Collagen Amino Acid Research Articles

The influence of single and binary mixtures of collagen amino acids on the structure of synthetic calcium hydroxyapatite as a nanobiomaterial.

The modifications carried out as part of this study were aimed at examining the effect of the addition of collagen amino acids: glycine, proline and hydroxyproline (used separately and in binary mixtures) on the physicochemical properties of hydroxyapatite obtained in their presence in vitro. The influence of mixtures of amino acids on these properties is an important element of scientific novelty. The obtained samples were tested with the use of instrumental methods: FT-IR, TEM, EDXMA, PXRD and UV spectrophotometry. The results showed the influence of the amino acids used on changes in the relative content of the labile phosphate groups constituting the structure of the hydrated surface layer of crystals. As a consequence, there were differences in some physicochemical properties of the obtained hydroxyapatites (degree of crystallinity, molar Ca/P ratio). It was also determined how the ability of the used amino acids to bind to hydroxyapatite changes.

Sequence-specific response of collagen-mimetic peptides to osmotic pressure

Native collagen molecules usually contract upon dehydration, but the details of their interaction with water are poorly understood. Previous molecular modeling studies indicated a spatially inhomogeneous response, with a combination of local axial expansion and contraction. Such sequence-dependent effects are difficult to study with native collagen. In this article, we use collagen-mimetic peptides (CMPs) to investigate the effect of osmotic pressure on several collagen-mimetic sequences. Synchrotron x-ray diffraction combined with molecular dynamics simulations shows that CMPs pack differently depending on osmotic pressure and exhibit changes in the helical rise per residue of individual molecules. Infrared spectroscopy reveals that osmotic pressure affects the stability of the triple helix through changes in triple helix-stabilizing hydrogen bonds. Surprisingly, CMPs with the canonical collagen sequence glycine–proline–hydroxyproline are found to elongate upon dehydration, while sequence modifications are able to reverse this tendency. This strongly suggests that the overall contraction of native collagen molecules is not programmed into the canonical sequence but is specific to local amino acids that substitute for proline or hydroxyproline along the protein chain. Collagen is an essential protein in mammalian extracellular tissues and a better understanding of its mechanical function is important both from a materials science and from a biomedical viewpoint. Recently, collagen has been shown to contract along the fibre direction when subjected to osmotic stress, a process that could play important roles in strengthening bone and in developing tissue tension during extracellular matrix development. The present work uses collagen-like short peptides to show that the canonical collagen sequence is not responsible for this contraction. The conclusion is that the collagen amino acid sequence must have evolved to include guest sequences within the canonical glycine-proline-hydroxyproline repeat that provide the observed contractility.Impact statementCollagen is an essential protein in mammalian extracellular tissues and a better understanding of its mechanical function is important both from a materials science and from a biomedical viewpoint. Recently, collagen has been shown to contract along the fibre direction when subjected to osmotic stress, a process that could play important roles in strengthening bone and in developing tissue tension during extracellular matrix development. The present work uses collagen-like short peptides to show that the canonical collagen sequence is not responsible for this contraction. The conclusion is that the collagen amino acid sequence must have evolved to include guest sequences within the canonical glycine-proline-hydroxyproline that provide the observed contractility.Graphic

Studies on the Development of Benzoyl Peroxide Catalysed Rapid Oil Tanning using Linseed Oil

Leather tanning is a stabilisation process of skin fibers. This is achieved by the interaction of collagen amino acids with tanning agents to stabilise skin from putrefaction. Tanning of collagen with oil is a special class of tanning known as chamois tanning. Chemically, the oil tanning involves oxidation of unsaturation present in the oil, which is generally achieved by exposing oil treated skins to air. In this study, Benzoyl peroxide has been used as an accelerating agent for oxidation of unsaturated bonds present in the linseed oil for oil tanning process. Results shows remarkable reduction in tanning duration from fifteen days to two days. The chamois leathers prepared using oxidation accelerant (Benzoyl peroxide) have been evaluated for physical properties such as water absorption (611%), tensile strength (18 N/mm2) and percentage of elongation (66 %) which are found to be better than control leathers.

