Two Novel Multi-Functional Peptides from Meat and Visceral Mass of Marine Snail Neptunea arthritica cumingii and Their Activities In Vitro and In Vivo

Abstract

Neptunea arthritica cumingii (Nac) is a marine snail with high nutritional and commercial value; however, little is known about its active peptides. In this study, two multi-functional peptides, YSQLENEFDR (Tyr-Ser-Gln-Leu-Glu-Asn-Glu-Phe-Asp-Arg) and YIAEDAER (Tyr-Ile-Ala-Glu-Asp-Ala-Glu-Arg), were isolated and purified from meat and visceral mass extracts of Nac using a multi-bioassay-guided method and were characterized by using liquid chromatography-tandem mass spectrometry. Both peptides showed high antioxidant, angiotensin-converting enzyme (ACE)-inhibitory, and anti-diabetic activities, with half-maximal effective concentrations values less than 1 mM. Antioxidant and ACE-inhibitory activities were significantly higher for YSQLENEFDR than for YIAEDAER. In a zebrafish model, the two peptides exhibited strong scavenging ability for reactive oxygen species and effectively protected skin cells against oxidative damage without toxicity. Molecular docking simulation further predicted the interactions of the two peptides and ACE. Stability analysis study indicated that the two synthetic peptides maintained their activities under thermal stress and simulated gastrointestinal digestion conditions. The low molecular weight, high proportion of hydrophobic and negatively-charged amino acids, and specific C-terminal and N-terminal amino acids may contribute to the observed bio-activities of these two peptides with potential application for the prevention of chronic noncommunicable diseases.

Keywords: ACE-inhibitory activity; Neptunea arthritica cumingii; anti-diabetic activity; antioxidant activity; multi-functional peptides.

Figure 1

Absorbances and activities of fractions isolated from the meat and visceral mass of Neptunea arthritica cumingii (Nac) by using gel filtration column packed with Sephadex G25 gel. (a) the 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH) radical scavenging activity, (c) angiotensin-converting enzyme (ACE)-inhibitory activity, and (e) α-amylase inhibitory activity of meat fractions; and (b) the DPPH radical scavenging activity, (d) ACE-inhibitory activity, and (f) α-amylase inhibitory activity of visceral mass fractions.

Figure 2

(a) Elution profiles of active fractions from the meat of Nac by hydrophilic interaction chromatography (HILIC) at 214 nm; (b) elution profiles of active fractions from the visceral mass of Nac by HILIC at 214 nm.

Figure 3

Bioactivities of two peptides. (a) half maximal inhibitory concentration (EC₅₀) values in different models (** p < 0.01 compared with the VM-P7), (b) DPPH radical scavenging activity, (c) OH radical scavenging activity, (d) reducing power, (e) ACE-inhibitory activity, (f) α-amylase inhibitory activity, and (g) α-glucosidase inhibitory activity.

Figure 4

In vivo antioxidant activity of active peptides in zebrafish embryos (n = 10, mean ± standard deviation). (a) In vivo visualization of zebrafish skin fluorescence treatment with vehicle (A), metronidazole (MTZ; (B)), vitamin C (C), and low (D), medium (E), and high (F) concentrations of M-P6, as well as low (G), medium (H), and high (I) concentrations of VM-P7; (b) FS number statistic results of all groups; (c) In vivo antioxidant activity of all samples. ** indicates significant differences compared with the MTZ treatment group (p < 0.01).

Figure 5

The molecular docking of YIAEDAER (a) from visceral mass and YSQLENEFDR (b) from meat to angiotensin-converting enzyme.

Figure 6

The two-dimensional diagram of molecular docking simulation of YIAEDAER (a) from visceral mass and YSQLENEFDR (b) from meat to angiotensin-converting enzyme.

Figure 7

EC₅₀ values of DPPH radical scavenging (a) and ACE inhibitors (b) of two synthetic peptides treated with thermal treatment. The same numbers means no significantly different in a group (p > 0.05).

Figure 8

EC₅₀ values of DPPH radical scavenging (a) and ACE inhibitors (b) of two synthetic peptides treated with gastrointestinal digestion treatment. The same numbers indicate no significant difference in a group (p > 0.05).