Physicochemical Properties Of Collagen Research Articles

Study on Interaction Mechanism between Neutral Salts and Collagen by Combining Experiments with Molecular Dynamics Simulation

The effect of salt on the collagen of hide/skin is of great significance in leather-making. However, the interaction between neutral salts and collagen has not been clear, since the microscopic interaction is hard to be observed directly from the macro level of hide/skin collagen. In this study, the collagen solutions in the typical neutral salts (NaCl, CaCl2, and Na2SO4) systems were used to explore the interaction mechanism between neutral salts and collagen via combining experiments with molecular dynamics (MD) simulation. The results of fluorescence measurements of pyrene, dynamic light scattering, atomic force microscopy, and isoelectric point suggested that the variation of the interaction between different neutral salts and collagen was accompanied with the changes in physicochemical properties of collagen. MD simulation further revealed more detailed information on the interaction mechanism between neutral salts and collagen at the molecular level. The computational results of non-bond energy of the collagen-salt model boxes indicated that the electrostatic interactions of different salts with collagen molecules had the order of CaCl2> Na2SO4> NaCl. The analyses of the visualized conformation and the radial distribution functions showed that CaCl2 with Ca2+ as contributing ion tended to form intramolecular salt bridges with collagen, while Na2SO4 with SO42-as contributing ion more likely formed salt bridges between collagen molecules in the shape of agglomerates. In contrast, NaCl with Cl-as contributing ion was scattered around the collagen models, and its effect on collagen was much smaller. The study elaborated the interaction mechanism of typical neutral salts and collagen to be helpful for further understanding and improving the use of neutral salts in many steps involved in leather production.

Effect of Extraction Time on the Extractability and Physicochemical Properties of Pepsin—Soluble Collagen (PCS) from the Skin of Silver Catfish (Pangasius sp.)

The current study aimed to determine the effects of extraction time on the extractability and physicochemical properties of collagen from the skin of silver catfish (Pangasius sp.). Pepsin soluble collagen (PSC) was extracted for 24 and 48 h and analysed in terms of chemical composition, solubility, functional group, microstructure, and rheological properties. The yields of PSC at 24 h and 48 h extraction time were 23.64% and 26.43%, respectively. The chemical composition exhibited significant differences, with PSC extracted at 24 h showing better moisture, protein, fat, and ash content. Both collagen extractions indicated the highest solubility at pH 5. In addition, both collagen extractions exhibited Amide A, I, II, and III as fingerprint regions for collagen structure. The morphology of the extracted collagen appeared porous with a fibril structure. The dynamic viscoelastic measurements of complex viscosity (η*) and loss tangent (tan δ) decreased as temperature increased, and the viscosity increased exponentially as the frequency increased, whereas the loss tangent decreased. In conclusion, PSC extracted at 24 h showed similar extractability to that extracted at 48 h but with a better chemical composition and shorter extraction time. Therefore, 24 h is the best extraction time for PSC from silver catfish skin.

Proteases for obtaining of food protein hydrolysates from proteinaceous by-products

Due to the increasing shortage of food protein in the world, the most effective and complete use of proteinaceous substrates is an urgent task. The most promising way to utilize secondary protein-containing raw materials is to increase its nutritional value through enzymatic hydrolysis. The use of protein hydrolysates obtained from protein-containing by-products has great potential in various areas of the food industry, as well as in the production of foods for medical and special dietary uses. The aim of the research was to propose optimal methods for processing protein substrates to obtain hydrolysates with desired properties, taking into account the characteristics of the main types of proteinaceous by-products and the specificity of proteases used. Material and methods. We used the data contained in PubMed, WoS, Scopus, and eLIBRARY.RU databases, which meet the requirements of scientific reliability and completeness. Results. Collagen-containing wastes from the meat, poultry and fish processing industries, whey, soy protein and gluten are the main types of protein-containing by-products successfully used to produce food and functional hydrolysates. The molecular structure, basic biological and physico-chemical properties of collagen, whey proteins, various protein fractions of wheat gluten and soy protein are described. The expediency of enzymatic treatment of protein-containing by-products using proteases is shown to reduce antigenicity and eliminate anti-nutritional properties, improve nutritional, functional, organoleptic and bioactive properties for subsequent use in food production, including those for medical and special dietary uses. Information is presented on the classification of proteolytic enzymes, their main properties, and the effectiveness of their use in the processing of various types of proteinaceous by-products. Conclusion. Based on the literature data analysis, the most promising methods for obtaining food protein hydrolysates from secondary protein-containing raw materials are proposed, including pretreatment of substrates and the selection of proteolytic enzymes with a certain specificity.

