Are seed proteins a problem or a boon?

Transcription

1 Are seed proteins a problem or a boon?, Biochemist Department of AgriFood Molecular Sciences Faculty of Agriculture University of Milan, Italy Main sources Production Concluding remarks Seed proteins Protein metabolic fate Nutritional facts Antinutritional aspects Nutraceutical aspects

2 Main seed sources of dietary proteins (figures are percentages) Cereals Average amount: 11.0 Legumes (including pulses and oil crops) Average amount: 26.2 Lowest: Rice 7.3 Lowest: Kidney bean 20.2 Highest: Rye 14.8 Highest: Soybean 36.8 Pulses and soybean world production % Serie1 Serie

3 Very general nutritional facts on seed dietary proteins (1/2) Legume and cereals are consumed by human beings as sources of starch, oil and proteins since thousand of years Man has developed a simple process to make them fully edible, i.e. cooking. As a consequence, seed proteins are essentially nutritious and safe Very general nutritional facts on dietary seed proteins (2/2) The relative unbalance of some essential amino acid intake is overcome with the combination of cereal and legume proteins in a number of food preparations, many of which belong to the Mediterranean dietary tradition The antinutritive effects of some seed proteins frequently parallel extraordinary biological activities, which deserve more investigation for their optimal exploitation

4 Metabolic fate of dietary proteins Dietary proteins are the source of amino acid for the body Proteins are normally degraded to amino acids by proteases during the digestion processes in the gastrointestinal tract Digestion of proteins can be incomplete Full-lenght proteins or their fragments present in the gut may have various local and systemic effects Examples of biologically active seed proteins Protein family Examples Type of protein Source Adverse activity Proteinase inhibitors BBI Small, compact Many seeds Inhibition of endogenous proteolytic enzymes Amylase inhibitors 2S albumin Small Many seeds Inhibition of endogenous amylolytic enzymes Conglycinin α subunit Large chain Soybean Storage proteins Conglutin gamma Large chain Lupin Vicilin Fragment Lupin Lectins PHA Medium size Many legume seeds Hemagglutination Peptides ACEIn Very small Few seeds Not known Thiamine BP PA2 Small Many seed

5 Examples of biologically active seed proteins Protein family Examples Type of protein Source Adverse activity Beneficial activity Proteinase inhibitors BBI Small, compact Many seeds Inhibition of endogenous proteolytic enzymes Anticarcinogenic, anti-inflammatory Amylase inhibitors 2S albumin Small Many seeds Inhibition of endogenous amylolytic enzymes Anti-obesity, diabetes, metabolic syndrome Conglycinin α subunit Large chain Soybean Hypolipidemic Storage proteins Conglutin gamma Large chain Lupin Hypoglycemic Vicilin Fragment Lupin Lectin Lectins PHA Medium size Many legume seeds Hemagglutination Immuno-modulation Peptides ACE Small Few seeds Not known Hypotensive Thiamine BP PA2 Small Many seed Vitamin vehiculation The original nutraceutical concept Marcello Dunranti Nutraceutical is any food, or part of food, considered to provide health benefits, including the prevention and treatment of disease Stephen De Felice, 1989 Let your food be your medicine and let your medicine be your food Hippocrates ( B.C.)

6 Lentil Bowman-Birk inhibitor 3D structure Incidence of diabetes in 2000, 2010 and % increase World 2000: 151 million 2010: 221 million Increase: 46% Zimmer, Albert, Shaw, Nature 414, 732, 2001

7 2-D reference map of lupin seed proteome Mr, kda ph Influence of conglutin γ on rat plasma glucose concentrations during glucose overloading trials control +30 mg/kg +60 mg/kg +120 mg/kg +120 Type F +50 metformin (Doses: mg.kg -1 ) *: P<0.05, **: P<0.01, ***: P<0.001 vs. control

8 Effect of dietary habits on heart deaths From J. Furhman ( alfa Soybean 7S globulin α, α and β mature subunits MW, kda 68 a.a. 576 core domain extension region alfa core domain extension region beta core domain

9 Effects of soybean proteins on plasma total cholesterol (A) and triglyceride (B) levels in rats Doses are: mg product administered/ (kg body weight x d) Mature tα Cloning and yeast expression of a truncated form of alfa chain

10 Various international scientific boards have stated that: A handful of beans a day can be beneficial to health, by preventing and controlling various pathological conditions, especially the so-called civilization diseases. The molecular nutraceutics concept Individual target molecule analyses, involving: Isolation from the wild source and/or cloning/expression from heterologous hosts Molecular characterisation Biological activity measurements Elucidation of the mechanism(s)

11 Nutraceutical proteins from seeds of: Lupin: Lupinus albus Soybean: Glycine max Lentil: Lens culinaris Pea: Pisum sativum; Common bean: Phaseolus vulgaris; Chickpea: Cicer arietinum Concluding remarks Plant protein drug discovery is an innovative and extremely interesting area of research activity Novel outstanding achievements can seemingly be expected soon This new body of information is the gateway to the development of novel, safe and healthy foods which may respond the increasing consumers awareness of the role of dietary habits on human well-being meantime, actions aimed at supporting the increase in consumption of whole seeds should be undertaken