Priprema, identifikacija i antioksidacijska svojstva kelatnog kompleksa željeza i oligopeptida izoliranog iz mesa japanske svilaste crne kokoši (Gallus galllus domesticus Brisson)

Black-bone silky fowl iron(II)-oligopeptide chelate was synthesized from iron(II) solution and the black-bone silky fowl oligopeptide, which was extracted from the muscle protein of black-bone silky fowl (Gallus gallus domesticus Brisson). Orthogonal array analysis was used to determine the optimal conditions for the iron(II)-oligopeptide chelate preparation. Ultraviolet-visible (UV-Vis) spectroscopy, electron microscopy, and Fourier transform infrared (FTIR) spectroscopy were used to identify the structure of iron(II)-oligopeptide chelate. 2-Diphenyl-1-picrylhydrazyl (DPPH) and superoxide radical scavenging assays were performed to compare the antioxidant abilities of the black-bone silky fowl oligopeptide and iron(II)-oligopeptide chelate. The optimal conditions for iron(II) oligopeptide chelate preparation were 4 % of the black-bone silky fowl oligopeptide and a ratio of the black-bone silky fowl oligopeptide to FeCl2·4H2O of 5:1 at pH=4. Under these conditions, the chelation rate was (84.9±0.2) % (p<0.05), and the chelation yield was (40.3±0.1) % (p<0.05). The structures detected with UV-Vis spectroscopy, electron microscopy and FTIR spectra changed significantly after chelation, suggesting that Fe(II) ions formed coordinate bonds with carboxylate (-RCOO¯) and amino (-NH2) groups in the oligopeptides, confirming that this is a new oligopeptide-iron chelate. The iron(II)-oligopeptide chelate had stronger scavenging activity towards DPPH and superoxide radicals than did the black-bone silky fowl oligopeptide.Kelatni kompleks željeza i oligopeptida sintetiziran je dodatkom praha proteina izoliranog iz mesa japanske svilaste crne kokoši (Gallus galllus domesticus Brisson) otopini iona Fe2+. Optimalni uvjeti keliranja određeni su pomoću ortogonalnog plana. Struktura kelata ispitana je pomoću UV-Vis spektroskopije, elektronskog mikroskopa i FTIR spektroskopije. Uspoređena je antioksidacijska aktivnost oligopeptida i kelata, i to ispitivanjem sposobnosti uklanjanja DPPH i superoksidnih radikala. Optimalni uvjeti keliranja bili su: omjer mase oligopeptida i volumena otopine od 4 %, maseni omjer oligopeptida i otopine željezovog(II) klorida od 5:1 i pH-vrijednost od 4. Pri tim je uvjetima uspješnost keliranja bila (84,9±0,2) % (p˂0,05), a prinos kelata (40,3±0,1) % (p˂0,05). Isptivanjem spojeva pomoću UV-Vis spektroskopije, elektronskog mikroskopa i FTIR spektroskopije utvrđeno je da se struktura kelata bitno promijenila, te da je nastao novi spoj, najvjerojatnije vezivanjem iona Fe2+ s karboksilnom i amino skupinom oligopeptida. Kelatni kompleks imao je izraženiju sposobnost uklanjanja DPPH i superoksidnih radikala od oligopeptida

A multibody dynamic model of the drilling system with drilling fluid

This article is intended to present a multibody dynamic model of the drilling system, consisting of drillstring and drilling fluid. The drillstring is a complex rigid–flexible coupling system, including rigid bodies, Euler–Bernoulli beam elements, constraints and dynamic loads, and its dynamic model is established using the absolute nodal coordinate formulation. The drilling fluid, composed of internal, annulus, and under-bit fluids, is modeled as one-dimensional compressible fluid; the relative flow of the drilling fluid is modeled using the Arbitrary Lagrangian–Eulerian description; the force of the drillstring acting on the drilling fluid is introduced through the drilling fluid transport motion; meanwhile, the reaction force acting on the drillstring is taken as an external load. The contact between the drillstring and drilling fluid is simulated based on Hertz contact theory, and the rock penetration model is built based on the rock-breaking velocity equation. Based on this model, the coupled vibration of the drillstring and the effects of the drilling fluid flow rate and density on the drilling process are investigated through several examples

Preparation, Identification and Antioxidant Properties of Black-Bone Silky Fowl (Gallus gallus domesticus Brisson) Iron(II)-Oligopeptide Chelate

Black-bone silky fowl iron(II)-oligopeptide chelate was synthesized from iron(II) solution and the black-bone silky fowl oligopeptide, which was extracted from the muscle protein of black-bone silky fowl (Gallus gallus domesticus Brisson). Orthogonal array analysis was used to determine the optimal conditions for the iron(II)-oligopeptide chelate preparation. Ultraviolet-visible (UV-Vis) spectroscopy, electron microscopy, and Fourier transform infrared (FTIR) spectroscopy were used to identify the structure of iron(II)-oligopeptide chelate. 2-Diphenyl-1-picrylhydrazyl (DPPH) and superoxide radical scavenging assays were performed to compare the antioxidant abilities of the black-bone silky fowl oligopeptide and iron(II)-oligopeptide chelate. The optimal conditions for iron(II) oligopeptide chelate preparation were 4 % of the black-bone silky fowl oligopeptide and a ratio of the black-bone silky fowl oligopeptide to FeCl2·4H2O of 5:1 at pH=4. Under these conditions, the chelation rate was (84.9±0.2) % (p<0.05), and the chelation yield was (40.3±0.1) % (p<0.05). The structures detected with UV-Vis spectroscopy, electron microscopy and FTIR spectra changed significantly after chelation, suggesting that Fe(II) ions formed coordinate bonds with carboxylate (-RCOO¯) and amino (-NH2) groups in the oligopeptides, confirming that this is a new oligopeptide-iron chelate. The iron(II)-oligopeptide chelate had stronger scavenging activity towards DPPH and superoxide radicals than did the black-bone silky fowl oligopeptide

Plant‐derived peptides for the improvement of Alzheimer's disease: Production, functions, and mechanisms

Abstract Alzheimer's disease (AD) is a progressive neurodegenerative disease with an insidious onset that seriously affects human health. Plant‐derived peptides have been found to hinder the development of AD pathologies, which is an excellent candidate for preventing AD. However, due to the excessively complicated pathogenesis of AD and the fact that most studies on the activity of plant‐derived peptides are single and not deep enough, which restricted the development and application of plant‐derived AD‐prevention peptides (PADPs). This review summarized the currently available means of obtaining PADPs, in vitro and in vivo AD‐prevention activity validation protocols, molecular pathways of PADPs, the structure–activity relationship between plant‐derived peptides and AD‐prevention activity, and some perspectives of current advanced technologies. This paper will help to develop the foundation for the production and exploitation of PADPs