Identification of Novel Peptides in Distillers' Grains as Antioxidants, α-Glucosidase Inhibitors, and Insulin Sensitizers: In Silico and In Vitro Evaluation.

Distillers' grains are rich in protein and constitute a high-quality source of various bioactive peptides. The purpose of this study is to identify novel bioactive peptides with α-glucosidase inhibitory, antioxidant, and insulin resistance-ameliorating effects from distiller's grains protein hydrolysate. Three novel peptides (YPLPR, AFEPLR, and NDPF) showed good potential bioactivities, and the YPLPR peptide had the strongest bioactivities, whose IC50 values towards α-glucosidase inhibition, radical scavenging rates of 2,2'-azino-bis (3-ethylbenzothiazoline-6- sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) were about 5.31 mmol/L, 6.05 mmol/L, and 7.94 mmol/L, respectively. The glucose consumption of HepG2 cells treated with YPLPR increased significantly under insulin resistance condition. Moreover, the YPLPR peptide also had a good scavenging effect on intracellular reactive oxygen species (ROS) induced by H2O2 (the relative contents: 102.35% vs. 100%). Molecular docking results showed that these peptides could stably combine with α-glucosidase, ABTS, and DPPH free radicals, as well as related targets of the insulin signaling pathway through hydrogen bonding and van der Waals forces. This research presents a potentially valuable natural resource for reducing oxidative stress damage and regulating blood glucose in diabetes, thereby increasing the usage of distillers' grains peptides and boosting their economic worth.

Exploring the Promotive Effects and Mechanisms of Different Polyphenolic Extracts from Prinsepia utilis Royle Seed Shell on Tyrosinase.

Prinsepia utilis Royle (P. utilis) is commonly used as a food ingredient and herbal medicine according to folk records, yet little research has been done on the seed shell, a processing waste. The aim of this study was to investigate the distribution of polyphenolic components and the tyrosinase activation activity of different extracts from the seed shell by UHPLC-ESI-HRMS/MS, in vitro tyrosinase activity assay, molecular docking and molecular dynamics. A total of 16 phytochemicals were identified, of which (+)-catechin and (-)-epicatechin were the major polyphenolic compounds. Both the esterified and insoluble bound polyphenols exhibited tyrosinase activation activity, and the esterified polyphenols showed better tyrosinase activation activity. (+)-Catechin and (-)-epicatechin might be the main activators of tyrosinase, both of which may act as substrate to affect tyrosinase activity. By molecular docking and molecular dynamics simulation studies, (+)-catechin and (-)-epicatechin can be efficiently and stably bound to the tyrosinase active site through hydrogen bonds, van der Waals forces and π-bonds. The results of this study may not only provide a scientific basis for exploring P. utilis seed shell as a potential activator of tyrosinase, but also contribute to the high value utilization of P. utilis processing by-products.

Effects and interaction mechanism of soybean 7S and 11S globulins on anthocyanin stability and antioxidant activity during in vitro simulated digestion.

The objective of this study was to investigate the effects of soybean 7S and 11S globulins on the stability and antioxidant capacity of cyanidin-3-O-glucoside (C3G) in the simulated gastrointestinal environment, and further to elucidate their interaction mechanism. The stability and total content of anthocyanins (ACNs) before and after simulated digestion were determined by Ultraviolet-visible (UV-Vis) spectroscopic and pH differential methods, respectively, and free radical scavenging activity of C3G after simulated digestion were measured using ABTS and DPPH assays. The interaction mechanism was further investigated using molecular docking and molecular dynamics simulation. The analysis results showed that soybean 7S and 11S globulins had a protective effect on the stability of C3G during simulated digestion and improved the antioxidant capacity of C3G after simulated digestion. Soybean 11S globulin had a better effect than soybean 7S globulin in protecting the stability and antioxidant capacity of C3G against simulated gastrointestinal environment. In silico results showed that the binding interactions between C3G and 7S and 11S globulins were mainly hydrogen bonds and van der Waals forces, followed by hydrophobic interactions. Among them, ASN69 and THR101 are the key amino acid residues for 7S-C3G binding, and THR82 and PRO86 are the key amino acid residues for 11S-C3G binding. The results suggested that it may be helpful to use soybean 7S and 11S globulins as carriers to improve the stability and antioxidant activity of ACNs.

[Hydrochemical Characteristics and Formation Causes of Ground Karst Water Systems in the Longzici Spring Catchment].

