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Bioactive Natural Peptides As A Pipeline For Therapeutics
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Bioactive Natural Peptides As A Pipeline For Therapeutics

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Natural Products Chemistry".

Deadline for manuscript submissions: closed (30 September 2017) | Viewed by 106704

Special Issue Editor

Dr. Philippe Bulet

E-Mail Website
Guest Editor
1. University Grenoble Alpes, Institute for Advanced Biosciences, Inserm 1209, CNRS UMR5309, Equipe Immunologie Analytique des Pathologies Chroniques, F-38000 Grenoble, France
2. Plateforme BioPark d'Archamps, Bât. Le Forum 1, 260 Avenue Marie Curie, Archamps Technopole, F-74166 Saint Julien en Genevois Cedex, France
Interests: biochemistry; inflammation; innate immunity

Special Issue Information

Dear Colleagues,

Biodiversity is an extraordinarily ingenious provider of diverse natural products, among which bioactive natural peptides are important contributors.

Bioactive natural peptides are ubiquitous in all living organisms. They have been reported in marine and terrestrial organisms, including plants and are targeting vital physiological processes. In addition, to maintain homeostasis of the host, bioactive natural peptides are mediating a number of physiological responses that lead to protection of the organism against attacks (i.e., innate immunity, venom). Our knowledge of bioactive natural peptides has been largely enriched thanks to the peptides originated from venoms and from the armamentarium, developed by the living organisms to fight off infections through the innate immune defenses. As bioactive peptides obtained from nature have been subjected to eons of selective pressure, they show several advantages over in silico designed peptide-like compounds. The extensive investigations of the different sources of bioactive natural peptides (i.e., defense peptides, toxins) have identified thousands of structures, adopting different conformations. For example, they can exhibit α-helical conformations, amphipathic β-hairpin-like β-sheet, β-sheet, α-helix/β-sheet mixed folds up or multi fingers folds. Interestingly, structural analyses between toxins and defense peptides revealed important interrelations between these two groups of bioactive peptides (toxic versus antimicrobial). Genomic analyses suggest that these bioactive molecules share a common ancestor. Bioactive natural peptides can exert highly specific activities, or, in contrast, have multifunctional properties. Therefore, it is not surprising that research has focused on identifying bioactive natural peptides for their development of new therapeutics. Captopril, exenatide and ziconotide, are examples of already marketed therapeutics developed from bioactive peptides isolated from venoms. In the field of antimicrobial peptides, so far magainin has reached the very last stages of the FDA approval. Bioactive natural peptides should definitively continue to fill pharmaceutical and biotechs pipelines, in the ongoing global search for therapeutic agents in the treatment of human and animal pathologies, and for phytosanitary purposes. This Special Issue will examine the recent progress in the search for bioactive natural peptides lead compounds and their potential therapeutic development; for example, in the field of medicinal application as antitumoral, antimicrobial, anticoagulating, and for analgesic properties.

Dr. Philippe Bulet
Guest Editor

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Keywords

  • bioactive natural peptides
  • molecular diversity
  • toxins
  • defense peptides
  • biodiversity
  • therapeutic peptides

Published Papers (15 papers)