The Pro-Gly or Hyp-Gly Containing Peptides from Absorbates of Fish Skin Collagen Hydrolysates Inhibit Platelet Aggregation and Target P2Y12 Receptor by Molecular Docking.

Previous studies found that the collagen hydrolysates of fish skin have antiplatelet activity, but this component remained unknown. In this study, eleven peptides were isolated and identified in the absorbates of Alcalase-hydrolysates and Protamex®-hydrolysates of skin collagen of H. Molitrix by reverse-phase C18 column and HPLC-MS/MS. Nine of them contained a Pro-Gly (PG) or Hyp-Gly (OG) sequence and significantly inhibited ADP-induced platelet aggregation in vitro, which suggested that the PG(OG) sequence is the core sequence of collagen peptides with antiplatelet activity. Among them, OGSA has the strongest inhibiting activities against ADP-induced platelet aggregation in vitro (IC50 = 0.63 mM), and OGSA inhibited the thrombus formation in rats at a dose of 200 μM/kg.bw with no risk of bleeding. The molecular docking results implied that the OG-containing peptides might target the P2Y12 receptor and form hydrogen bonds with the key sites Cys97, Ser101, and Lys179. As the sequence PG(OG) is abundant in the collagen amino acid sequence of H. Molitrix, the collagen hydrolysates of H. Molitrix might have great potential for being developed as dietary supplements to prevent cardiovascular diseases in the future.

Improved quality control criteria for stable carbon and nitrogen isotope measurements of ancient bone collagen

The carbon (δ13C) and nitrogen (δ15N) isotopic compositions of bone and tooth collagen provide a powerful tool for studying past biological, environmental, and cultural phenomena. Collagen has a well-understood chemical composition that has enabled the development of invaluable quality control (QC) criteria for isotopic data – something that is extremely rare among biogeochemical research on ancient biomolecules as a whole. The most important of these collagen QC criteria is atomic C:N ratio (ratio of carbon to nitrogen atoms), which provides an indicator of the extent to which the amount of carbon and nitrogen present in a sample matches the known composition of pure collagen, thereby indicating whether contamination or diagenesis may be influencing a sample's isotopic compositions. We present a model describing the relationship between the carbon and nitrogen isotopic and elemental compositions that accounts for the isotopic composition of the endogenous collagen and exogenous contaminants as well as taxon-specific information about the collagen's amino acid composition. In some cases the traditional C:N QC parameters are applicable, while in others they can result in the inclusion of unreliable (altered) isotopic data primarily due to contamination from humic substances. Using new and previously published data on taxa commonly encountered in ancient studies, we further illustrate how using traditional C:N QC parameters may lead to the inclusion of altered isotopic compositions in real archaeological and paleontological scenarios. We argue that the traditional ‘one size fits all’ approach to the C:N QC criterion should be avoided and we outline new collagen QC criteria specific to certain taxa and environments on the basis of the results of our model. These revised criteria will help to improve the interpretation of isotopic data by more accurately identifying samples with isotopic compositions altered by contamination.

Anti-fatigue Effects of Santé Premium Silver Perch Essence on Exhaustive Swimming Exercise Performance in Rats.

