Preparation and Characterization of Thermally Stable Collagens from the Scales of Lizardfish (Synodus macrops)

Marine collagen is gaining vast interest because of its high biocompatibility and lack of religious and social restrictions compared with collagen from terrestrial sources. In this study, lizardfish (Synodus macrops) scales were used to isolate acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC). Both ASC and PSC were identified as type I collagen with intact triple-helix structures by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and spectroscopy. The ASC and PSC had high amino acids of 237 residues/1000 residues and 236 residues/1000 residues, respectively. Thus, the maximum transition temperature (Tmax) of ASC (43.2 °C) was higher than that of PSC (42.5 °C). Interestingly, the Tmax of both ASC and PSC was higher than that of rat tail collagen (39.4 °C) and calf skin collagen (35.0 °C), the terrestrial collagen. Solubility tests showed that both ASC and PSC exhibited high solubility in the acidic pH ranges. ASC was less susceptible to the “salting out” effect compared with PSC. Both collagen types were nontoxic to HaCaT and MC3T3-E1 cells, and ASC was associated with a higher cell viability than PSC. These results indicated that ASC from lizardfish scales could be an alternative to terrestrial sources of collagen, with potential for biomedical applications.

The influence of extraction period on the characteristics of acid soluble collagen from sea catfish (Arius thalassinus) swim bladder

The sea catfish in Indonesia is commonly processed into smoked fish and salted fish. The processing of these two products leaves a by-product, namely a swim bladder of 2%. The study investigated the influence of extraction period on the characteristics of collagen from sea catfish (Arius thalassinus) swim bladder. Collagen was extracted from the swim bladder using 0.5 M citric acid with different extraction periods (8, 12, and 16 h). The extraction period of 12 h produced the highest yield of collagen, namely 40.33%. The results showed that the longer extraction, the more amino acids could be extracted from the swim bladder. Glycine was an amino acid that dominates collagen in the amount of 138544.9 to 175420.0 mg/kg. The electrophoresis pattern of protein fraction indicated that the collagen were of type I because it consists of α1 and α2 chains with a molecular weight of approximately 100 to 150 kDa and β chain of 250 kDa. Fourier Transform Infrared (FTIR) spectra of collagen showed the regions of amide A, B, I, II, and III. However, based on the results of the Differential Scanning Colorimetry (DSC), collagen extracted for 16 h had lower thermal stability than the extraction period of 8 and 12 h. Based on these data, sea catfish swim bladder can be used as an alternative raw material for collagen production because it has a higher thermal stability than mammalian collagen, also can be used in the food, pharmaceutical, and nutraceutical industries.

Isolation and properties of collagen extracted from mixed by-products obtained from different fish species

Fish by-products consisting of skin, bones, or scales are collagen sources. Acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) mixed by-products derived from different fish species were extracted and evaluated. The properties evaluated for both collagens were chemical composition, amino acid- and SDS-PAGE- protein profiles, Fourier transform infrared spectroscopy (FTIR), denaturation temperature (Tmax), enthalpy (ΔH), and solubility. The ASC and PSC registered a protein content of 48.56 and 38.80 %, respectively. From the total amino acids detected, hydroxyproline accounted for 7 % and 6 % for ASC and PSC, respectively. The electrophoretic profile showed the presence of the type I collagen bands (α1, α2, β, and γ), whereas FTIR spectrum showed the presence of diverse collagen functional groups (Amide A, B, I, II, and III) for both extracted types, and demonstrated that the extraction process did not affect the collagen´s triple-helical structure. The Tmax of ASC and PSC were 38.27 and 38.07° C, respectively, whereas ΔH were 0.64 and 0.33 J g-1. The lowest solubility was registered at pH 5 for ASC and pH 9 for PSC. The caractheristics of the collagen extracted, indicated that a mixture of by-products from different species could be an alternative for their reutilization by the local markets.

