Thinned Nectarines, an Agro-Food Waste with Antidiabetic Potential: HPLC-HESI-MS/MS Phenolic Characterization and In Vitro Evaluation of Their Beneficial Activities

Abstract

Due to the side effects of synthetic drugs, the interest in the beneficial role of natural products in the management of diabetic conditions is growing over time. In the context of agro-food waste products, a screening of different fruit thinning by-products identified thinned nectarines (TN) as the richest matrices of abscisic acid (ABA), a phytohormone with well-documented hypoglycemic potential. These waste-food matrices may represent not only precious sources of ABA but also other bioactive molecules with potential health benefits, such as polyphenols. Therefore, we aimed to perform a qualitative and quantitative characterization of a polyphenolic profile of a TN-based nutraceutical formulation through HPLC-HESI-MS/MS and HPLC-DAD-FLD analyses. Additionally, the in vitro antioxidant and antidiabetic potential of TN was investigated. HPLC analyses allowed us to identify forty-eight polyphenolic compounds, nineteen of which were quantified. Moreover, the results obtained through different in vitro assays showed the antioxidant and antidiabetic potential exerted by the tested nutraceutical formulation. In conclusion, the concomitant presence of different bioactive compounds in TN-based nutraceutical formulation, such as ABA and polyphenols, would reasonably support TN as an innovative nutraceutical formulation useful for the management of glucose homeostasis. Further in-depth animal-based studies and clinical trials are needed to deepen these aspects.

Beneficial Contribution to Glucose Homeostasis by an Agro-Food Waste Product Rich in Abscisic Acid: Results from a Randomized Controlled Trial

“…Moreover, the decrease in TG levels observed in the TN treatment groups may be justified both by the reported beneficial effects exerted by polyphenols on the management of hypertriglyceridemia [ 36 ] and by the positive response of plasma TG levels resulting from improved glycemic control, as described by scientific evidence [ 37 ]. In agreement with this hypothesis, our characterization of the TN polyphenolic profile performed by a validated HPLC-DAD method [ 38 ] highlights the high potential of this matrix in terms of polyphenol content [ 22 ]. In this sense, increasing evidence suggests a pivotal role played by oxidative stress in the pathogenesis of both types of DM [ 39 , 40 ] and the related beneficial role exerted by polyphenolic compounds [ 41 , 42 ].…”

“…With respect to the lipid profile, a significant increase in HDL-C values was observed in both the groups treated with TN compared to baseline, whereas no significant differences were observed in the placebo group. This unexpected result could be explained by the high content of polyphenolic compounds in our food matrix [ 22 ]. As reported in scientific studies, polyphenols can positively influence cholesterol metabolism, especially regarding the B2 class of dimeric procyanidins [ 35 ].…”

“…Moreover, the above-mentioned study demonstrated a significantly improved postprandial glycemic response in healthy humans after an acute administration of a TN-based formulation, in association with an insulin-sparing effect [ 21 ]. Subsequently, the beneficial properties of this byproduct were further investigated by qualitatively and quantitatively characterizing the polyphenolic composition through an HPLC-HESI-MS/MS analysis [ 22 ]. The resultant high concentration of polyphenolic compounds, together with the antioxidant and antidiabetic results obtained by in vitro assays, reasonably prompt us to test the clinical potential of TN supplementation with respect to glucose homeostasis.…”

Optimization of Phlorizin Extraction from Annurca Apple Tree Leaves Using Response Surface Methodology

“…The inhibition of AGE generation by OAALE extract and the standard phenolic rutin was performed according to the method reported by Schiano et al [ 15 ] with slight modifications. The amount of 500 µL of serial dilutions for each sample (0.075–70 mg/mL of final concentrations for OAALE and 0.05–2 mg/mL for rutin) prepared in distilled water were added to a working solution composed of 500 µL of bovine serum albumin (50 mg/L), 250 µL fructose (1.25 mol/L) and 250 µL of glucose (25 mol/L).…”

“…The main natural sources of phlorizin are the plants of the Malus genus, although it also reaches a valuable concentration in other plant species, such as Punica granatum (pulp) [ 7 ], Polygonum cuspidatum (flower), Prunus persica (pulp) [ 8 ], Rosa canina (flesh) [ 9 ], Vaccinium vitis-idaea (flesh) [ 10 ], and Vaccinium macrocarpon [ 11 ]. Specifically, phlorizin is not equally distributed in all parts of the apple tree, however, it reaches its maximum concentration in the non-edible parts of the plant, e.g., leaves [ 12 ], twigs [ 13 ], root bark, seeds [ 14 ], and unripe fruits [ 15 ]. Phloretin, and its glucoside phlorizin, are found to be the major phenolic compounds in apple leaves, reaching a concentration ranging from 5.4% to 14% of leaf dry weight (DW) [ 12 ] Moreover, the phlorizin content of leaves seems to be less affected by some variables, such as apple cultivar or harvesting period, than its aglycone, making phlorizin concentration stable over time and in the type of apple cultivar analyzed.…”