Gastrointestinal digestion of food proteins: Anticancer, antihypertensive, anti-obesity, and immunomodulatory mechanisms of the derived peptides

Food proteins and their peptides play a significant role in the important biological processes and physiological functions of the body. The peptides show diverse biological benefits ranging from anticancer to antihypertensive, anti-obesity, and immunomodulatory, among others. In this review, an overview of food protein digestion in the gastrointestinal tract and the mechanisms involved was presented. As some proteins remain resistant and undigested, the multifarious factors (e.g. protein type and structure, microbial composition, pH levels and redox potential, host factors, etc.) affecting their colonic fermentation, the derived peptides, and amino acids that evade intestinal digestion are thus considered. The section that follows focuses on the mechanisms of the peptides with anticancer, antihypertensive, anti-obesity, and immunomodulatory effects. As further considerations were made, it is concluded that clinical studies targeting a clear understanding of the gastrointestinal stability, bioavailability, and safety of food-based peptides are still warranted.

Antioxidant and antiproliferative activity of enzymatic hydrolysates from red tilapia (Oreochromis spp.) viscera

The antioxidant and antiproliferative activity of red tilapia (Oreochromis spp.) viscera hydrolysates (RTVH) was evaluated. For that, the hydrolysates was applied to three cancer cell lines (HepG2, Huh7 and SW480) and the control (CCD-18Co). Finally, the line on which the hydrolysate had the greatest effect (SW480) and the control (CCD-18Co) were subjected to the ApoTox-Glo Triplex Assay to determine apoptosis, toxicity, and cell viability. The result showed that hydrolysate had a dose-dependent cytotoxic effect selective on the three cancer cell lines, compared to the control cells. There is a relationship between the antioxidant capacity of RTVHs and their antiproliferative capacity on cancer cells evaluated, which achieved cell viability by action of RTVH of 34.68 and 41.58 and 25.41 %, to HepG2, Huh7 and SW480, respectively. The action of RTVH on cancer cell line SW480 is not due to the induction of apoptosis but to the rupture of the cell membrane.

Bioactive milk peptides: an updated comprehensive overview and database

Partial digestion of milk proteins leads to the formation of numerous bioactive peptides. Previously, our research team thoroughly examined the decades of existing literature on milk bioactive peptides across species to construct the milk bioactive peptide database (MBPDB). Herein, we provide a comprehensive update to the data within the MBPDB and a review of the current state of research for each functional category from in vitro to animal and clinical studies, including angiotensin-converting enzyme (ACE)-inhibitory, antimicrobial, antioxidant, dipeptidyl peptidase (DPP)-IV inhibitory, opioid, anti-inflammatory, immunomodulatory, calcium absorption and bone health and anticancer activity. This information will help drive future research on the bioactivities of milk peptides.

Structural, spectroscopic, in silico, in vitro and DNA binding evaluations of tyrosyl-lysyl-threonine

The main objective of the present study is to investigate the molecular structure and DNA binding interaction of the tyrosyl-lysyl-threonine (YKT) tripeptide, which has anticancer, antioxidant and analgesic properties, using various in silico (MD, QM, molecular docking), spectroscopic (UV, FT-IR, FTIR-ATR, Raman, gel electrophoresis) and in vitro (MCF-7 and HeLa cancer cell lines and BEAS-2B cell line) methods. The optimized geometry, vibrational wavenumbers, molecular electrostatic potential (MEP), natural bond orbital (NBO) and HOMO-LUMO (highest occupied molecular orbital- lowest unoccupied molecular orbital) calculations were carried out with Density Functional Theory (DFT) using B3LYP/6-311++G(d,p) basis set to indicate conformational, vibrational and intramolecular charge transfer characteristics. The assignment of all fundamental theoretical vibration wavenumbers was performed using potential energy distribution analysis (PED). DNA is a significant pharmacological target of drugs in several diseases such as cancer. For this reason, molecular docking calculation was used to elucidate the binding and interaction between YKT tripeptide and DNA at the atomic level. Also, the dynamic behaviors of YKT and DNA was examined using MD simulations. Besides, the interaction of YKT with DNA was experimentally examined by UV titration method and agarose gel electrophoresis method. Experimental results showed that YKT was intercalatively and electrostatically bound to CT-DNA (Calf thymus DNA) and cleavage pBR322 DNA in the presence of H₂O₂. The pharmacokinetic profile of YKT was also obtained. Cytotoxic effect of YKT was evaluated on MCF-7, HeLa and BEAS-2B cell lines. Hence, these studies about YKT tripeptide may pave the way for the development of various cancer drugs. Communicated by Ramaswamy H. Sarma.

