Extraction and Characterization of Pepsin Soluble Collagen from the Body Wall of Sea Cucumber Acaudina leucoprocta

A review on sea cucumber (Bengali: Somuddro Sosha) as a bioindicator of heavy metal contamination and toxicity

This review paper exhibits the underexplored realm of heavy metal contamination and associated risks in sea cucumbers (SCs), which hold significant importance in traditional Asian marine diets and are globally harvested for the Asian market. The assessment focuses on heavy metals (HMs) presence in various SC species, revealing a global trend in HMs concentrations across anatomical parts: Fe > Zn > As > Cu > Hg > Pb > Mn > Cr > Ni > Cd. Specific species, such as Eupentacta fraudatrix, Holothuria mammata, Holothuria polii, Holothuria tubulosa, and Holothuria atra, exhibit heightened arsenic levels, while Stichopus herrmanni raises concerns with mercury levels, notably reaching 3.75 mg/kg in some instances, posing potential risks, particularly for children. The study sheds light on anthropogenic activities such as cultivation, fishing, and shipping, releasing HMs into marine ecosystems and thereby threatening ocean and coastal environments due to the accumulation and toxicity of these elements. In response to these findings, the paper suggests SCs as promising bioindicator species for assessing metal pollution in marine environments. It underscores the adverse effects of human actions on sediment composition and advocates for ongoing monitoring efforts both at sea and along coastlines.

Rheological properties, thermal stability and conformational changes of collagen from sea cucumber (Apostichopus japonicas)

Sea cucumber collagen (SCC) properties affected the thermal processing of sea cucumber. SCC showed the shear-thinning and pseudo-plastic properties, and the viscosity and frequency of viscoelastic crossover were decreased gradually with the temperature from 15 to 30 °C. Differential scanning calorimetry of SCC confirmed that it was thermolabile with the increase of temperatures, acid or NaCl concentrations. As the temperature increasing, the triple helix of SCC disappeared with the decrease of the relative proportion of P2 structures by circular dichroism spectrometry and Fourier transform infrared spectroscopy, and shearing could accelerate the change. Intramolecular changes investigated by molecular dynamics simulation showed the average number of hydrogen bonds decreased from 47 (20 °C) to 42 (80 °C), indicating triple helix of SCC was triggered to uncoil within 250 ns. These results could provide a scientific basis for processing of sea cucumbers.

Sea Cucumber Derived Type I Collagen: A Comprehensive Review

Collagen is the major fibrillar protein in most living organisms. Among the different types of collagen, type I collagen is the most abundant one in tissues of marine invertebrates. Due to the health-related risk factors and religious constraints, use of mammalian derived collagen has been limited. This triggers the search for alternative sources of collagen for both food and non-food applications. In this regard, numerous studies have been conducted on maximizing the utilization of seafood processing by-products and address the need for collagen. However, less attention has been given to marine invertebrates and their by-products. The present review has focused on identifying sea cucumber as a potential source of collagen and discusses the general scope of collagen extraction, isolation, characterization, and physicochemical properties along with opportunities and challenges for utilizing marine-derived collagen.

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.

Preparation of Antioxidant Peptide by Microwave- Assisted Hydrolysis of Collagen and Its Protective Effect Against H2O2-Induced Damage of RAW264.7 Cells

Antioxidant peptides have elicited interest for the versatility of their use in the food and pharmaceutical industry. In the current study, antioxidant peptides were prepared by microwave-assisted alkaline protease hydrolysis of collagen from sea cucumber (Acaudina molpadioides). The results showed that microwave irradiation significantly improved the degree of hydrolysis of collagen and the hydroxyl radical (OH⋅) scavenging activity of hydrolysate. The content and OH⋅ scavenging activity of collagen peptides with molecular weight ≤ 1 kDa (CP_S) in the hydrolysate obtained at 250 W increased significantly compared with the non-microwave-assisted control. CP_S could scavenge OH⋅ and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical in a dose-dependent manner. The scavenging activity of OH⋅ and DPPH radical was 93.1% and 41.2%, respectively, at CP_S concentration of 1 mg/mL. CP_S could significantly promote RAW264.7 cell proliferation and reduce the Reactive Oxygen Species (ROS) level of H₂O₂-induced damage in RAW264.7 cells in a dose-dependent manner. Furthermore, all CP_S-treated groups exhibited an increase in superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and a decrease in malondialdehyde (MDA) level compared with the control. These results showed that CP_S could effectively protect RAW264.7 cells from H₂O₂-induced damage, implying the potential utilization of CP_S as a natural antioxidant for food and pharmaceutical applications.

