Identification of novel peptides with high stability against in vitro hydrolysis from bovine elastin hydrolysates and evaluation of their elastase inhibitory activity

The Anti-Photoaging Activity of Peptides from Pinctada martensii Meat

Long-term exposure to ultraviolet-B (UVB) can cause photoaging. Peptides from Pinctada martensii meat have been shown to have anti-photoaging activities, but their mechanism of action is rarely studied. In this study, Pinctada martensii meat hydrolysates (PME) were prepared by digestive enzymes and then separated by ultrafiltration and Sephadex G-25 gel filtration chromatography to obtain a purified fraction (G2). The fraction G2 was identified by ultra-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS), and peptide sequences were synthesized by solid-phase synthesis. The mechanism of anti-photoaging activities was investigated using a human immortalised epidermal (HaCaT) cell model. Results showed that peptides from Pinctada martensii meat increased UVB-induced cell viability and reduced the contents of interstitial collagenase (MMP-1) and matrix lysing enzyme (MMP-3) in HaCaT cells. Furthermore, the fraction of G2 significantly downregulated the expression of p38, EKR, JNK, MMP-1, and MMP-3 in HaCaT cells. The peptide sequences Phe-His (FH), Ala-Leu (AL), Met-Tyr (MY), Ala-Gly-Phe (AGF), and Ile-Tyr-Pro (IYP) were identified and synthesized. Besides, FH reduced the contents of MMP-1 and MMP-3 in HaCaT cells, combining them effectively in molecular docking analysis. Thus, peptides from Pinctada martensii meat showed anti-photoaging activities and might have the potential to be used as an anti-photoaging agent in functional foods.

Identification of chia seed (Salvia hispanica L.) peptides with enzyme inhibition activity towards skin-aging enzymes

Chia (Salvia hispanica) seed peptides have drawn attention because of their antioxidant, antihypertensive and anti-inflammatory activities, making them ideal candidates for development of cosmeceutical skin products. However, there are no preceding reports that address their aging-related enzyme inhibitory activities. The aim of this study was to investigate the in vitro and in silico inhibitory activity of chia seed peptides towards the main aging-related enzymes. Enzyme-inhibition activity of < 3 kDa chia seed peptides towards collagenase, hyaluronidase, tyrosinase, and elastase was evaluated. Further fractions were obtained by size exclusion chromatography (SEC) and re-tested for enzyme inhibitory activity. Peptide sequences were identified from the most effective fraction and used for in silico analysis. The < 3 kDa peptides exhibited inhibitory activities towards elastase (65.32%, IC₅₀ = 0.43 mg/mL), tyrosinase (58.74%, IC₅₀ = 0.66 mg/mL), hyaluronidase (26.96%, IC₅₀ = 1.28 mg/mL), and collagenase (28.90%, IC₅₀ = 1.41 mg/mL). They showed mixed-type inhibition patterns towards elastase and hyaluronidase, while a non-competitive inhibition pattern was observed towards collagenase and tyrosinase. Fraction II obtained by SEC, showed higher enzyme inhibitory activity. Seven peptides were identified in this fraction (APHWYTN, DQNPRSF, GDAHWAY, GDAHWTY, GDAHWVY, GFEWITF, and KKLKRVYV), which according to in silico analysis, possess 19-29 enzyme-peptide pair interactions towards elastase and three peptide sequences shared homology sequence (GDAHW). These results demonstrate that peptides from chia seeds may contribute in the improvement of skin health by offering protection against aging-related enzymes by preventing degradation of the protein matrix on the skin; however, further in vivo studies are needed to evaluate its actual capability.