Aim: Fish soup is a traditional Chinese food usually offered as a healthy supplement to elders, pregnant women and persons who just had surgery. Silver perch (Santé premium silver perch essence, SPSPE) extract contains various quality proteins, collagen, minerals, trace elements, and branch chain amino acids (BCAA) that could help individuals recover from exhaustion and control body weight. However, there are very limited studies exploring the effects of fish extracts on exercise performance and fatigue, and relevant physiological mechanisms. Therefore, the purpose of this study was to investigate the effects of chronic SPSPE administration on exhaustive exercise performance.Method: Male Wistar rats weighing around 250 g were divided into 4 groups: Control, 1X SPSPE (6.2 ml/kg), 2X SPSPE (12.4 ml/kg) and 5X SPSPE (31.0 ml/kg). Rats were administrated SPSPE by oral gavage feeding every day for 33 days. Their body weight were measured every week. Before and after the exhaustive swimming test, the blood was collected for circulating lactate, glucose, ammonia, hormones, and myoglobin analysis. Rats were sacrificed after performing an exhaustive swimming exercise test. The liver tissues were collected for glycogen content and H&E staining.Results: After the administration of 1X and 5X SPSPE, swimming fatigue was significantly delayed (p = 0.024). There was no difference in the hormone plasma level between the control and SPSPE groups. The induction of plasma corticosterone and TBARS by exhaustive swimming exercise could be decreased by SPSPE administration. The increased plasma myoglobin concentration from exhaustive swimming exercise was weakened by SPSPE supplementation. The higher glycogen sparing contained in liver tissue was observed in SPSPE-treated groups (p < 0.05).Conclusion: SPSPE could efficiently delay swimming fatigue through sparing of liver glycogen and attenuation of plasma TBARS, myoglobin induction by exhaustive exercise. Our findings provide a scientific-based fundamental information and better understanding for developing a fish extract-based anti-fatigue supplement.

Characterization of Properties, In Vitro and In Vivo Evaluation of Calcium Phosphate/Amino Acid Cements for Treatment of Osteochondral Defects.

Novel calcium phosphate cements containing a mixture of four amino acids, glycine, proline, hydroxyproline and either lysine or arginine (CAL, CAK) were characterized and used for treatment of artificial osteochondral defects in knee. It was hypothesized that an enhanced concentration of extracellular collagen amino acids (in complex mixture), in connection with bone cement in defect sites, would support the healing of osteochondral defects with successful formation of hyaline cartilage and subchondral bone. Calcium phosphate cement mixtures were prepared by in situ reaction in a planetary ball mill at aseptic conditions and characterized. It was verified that about 30–60% of amino acids remained adsorbed on hydroxyapatite particles in cements and the addition of amino acids caused around 60% reduction in compressive strength and refinement of hydroxyapatite particles in their microstructure. The significant over-expression of osteogenic genes after the culture of osteoblasts was demonstrated in the cement extracts containing lysine and compared with other cements. The cement pastes were inserted into artificial osteochondral defects in the medial femoral condyle of pigs and, after 3 months post-surgery, tissues were analyzed macroscopically, histologically, immunohistochemically using MRI and X-ray methods. Analysis clearly showed the excellent healing process of artificial osteochondral defects in pigs after treatment with CAL and CAK cements without any inflammation, as well as formation of subchondral bone and hyaline cartilage morphologically and structurally identical to the original tissues. Good integration of the hyaline neocartilage with the surrounding tissue, as well as perfect interconnection between the neocartilage and new subchondral bone tissue, was demonstrated. Tissues were stable after 12 months’ healing.

Bone need not remain an elephant in the room for radiocarbon dating.

Radiocarbon (14C) analysis of skeletal remains by accelerator mass spectrometry is an essential tool in multiple branches of science. However, bone 14C dating results can be inconsistent and not comparable due to disparate laboratory pretreatment protocols that remove contamination. And, pretreatments are rarely discussed or reported by end-users, making it an ‘elephant in the room’ for Quaternary scientists. Through a questionnaire survey, I quantified consensus on the reliability of collagen pretreatments for 14C dating across 132 experts (25 countries). I discovered that while more than 95% of the audience was wary of contamination and would avoid gelatinization alone (minimum pretreatment used by most 14C facilities), 52% asked laboratories to choose the pretreatment method for them, and 58% could not rank the reliability of at least one pretreatment. Ultrafiltration was highly popular, and purification by XAD resins seemed restricted to American researchers. Isolating and dating the amino acid hydroxyproline was perceived as the most reliable pretreatment, but is expensive, time-consuming and not widely available. Solid evidence supports that only molecular-level dating accommodates all known bone contaminants and guarantees complete removal of humic and fulvic acids and conservation substances, with three key areas of progress: (i) innovation and more funded research is required to develop affordable analytical chemistry that can handle low-mass samples of collagen amino acids, (ii) a certification agency overseeing dating-quality control is needed to enhance methodological reproducibility and dating accuracy among laboratories, and (iii) more cross-disciplinary work with better 14C reporting etiquette will promote the integration of 14C dating across disciplines. Those developments could conclude long-standing debates based on low-accuracy data used to build chronologies for animal domestications, human/megafauna extirpations and migrations, archaeology, palaeoecology, palaeontology and palaeoclimate models.

