In silico study to predict potential precursors of human dipeptidyl peptidase-IV inhibitors from hazelnut

Food-derived dipeptidyl peptidase IV inhibitory peptides: Production, identification, structure-activity relationship, and their potential role in glycemic regulation

Dipeptidyl Peptidase IV (DPP-IV) inhibitory peptides are attracting increasing attention, owing to their potential role in glycemic regulation by preventing the inactivation of incretins. However, few reviews have summarized the current understanding of DPP-IV inhibitory peptides and their knowledge gaps. This paper reviews the production, identification and structure-activity relationships (SAR) of DPP-IV inhibitory peptides. Importantly, their bioavailability and hypoglycemic effects are critically discussed. Unlike the traditional method to identifying peptides after separation step by step, the bioinformatics approach identifies peptides via virtual screening that is more convenient and efficient. In addition, the bioinformatics approach was also used to investigate the SAR of peptides. Peptides with proline (Pro) or alanine (Ala) residue at the second position of N-terminal are exhibit strong DPP-IV inhibitory activity. Besides, the bioavailability of DPP-IV inhibitory peptides is related to their gastrointestinal stability and cellular permeability, and in vivo studies showed that the glucose homeostasis has been improved by these peptides. Especially, the intestinal transport of DPP-IV inhibitory peptides and cell biological assays used to evaluate their potential role in glycemic regulation are innovatively summarized. For further successful development of DPP-IV inhibitory peptides in glycemic regulation, future study should elucidate their SAR and in vivo hypoglycemic effects .

Diversity Assessment and DNA-Based Fingerprinting of Sicilian Hazelnut (Corylus avellana L.) Germplasm

The characterization of plant genetic resources is a precondition for genetic improvement and germplasm management. The increasing use of molecular markers for DNA-based genotype signature is crucial for variety identification and traceability in the food supply chain. We collected 75 Sicilian hazelnut accessions from private and public field collections, including widely grown varieties from the Nebrodi Mountains in north east Sicily (Italy). The germplasm was fingerprinted through nine standardized microsatellites (SSR) for hazelnut identification to evaluate the genetic diversity of the collected accessions, validating SSR discrimination power. We identified cases of homonymy and synonymy among acquisitions and the unique profiles. The genetic relationships illustrated by hierarchical clustering, structure, and discriminant analyses revealed a clear distinction between local and commercial varieties. The comparative genetic analysis also showed that the Nebrodi genotypes are significantly different from the Northern Italian, Iberian, and Turkish genotypes. These results highlight the need and urgency to preserve Nebrodi germplasm as a useful and valuable source for traits of interest employable for breeding. Our study demonstrates the usefulness of molecular marker analysis to select a reference germplasm collection of Sicilian hazelnut varieties and to implement certified plants’ production in the supply chain.

Tombul hazelnut (Corylus avellana L.) peptides with DPP-IV inhibitory activity: In vitro and in silico studies

Cold press technology generates high quality value-added oil products along with highly stable oilseed cakes. Hazelnut cakes are characterized by high protein concentrations that can be industrially valorized. Here, using an aqueous extraction scheme along with enzymatic proteolysis and FPLC (fast protein liquid chromatography)-based fractionation, a variety of hazelnut peptide fractions with varying bioactive properties were manufactured and their sequences were determined based on mass spectrometry. DPP-IV inhibitory attributes were determined based on an in vitro DPP-IV assay and in silico techniques were administered for for the analysis of overall bioactive potential and DPP-IV inhibitory characteristics of peptides. Based on these investigations, 256 peptides were identified in 81 different fractions. The majority of fractions were characterized with low to moderate DPP-IV inhibitory activity possibly due to their dilute nature. Some hazelnut peptides were characterized by comparable IC₅₀ values as the positive control (Diprotin-A). The most influential 7 peptides were shown to generate higher docking scores than the control. The main interaction mechanism between hazelnut peptides and DPP-IV possibly depended on hydrophobic interactions. While further concentration could enhance the DPP-IV inhibitory potential of hazelnut peptides, hazelnut cakes represent a sustainable resource of potentially antidiabetic peptides.