Electrospun Collagen Scaffold Bio-Functionalized with Recombinant ICOS-Fc: An Advanced Approach to Promote Bone Remodelling.

The treatment of osteoporotic fractures is a severe clinical issue, especially in cases where low support is provided, e.g., pelvis. New treatments aim to stimulate bone formation in compromised scenarios by using multifunctional biomaterials combined with biofabrication techniques to produce 3D structures (scaffolds) that can support bone formation. Bone’s extracellular matrix (ECM) is mainly composed of type I collagen, making this material highly desirable in bone tissue engineering applications, and its bioactivity can be improved by incorporating specific biomolecules. In this work, type I collagen membranes were produced by electrospinning showing a fibre diameter below 200 nm. An optimized one-step strategy allowed to simultaneously crosslink the electrospun membranes and bind ICOS-Fc, a biomolecule able to reversibly inhibit osteoclast activity. The post-treatment did not alter the ECM-like nanostructure of the meshes and the physicochemical properties of collagen. UV-Vis and TGA analyses confirmed both crosslinking and grafting of ICOS-Fc onto the collagen fibres. The preservation of the biological activity of grafted ICOS-Fc was evidenced by the ability to affect the migratory activity of ICOSL-positive cells. The combination of ICOS-Fc with electrospun collagen represents a promising strategy to design multifunctional devices able to boost bone regeneration in osteoporotic fractures.

Physicochemical Properties of Collagen from the Bone of Harpadon nehereus and Its Protective Effects against Angiotensin II-Induced Injury in Human Umbilical Vein Endothelial Cells.

The physicochemical characterization of a new collagen from the bone of Harpadon nehereus (HNBC) and its protective effects against Ang II-induced injury of human umbilical vein endothelial cells (HUVEC) were investigated. The triple helix of HNBC analyzed by SDS-PAGE was formed as (α1)2α2, belonging to type I collagen. UV spectra showed that HNBC had a maximum absorbance at 230 nm. FTIR spectra indicated the triple helical structure and activity of HNBC. The high solubility of HNBC was observed in the low pH ranges (≤4) and NaCl concentrations (≤2%, w/v). The maximum transition (Tm) of HNBC was determined to be 48.5 °C. The amino acid composition analysis showed that glycine, glutamic acid, proline, and alanine were the abundant amino acids available in HNBC. HNBC showed free radical (DPPH and OH·) scavenging activities in the tested concentrations (0.5–6 mg/mL). In addition, HNBC could effectively protect against Ang II-induced injury of HUVEC by increasing the activities of antioxidant enzymes, such as CAT, SOD, and GSH-Px. Overall, collagen from the bone of H. nehereus has promising prospects in functional food and biomedical industries.

Self-Assembled Nanofibrous Marine Collagen Matrix Accelerates Healing of Full-Thickness Wounds.

