecular aspects of celiac sprue. Applications to reduce celiac pathogenesis (chemical and enzyme modifications of gluten, "glutenases", etc.).
Plant "toxic" proteins. Ribosome-inactivating proteins (RIPs). The N-glycosidase activity of RIPs. The ricin cytotoxicity mechanism. Antiviral RIP activity. General structure of antibodies. The immunotoxins.
Biofilm and its economic-social impact. Beneficial biofilms. Biofilm structure and genesis and the role of quorum-sensing molecules. Antibiofilm molecules.
The following topics will be deepened or refreshed: transamination reactions; recombinant expression of proteins (hints); protein mutagenesis (hints); general canonical procedure to produce GMO plants (hints); the Double Strand Breaks and genome editing through CRISPR/Cas9 system (hints); GS/GOGAT system; cytochrome P450 superfamily; hints on general structure of promoters, biotechnological importance of promoters and promoter analysis; functional omics (metabolomics); immunolabeling; photo-affinity labeling; general procedure for plant cell colture (hints); protein transmembrane domains through primary structure analysis; molecular docking (hints); epitopes mapping (hints); protein allergen identification approach.
Laboratory practices: enzyme reaction inhibition; The IC50 value meaning and its extrapolation from dose-response plots; the colorimetric assay for phosphatase; the phosphatases and the intestinal alkaline phosphatase; organization of a laboratory report.