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15 pages, 2552 KiB  
Article
Separation and Characterization of Antioxidative and Angiotensin Converting Enzyme Inhibitory Peptide from Jellyfish Gonad Hydrolysate
by Qin Zhang, Chengcheng Song, Jun Zhao, Xiaomei Shi, Meiling Sun, Jing Liu, Yinghuan Fu, Wengang Jin and Beiwei Zhu
Molecules 2018, 23(1), 94; https://doi.org/10.3390/molecules23010094 - 05 Jan 2018
Cited by 45 | Viewed by 4799
Abstract
The gonad of jellyfish (Rhopilema esculentum Kishinouye), containing high protein content with a rich amino acid composition, is suitable for the preparation of bioactive peptides. Jellyfish gonad was hydrolysed with neutral protease to obtain jellyfish gonad protein hydrolysate (JGPH), which was [...] Read more.
The gonad of jellyfish (Rhopilema esculentum Kishinouye), containing high protein content with a rich amino acid composition, is suitable for the preparation of bioactive peptides. Jellyfish gonad was hydrolysed with neutral protease to obtain jellyfish gonad protein hydrolysate (JGPH), which was then purified sequentially by ultrafiltration, gel filtration chromatography, and RP-HPLC. The peptides were characterized with HPLC-MS/MS. One peptide with amino acid sequence Ser-Tyr (SY) was identified and synthesized, which showed good ACE inhibitory and antioxidant activity. The IC50 of this peptide on DPPH, ·OH, super oxygen anion scavenging activities, and ACE inhibitory activity are 84.623 μM, 1177.632 μM, 456.663 μM, and 1164.179 μM, respectively. The anchor in the binding site of SY and ACE C-domain (ACE-C) was obtained by molecular simulations. The results showed that the dipeptide purified from jellyfish gonad protein hydrolysates can be used as functional food material and is helpful in the study of antioxidant and inhibition of ACE. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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994 KiB  
Article
Large-Scale Analysis of Antimicrobial Activities in Relation to Amphipathicity and Charge Reveals Novel Characterization of Antimicrobial Peptides
by Chien-Kuo Wang, Ling-Yi Shih and Kuan Y. Chang
Molecules 2017, 22(11), 2037; https://doi.org/10.3390/molecules22112037 - 22 Nov 2017
Cited by 43 | Viewed by 6611
Abstract
It has been unclear to which antimicrobial activities (e.g., anti-gram-positive bacterial, anti-gram-negative bacterial, antifungal, antiparasitic, and antiviral activities) of antimicrobial peptides (AMPs) a given physiochemical property matters most. This is the first computational study using large-scale AMPs to examine the relationships between antimicrobial [...] Read more.
It has been unclear to which antimicrobial activities (e.g., anti-gram-positive bacterial, anti-gram-negative bacterial, antifungal, antiparasitic, and antiviral activities) of antimicrobial peptides (AMPs) a given physiochemical property matters most. This is the first computational study using large-scale AMPs to examine the relationships between antimicrobial activities and two major physiochemical properties of AMPs—amphipathicity and net charge. The results showed that among all kinds of antimicrobial activities, amphipathicity and net charge best differentiated between AMPs with and without anti-gram-negative bacterial activities. In terms of amphipathicity and charge, all the AMPs whose activities were significantly associated with amphipathicity and net charge were alike except those with anti-gram-positive bacterial activities. Furthermore, the higher the amphipathic value, the greater the proportion of AMPs possessing both antibacterial and antifungal activities. This dose–response-like pattern suggests a possible causal relationship—dual antibacterial and antifungal activities of AMPs may be attributable to amphipathicity. These novel findings could be useful for identifying potent AMPs computationally. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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1440 KiB  
Article
Amaranth Protein Hydrolysates Efficiently Reduce Systolic Blood Pressure in Spontaneously Hypertensive Rats
by Giovanni Ramírez-Torres, Noé Ontiveros, Verónica Lopez-Teros, Jesús Aurelio Ibarra-Diarte, Cuauhtémoc Reyes-Moreno, Edith Oliva Cuevas-Rodríguez and Francisco Cabrera-Chávez
Molecules 2017, 22(11), 1905; https://doi.org/10.3390/molecules22111905 - 09 Nov 2017
Cited by 27 | Viewed by 4523
Abstract
Alcalase is the enzyme of choice to release antihypertensive peptides from amaranth proteins, but the hydrolysis conditions have not been optimized yet. Furthermore, in vivo assays are needed to confirm such a hypotensive effect. Our aim was to optimize the hydrolysis of amaranth [...] Read more.