Molecular docking studies of YKT tripeptide and drug delivery system with poly(ε-caprolactone) nanoparticles

Tyrosyllysylthreonine (YKT) is a peptide structure that contains three different amino acids in its structure and has anticancer properties. The main purpose of this study is to reveal the structural interactions of the peptide and to increase the efficiency of the peptide with nanoformulation. For these purposes, YKT-loaded poly(ε-caprolactone) (PCL) nanoparticles (NPs) were synthesized using the double-emission precipitation method and the obtained NPs were characterized with a Zeta Sizer, UV-Vis, Fourier transform infrared-attenuated total reflection spectrometers, scanning electron microscopy, and transmission electron microscopy. The in vitro release profile of the peptide-loaded PCL NPs was determined. In molecular modeling studies, PCL, PCL-polyvinyl alcohol (PVA), and PCL-PVA-YKT systems were simulated in an aqueous medium by molecular dynamics simulations, separately. The information about the interactions between the YKT tripeptide and the epidermal growth factor and androgen, estrogen, and progesterone receptors were obtained with the molecular docking study. Additionally, the ADME profile of YKT was determined as a result of each docking study. In conclusion, tripeptide-based nanodrug development studies of the YKT tripeptide are presented in this study.

Use of anticancer peptides as an alternative approach for targeted therapy in breast cancer: a review

Breast cancer is the most common cancer in women worldwide. Traditional therapies are expensive and cause severe side effects. Targeted therapy is a powerful method to circumvent the problems of other therapies. It also allows drugs to localize at predefined targets in a selective manner. Currently, there are several monoclonal antibodies which target breast cancer cell surface markers. However, using antibodies has some limitations. In the last two decades, many investigators have discovered peptides that may be useful to target breast cancer cells. In this article, we provide an overview on anti-breast cancer peptides, their sources and biological activities. We further discuss the pros and cons of using anticancer peptides with further emphasis on how to improve their effectiveness in cancer therapy.

Protein Recovery from Underutilised Marine Bioresources for Product Development with Nutraceutical and Pharmaceutical Bioactivities

The global demand for dietary proteins and protein-derived products are projected to dramatically increase which cannot be met using traditional protein sources. Seafood processing by-products (SPBs) and microalgae are promising resources that can fill the demand gap for proteins and protein derivatives. Globally, 32 million tonnes of SPBs are estimated to be produced annually which represents an inexpensive resource for protein recovery while technical advantages in microalgal biomass production would yield secure protein supplies with minimal competition for arable land and freshwater resources. Moreover, these biomaterials are a rich source of proteins with high nutritional quality while protein hydrolysates and biopeptides derived from these marine proteins possess several useful bioactivities for commercial applications in multiple industries. Efficient utilisation of these marine biomaterials for protein recovery would not only supplement global demand and save natural bioresources but would also successfully address the financial and environmental burdens of biowaste, paving the way for greener production and a circular economy. This comprehensive review analyses the potential of using SPBs and microalgae for protein recovery and production critically assessing the feasibility of current and emerging technologies used for the process development. Nutritional quality, functionalities, and bioactivities of the extracted proteins and derived products together with their potential applications for commercial product development are also systematically summarised and discussed.