Biohydrogel Based on Dynamic Covalent Bonds for Wound Healing Applications

In this work, a biohydrogel based on alginate and dynamic covalent B-O bonds, and derived composites, has been evaluated for wound healing applications. In particular, a phenylboronic acid–alginate (PBA-Alg) complex was synthesized by coupling 3-aminophenylboronic acid onto alginate, and used to prepare varied concentrations of hydrogels and silicate-based nanocomposites in PBS. The resulting hydrogels were characterized in terms of interfacial tension, moisture uptake and loss, interaction with fresh acid-soluble collagen, self-healing ability, effects on blood clotting and wound healing. The interfacial tension between the hydrogels and biorelevant fluids was low and moisture loss of 55%–60% was evident without uptake from the environment. The components of the hydrogels and their mixtures with collagen were found to be compatible. These hydrogels showed efficient self-healing and thixotropic behavior, and the animals in the treatment groups displayed blood clotting times between 9.1 min and 10.7 min. In contrast, the composites showed much longer or shorter clotting times depending on the silicate content. A significant improvement in wound healing was observed in 3% w/v PBA-Alg formulations. Overall, the PBA-Alg hydrogels exhibit self-healing dynamic covalent interactions and may be useful in dressings for incision wounds.

Characterization of Acid-Soluble Collagen from Food Processing By-Products of Snakehead Fish (Channa striata)

The isolation of acid-soluble collagen (ASC) from by-products of snakehead fish (Channa striata), including skin and the mixture of skin and scale, has been investigated. The recovery yield of fish skin ASC (13.6%) was higher than ASC from fish skin and scale (12.09%). Both ASCs were identified as type I collagen and showed maximal solubility at pH 2. Collagen samples from the mixture of skin and scale had higher imino acid content (226 residues/1000 residues) and lower wavenumber in the amide I and amide III region (1642 and 1203 cm−1, respectively) than the fish skin ASC (the imino acid content was 220 residues/1000 residues and the wavenumber in the amide I and amide III were 1663 and 1206 cm−1, respectively. The difference scanning calorimeter (DSC) showed higher thermal stability in ASC from the mixture of skin and scale (Td of 35.78 °C) than fish skin ASC (34.21 °C). From the result, the denaturation temperature of ASC had a close relationship with the content of imino acid as well as with the degradation of α-helix in amide I and III. These results suggest that collagen could be obtained effectively from snakehead fish by-products and has potential as a realistic alternative to mammalian collagens.

Salt-Cured Atlantic Cod Skin: A Sustainable Source of Acid-Soluble Type I Collagen

Collagen is the most abundant protein in the animal kingdom. Industrial collagen is mainly bovine and porcine origin. However, due to religious beliefs, allergic issues, and infectious diseases, alternative sources of collagen as marine are gaining increasing interest. In this work, the acid-soluble collagen (ASC) were extracted from salt-cured Atlantic cod (Gadus morhua) skin and characterized. The extraction yield was about 2.0%, equivalent to the extraction yield reported for other fish skins. The electrophoretic pattern showed the typical type I structure (α, β and γ chains). UV-VIS and FTIR absorbance spectra suggested a very pure ASC with an intact triple helical structure. The integrity and the adequate porosity required for different applications were then confirmed by electron micrograph. Our findings allow us to say that, for the first time, we extracted acid-soluble type I collagen from salt-cured Atlantic cod skin, with characteristics suitable for application in various fields, such as biomedical.

The potency of spice extracts in fish skin collagen production

Spices can be used as an alternative washing agent in fish collagen production, replacing organic materials' commonly used washing agent. Many Asians, including Indonesian traditional culinary use spices to remove the fishy odor. Therefore this research was conducted to obtain a suitable spice used as a washing agent in fish collagen production. Ginger, galangal, lemongrass, bay leaves, lime leaves, and pandan leaves were used as the tested spices in the form of 5% liquid extract in water. The ANOVA and LSD test on fishy odor test data showed that most respondents preferred Pangasius skin soaked in galangal liquid extract and had no significant difference in odor compared to the control (ethanol). Pangasius skin soaked in galangal extract had the total protein and ash content lower than control, while the total fat and water content were higher. Soaking in galangal extract also made Pangasius skin have a higher degree in swelling and total protein content in its acid-soluble collagen (ASC) extract than in control. The higher value of the two latter parameters was also found in the descaling Tuna skin soaked in galangal extract.