Marine invertebrates’ proteins: A recent update on functional property

2.1 Biological action of protein sequence based on molecular weight

Bioactive peptides are discharged during enzymatic dehydration or solvent extraction; their biological activity might affect the type of protein fractions, hydrolytic compounds, catalyst substrate proportion, temperature and time of response (Xu et al., 2013). These conditions would influence the sub-atomic weight and peptides fractions and, this influence the functional property of proteins. As per recent report jellyfish had highest amount of bioactive peptides due to high protein content, mainly collagen from 40 to 60% of DW. Besides, the peptides PIIVYWK (Pro-Iso-Iso-Val-Tyr-Try-Lys) (1004.57 Da), and FSVVPSPK (Phe-Ser-Val-Val-Pro-Ser-Pro-Lys) (860.09 Da) from mytilus edulis exhibit hepatoprotective activity through upregulation of heme oxygenase-1 (HO-1) on hepatocytes against H₂O₂-induced hepatic damage (Park et al., 2016). The hydrolysis of ark shell Scapharca subcrenata by pepsin yielded two peptides MCLDSCLL(P1)(Met-Cys-Leu-Asp-Ser-Cys-Leu-Leu) and HPLDSLCL(P2) (His-Pro-Leu-Asp-Ser-Leu-Cys-Leu) with MW of 897.5 Da showed potent free radical scavenging activity to (2,2-diphenyl-1-picrylhydrazyl) DPPH, ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and (oxygen radical absorbance capacity) ORAC (Jin et al., 2018). However, ark shell protein hydrolysate with less than 1 kDa fractions stimulate the production of bone morphogenetic protein-2 (BMP-2), p-Smad1/5, Runx2, Dlx5, osterix, and mitogen-activated protein kinase (MAPKs) in mouse mesenchymal stem cells (MSC) and also up-regulated alkaline phosphatase (ALP) activity, mineralization, type I collagen and osteocalcin seen in MSC (Hyung et al., 2017). Similarly, Hyung et al. (2018) reported that blue mussel M. edulis protein hydrolysates with less than 1 kDa stimulate the osteoblast differentiation in mouse MSC through enhance the ALP initiation, osteocalcin and type I collagen activity along with calcium deposition. In addition, the peptic hydrolysate of ark shell with the average MW of 235.17–897.52 Da showed inhibition of adipogenesis through down-regulating adipocyte-specific protein expression together with peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding protein α, with sterol regulatory element-binding protein 1c, but this action down-regulated fatty acid synthase expression and lipoprotein lipase (Hyung et al. 2017). This confirms that based on the amino acid sequences, peptides derived from different marine invertebrates had varied biological property (Fig. 1).

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Fig. 1

Functional protein and peptides from marine invertebrate.

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2.2 Anticancer and antioxidant activity of protein and peptide of marine invertebrates

According to Hu et al. (2012) reported that polypeptide fraction from Arca subcrenata showed antitumor activity in vitro and in vivo HeLa and HT-29 (colon cancer cell line) cell lines (IC₅₀ of 11.43 μg/mL for HeLa (cervical cancer cell line) and 13.00 μg/mL for HT-29, similarly the same species with purified polypeptide (H3) shows MW of 20,491.0 Da exhibited antioxidant action ranges from 56.8% and 47.5% against (DPPH). However, higher MW from protein-enriched fraction of M. edulis (50 kDa) displayed 90%, 89%, 85% and 81% mortality rate against PC3 (prostate cancer cell), A549 (type II pulmonary epithelial cell), HCT15 (colon carcinoma cell) and BT549 (breast carcinoma cell) cell lines, respectively at the concentration of 44 µg/mL (Beaulieu et al., 2013). The polypeptide fraction of A. subcrenata mediates anticancer activity through apoptosis which arrests the G2/M phase via ROS-Mediated MAPKs Pathways (Hu et al., 2015). The M. edulis α-chymotrypsin hydrolysate protect the human umbilical vein endothelial cells (HUVECs) against H₂O₂-Induced cytotoxicity and increased HUVEC viability up to 85.35% at the concentration of 0.5 mg/mL. The M. edulis α-chymotrypsin hydrolysate increased HUVEC cell viability of toxicity induced by H₂O₂ was mediated by inhibition of apoptotic pathway via downregulating apoptotic gene p53, caspase-3, and the bax and upregulating bcl-2. Besides, M. edulis α-chymotrypsin hydrolysate increase the intracellular antioxidant status, such as glutathione (GSH) , superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) (Oh et al., 2019).