The antioxidant potential of peptides obtained from the spotted babylon snail (Babylonia areolata) in treating human colon adenocarcinoma (Caco-2) cells

This research study investigated the free radical-scavenging activities of peptides which were obtained from the protein hydrolysates of the spotted babylon snail using a combination of pepsin and pancreatin proteolysis which can replicate the conditions of gastrointestinal digestion. In this study, spotted babylon protein hydrolysate (SPH) derived from a sequential 3 hour digestion, first with pepsin and then with pancreatin, was examined. SPH was fractionated using molecular weight cut-off membranes for 10 kDa, 5 kDa, 3 kDa, and 0.65 kDa. It was found that the MW < 0.65 kDa fraction provided the greatest levels of 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazl (DPPH), and nitric oxide (NO) radical scavenging activity. Three subfractions of the MW < 0.65 kDa fraction were then generated via RP-HPLC. The subfraction which subsequently demonstrated the greatest free radical scavenging activity was F₃, which was accordingly chosen for further investigation commencing with quadrupole-time-of-flight-electron spin induction-mass spectrometry-based de novo peptide sequencing. This resulted in the identification of a pair of novel peptides: His–Thr–Tyr–His–Glu–Val–Thr–Lys–His (HTYHEVTKH), and Trp–Pro–Val–Leu–Ala–Tyr–His–Phe–Thr (WPVLAYHF). The WPVLAYHF peptide exhibited greater antioxidant activity. The study also confirmed that the F₃ sub-fraction was able to prevent hydroxyl radicals from causing DNA damage by conducting tests which involved the pKS, pUC19, and pBR322 plasmids using the Fenton reaction. In addition, cellular antioxidant activity was demonstrated by two synthetic peptides toward the human adenocarcinoma colon (Caco-2) cell line, with the potency of the activity dependent upon the peptide concentration.

The isolation and subsequent identification of the two novel antioxidant peptides, HTYHEVTKH, and WPVLAYHF from the spotted babylon snail was achieved. In the Caco-2 cell line, two synthetic peptides produced a dose-dependent response on antioxidant activity.

Peptides obtained from edible mushrooms: Hericium erinaceus offers the ability to scavenge free radicals and induce apoptosis in lung cancer cells in humans

This research examined the antioxidant abilities of peptides derived from the Hericium erinaceus mushroom produced via three microbial proteases at varying concentrations.

Antibacterial and antiproliferative peptides in synbiotic yogurt-Release and stability during refrigerated storage

The search for alternative therapeutics is on the rise due to the extensive increase in bacterial resistance to various conventional antibiotics and side effects of conventional cancer therapies. Bioactive peptides released from natural sources such as dairy foods by lactic acid bacteria have received attention as a potential source of biotherapeutic peptides. However, liberation of peptides in yogurt depends on proteolytic activities of the cultures used. Thus, this research was conducted to establish generation of inhibitory peptides in yogurt against pathogenic bacteria and cancer cells during storage at 4°C for 28d. Water-soluble crude peptide extracts were prepared by high-speed centrifugation of plain and probiotic yogurts supplemented with or without pineapple peel powder (PPP). The inhibition zones against Escherichia coli and Staphylococcus aureus by PPP-fortified probiotic yogurt at 28d of storage were, respectively, 25.89 and 11.72mm in diameter, significantly higher than that of nonsupplemented control yogurts. Antiproliferative activity against HT29 colon cancer cells was also significantly higher in probiotic yogurt with PPP than in nonsupplemented probiotic yogurt. Overall, crude water-soluble peptide extracts of the probiotic yogurt with PPP possessed stronger inhibitory activities against bacteria and cancer cells than controls, and these activities were maintained during storage. However, activities were lowered substantially during in vitro gastrointestinal digestion. These findings support the possibility of utilizing dairy-derived bioactive peptides in the development of a superior alternative to the current generation of antibacterial and anticancer agents, as well as a functional ingredient in foods, nutraceuticals, and pharmaceuticals.