Diabetes is a chronic metabolic disorder which leads to high blood sugar levels over a prolonged period. Type 2 diabetes mellitus (T2DM) is the most common form of diabetes and results from the body’s ineffective use of insulin. Over ten dipeptidyl peptidase IV (DPP-IV) inhibitory drugs have been developed and marketed around the world in the past decade. However, owing to the reported adverse effects of the synthetic DPP-IV inhibitors, attempts have been made to find DPP-IV inhibitors from natural sources. Food-derived components, such as protein hydrolysates (peptides), have been suggested as potential DPP-IV inhibitors which can help manage blood glucose levels. This review focuses on the methods of discovery of food-derived DPP-IV inhibitory peptides, including fractionation and purification approaches, in silico analysis methods, in vivo studies, and the bioavailability of these food-derived peptides. Moreover, food-derived DPP-IV inhibitory peptides discovered during this decade are listed and distributed in a 3D scatter plot graph based on their IC₅₀, molecular weight, and grand average of hydropathicity values, which can help us to understand the relationship between the features of the peptides and their activities.

In order to part address the problem of drug-resistant pathogens, antimicrobial peptides (AMPs) have been proposed as alternatives to traditional antibiotics. Herein, a novel phylloseptin peptide, named phylloseptin-PV1 (PPV1), is described from the defensive skin secretion of the Neotropical white-lined leaf frog, Phyllomedusa vaillantii. The peptide was synthesized by solid phase peptide synthesis (SPPS) and purified by RP-HPLC, prior to assessment of its biological activities. PPV1 not only demonstrated potent antimicrobial activity against planktonic ESKAPE microorganisms and the yeast, Candida albicans, but also inhibited and eradicated Staphylococcus aureus and MRSA biofilms. The antimicrobial mechanism was shown to include permeabilization of target cell membranes. The in vivo antimicrobial activity of the peptide was then evaluated using mice. PPV1 also exhibited antiproliferative activity against the cancer cell lines, H157, MCF-7, and U251MG, but had a lower potency against the normal cell line, HMEC-1. Although, the peptide possessed a moderate hemolytic action on mammalian red blood cells in vitro, it did not induce significant hepatic or renal toxicity in injected infected mice. These studies have thus found PPV1 to be a potent phylloseptin group AMP, which can effectively inhibit staphylococci, both in vitro and in vivo, without eliciting toxicity. These data thus provide support for further evaluation of PPV1 as a novel antimicrobial agent with therapeutic potential.

Lysimachiae Herba (LH), called Jinqiancao in Chinese, is an authentic medical herb in Sichuan Province often used in the prescription of traditional Chinese medicine (TCM). However, in recent years, there has been a lack of comprehensive research on its chemical components. In addition, the landform of Sichuan Province varies greatly from east to west and the terrain is complex and diverse, which has an important influence on the chemical constituents in LH. In this study, ultrafast liquid chromatography coupled with triple-quadrupole time-of-flight tandem mass spectrometry (UFLC-triple TOF-MS/MS) was used to analyze the samples of LH from eight different habitats in Sichuan Basin. The constituents were identified according to the precise molecular weight, the fragment ions of each chromatographic peak and the retention time of the compound obtained by high-resolution mass spectrometry, combined with software database searches, standard comparisons and the related literature. Differential chemical constituents were screened using partial least squares discriminant analysis (PLS-DA) and t-tests. The results showed that a total of 46 constituents were identified and inferred, including flavonoids, phenolic acids, amino acids, tannins, fatty acids and coumarins; the fragmentation pathways of the main constituents were preliminarily deduced. According to the variable importance in projection (VIP) and p-values, four common differential constituents were screened out, 2-O-galloylgalactaric acid, quercetin 3-O-xylosyl-rutinoside, nicotiflorin and kaempferol 3-rutinosyl 7-O-alpha-l-rhamnoside. This study provides basic information for the establishment of a comprehensive quality evaluation system for LH.