There is an urgent clinical need for wound dressings to treat skin injuries, particularly full-thickness wounds caused by acute and chronic wounds. Marine collagen has emerged as an attractive and safer alternative due to its biocompatibility, diversity, and sustainability. It has minimum risk of zoonotic diseases and less religious constraints as compared to mammalian collagen. In this study, we reported the development of a self-assembled nanofibrous barramundi (Lates calcarifer) collagen matrix (Nano-BCM), which showed good biocompatibility for full-thickness wound-healing applications. The collagen was extracted and purified from barramundi scales and skin. Thereafter, the physicochemical properties of collagen were systematically evaluated. The process to extract barramundi skin collagen (BC) gave an excellent 45% yield and superior purity (∼100%). More importantly, BC demonstrated structural integrity, native triple helix structure, and good thermal stability. BC demonstrated its efficacy in promoting human primary dermal fibroblast (HDF) and immortalized human keratinocytes (HaCaT) proliferation and migration. Nano-BCM has been prepared via self-assembly of collagen molecules in physiological conditions, which resembled the native extracellular matrix (ECM). The clinical therapeutic efficacy of the Nano-BCM was further evaluated in a full-thickness splinted skin wound mice model. In comparison to a clinically used wound dressing (DuoDerm), the Nano-BCM demonstrated significantly accelerated wound closure and re-epithelization. Moreover, Nano-BCM nanofibrous architecture and its ability to facilitate early inflammatory response significantly promoted angiogenesis and differentiated myofibroblast, leading to enhanced wound healing. Consequently, Nano-BCM demonstrates great potential as an economical and effective nonmammalian substitute to achieve skin regeneration.

Physicochemical Properties of Collagen from Acaudina Molpadioides and Its Protective Effects against H2O2-Induced Injury in RAW264.7 Cells.

Collagen is a promising biomaterial used in the beauty and biomedical industries. In this study, the physicochemical characterization, antioxidant activities, and protective effects against H2O2-induced injury of collagen isolated from Acaudina molpadioides were investigated. The amino acid composition analysis showed that the collagen was rich in glycine (Gly), alanine (Ala), and glutamic acid (Glu), but poor in tyrosine (Tyr) and phenylalanine (Phe). Zeta potential analysis revealed that the isoelectric point (pI) of collagen from Acaudina molpadioides was about 4.25. It possessed moderate scavenging activities of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radicals in a dose-dependent manner. In addition, the collagen was able to effectively improve cell viability and morphology, inhibit the production of Malondialdehyde (MDA), and increase the activities of Superoxide Dismutase (SOD) and Glutathione Peroxidase (GSH-Px) in cultured RAW264.7 cells, resulting in a protective effect against H2O2-induced injury. Overall, the results showed that collagen extracted from A. molpadioides has promising prospects in the beauty and cosmetics industries.

МОДИФИЦИРОВАНИЕ КОЛЛАГЕНА И ЖЕЛАТИНА ПОД ДЕЙСТВИЕМ МИКРОВОЛНОВОГО ПОЛЯ

The microwave field influence on the physicochemical properties of collagen and gelatin was studied. It is shown that when microwave field acts on the studied protein samples, a change in the molecules structure formation occurs. It was experimentally established that microwave exposure leads to the structural modification of collagen and gelatin molecules. This modification is accompanied by a change in the physicochemical properties of the studied biopolymers. It is shown that microwave field exposure leads to a decrease in the viscosity of collagen and gelatin solutions. A decrease in viscosity indicates that there’s a structural or transient processes occurring in protein molecules.The kinetics of swelling with time for collagen and gelatin samples was studied. It is shown that the use of a microwave field leads to a decrease in the rate constant of swelling. The swelling degree of the studied samples decreases on average by 60%. It is shown that isoelectric points of the proteins are shifted (pI from 5 to 6 for collagen and up to 5.5 for gelatin).

MODERN POSSIBILITIES OF HIGH FREQUENCY RADIO WAVE CURRENTS IN AESTHETIC MEDICINE

The radio wave effect on biological tissues is of great interest to dermatologists, cosmetologists, and plastic surgeons. The modern information about radio wave therapy of involutional changes of face and neck skin is shown. A literature review of the physical aspects of the high-frequency current of the radio wave range is presented. The thermal and oscillation effects of radio frequency (RF) on biological tissues are shown, the mechanism of these effects at the cellular level is described. Primary targets of high-frequency currents exposure in the skin, their effect on the physicochemical properties of collagen and unicellular organisms are described. The mechanism of pulsed and continuous radio wave technologies and the possibility of their use in medical practice are described. Types of minimally invasive and non-invasive electrodes, when the choice of electrode diameter determines the therapy of specific clinical cases, are shown. The multifunctional minimally invasive RF device Innofill with needle and cannula active electrodes is presented. The technical characteristics and exposure modes of the device are considered. The features of the cannula electrode and the possibilities of its use in solving various dermatological and cosmetic problems are highlighted. A histological study of a combined technique of the Innofill radio wave method with the filler based on hyaluronic acid, was performed. A change in the amount of collagen and elastin fibers was noted. The distribution of the filler in the tissues was evaluated after the injection of the filler based on hyaluronic acid, after 30 and 60 seconds of RF exposure and after 30 seconds of RF exposure in a tunnel technique with the formation of a collagen channel. Histological material was stained with hematoxylin-eosin, Masson and Van Gieson trichrome. High efficiency, safety and prolonged effect of this exposure were described.

