Poliphenolic content, antioxidant properties and amylase inhibition by Capsicum annuum L. var. “Cornetto di Pontecorvo DOP”.

The present study investigated the potential beneficial properties of Capsicum annuum L. var. “Cornetto di Pontecorvo DOP” (CPP), in order to highlight its potential role as a functional food. Particularly, the antioxidant activity and the in vitro inhibitory potential against α-amylase of CPP were studied in relation to its polyphenolic composition. α-Amylase inhibitors have been shown to play an important role in managing hyperglycemia and diabete, by delaying carbohydrate digestion and reducing glucose absorption. Hyperglycemia triggers free radical generation and development of oxidative stress. Therefore, improving the antioxidant defences is essential as a support therapeutic strategy for diabetes treatment. Polyphenols, which are widespread constituents in plants and edible vegetables, among which pepper and tomato, have been shown to possess both antioxidant and α-amylase inhibitory properties. In this context, CPP supplementations could represent a new dietary strategy for managing hyperglicemia complications. CPP vegetables, carrying DOP certification, were obtained by the producer’s association at the end of August 2013. Extracts of peel (CPe), pulp (CPu), seeds (CPs) and whole fruit without seeds (CPf) were prepared by 70% ethanol maceration, then the solvent was evaporated under vacuum. The polyphenolic profiles were evaluated by high-performance thin-layer chromatography (HPTLC) and densitometric analysis; in addition, the total polyphenol amount was determined colorimetrically. Different antioxidant mechanisms, among which radical scavenging power against the synthetic DPPH and ABTS radicals, and against the ROS (oxygen reactive species) compounds, superoxide anion and hydroxyl radical, the inhibition of ROS-mediated lipid peroxidation and the ROS generation block (by reducing and/or chelating mechanisms) were studied. Finally, the α-amylase inhibition was evaluated by 3,5-dinitrosalicylic acid method. The HPTLC analysis showed the presence of different polyphenols in all the extracts tested, highlighted as fluorescent spots before NPR and anisaldehyde derivatization. Total polyphenols were particularly high in CPf and CPs, although a significant content was also present in CPe and CPu. As regard the antioxidant activity, the extracts CPs, CPf and CPe were in general more active than CPu, being able to strongly scavenge both the synthetic radicals and the ROS species, to inhibit the ROS-mediated lipid peroxidation and to inhibit ROS generation by chelating mechanisms. All the extracts were also active as α-amylase inhibitors. On the basis of these results, the biological activity of the tested extracts seems to be related to the polyphenol content. For instance, CPs evidenced strong radical-scavenging activity, lipoperoxidation and α-amylase inhibition, associated with a high polyphenol levels. Although further evaluations are needed for identifying the polyphenols involved in the bioactivities found, present results suggest a possible role of CPP supplementation (as both whole product or fractions) for supporting conventional diabetes therapies.