Alcalase is the enzyme of choice to release antihypertensive peptides from amaranth proteins, but the hydrolysis conditions have not been optimized yet. Furthermore, in vivo assays are needed to confirm such a hypotensive effect. Our aim was to optimize the hydrolysis of amaranth protein with alcalase and to test in vivo the hypotensive effect of the hydrolysates. A response surface analysis was carried out to optimize the hydrolysis reaction. The response variable was the Angiotensin Converting Enzyme (ACE-I) inhibition. The hydrolysis degree was determined (free alpha-amino groups measurement). The optimized hydrolysate bioavailability was assessed in the sera of mice and the hypotensive effect was assessed in spontaneously hypertensive rats. Control groups were administered captopril or water. The optimized hydrolysis conditions were: pH = 7.01, temperature = 52 °C, enzyme concentration 0.04 mU/mg, and time = 6.16 h. The optimized hydrolysate showed a 93.5% of ACE-I inhibition and a hydrolysis degree of 74.77%. After supplementation, the hydrolysate was bioavailable in mice from 5 to 60 min, and the hypotensive effect started at 4 h in spontaneously hypertensive rats (p < 0.05 vs. water group). This effect was similar to the captopril hypotensive effect for the next 3 h (p > 0.05). The use of amaranth-optimized hydrolysates as hypotensive supplements or ingredient for functional foods seems feasible. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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5073 KiB  
Article
Dermaseptin-PH: A Novel Peptide with Antimicrobial and Anticancer Activities from the Skin Secretion of the South American Orange-Legged Leaf Frog, Pithecopus (Phyllomedusa) hypochondrialis
by Linyuan Huang, Dong Chen, Lei Wang, Chen Lin, Chengbang Ma, Xinping Xi, Tianbao Chen, Chris Shaw and Mei Zhou
Molecules 2017, 22(10), 1805; https://doi.org/10.3390/molecules22101805 - 24 Oct 2017
Cited by 56 | Viewed by 7462
Abstract
The dermaseptin peptides, mainly derived from the skin secretions of Hylidae frogs, belong to a superfamily of antimicrobial peptides and exhibit diverse antimicrobial and anticancer activities with low cytotoxicity. Here, we reported a novel dermaseptin peptide, from the South American orange-legged leaf frogs, [...] Read more.
The dermaseptin peptides, mainly derived from the skin secretions of Hylidae frogs, belong to a superfamily of antimicrobial peptides and exhibit diverse antimicrobial and anticancer activities with low cytotoxicity. Here, we reported a novel dermaseptin peptide, from the South American orange-legged leaf frogs, Pithecopus (Phyllomedusa) hypochondrialis, processing the shortest peptide length, namely Dermaseptin-PH. The complementary DNA (cDNA) encoding biosynthetic precursor of Dermaseptin-PH was initially identified by the rapid amplification of cDNA ends PCR (RACE-PCR) technique from the skin secretion. The predicted primary structure was confirmed by a combination of reverse-phase high performance liquid chromatography (RP-HPLC) and MS/MS fragmentation from the skin secretion. Chemically-synthetic Dermaseptin-PH was investigated using a range of bioactivity assessment assays to evaluate the biological activities and cytotoxicity of Dermaseptin-PH. Dermaseptin-PH inhibited the growth of Gram-negative bacteria, Gram-positive bacteria, and pathogenic yeast Candida albicans. In addition, Dermaseptin-PH showed a broad-spectrum of anticancer activities against several cancer cell lines including MCF-7, H157, U251MG, MDA-MB-435S, and PC-3. The potent antimicrobial and anticancer activities of Dermaseptin-PH make it a promising candidate in the discovery of new drugs for clinical applications, and the relatively short sequence of Dermaseptin-PH can provide new insight for the research and structural modification of new peptide drugs. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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1731 KiB  
Article
Pharmacological Effects of Two Novel Bombesin-Like Peptides from the Skin Secretions of Chinese Piebald Odorous Frog (Odorrana schmackeri) and European Edible Frog (Pelophylax kl. esculentus) on Smooth Muscle
by Xiaowei Zhou, Chengbang Ma, Mei Zhou, Yuning Zhang, Xinping Xi, Ruimin Zhong, Tianbao Chen, Chris Shaw and Lei Wang
Molecules 2017, 22(10), 1798; https://doi.org/10.3390/molecules22101798 - 23 Oct 2017
Cited by 6 | Viewed by 5084
Abstract
Bombesin-like peptides, which were identified from a diversity of amphibian skin secretions, have been demonstrated to possess several biological functions such as stimulation of smooth muscle contraction and regulation of food intake. Here, we report two novel bombesin-like peptides, bombesin-OS and bombesin-PE, which [...] Read more.
