Assessing the Role of African Indigenous Vegetables to Improve Agriculture Sustainability and Diet Quality

THIS THESIS WORK IS ABOUT THE IDENTIFICATION OF RESISTANT CROPS ABLE TO COUNTERACT THE NEGATIVE EFFECTS POSED BY CLIMATE CHANGE (E.G., DROUGHT) AND TO YIELD WITHOUT LOSSES UNDER SUSTAINABLE MANAGEMENTS PRACTICES. MOREOVER THE AIM IS TO IDENTIFY PLANT SPECIES ABLE TO EXERT BENEFICIAL AND PREVENTIVE PROPERTIES TO SAFEGUARD HUMAN HEALTH. THE IDENTIFICATION OF PLANT SPECIES WITH THESE FEATURES WAS PERFORMED BY EXPLORING THE AFRICAN BIODIVERSITY WHICH IS A SOURCE OF SEMI-DOMESTICATED AND VERY NUTRITIOUS SPECIES. IN PARTICULAR THE WORK FOCUSED ON THE EVALUATION OF GROWTH CAPABILITIES UNDER CONVENTIONAL VS CONSERVATION AGRICULTURE MANAGEMENT (I.E., NO TILLAGE, COVER CROP MAINTENANCE) OF VIGNA UNGUICULATA L. WALP AND CORCHORUS OLITORIUS L. THESE TREATMENTS WERE COUPLED TO NORMAL IRRIGATION VS. LOW WATER REGIME TO TEST THE SUITABILITY OF THE ABOVEMENTIONED SPECIES TO RESIST TO DROUGHT. THE INVESTIGATED PARAMETERS WERE MORPHOLOGY TRAITS, PHOTOSYNTHETIC ACTIVITY, BIOMASS PRODUCED AND THE METABOLIC PROFILE OF THE EDIBLE PORTIONS OF THE PLANTS (I.E., V. UNGUICULATA BEANS AND C. OLITORIUS LEAVES) . RESULTS SHOWED THE SUITABILITY OF BOTH THE CROPS TO BE GROWN UNDER CONSERVATION AGRICULTURE MANAGEMENT, SINCE BOTH AT THE YIELD AND METABOLIC LEVEL THEY DID NOT SHOWED SIGNIFICATIVE DIFFERENCES. AT THE NUTRACEUTICAL LEVELS. DIFFERENT EXPERIMENTS WERE PERFORMED. CORCHORUS OLITORIUS LEAVES WERE EVALUATED FOR THE CONTENT OF ANTIOXIDANT COMPOUNDS, MAINLY POLYPHENOLS. THE CHEMICAL CHARACTERIZATION REVEALED HUGE AMOUNTS OF FLAVONOIDS, ESPECIALLY QUERCETIN DERIVATIVES. INTERESTINGLY THESE COMPOUNDS WERE FOUND TO BE PRESENT EVEN AFTER BOILING, A TRATMENT WHICH LEAVES WERE UNDERGONE TO IN ORDER TO MIMIC THE CONDITION OF CONSUMPTION. MOREOVER, THESE FRACTIONS WERE FOUND TO BE ABLE TO EXERT SELECTIVE CYTOTOXIC PROPERTIES AGAINST A COLON CANCER CELL LINE (CACO-2) WITHOUT DETRIMENTAL EFFECTS ON THE HEALTHY ONE CCD841. THIS BIOACTIVITY DISPLAYED ON THE CACO-2 CELL LINE IS EXPLAINED BY AN INCREASE IN THE REACTIVE OXYGEN SPECIES LEVELS AFTER TREATMENT WITH THE PHENOLIC FRACTIONS AND BY A CONCOMITANT DECREASE IN THE ACTIVITY OF THE GLUTATHIONE INDEPENDENT ANTIOXIDANT ENZYMES. AS FAR AS VIGNA UNGUICULATA IS CONCERNED, THE BEAN OF THIS SPECIES WAS STUDIED IN TERMS OF NEUROPROTECTIVE AND ANTICANCER PROPERTIES. AQUEOUS EXTRACTS OF V. UNGUICULATA BEANS DELAYED CHRONOLOGICAL LIFESPAN IN BUDDING YEAST AS WELL AS IN DROSOPHILA MELANOGASTER LARVAE. MOREOVER THEY WERE ABLE TO RESCUE THE PHENOTYPE OF MUTANT YEAST CELLS OVEREXPRESSING THE ALPHA-SYNUCLEIN GENE. AT THE NEURONAL LEVEL, EXTRACTS WERE FOUND TO INDUCE THE LOCALIZATION OF ALPHA SYNUCLEIN IN CELL CYTOPLASMS INSTEAD OF IN THE PLASMATIC MEMABRANE, A CONDITION THAT POSES A LOWER CYTOTOXICITY. V. UNGUICULATA BEANS WERE FOUND ALSO TO RESCUE THE PHENOTYPE OF HUMAN NEURONES EXPRESSING ALPHA SYNUCLEIN AS A CONSEQUENCE OF A REDUCED LEVEL OF REACTIVE OXYGEN SPECIES PRODUCTION. FURTHERMORE, V. UNGUICULATA EXTRACTS WERE FOUND TO REDUCE THE NUMBER OF DEGENERATING NEURONES IN A CAENORHABDITIS ELEGANS MODEL. V. UNGUIXULATA AQUEOUS EXTRACT WAS STUDIED ALSO FOR ITS ABILITY TO EXERT CYTOTOXIC PROPERTIES AGAINST HUMAN COLON CANCER CELL LINES WITH NO EFFECTS ON THE HEALTHY CELL LINE. THE CYTOTXIC ACTIVITY WAS FOUND TO BE MEDIATED BY A DOWN-REGULATION OF THE EGFR PHOSPHORILATION LEVEL. THESE CANCER PREVENTIVE PROPERTIES WERE FOUND ALSO TO BE ABLE TO SUPPORT THE TREATMENT WITH A CHEMIOTERAPIC DRUG, THE MONOCLONAL ANTIBODY CETUXIMAB, USUALLY EXPLOITED FOR COLON CANCER CHEMOTHERAPETIC CYCLES. IN PARTICULAR, WHEN COLON CANCER CELLS ARE TREATED WITH V. UNGUICULATA BEAN EXTRACT, THE AMOUNT OF THE ADMINISTERED DRUG CAN BE SIGNIFICANTLY REDUCED. OVERALL THESE FINDINGS SUPPORT THE ADOPTION OF AFRICAN INDIGENOUS SPECIES SUCH AS V. UNGUICULATA AND C. OLITORIUS TO SUPPORT AGRICULTURE SUSTAINABILITY ALSO IN FORECAST OF CLIMATE CHANGE AND TO SAFEGUARD HUMAN HEALTH BY ACTING AS NUTRACEUTICAL ELEMENT IN THE DIET.