Evidence of a significant marine plant diet in a Pleistocene caribou from Haida Gwaii, British Columbia, through compound-specific stable isotope analysis

The Northwest Coast of Canada was likely an important location for glacial refugia in the Late Pleistocene. Recently, a caribou (Rangifer tarandus) antler fragment was reported from Graham Island dating prior to the Fraser Glaciation (MIS 3; 48,200–45,200 cal yr BP). The high carbon and nitrogen stable isotope values found in the bulk collagen samples of this caribou prompted further investigation into its diet and palaeoecological context. Today, caribou in British Columbia face rapid population and range decline, and have been placed on threatened and endangered species lists by both the U.S. and Canadian governments. Further insights into this species and its responses to changing environmental conditions can both improve our understanding of the Late Pleistocene ecosystems of the Northwest Coast and add relevant data to modern conservation issues. We employed compound-specific carbon and nitrogen stable isotope analysis to the individual amino acids of antler collagen to better understand the isotopic signal of this specimen. Our results suggest a significant marine plant contribution to the caribou's spring–summer diet, potentially reflecting an intensive foraging behavior observed in some modern-day Rangifer tarandus populations under conditions of terrestrial resource restriction.

A new mechanism for reduced cell adhesion: Adsorption dynamics of collagen on a nanoporous gold surface

Nanostructured materials such as nanoparticles and nanoporous materials strongly affect cell behaviors such as cell viability. Because cellular uptake of nanoporous materials does not occur, mechanisms for the effects of nanoporous materials on cells are different from those of nanoparticles. The effects of nanoporous materials on cells are thought to result from large conformational changes in the extracellular matrix (ECM) induced by the nanoporous materials, although the mechanotransduction and the critical focal adhesion cluster size also have an effect on the cell response. However, we show that the adhesion of mesenchymal stem cells to a gold surface is reduced for nanoporous gold (NPG), despite the conformational changes in collagen induced by NPG being below the detection limits of the experimental analyses. The adsorption dynamics of collagen on NPG are investigated by molecular dynamics simulations to determine the origin of the reduced cell adhesion to NPG. The adsorption energy of collagen on NPG is lower than that on flat gold (FG) despite there being little difference between the global conformation of collagen segments adsorbed on NPG compared with FG. This finding is related to the surface strain of NPG and the limited movement of collagen amino acids owing to interchain hydrogen bonds. The results obtained in this study provide new insight into the interactions between nanostructured materials and the ECM.

Quality control for modern bone collagen stable carbon and nitrogen isotope measurements