Bombesin-like peptides, which were identified from a diversity of amphibian skin secretions, have been demonstrated to possess several biological functions such as stimulation of smooth muscle contraction and regulation of food intake. Here, we report two novel bombesin-like peptides, bombesin-OS and bombesin-PE, which were isolated from Odorrana schmackeri and Pelophylax kl. esculentus, respectively. The mature peptides were identified and structurally confirmed by high performance Scliquid chromatography (HPLC) and tandem mass spectrometry (MS/MS). Subsequently, the effects of these purified chemically-synthetic peptides on smooth muscle were determined in bladder, uterus, and ileum. The synthetic replications were revealed to have significant pharmacological effects on these tissues. The EC50 values of bombesin-OS for bladder, uterus and ileum, were 10.8 nM, 33.64 nM, and 12.29 nM, respectively. Furthermore, compared with bombesin-OS, bombesin-PE showed similar contractile activity on ileum smooth muscle and uterus smooth muscle, but had a higher potency on bladder smooth muscle. The EC50 value of bombesin-OS for bladder was around 1000-fold less than that of bombesin-PE. This suggests that bombesin-OS and bombesin-PE have unique binding properties to their receptors. The precursor of bombesin-OS was homologous with that of a bombesin-like peptide, odorranain-BLP-5, and bombesin-PE belongs to the ranatensin subfamily. We identified the structure of bombesin-OS and bombesin-PE, two homologues peptides whose actions may provide a further clue in the classification of ranid frogs, also in the provision of new drugs for human health. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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5543 KiB  
Article
Discovery of Phylloseptins that Defense against Gram-Positive Bacteria and Inhibit the Proliferation of the Non-Small Cell Lung Cancer Cell Line, from the Skin Secretions of Phyllomedusa Frogs
by Jia Liu, Qing Wu, Lei Li, Xinping Xi, Di Wu, Mei Zhou, Tianbao Chen, Chris Shaw and Lei Wang
Molecules 2017, 22(9), 1428; https://doi.org/10.3390/molecules22091428 - 29 Aug 2017
Cited by 17 | Viewed by 5158
Abstract
The growing occurrence of bacterial resistance to conventional antibiotics has called for the development of new classes of antimicrobial agents. Antimicrobial peptides (AMPs) with broad antimicrobial spectrum derived from frog skin secretions have been demonstrated to be promising candidates for new antibiotic development. [...] Read more.
The growing occurrence of bacterial resistance to conventional antibiotics has called for the development of new classes of antimicrobial agents. Antimicrobial peptides (AMPs) with broad antimicrobial spectrum derived from frog skin secretions have been demonstrated to be promising candidates for new antibiotic development. A proven rich source of these compounds are the skin secretions of the frogs in the Phyllomedusa genus. In this study, two novel phylloseptin peptides—phylloseptin-PTa and phylloseptin-PHa—were isolated from the skin secretions of the South American frogs, Phyllomedusa tarsius (P. tarsius) and Phyllomedusa hypochondrialis (P. hypochondrialis) through parallel transcriptomic and peptidomic studies. Replicates obtained by chemical synthesis were structurally analysed and shown to adopt an α-helix configuration in an amphiphilic environment. Both peptides demonstrated antimicrobial activities against planktonic Gram-positive bacteria strains, including Staphylococcus aureus, Enterococcus faecalis and methicillin-resistant Staphylococcus aureus , biofilms, as well as cytostatic effects on the non-small cell lung cancer cell line, NCI-H157, with relatively low haemolysis on horse erythrocytes and low cytotoxicity on the human microvascular endothelial cell line, HMEC-1. The discovery of phylloseptin peptides may further inspire the development of new types of antibiotics. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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984 KiB  
Article
Identification of a Novel Vasodilatory Octapeptide from the Skin Secretion of the African Hyperoliid Frog, Kassina senegalensis
by Qiang Du, Hui Wang, Chengbang Ma, Yue Wu, Xinping Xi, Mei Zhou, Tianbao Chen, Chris Shaw and Lei Wang
Molecules 2017, 22(7), 1215; https://doi.org/10.3390/molecules22071215 - 19 Jul 2017
Cited by 3 | Viewed by 4134
Abstract
The defensive skin secretions of amphibians continue to be an excellent source of novel biologically-active peptides. Here we report the identification and pharmacological activity of a novel C-terminally amided myotropic octapeptide from the skin secretion of the African hyperoliid frog, Kassina senegalensis. [...] Read more.
