Daliu, Patricia (2021) New Nutraceuticals from natural matrices by product to prevent diabetes. [Tesi di dottorato]

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Abstract

The control of glucose homeostasis is the main goal for both the prevention and management of type 2 diabetes (TD2) and pre-diabetes. While T2D is an irreversible condition, pre-diabetes is not. The objective of this research thesis has been to approach the pre-diabetes conditionand and develop from natural sources a successful preventive and therapeutic strategy by increasing in the diet the levels of active compounds capable to control the glycemia. Currently, a great interest has been focused on the valorization of agro-food byproducts, since these matrices could be a source of essential bioactive substance useful to the nutraceuticaland food supplements industry. Supporting the perspective of food as medicine, the aim of the thesis has been to provide an innovative alternative tool through the determination of various phytochemical compounds (e.g. carotenoids, polyphenols, terpenoids,abscisic acid)capable to prevent and/or to control the diabetes. The effect of different Lactobacillus strains has been evaluated as a suitable alternative of biocontrol to protect crops, in particular tomatoes, and a case study is presented. The possibility to use Lactobacillus to avoid/prevent the presence of secondary metabolites has been assessed. The following steps of this Thesis regarded the characterization, analysis, purification, formulation, andin vitro and in vivo tests of phytocomplexes from differet vegetal matrices. For this purpose, two double blind, randomized, clinical trials have been realized to verify the efficacy of novel nutraceutical formulations from: i)nectarines (NecP); ii)tomato peels (TP); iii) olive leaves (EOL), on glycaemic and insulinemic responses, in postprandial glycaemia (PPG), impaired fasting glucose (IFG), and impaired glucose tolerance (IGT) conditions. All the three formulations significantly lowered the 30 min glucose plasma peak (p <0.05). NecP and TP also significantly lowered the 30 min insulin plasma peak (p<0.05). As a part of this Thesis, lacto-fermented tomatoes pomace puree enriched with two strains of probiotics has been formulated to evaluate, after the fermentation, the in vitroandin vivopotential through the Oral Glucose Tolerance Test (OGTT) to verify the beneficial effect in glucose metabolism.The data obtained by HPLC-DAD/Spectrometric-UV showed how the fermentation may impact positively on bioactive compound content, enzymatic response, and decrease the glucose concentration. All these results are promising for further investigation in the clinical research area.

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