Abstract Isotopic analyses of collagen, the main protein preserved in subfossil bone and tooth, has long provided a powerful tool for the reconstruction of ancient diets and environments. Although isotopic studies of contemporary ecosystems have typically focused on more accessible tissues (e.g. muscle, hair), there is growing interest in the potential for analyses of collagen because it is often available in hard tissue archives (e.g. scales, skin, bone, tooth), allowing for enhanced long‐term retrospective studies. The quality of measurements of the stable carbon and nitrogen isotopic compositions of ancient samples is subject to robust and well‐established criteria for detection of contaminants and diagenesis. Among these quality control (QC) criteria, the most widely utilized is the atomic C:N ratio (C:NAtomic), which for ancient samples has an acceptable range between 2.9 and 3.6. While this QC criterion was developed for ancient materials, it has increasingly being applied to collagen from modern tissues. Here, we use a large survey of published collagen amino acid compositions (n = 436) from 193 vertebrate species as well as recent experimental isotopic evidence from 413 modern collagen extracts to demonstrate that the C:NAtomic range used for ancient samples is not suitable for assessing collagen quality of modern and archived historical samples. For modern tissues, collagen C:NAtomic falling outside 3.00–3.30 for fish and 3.00–3.28 for mammals and birds can produce systematically skewed isotopic compositions and may lead to significant interpretative errors. These findings are followed by a review of protocols for improving C:NAtomic criteria for modern collagen extracts. Given the tremendous conservation and environmental policy‐informing potential that retrospective isotopic analyses of collagen from contemporary and archived vertebrate tissues have for addressing pressing questions about long‐term environmental conditions and species behaviours, it is critical that QC criteria tailored to modern tissues are established.

Diabetes and Collagen: Interrelations

This review summarizes information on interrelations between diabetes development and collagen metabolism and structure. The growing global problem of diabetes requires the search for new strategies of its complications correction. Among them collagen structure violations and/or its impaired metabolism most often lead to profound disability. Even after several decades of intense studies, pathophysiological mechanisms underlying collagen changes in diabetes mellitus are still not well clear. The main complication is that not only diabetes cause changes in collagen metabolism and structure. Collagens via some mechanisms also may regulate glucose homeostasis, both directly and indirectly. The author also presented the results of own studies on bone and skin type I collagen amino acid composition changes with diabetes. Deepening our understanding of collagen metabolism and diabetes interrelations allows us to optimize approaches to overcome the collagen-mediated consequences of this disease. Recently, it has been clearly demonstrated that use of only antidiabetic agents cannot fully correct such violations. Preparations on the base of flavonoids, collagens and amino acids could be considered as perspective directions in this area of drug development.

Collagen-Inspired Self-Assembly of Twisted Filaments.

Collagen consists of three peptides twisted together through a periodic array of hydrogen bonds. Here we use this as inspiration to find design rules for programmed specific interactions for self-assembling synthetic collagenlike triple helices, starting from disordered configurations. The assembly generically nucleates defects in the triple helix, the characteristics of which can be manipulated by spatially varying the enthalpy of helix formation. Defect formation slows assembly, evoking kinetic pathologies that have been observed to mutations in the primary collagen amino acid sequence. The controlled formation and interaction between defects gives a route for hierarchical self-assembly of bundles of twisted filaments.

Preserved collagen reveals species identity in archaeological marine turtle bones from Caribbean and Florida sites.

Advancements in molecular science are continually improving our knowledge of marine turtle biology and evolution. However, there are still considerable gaps in our understanding, such as past marine turtle distributions, which can benefit from advanced zooarchaeological analyses. Here, we apply collagen fingerprinting to 130 archaeological marine turtle bone samples up to approximately 2500 years old from the Caribbean and Florida's Gulf Coast for faunal identification, finding the vast majority of samples (88%) to contain preserved collagen despite deposition in the tropics. All samples can be identified to species-level with the exception of the Kemp's ridley (Lepidochelys kempii) and olive ridley (L. olivacea) turtles, which can be separated to genus level, having diverged from one another only approximately 5 Ma. Additionally, we identify a single homologous peptide that allows the separation of archaeological green turtle samples, Chelonia spp., into two distinct groups, which potentially signifies a difference in genetic stock. The majority of the archaeological samples are identified as green turtle (Chelonia spp.; 63%), with hawksbill (Eretmochelys imbricata; 17%) and ridley turtles (Lepidochelys spp.; 3%) making up smaller proportions of the assemblage. There were no molecular identifications of the loggerhead turtle (Caretta caretta) in the assemblage despite 9% of the samples being morphologically identified as such, highlighting the difficulties in relying on morphological identifications alone in archaeological remains. Finally, we present the first marine turtle molecular phylogeny using collagen (I) amino acid sequences and find our analyses match recent phylogenies based on nuclear and mitochondrial DNA. Our results highlight the advantage of using collagen fingerprinting to supplement morphological analyses of turtle bones and support the usefulness of this technique for assessing their past distributions across the Caribbean and Florida's Gulf Coast, especially in these tropical environments where DNA preservation may be poor.