Characterization of Carcass Color Differences Between Hen (Small Birds) and Meat-Type (Large Birds) Pheasant Lines Associated with Freezing

ObjectivesThe aim of this study was to determine the cause of why hen carcasses turn red on freezing in contrast to meat-type male pheasants.Materials and MethodsHen pheasant carcasses (n = 5) that were visibly red on the outside and larger meat-type pheasants (n = 5, not red) from the same harvest day at a commercial plant were obtained. The frozen carcasses in their original, sealed plastic bag were brought to the University of Wisconsin Meat Science Laboratory and stored in a –25°C freezer prior to being semi-thawed for about 24 h (4°C). Breast muscles (M. pectoralis major) were collected, cut into similar sections (approx. 2.5 cm × 2.5 cm × 1.5 cm), vacuum-packaged in a Nylon/PE vacuum bag, and stored in the –25°C freezer. The frozen samples were ground (9.5 mm plate). Skins were trimmed of excessive fat prior to pulverization in liquid nitrogen. Instrumental color, pH, proximate composition, myoglobin content (myoglobin-based methodology, Mb), and muscle fiber type determination were conducted. All data were analyzed using the PROC MIXED procedure of the SAS statistical analysis software. Dependent variable means were separated (P < 0.05) by pairwise comparisons using the PDIFF option.ResultsHens exhibited greater redness (CIE a*, 4.87) and were darker (CIE L*, 53.33) than the meat-type pheasants (CIE a*, 4.31 and CIE L*, 55.74) on frozen/semi-thawed breast muscles (P < 0.05), whereas no difference was observed in the yellowness (CIE b*) between the different pheasant types (P > 0.05). The highest pH (6.38) and Mb (1.89 mg/g) values were obtained from the skin of the hen carcasses compared to the skin of the meat-type pheasants (pH 6.21, Mb 1.22 mg/g). In addition, the breast muscle of the hens had a higher pH and Mb content. The hen skin exhibited the highest moisture and protein content as well as a lower fat content than the skin from meat-type pheasants. The intermediate fiber (IIA) type was the only type found in the pectoralis major muscles, regardless of the different pheasant types.ConclusionThe results of the current study reveal that hen carcasses had more red pigmentation and exhibited significantly higher pH values, redness, and Mb level than the meat-type pheasants. In this regard, a higher pH might suggest hens were more stress-susceptible which produced the darker red meat. Also, higher ultimate pH values could protect myoglobin and hemoglobin from denaturation. A major part of the darkening might be related to the lower amount of fat within the skin which may have facilitated transparency to the darker, more red breast muscle. Genetics or production practices differences did not appear to alter muscle fiber types. Our findings suggest that the more intense red appearance may be associated with the presence of hemoglobin rather than myoglobin. Future evaluation of the effects of soaking pheasant skin with various pH solutions and scalding variations on the physicochemical properties of collagen may merit investigation.

Is quercetin an alternative natural crosslinking agent to genipin for long-term dermal scaffolds implantation?