The water of the Longzici Spring catchment is the source of industrial, agricultural, and urban domestic water in Linfen City, Shanxi Province. It is of great significance to identify the sources and influencing factors of karst water resources for their development and utilization, and the protection of the ecological environment. Taking the karst groundwater in the Longzici Spring Area as the research object, systematic sample collection and isotope analysis were carried out. Hydrochemistry methods (Durov diagram, ion ratio system, Gibbs diagram, hydrogen and oxygen isotopes, and sulfur isotopes) were used to analyze the hydrochemical characteristics of groundwater. The hydrogeochemical and environmental isotopic characteristics of Longzici Spring water are revealed. The hydrochemical field of karst groundwater in the Longzici Spring domain has obvious zonation, from the deep buried detention area to the supply area to the runoff and discharge area. The hydrochemical types of karst groundwater detention area are SO4-Ca and SO4-Ca·Mg, with total dissolved solids (TDS) of 960.5-2340 mg·L-1; the supply area is HCO3-Ca·Mg and HCO3·SO4-Ca·Mg, with TDS of 340.5-562 mg·L-1; and the runoff and discharge areas are SO4·HCO3-Ca·Mg·Na, SO4·HCO3-Ca, and SO4·HCO3-Ca·Mg, with TDS of 494.0-1168.5 mg·L-1. The karst groundwater is mainly SO4·HCO3-Ca and SO4·HCO3-Ca·Mg type water. The content range of sulfate ions is 61.6-1503 mg·L-1, with an average of 481.4 mg·L-1. A total of 70.3% of the karst groundwater SO42- samples exceed the standard. The sulfate ions in karst groundwater mainly come from the dissolution of gypsum in the Ordovician aquifer and the oxidation of pyrite in a coal aquifer. The ratio of sulfate ions in the Longzici Spring catchment that come from pyrite oxidation in water is 20.2%. According to the analysis of hydrogen, oxygen and sulfur isotopes, 70% of karst groundwater is polluted by the acid water of coal mines to different degrees. Using the software PHREEQC, it is concluded that the hydrochemical characteristics of the study area are mainly affected by dissolution and dedolomitization, rock salt, and gypsum.

A study of the characteristics of karst groundwater circulation based on multi-isotope approach in the Liulin spring area, North China.

Due to the significance of karst groundwater for water supply in arid and semi-arid regions, the characteristics of the karst groundwater flow system in the Liulin spring area, North China, are analysed through isotopic tracing (δ(2)H, δ(18)O, δ(13)C and (3)H) and dating approaches ((14)C). The results show that the primary recharge source of karst groundwater is precipitation. Evaporation during dropping and infiltration of rainfall results in a certain offset in the values of δ(2)H and δ(18)O in groundwater samples from the global meteoric water line (GMWL) and the local meteoric water line (LMWL). The altitudes of the recharge region calculated by δ(18)O range from 1280 to 2020 m above sea level, which is consistent with the altitudes of the recharge area. The Liulin spring groups could be regarded as the mixing of groundwater with long and short flow paths at a ratio of 4:1. In the upgradient of the Liulin spring, the groundwater represents modern groundwater features and its [Formula: see text] is mainly derived from dissolution of soil CO(2), while in the downgradient of the Liulin spring, the (14)C age of dissolved inorganic carbon (DIC) in groundwater shows an apparent increase and [Formula: see text] is mainly derived from the dissolution of carbonate rocks. The mean flow rate calculated by (14)C ages of DIC between IS10 and IS12 is 1.23 m/year.

Improving spatial adaptivity of nonlocal means in low-dosed CT imaging using pointwise fractal dimension.

NLMs is a state-of-art image denoising method; however, it sometimes oversmoothes anatomical features in low-dose CT (LDCT) imaging. In this paper, we propose a simple way to improve the spatial adaptivity (SA) of NLMs using pointwise fractal dimension (PWFD). Unlike existing fractal image dimensions that are computed on the whole images or blocks of images, the new PWFD, named pointwise box-counting dimension (PWBCD), is computed for each image pixel. PWBCD uses a fixed size local window centered at the considered image pixel to fit the different local structures of images. Then based on PWBCD, a new method that uses PWBCD to improve SA of NLMs directly is proposed. That is, PWBCD is combined with the weight of the difference between local comparison windows for NLMs. Smoothing results for test images and real sinograms show that PWBCD-NLMs with well-chosen parameters can preserve anatomical features better while suppressing the noises efficiently. In addition, PWBCD-NLMs also has better performance both in visual quality and peak signal to noise ratio (PSNR) than NLMs in LDCT imaging.