Recently, there has been a growing interest in collagen peptides derived from marine sources for their notable ability to protect skin cells against apoptosis induced by oxidants. Therefore, the current study aimed to investigate the fundamental properties of collagen peptides, including their physicochemical, thermal, structural, stem-cell-regenerative, and skin-cell-protective effects, in comparison to commercial collagen peptides. The acid-soluble (ASC) and pepsin-soluble (PSC) collagens exhibited three distinct bands on SDS-PAGE, namely α (α₁ and α₂), β, and γ chains, confirming a type I pattern. The thermal profiles obtained from TG and DSC analyses confirmed the denaturation of PSC and ASC at temperatures ranging from 51.94 to 56.4 °C and from 52.07 to 56.53 °C, respectively. The purified collagen peptides were analyzed using SDS-PAGE and MALDI-TOF mass spectrometry, revealing a mass range of 900–15,000 Da. Furthermore, the de novo peptide sequence analysis confirmed the presence of the Gly-X-Y repeating sequence in collagen peptides. Collagen peptide treatments significantly enhanced HFF-1 cell proliferation and migration compared to the control group. ELISA results confirmed the potential interactions between collagen peptides and HFF-1 cells through α₂β₁, α₁₀β₁, and α₁₁β₁ integrin receptors. Notably, collagen peptide treatment effectively restored the proliferation of HFF-1 cells damaged by H₂O₂. Consequently, the advantageous characteristics of squid skin collagen peptides highlight their promising role in regenerative medicine.

As the focus on green chemistry intensifies, researchers are progressively looking to incorporate biodegradable and environmentally friendly solvents. Given the prevalent use of inorganic solvents in conventional methods for detecting selenium content, this study utilized a mixture design approach to create four deep eutectic solvents (DESs). The elements of the DESs consisted of six different compounds: guanidine hydrochloride, fructose, glycerol, citric acid, proline, and choline chloride. The synthesized deep eutectic solvents (DESs) exhibited a uniform and transparent appearance. The ideal ratios for each DES were established based on their density and viscosity measurements, leading to the formulations of DES1 (34% guanidine hydrochloride, 21% fructose, 45% water), DES2 (23% guanidine hydrochloride, 32% glycerol, 45% water), DES3 (27.5% citric acid, 27.5% proline, 45% water), and DES4 (30% choline chloride, 25% citric acid, 45% water). The characterization of the deep eutectic solvents (DESs) was performed using nuclear magnetic resonance (NMR) spectroscopy and infrared (IR) spectroscopy, which confirmed the molecular formation of each DES. Following this, the DESs were applied as extraction solvents in a process involving ultrasonic-assisted microextraction (UAE) combined with inductively coupled plasma mass spectrometry (ICP-MS) to assess the selenium levels in selenium-rich rice. The results were benchmarked against traditional microwave-assisted acid digestion (TM-AD), revealing selenium recovery rates ranging from 85.5% to 106.7%. These results indicate that UAE is an effective method for extracting selenium from selenium-rich rice, thereby establishing a solid data foundation for the environmentally friendly analysis of selenium content in rice.

Fibrillins are microfibril-associated macro glycoproteins found in connective tissues and structurally related to latent TGF-β-binding proteins (LTBPs). The special cellular immunity and blocking glycoprotein receptors IIb and IIIa of fibrillins are emerging topics in recent years. In this study, Nile Tilapia type IIcollagen (NTCII) was extracted and purified from the skull cartilages by a pepsin-soluble method. Amino acid analysis indicated that NTCII consisted of 315/1000 glycine residues, 72/1000 hydroxyproline residues and 108/1000 proline residues. SDS-PAGE analysis showed that NTCII was composed of three identical 130 kDa α-chains. The results of glycoprotein/carbohydrate assay indicated that the total polysaccharide content of NTCII was 5.6–19.0%. The IR spectrum of NTCII displayed five characteristic peaks of amide I, II, III, A, B. NTCII at 10–100 μg/mL concentration downregulated the content of cytokines in the presence or absence of LPS, especially the secretion of cytokines IL-6, IL-1β and TNF-α. Interestingly, NTCII promoted the secretion of Fas/Apo-1 compared to the control group and 25 μg/mL of NTCII resulted in a higher Fas/Apo-1 secretion level in CD8⁺ T cells. FITC-TCII fluorescence images confirmed that NTCII could bind to the membrane surface of CD8⁺ T cells, leading to the induction of rigidity. NTCII could bind to the membrane surface of CD8⁺ T cells that leads to the induction of rigidity, as evidenced by the FITC-NTCII fluorescence images. The qRT-PCR gene expression analysis of caspase-8 collected with Fas/Apo-1 was upregulated significantly in the 1 and 50 μg/mL NTCII-treated groups compared with the control group. Overall, the results conclude that the rigidity did not lead to an increase in inflammatory factors in CD8⁺ T cells treated with NTCII. The oral administration of NTCII 3 mg/kg dosage caused more prominent repair of damaged ankle cartilage than the 1 mg/kg dosage in Freund’s adjuvant-induced model of arthritis in rats. Therefore, this study disclosed the immunological and anti-arthritic effect of fibrillar collagen, which could be a potential biomaterial for practical applications with lower toxicity.