Isolation of collagen from chicken feet with hydro-extraction method and its physico-chemical characterisation

Chicken slaughterhouses generate a large volume of chicken feet as a waste or by product. Nowadays, the chicken feet have not been optimally utilised. One of the ways to increase added value of the chicken feet is to utilize collagen contained in it. The objectives of this study were to obtain the best treatments in pre-treatment and hydrolysis stages of collagen extraction from chicken feet using hydro-extraction method, and to characterise the physico-chemical properties of the isolated collagen. Collagen extraction consisted of three stages of pre-treatment, hydrolysis, and hydro-extraction. Pre-treatment stage used NaOH concentrations of 0.5, 1, and 2 M, and soaking times of 2, 4, 6, and 8 hours. The hydrolysis used CH3COOH concentrations of 0.1, 0.3, and 0.5 M, and soaking times of 1, 2, and 3 hours. The best condition of pre-treatment was 0.5 M NaOH concentration with 6 hours of soaking time, while the best condition of hydrolysis was 0.5 M CH3COOH concentration with 1 hour soaking time. FTIR spectroscopy showed that the isolated collagen amino acids consisted of amide A, amide B, amide I, amide II, and amide III groups. The dominant amino acid contents were glycine, L-serine, L-proline, L-glutamic acid, and L-alanine.

Application Properties of Bath Liquids for Children Based on Sodium Laureth Sulfate with Addition of Different Molecular Weight Collagens Derived from Marine Sources

AbstractThis article investigates the influence of marine collagen of various molecular weights (Collagen Amino Acids—150 Da, Hydrolyzed Collagen—12,000 Da and Soluble Collagen—300,000 Da) on the functional properties of bath liquids for children based on anionic surfactants—sodium laureth sulfate. In addition to the aspects related to safety‐in‐use, which were presented in the authors' first work about marine collagen, consumers also expect bath cosmetics for children to have specific functional characteristics including viscosity or foaming properties. An increase in the molecular mass of marine collagen was found to be accompanied by an increase in dynamic viscosity and foaming ability and a decrease in the ability to emulsify fatty soil in the formulations under study. It can, therefore, be concluded that the addition of the highest molecular weight of marine collagen (300,000 Da) to bath liquids for children contributes not only to reducing the irritant effect caused by anionic surfactants, but also improves the usable properties of these types of cosmetics.

Unraveling the Role of Hydroxyproline in Maintaining the Thermal Stability of the Collagen Triple Helix Structure Using Simulation.

The thermal stability of collagen has an important effect on its practical applications. Many believe that hydroxyproline (Hyp) improves the structural stability of collagen molecules. In this study, for the first time, a method of building natural collagen molecular models was described. We constructed a collagen model with typical triple-helix structure and calculated the hydrogen bond energy between collagen α chains. The calculated hydrogen bond energy was consistent with the experimental results of differential scanning calorimetry. After the calculation simulation, we verified that the hydrogen bond energy between collagen chains was positively correlated with Hyp content in the models and an increased Hyp content in the model was beneficial in improving the thermal resistance of the structure. In addition, we found that thermal unfolding did not occur simultaneously along the entire molecule but started in the regions with less Hyp content. This study provides a collagen model with a natural collagen amino acid sequence, which will be helpful for further investigation of the physical and chemical properties of natural collagen.