The defensive skin secretions of amphibians continue to be an excellent source of novel biologically-active peptides. Here we report the identification and pharmacological activity of a novel C-terminally amided myotropic octapeptide from the skin secretion of the African hyperoliid frog, Kassina senegalensis. The 8-amino acid peptide has the following primary structure: WMSLGWSL-amide and has a molecular mass of 978 Da. The primary structure and organisation of the biosynthetic precursor of WL-8 amide was successfully deduced from cloned skin secretion-derived cDNA. The open-reading frame encoded a single copy of WL-8, located at the C-terminus. Synthetic WL-8 amide was found to cause relaxation of rat tail artery smooth muscle with an EC50 of 25.98 nM. This peptide is unique in terms of its primary structure and is unlike any other peptide previously isolated from an amphibian source which has been archived in the NCBI database. WL-8 amide thus represents the prototype of a novel family of myotropic peptide from amphibian defensive skin secretions. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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5014 KiB  
Article
Ranatensin-HL: A Bombesin-Related Tridecapeptide from the Skin Secretion of the Broad-Folded Frog, Hylarana latouchii
by Yan Lin, Tianbao Chen, Mei Zhou, Lei Wang, Songkun Su and Chris Shaw
Molecules 2017, 22(7), 1110; https://doi.org/10.3390/molecules22071110 - 04 Jul 2017
Cited by 6 | Viewed by 4122
Abstract
Bombesin-related peptides are a family of peptides whose prototype was discovered in amphibian skin and which exhibit a wide range of biological activities. Since the initial isolation of bombesin from Bombina bombina skin, diverse forms of bombesin-related peptides have been found in the [...] Read more.
Bombesin-related peptides are a family of peptides whose prototype was discovered in amphibian skin and which exhibit a wide range of biological activities. Since the initial isolation of bombesin from Bombina bombina skin, diverse forms of bombesin-related peptides have been found in the skins across Anura. In this study, a novel bombesin-related peptide of the ranatensin subfamily, named ranatensin-HL, was structurally-characterised from the skin secretion of the broad-folded frog, Hylarana latouchii, through combination of molecular cloning and mass spectrometric methodologies. It is composed of 13 amino acid residues, pGlu-RAGNQWAIGHFM-NH2, and resembles an N-terminally extended form of Xenopus neuromedin B. Ranatensin-HL and its C-terminal decapeptide (ranatensin-HL-10) were chemically synthesised and subjected to in vitro smooth muscle assays in which they were found to display moderate stimulatory effects on rat urinary bladder and uterus smooth muscles with EC50 values in the range of 1–10 nM. The prepro-ranatensin-HL was highly homological to a bombesin-like peptide from Rana catesbeiana at both nucleotide and amino acid levels, which might provide a clue for the taxonomic classification of ranid frogs in the future. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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892 KiB  
Article
Production of Recombinant Antimicrobial Polymeric Protein Beta Casein-E 50-52 and Its Antimicrobial Synergistic Effects Assessment with Thymol
by Shohreh Fahimirad, Hamid Abtahi, Seyed Hadi Razavi, Houshang Alizadeh and Mansour Ghorbanpour
Molecules 2017, 22(6), 822; https://doi.org/10.3390/molecules22060822 - 31 May 2017
Cited by 22 | Viewed by 5492
Abstract
Accelerating emergence of antimicrobial resistance among food pathogens and consumers’ increasing demands for preservative-free foods are two contemporary challenging aspects within the food industry. Antimicrobial packaging and the use of natural preservatives are promising solutions. In the present study, we used beta-casein—one [...] Read more.
Accelerating emergence of antimicrobial resistance among food pathogens and consumers’ increasing demands for preservative-free foods are two contemporary challenging aspects within the food industry. Antimicrobial packaging and the use of natural preservatives are promising solutions. In the present study, we used beta-casein—one of the primary self-assembly proteins in milk with a high polymeric film production capability—as a fusion partner for the recombinant expression of E 50-52 antimicrobial peptide in Escherichia coli. The pET21a-BCN-E 50-52 construct was transformed to E. coli BL21 (DE3), and protein expression was induced under optimized conditions. Purified protein obtained from nickel affinity chromatography was refolded under optimized dialysis circumstances and concentrated to 1600 µg/mL fusion protein by ultrafiltration. Antimicrobial activities of recombinant BCN-E 50-52 performed against Escherichia coli, Salmonella typhimurium, Listeria monocytogenes, Staphylococcus aureus, Aspergillus flavus, and Candida albicans. Subsequently, the synergistic effects of BCN-E 50-52 and thymol were assayed. Results of checkerboard tests showed strong synergistic activity between two compounds. Time–kill and growth kinetic studies indicated a sharp reduction of cell viability during the first period of exposure, and SEM (scanning electron microscope) results validated the severe destructive effects of BCN E 50-52 and thymol in combination on bacterial cells. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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381 KiB  