In recent years, arginine-rich basic proteins have garnered significant attention due to their essential roles in various biological processes. However, the potential of marine-derived proteins in this domain remains largely unexplored. This study presents, for the first time, the isolation and purification of a 14.3 kDa protamine (SOP) from the mature spermatogonial tissues of Symplectoteuthis oualaniensis. Additionally, we obtained an 18.5 kDa PEGylated derivative, SOP-PEG. The physicochemical properties of both SOP and SOP-PEG were comprehensively characterized using SEM, FTIR, CD, and TGA. PEGylation markedly altered the surface morphology, secondary structure, and thermal stability of SOP. In vitro studies demonstrated that PEGylation significantly enhanced the biocompatibility of SOP, leading to improved proliferation of L-929 fibroblasts. Furthermore, both SOP and its PEGylated derivative (SOP-PEG) regulated the cell cycle, activated the PI3K-Akt signaling pathway, and modulated anti-apoptotic mechanisms, suggesting their potential to support cell survival and facilitate tissue regeneration. Notably, SOP-PEG exhibited superior bioactivity, likely attributable to its enhanced delivery efficiency conferred by PEGylation. Collectively, these findings underscore the promising applications of SOP and SOP-PEG in regenerative medicine and highlight the pivotal role of PEGylation in augmenting the bioactivity of SOP.

One of the supporting factors behind the biomolecules recently used in anti-aging and skin nourishment is their antioxidant properties. Hydrogen peroxide (H₂O₂) is a well-known small molecule oxidant that induces apoptosis in human skin fibroblast (HSF) cells through the synthesis of inflammatory cytokines. Hence, this study aimed to investigate the antioxidant activities of protein hydrolysates prepared from Iris squid (Symplectoteuthis oualaniensis) (PHCSO) in vitro. Firstly, two peptides with MWs more than 10 kDa (PHCSO-1) and less than 10 kDa (PHCSO-2) were obtained through ultrafiltration and were characterized (molecular pattern amino acid composition, FTIR) before testing the antioxidant activity (DPPH radical scavenging activity and hydroxyl radical scavenging activity). Then, the effects of PHCSOs on HSF cell viability, H₂O₂-induced oxidative stress model of HSF cells, ROS fluorescence staining, level of cytokines (IL-1, IL-6 and TNF-α) and cellular antioxidant properties (SOD activity, CAT activity, GSH and MDA content) were investigated. The cell morphology was examined through fluorescence staining and inflammatory factors and antioxidant activity analysis showed that superior properties were observed in PHCSO-2 peptide compared to PHCSO-1 and PHCSO. Among the peptides, PHCSO-2 (5 mg/mL) had higher DPPH and hydroxyl radical scavenging activities of 58% and 57%, respectively. On the other hand, the PHCSO-2 treatment reduced the TNF-α activity by 25%, which indicated the effective protection of PHCSO-2 from oxidative stress damage in the skin. These findings proved that peptides with less than 10 kDa were more suitable for therapeutic purposes, with good antioxidant properties. Accordingly, the protein hydrolysate from S. oualaniensis proved to be an excellent marine-based antioxidant peptide, which could be applied in cosmetic, pharmaceutical and food industries.