The peptide obtained from pepsin hydrolysate of Octopus aegina exhibited DPPH scavenging activity of 44.39% at the concentration of 1.5 mg/mL and hydroxyl activity of 38.84% at a concentration of 0.25 mg/mL (Sudhakar and Nazeer, 2017). The different type of peptide was obtained by hydrolysis of M. edulis with eight different types of protease like alcalase, α-chymotrypsin, flavourzyme, neutrase, papain, pepsin, protamex, and trypsin. Amongst α-chymotrypsin mediated hydrolysate had highest ABTS⁺ radical scavenging (117 μM TE/mg sample), ORAC (199.62 μM TE/mg sample) and DPPH radical scavenging activity (IC₅₀ of 0.35 mg/mL). The report from Yang et al. (2019), purified six antioxidant peptides EPLSD (Glu-Pro-Leu-Ser-Asp), WLDPDG (Trp-Ile-Asp-Pro-Asp-Gly), MDLFTE (Met-Asp-Leu-Phe-Thr-Glu), WPPD (Trp-Pro-Pro-Asp), EPVV (Glu-Pro-Val-Val), and CYIE (Cys-Tyr-Ile-Glu) from marine bivalve mollusk tergillarca granosa. These peptides could be applied as functional food ingredients to enhance the nutraceutical value of regular diet (Fig. 2).

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Fig. 2

Biological activity of peptides and proteins from marine invertebrate; A – Anticancer activity; B – Antioxidant activity; C – antimicrobial activity.

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2.3 Antimicrobial activity of protein sequence from edible marine invertebrates

Seo et al. (2013) reported that polypeptide ubiquitin (74 amino acid residues) with MW of 8.47 kDa exhibited strong antimicrobial activity against gram-negative, positive bacteria including Streptococcus iniae and Vibrio parahaemolyticus with the minimal inhibitory concentrations (MIC) ranging from 7.8 and 9.8 (μg/mL) without hemolytic activity, respectively. The cysteine-rich polypeptide myricetin-CB from M. coruscus showed better antimicrobial activity against gram-positive strains like Bacillus subtilis, Staphylococcus aureus, S. luteus and B. megaterium with MIC of less than 5 μM and showed moderate antifungal active against Candida albicans and Monilia albican (MIC > 5 μM) (Qin et al., 2014). Similarly, pacific oyster Crassostrea gigas protein with MW 6.4 kDa consists of 60S ribosomal protein L29 displayed potent antimicrobial activity (Seo et al., 2017). Molluscidin, a polypeptide from Haliotis discus has MW of 4.76 kDa with 46 amino acids and showed broad and potent antimicrobial spectrum without hemolysis (Seo et al., 2016), besides, molluscidin (5.6 kDa) purified from Atrina pectinata had 59 amino acid residues with repeats of Lys-Lys and Lys-Gly di-basic amino acid reported antimicrobial activity against B. subtilis at MIC of 2.1 μg/mL and Escherichia coli of MIC = 0.5 μg/mL, without hemolytic activity (Hong et al., 2018). Antimicrobial activity of polypeptide defensins from Venerupis phlippinarum and reported that defensins increased the cell membrane permeability of bacteria (Yang et al., 2018), antiviral activity of proline-rich peptides from marine snail rapanavenosa and reported that its isoforms against Epstein-Barr virus (Dolashka et al., 2011; 2014). Further, defensins had broad spectrum of antimicrobial action against S. aureus, Micrococcus luteus, V. anguillarum, Enterobacter cloacae, V. harveyi, Proteus mirabilis, Enterobacter aerogenes, V. parahaemolyticus, V. splendidus and E. coli with the MIC ranging from 0.5 μM to 8 μM. The antimicrobial peptide defensin from V. philippinarum demonstrated potential inhibitory activity against M. luteus and destroyed this bacteria through membrane permeability (Zhang et al., 2015). The antimicrobial property of this peptide from marine invertebrate could act as a nutraceutical molecule with food preserving entity (Fig. 2).