As biocompatible matrices, porcine dermal scaffolds have limited application in tissue engineering due to rapid degradation following implantation. This study compared the physical, chemical and biomechanical changes that occurred when genipin and quercetin were used to crosslink dermal scaffolds and to determine whether quercetin could be used as an alternative to genipin. Physicochemical changes in the collagen were assessed using spectroscopic methods [X-ray diffraction analysis (XRD) and nuclear magnetic resonance (NMR) analysis]. The crosslinking reaction was evaluated by quantification of amino acids and the degree of this reaction by ninhydrin assay. Because the mechanical behaviour of the collagen matrices is highly influenced by crosslinking, the tensile strength of both sets of scaffolds was evaluated. The highest mechanical strength, stiffness, degree of crosslinking and changes in the packing features of collagen (measured by XRD) were achieved using genipin. Some of the results found in the quercetin-crosslinked scaffolds were possibly due to hydration and dehydration effects elicited by the solvents (phosphate-buffered saline or ethanol), as seen in the NMR results. In the quercetin-ethanol-crosslinked scaffolds, possible reorientation of the amino groups of the collagen molecule may have taken place. Therefore, depending on their proximity to the crosslinking reagent, different types and numbers of interactions may have occurred, inducing a higher crosslinking degree (as evidenced by the ninhydrin assay) and reduction in the free amino acids after reaction. Both crosslinking agents and solvents interfere in the physicochemical properties of collagen thereby inducing variations in the matrix structure. Quercetin-crosslinked scaffolds may have broader clinical application where a lower degree of crosslinking and stiffness is required. Copyright © 2016 John Wiley & Sons, Ltd.

Purification, optimization and physicochemical properties of collagen from soft-shelled turtle calipash

The present work was to optimize the purification conditions for soft-shelled turtle (Pelodiscus sinensis) calipash collagen (STCC) isolated by pepsin and to explore collagen physicochemical properties for potential biomaterial applications. Single-factor test and orthogonal method L9 (34) were employed with the STCC recovery yield as indicator. The optimum purification conditions were obtained when NaCl concentration, collagen concentration and purification time were 2M, 8g/L, and 24h, respectively. Purified STCC were characterized by SDS-PAGE, UV scanning, FTIR, solubility, thermal behavior and amino acid analysis. The results showed that STCC contained high hydroxyproline content than that of other fishery skins, belonging to typical type I collagen in form of [α1(I)] 2α2(I). FTIR spectra of STCC were quite similar to other aquatic animals’ collagens. It has the lowest solubility at pH 6, and when NaCl concentration decreased from 2% to 6% (w/v), solubility dropped. The denaturation temperature (Td) and melting temperature (Tm) were 35.1°C and 105.14°C, respectively. Morphology of STCC depicted as regular and porous network structure by SEM. In general, the results suggested that turtle calipash can be exploited as alternatives to mammalian collagen and could also be used for biomedical applications as a potential new material.

Is dialdehyde starch a valuable cross-linking agent for collagen/elastin based materials?

Collagen and elastin are the main structural proteins in mammal bodies. They provide mechanical support, strength, and elasticity to various organs and tissues, e.g. skin, tendons, arteries, and bones. They are readily available, biodegradable, biocompatible and they stimulate cell growth. The physicochemical properties of collagen and elastin-based materials can be modified by cross-linking. Glutaraldehyde is one of the most efficient cross-linking agents. However, the unreacted molecules can be released from the material and cause cytotoxic reactions. Thus, the aim of our work was to investigate the influence of a safer, macromolecular cross-linking agent—dialdehyde starch (DAS). The properties of hydrogels based on collagen/elastin mixtures (95/5, 90/10) containing 5 and 10 % of DAS and neutralized via dialysis against deionized water were tested. The homogenous, transparent, stiff hydrogels were obtained. The DAS addition causes the formation of intermolecular cross-linking bonds but does not affect the secondary structure of the proteins. As a result, the thermal stability, mechanical strength, and, surprisingly, swelling ability increased. At the same time, the surface properties test and in vitro study show that the materials are attractive for 3T3 cells. Moreover, the materials containing 10 % of DAS are more resistant to enzymatic degradation.