Article
Emulsion-Based Intradermal Delivery of Melittin in Rats
by Sang Mi Han, Se Gun Kim and Sok Cheon Pak
Molecules 2017, 22(5), 836; https://doi.org/10.3390/molecules22050836 - 19 May 2017
Cited by 5 | Viewed by 4443
Abstract
Bee venom (BV) has long been used as a traditional medicine. The aim of the present study was to formulate a BV emulsion with good rheological properties for dermal application and investigate the effect of formulation on the permeation of melittin through dermatomed [...] Read more.
Bee venom (BV) has long been used as a traditional medicine. The aim of the present study was to formulate a BV emulsion with good rheological properties for dermal application and investigate the effect of formulation on the permeation of melittin through dermatomed rat skin. A formulated emulsion containing 1% (w/v) BV was prepared. The emulsion was compared with distilled water (DW) and 25% (w/v) N-methyl-2-pyrrolidone (NMP) in DW. Permeation of melittin from aqueous solution through the dermatomed murine skin was evaluated using the Franz diffusion cells. Samples of receptor cells withdrawn at pre-determined time intervals were measured for melittin amount. After the permeation study, the same skin was used for melittin extraction. In addition, a known amount of melittin (5 μg/mL) was added to stratum corneum, epidermis, and dermis of the rat skin, and the amount of melittin was measured at pre-determined time points. The measurement of melittin from all samples was done with HPLC-MS/MS. No melittin was detected in the receptor phase at all time points in emulsion, DW, or NMP groups. When the amount of melittin was further analyzed in stratum corneum, epidermis, and dermis from the permeation study, melittin was still not detected. In an additional experiment, the amount of melittin added to all skin matrices was corrected against the amount of melittin recovered. While the total amount of melittin was retained in the stratum corneum, less than 10% of melittin remained in epidermis and dermis within 15 and 30 min, respectively. Skin microporation with BV emulsion facilitates the penetration of melittin across the stratum corneum into epidermis and dermis, where emulsified melittin could have been metabolized by locally-occurring enzymes. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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3252 KiB  
Article
High Hydrostatic Pressure (HHP)-Induced Structural Modification of Patatin and Its Antioxidant Activities
by Rizwan Elahi and Tai-Hua Mu
Molecules 2017, 22(3), 438; https://doi.org/10.3390/molecules22030438 - 10 Mar 2017
Cited by 27 | Viewed by 6326
Abstract
Patatin represents a group of homologous primary storage proteins (with molecular weights ranging from 40 kDa to 45 kDa) found in Solanum tuberosum L. This group comprises 40% of the total soluble proteins in potato tubers. Here, patatin (40 kDa) was extracted from [...] Read more.
Patatin represents a group of homologous primary storage proteins (with molecular weights ranging from 40 kDa to 45 kDa) found in Solanum tuberosum L. This group comprises 40% of the total soluble proteins in potato tubers. Here, patatin (40 kDa) was extracted from potato fruit juice using ammonium sulfate precipitation (ASP) and exposed to high hydrostatic pressure (HHP) treatment (250, 350, 450, and 550 MPa). We investigated the effect of HHP treatment on the structure, composition, heat profile, and antioxidant potential, observing prominent changes in HHP-induced patatin secondary structure as compared with native patatin (NP). Additionally, significant (p < 0.05) increases in β-sheet content along with decreases in α-helix content were observed following HHP treatment. Thermal changes observed by differential scanning calorimetry (DSC) also showed a similar trend following HHP treatment; however, the enthalpy of patatin was also negatively affected by pressurization, and free sulfhydryl content and surface hydrophobicity significantly increased with pressurization up to 450 MPa, although both interactions progressively decreased at 550 MPa. The observed physicochemical changes suggested conformational modifications in patatin induced by HHP treatment. Moreover, our results indicated marked enhancement of antioxidant potential, as well as iron chelation activities, in HHP-treated patatin as compared with NP. These results suggested that HHP treatment offers an effective and green process for inducing structural modifications and improving patatin functionality. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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4220 KiB  