Preparation and Evaluation of Peptides with Potential Antioxidant Activity by Microwave Assisted Enzymatic Hydrolysis of Collagen from Sea Cucumber Acaudina Molpadioides Obtained from Zhejiang Province in China

The present study was focused on the preparation and characterization of the antioxidant peptides by microwave-assisted enzymatic hydrolysis of collagen from sea cucumber Acaudina molpadioides (ASC-Am) obtained from Zhejiang Province in China. The results exhibited the effects of microwave irradiation on hydrolysis of ASC-Am with different protease. Neutrase was selected from the four common proteases (papain, pepsin, trypsin, and neutrase) based on the highest content and DPPH scavenging activity of hydrolysate Fa (Molecular weight < 1 kDa). The content and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of Fa obtained by hydrolysis of neutrase increased by 100% and 109% respectively at a microwave power of 300 W compared with no microwave irradiation. Five subfractions were obtained after performing the gel filtration chromatography, and the Fa.2 exhibited the highest DPPH scavenging activity. The amino acid analysis showed that the contents of Glutamic acid, Alanine, Tyrosine, and Phenylalanine in fraction Fa.2 increased significantly, but an obvious decrease in the content of Glycine was observed compared to Fa. Four peptides (Fa.2-A, Fa.2-B, Fa.2-C, and Fa.2-D) were purified from Fa.2 by high performance liquid chromatography, and Fa.2-C showed the highest DPPH scavenging activity. The sequence of Fa.2-C was identified as Phenylalanine-Leucine- Alanine-Proline with a half elimination ratio (EC₅₀) of 0.385 mg/mL. The antioxidant activity of Fa.2-C was probably attributed to the small molecular sizes and the presence of hydrophobic amino acid residues in its sequence. This report provided a promising method for the preparation of antioxidant peptides from collagen for food and medicinal purposes.

Isolation and Comparative Study on the Characterization of Guanidine Hydrochloride Soluble Collagen and Pepsin Soluble Collagen from the Body of Surf Clam Shell (Coelomactra antiquata)

The aim of this study was to characterize the collagens from the body of surf clam shell (Coelomactra antiquata). Guanidine hydrochloride and pepsin were used to extract collagens. Guanidine hydrochloride soluble collagen (GSC) and pepsin soluble collagen (PSC) were separately isolated from the body of surf clam shell. Results showed that the moisture, protein, carbohydrate, and ash contents of the body of surf clam shell were 82.46%, 11.56%, 3.05%, and 2.38%, respectively, but the fat content was only 0.55%. The yields were 0.59% for GSC and 3.78% for PSC. Both GSC and PSC were composed of α₁ and α₂ chains and a β chain, however, GSC and PSC showed distinct differences from each other and the type I collagen from grass carp muscle on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). GSC and PSC contained glycine as the major amino acid and had imino acid of 150 and 155 residues/1000 residues, respectively. Fourier transform infrared spectroscopy (FTIR) spectra of GSC and PSC revealed the presence of a triple helix. The GSC appeared to have a dense sheet-like film linked by random-coiled filaments and PSC had fine globular filaments under scanning electron microscopy (SEM). The maximum transition temperature (Tmax) of GSC and PSC was 33.05 °C and 31.33 °C, respectively. These results provide valuable scientific information for the texture study and development of surf clam shell or other bivalve mollusks.