尼罗罗非鱼皮胶原蛋白乳酸提取工艺条件优化及理化特性研究

以罗非鱼皮为原料，乳酸为介质提取胶原蛋白。通过单因素实验分别考察pH值、液固比和提取时间对胶原蛋白提取率的影响，在此基础上，利用Box-Behnken中心组合实验设计和响应面分析法对乳酸提取胶原蛋白条件进行优化，并对胶原蛋白的理化性质进行评估。结果表明：乳酸提取罗非鱼皮胶原蛋白(ASC)的优化工艺条件为pH2.1、液固比65:1 (mL/g)、时间44 h，在此条件下罗非鱼皮胶原蛋白提取率可达85.57%，ASC的亚基组成形式为(α1)2α2，热变性温度为32.56℃，呈现均匀的纤维结构。 This study was undertaken to optimize the acidic extraction of collagen from Nile tilapia (Oreoch-romis niloticus) skin. Lactic acid was used to extract collagen. Further, three process conditions affecting the yield of collagen extraction with lactic acid, such as pH value, liquid-to-solid ratio and extraction time, were optimized by single factor experiment. According to this, Box-Behnken ex-perimental design combined with response surface methodology was taken to optimize the ex-tracting conditions of collagen using lactic acid. Based on the optimized conditions, physicochemical properties of collagen were evaluated. The results indicated that the optimal conditions for collagen extraction were pH2.1, liquid-to-solid ratio 65:1 (mL/g) and extraction time 44 h, under which a yield of collagen of 85.57% was obtained. The ASC showed that SDS-PAGE pattern, the thermal denaturation temperature, and morphology were (α1)2α2, 32.56℃, and evenly fibrous structure, respectively.

Dielectric behaviour and conformational stability of collagen on interaction with DNA

Collagen–DNA interaction studies will aid in improving the stability of DNA against nucleases. In the present study, the effect of DNA on different physico-chemical properties of collagen like viscosity, conformation and dielectric behaviour has been studied. Increase of DNA concentration leads to the increment of viscosity of collagen at the pH 4 and 5, but the trend is reversed at the pH of 6 and 7 due to the formation of collagen fibrils. The temperature dependent CD spectroscopic studies for collagen–DNA conjugate showed that thermal stability of collagen is modulated with increasing molar concentration of DNA. It also shows that DNA interactions with collagen did not result in change in the triple helical structure of collagen. Impedance measurements show that the strength of ion pairs for different molar concentrations of collagen–DNA conjugates has changed. Nyquist plot for collagen–DNA conjugate posses higher Y″ at DNA concentration of 1:25 and 1:50 whereas at 1:1 and 1:10 lower Y″ than the native collagen have been observed. An understanding of this nature of the collagen–DNA interactions is helpful for gene delivery applications.

Collagen-curcumin interaction — A physico-chemical study

Curcumin is a widely used therapeutic agent with a wide spectrum of biological and physiological applications like wound healing and interacts with the skin protein, collagen. This work reports the effect of curcumin on various physico-chemical properties of collagen. The results suggest that significant changes in viscosity and surface tension occur on collagen interacting with curcumin. Secondary structure analysis using circular dichroism shows that curcumin does not alter the triple helical structure of collagen. Increasing concentration of curcumin resulted in aggregation of the protein. Further, curcumin imparts high level of thermal stability to collagen with shrinkage temperature of collagen increasing from 60 to 90°C.

Effect of surfactants on the thermal, conformational and rheological properties of collagen

Collagen is an important biomaterial and its interaction with surfactant is important in light of its use in various cosmetics and dermatological applications. Presently, the effect of surfactants on the physico-chemical properties of collagen has been studied. The thermal stability of collagen is reduced by sodium dodecyl sulfate and hexadecyltrimethylammmonium bromide, whereas Triton X-100 does not. The viscosity of collagen is influenced greatly depending on the surfactant concentrations. The secondary structure of collagen shows changes only in the molar ellipticity. The role of charge and concentration of surfactants in influencing the various physico-chemical properties of collagen has been elucidated.