2.4 Biological action of collagen and gelatin

Collagen and properase E hydrolysate from jellyfish had the ability to increase the moisture in skin of UV-induced mice and also restore the endogenous collagen and elastin fibers, through type I to III collagen (Fan et al., 2013). The collagenous peptide extracted from Chrysaora sp. by the action of enzyme trypsin displayed highest DPPH radical scavenging activities (94% at 2 mg/mL) which possess angiotensin-I-converting enzyme (ACE) inhibitory activity of 89% as compared to other protein hydrolysate extracted using enzymes alcalase and Protamex. The high biological activity of collagenous peptide from trypsin hydrolysate may due to high proposition of hydrophobic amino acids with unique amino acid arrangements (Barzideh et al., 2014). Similarly, jellyfish Nemopilema nomurai stimulate the immune system in mouse by activating bone marrow-derived dendritic cells and produces inflammatory cytokines tumor necrosis factor (TNF)-α, Interleukin 6 (IL-6), IL-1β and IL-12. This collagen peptide underwent macrophage J774.1 cells and stimulated cytokine production via activation of the (nuclear factor kappa-light-chain-enhancer of activated B cells) NF-κB and JNK (c-Jun N-terminal kinase) signalling cascades through TLR4 (Toll-like receptor 4) (Putra et al., 2015). The collagen from jellyfish Rhopilema esculentum acts like collagen type I which enhanced the hemostatic process. This mechanism of action was due to improved physical absorption of collagen on the system (Cheng et al., 2017) similar to other marine based biopolymer like carrageenan (Ganesan et al., 2018a, 2018b; Mohan et al., 2018). The collagen peptide fractions from R. esculentum with less than 25 kDa MW presented significant effects on scratch closure at a concentration of 6.25 μg/mL for 48 h and also showed that increased the production of β-fibroblast growth factor (β-FGF) and transforming growth factor-β₁ (TGF-β₁) expression (Felician et al., 2019). This confirms collagen found to be suitable candidate for wound dressing applications. Table 1 depicts the protein from the source of edible marine invertebrates and its biological action.

2.5 Collagen and gelatin prospective application

The commercially useful compounds from edible marine invertebrates are collagen and gelatin. Collagen is present in all animals in skins and bones around 30% of total content (Silva et al., 2014). Marine organism-based collagen is a promising candidate which replaces mammal-derived collagen and widely used for much biomedical application (Silva et al., 2014; Silvipriya et al., 2015). In food application, collagen is a primary raw material for the production of gelatin and acts as a functional protein for its gelling property. Further, the rheological properties of collagen found to be desirable such as improved elasticity, shear thinning and apparent viscosity which is directly used in food application as a texture enchancer (Ganesan et al., 2019). Gelatin is water soluble protein with MW of 80–250 k Da and it exhibits 88% protein, 10% moisture, and 1–2% salts. In gelatin and collagen, some of the amino acid derivatives are glycine, proline and hyroxyproline which play a role towards thermal stability and improve rheological properties. Moreover, using mammalian tissue causes serious health risk for human i.e hoof and mouth disease, bovine spongiform encephalopathy which is infectious disease spreading via food. Subsequently, marine source is the best alternative to prevent these kinds of disease widespread and also topped with functional properties (Silvipriya et al., 2015). Furthermore, the complex structure of gelatin is poly-ampholyte cross-linking and protein structure constituents biocompatible properties, because of this gelatin does not come under E-number which is classified as a food product (Ofokansi et al., 2010). In bioengineering, gelatin plays a crucial role as encapsulating material or coated gelatin shows efficient loading and drug release properties. There are many advantages of using gelatin in nanoencapsulation. This will improve the product deprivation, free from oxidation, and therefore extend core product shelf-life before its final (Nikkhah et al., 2016; Oh et al., 2019).