Reduction of Irritation Potential Caused by Anionic Surfactants in the Use of Various Forms of Collagen Derived from Marine Sources in Cosmetics for Children

AbstractSurfactants, which are the basic ingredients in washing cosmetics, can cause skin irritation. In the case of washing cosmetics intended for children, it is necessary to select the composition in such a way as to ensure maximum reduction or even elimination of the irritant effect of the final product. The paper attempts to improve the safety of bath cosmetics for children by introducing: collagen amino acids (150 Da), hydrolysed collagen (12000 Da) and soluble collagen (300 000 Da). Zein value, bovine albumin, and human keratinocyte cell line studies have shown a significant decrease in the irritant potential of the compositions following the introduction of the proposed additives, which is more pronounced with the increase in the molecular weight of marine collagen. An important part of this work is a mechanism proposed by the authors, according to which the addition of the proposed additives can increase safety of the application of cosmetics for children.

Study on the relationship between estrogen levels and osteoporosis in perimenopausal women

Objective To investigate the influence of perimenopausal estrogen levels on the occurrence of osteoporosis. Methods From January 2014 to January 2016, 106 cases of perimenopausal women in the Traditional Chinese Medicine Hospital of Shengzhou were selected in the study.According to the age, they were divided into two groups, with 53 cases in each group.The control group was aged from 45 to 50 years old.The observation group was 51 to 55 years old.The levels of serum estradiol (E2), β-collagen specific sequence (β-CTX), N-terminal osteocalcin (NMID), total type I collagen amino acid extended peptide (PINP) and bone mineral density (BMD) were compared between the two groups. Results The levels of E2[(31.56±10.33) ng/L]and BMD[(80.72±24.19) mg/cm3]in the observation group were significantly lower than those in the control group[(73.72±13.28) ng/L, (125.68±38.75) mg/cm3](t=18.24, 7.17, all P<0.05). The levels of β-CTX, NMID and PINP in the observation group were (0.29±0.04) ng/mL, (24.38±11.69) ng/mL, (47.66±16.88) μg/L, respectively, which were significantly higher than those in the control group[(0.17±0.01) ng/mL, (11.4±2.63) ng/mL, (26.79±14.42)μg/L], the differences were statistically significant (t=21.19, 8.04, 6.84, all P<0.05). Conclusion The level of perimenopausal hormone in women is related to the occurrence of osteoporosis.With the decrease of estrogen level, the incidence rate of osteoporosis is increased, which is of great reference value for the prevention, diagnosis and treatment of disease. Key words: Perimenopause; Osteoporosis; Estrogens

Antioxidant activity of collagen from skin of parang-parang fish (Chirocentrus dorab) using DPPH and CUPRAC methods

Gross Collagen is fibrous protein that becomes the main component of connective tissues. An alternative source of collagen derived from marine animals as a source of antioxidants is needed. Utilization waste from skin of parang-parang fish (Chirocentrus dorab) as a source of collagen can increase the sale value of waste. The purpose of this research were to extract the collagen from skin of parang-parang fish with acid soluble collagen method include salting out and dialysis, also to test the antioxidant activity of collagen with DPPH and CUPRAC method. Collagen extraction steps consisted of pretreatmented with 0.1 M NaOH for 12 hours, hydrolysed with CH3COOH 0.5 M for 48 hours, salting out with 1 M NaCl for 12 hours, and dialysed with distilled water for 12 hours. Concentration of dissolved protein for 12 hours pretreatment was 0.791 ppm. The yield of collagen was 0.9%. The characteristic of collagen analysed by FTIR spectra showed amide A (3425), B (2924.09), I (1647.21), II (1543.05), and III (1246.02) (cm-1). The yield amino acid of collagen was glycine (26.69%), proline (12.24%), glutamic acid (11.72%), arginine (9.81%), alanine (9.51%). IC50 from DPPH method was 926.25 ppm. The antioxidant capacity of 100 ppm collagen was 104.14 μmol trolox / g extract.