황다랑어 복부 껍질을 이용한 콜라겐의 제조 및 물리화학적 특성 해석

Processing of collagen from yellowfin tuna (Thunnus albacares) abdominal skins was optimized by response surface methodology and central composite design. The values of independent variables at optimal conditions were NaOH concentration: 0.5 N, NaOH treatment time: 36.2 hr, pepsin concentration: 1:4.9 ratio (0.245%, w/v), and digestion time: 48.1 hr, respectively. The collagen content estimated under optimal conditions was 33.1%, and the actual experimental collagen content was 32.3%. Physicochemical properties of collagen from yellowfin tuna abdominal skin were investigated by amino acids analysis, SDS-PAGE, FT-IR, viscosity and denaturation temperature. Amino acids content of the collagen was 21.0%. SDS-PAGE pattern of the collagen showed two different <TEX>$\alpha$</TEX>-chain (<TEX>${\alpha}_1$</TEX>- and <TEX>${\alpha}_2$</TEX>- chain), <TEX>$\beta$</TEX>-component and <TEX>$\gamma$</TEX>-component. The spectrum of FT-IR of the collagen showed wavenumber at 3,434, 1,650, 1,542 and <TEX>$1,235\;cm^{-1}$</TEX> representing the regions of amide A, I, II and III, respectively. Relative viscosity of the collagen decreased continuously on heating up to <TEX>$32^{\circ}C$</TEX>, and the rate of decrease was retarded in the temperature range of <TEX>$35-50^{\circ}C$</TEX>. Denaturation temperature (Td) of the collagen solution (0.06%, w/v) was <TEX>$31^{\circ}C$</TEX> and was lower than calf skin collagen (<TEX>$35^{\circ}C$</TEX>).

Taurine prevents fructose-diet induced collagen abnormalities in rat skin

Objective The aim of the study is to investigate the effect of taurine administration on the content and characteristics of skin collagen in high-fructose-fed rats. Research Design and Methods Adult male Wistar rats were divided into four groups of six each: a control group (CON) and a taurine-supplemented control group (CON+TAU), a high fructose diet-fed group (FRU), and a taurine supplemented fructose diet-fed group (FRU+TAU). After 30 days, collagen was isolated from the skin, and its physicochemical properties were studied. Results Fructose administration caused an accumulation of collagen and extensive cross-linking. This was evidenced by increases in glycation, fluorescence, and peroxidation in collagen samples. The physicochemical properties of collagen, like shrinkage temperature, aldehyde content, solubility pattern, and susceptibility to denaturing agents, were altered in the fructose-fed rats. The sodium dodecyl sulphate-polyacrylamide gel electrophoretic (SDS-PAGE) pattern of collagen from fructose-fed rats showed and elevated β component of Type I collagen. Simultaneous administration of taurine alleviated these changes. Conclusion The positive influence of taurine on both collagen content and its properties suggests a potential mechanism for the ability of taurine to delay diabetic complications.

Retracted] Fructose Diet‐Induced Skin Collagen Abnormalities Are Prevented by Lipoic Acid

Nonenzymatic glycation of proteins, leading to chemical modification and cross-linking are of importance in the pathology of diabetic complications.We studied the effect of α-lipoic acid (LA) on the content and characteristics of the protein collagen from skin of high-fructose fed rats. The rats were divided into 4 groups of 6 each. Two groups of rats were fed with a high fructose diet (60 g/100 g diet) and administered either LA (35 mg/kg b.w., i.p) (FRU+LA) or 0.2 ml vehicle (saline) (FRU) for 45 days. The other 2 groups were fed with control diet containing starch (60 g/100 g diet) and administered either saline (CON) or lipoic acid (CON+LA). The rats were maintained for 45 days and then sacrificed. Plasma glucose, insulin, fructosamine, protein glycation, and blood glycated hemoglobin (HbA1C) were measured. Collagen was isolated from skin and the physicochemical properties of collagen were studied. Fructose administration caused accumulation of collagen in skin. Extensive cross-linking was evidenced by enhanced glycation and AGE-linked fluorescence. Increased peroxidation and changes in physicochemical properties such as shrinkage temperature, aldehyde content, solubililty pattern, susceptibility to denaturing agents were observed in fructose-fed rats. SDS gel pattern of collagen from these rats showed elevated β component of type I collagen. These changes were alleviated by the simultaneous administration of LA. Administration of LA to fructose-fed rats had a positive influence on both quantitative and qualitative properties of collagen. The results suggest a mechanism for the ability of LA to delay diabetic complications.