Article
A Protein Isolate from Moringa oleifera Leaves Has Hypoglycemic and Antioxidant Effects in Alloxan-Induced Diabetic Mice
by Paulo C. Paula, Daniele O. B. Sousa, Jose T. A. Oliveira, Ana F. U. Carvalho, Bella G. T. Alves, Mirella L. Pereira, Davi F. Farias, Martonio P. Viana, Flavia A. Santos, Talita C. Morais and Ilka M. Vasconcelos
Molecules 2017, 22(2), 271; https://doi.org/10.3390/molecules22020271 - 11 Feb 2017
Cited by 57 | Viewed by 10188
Abstract
Moringa oleifera has been used in traditional medicine to treat diabetes. However, few studies have been conducted to relate its antidiabetic properties to proteins. In this study, a leaf protein isolate was obtained from M. oleifera leaves, named Mo-LPI, and the hypoglycemic [...] Read more.
Moringa oleifera has been used in traditional medicine to treat diabetes. However, few studies have been conducted to relate its antidiabetic properties to proteins. In this study, a leaf protein isolate was obtained from M. oleifera leaves, named Mo-LPI, and the hypoglycemic and antioxidant effects on alloxan-induced diabetic mice were assessed. Mo-LPI was obtained by aqueous extraction, ammonium sulphate precipitation and dialysis. The electrophoresis profile and proteolytic hydrolysis confirmed its protein nature. Mo-LPI showed hemagglutinating activity, cross-reaction with anti-insulin antibodies and precipitation after zinc addition. Single-dose intraperitoneal (i.p.) administration of Mo-LPI (500 mg/kg·bw) reduced the blood glucose level (reductions of 34.3%, 60.9% and 66.4% after 1, 3 and 5 h, respectively). The effect of Mo-LPI was also evidenced in the repeated dose test with a 56.2% reduction in the blood glucose level on the 7th day after i.p. administration. Mo-LPI did not stimulate insulin secretion in diabetic mice. Mo-LPI was also effective in reducing the oxidative stress in diabetic mice by a decrease in malondialdehyde level and increase in catalase activity. Mo-LPI (2500 mg/kg·bw) did not cause acute toxicity to mice. Mo-LPI is a promising alternative or complementary agent to treat diabetes. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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2192 KiB  
Article
Identification and Characterisation of the Antimicrobial Peptide, Phylloseptin-PT, from the Skin Secretion of Phyllomedusa tarsius, and Comparison of Activity with Designed, Cationicity-Enhanced Analogues and Diastereomers
by Yitian Gao, Di Wu, Xinping Xi, Yue Wu, Chengbang Ma, Mei Zhou, Lei Wang, Mu Yang, Tianbao Chen and Chris Shaw
Molecules 2016, 21(12), 1667; https://doi.org/10.3390/molecules21121667 - 03 Dec 2016
Cited by 32 | Viewed by 7008
Abstract
Antimicrobial peptides belonging to the phylloseptin family are mainly found in phyllomedusine frogs. These peptides not only possess potent antimicrobial activity but exhibit low toxicity against eukaryotic cells. Therefore, they are considered as promising drug candidates for a number of diseases. In a [...] Read more.
Antimicrobial peptides belonging to the phylloseptin family are mainly found in phyllomedusine frogs. These peptides not only possess potent antimicrobial activity but exhibit low toxicity against eukaryotic cells. Therefore, they are considered as promising drug candidates for a number of diseases. In a recent study, potent antimicrobial activity was correlated with the conserved structures and cationic amphiphilic characteristics of members of this peptide family. A phylloseptin peptide precursor was discovered here in the skin secretion of Phyllomedusa tarsius and the mature peptide was validated by MS/MS sequencing, and was subsequently named phylloseptin-PT. The chemically-synthesized and purified phylloseptin-PT displayed activity against Staphylococcus aureus and Candida albicans. Nevertheless, a range of cationicity-enhanced peptide analogues of phylloseptin-PT, which contained amino acid substitutions at specific sites, exhibited significant increases in antimicrobial activity compared to native phylloseptin-PT. In addition, alternative conformers which were designed and chemically-synthesized with d-lysine, showed potent antimicrobial activity and enhanced bioavailability. These data indicate that phylloseptins may represent potential candidates for next-generation antibiotics. Thus, rational design through modification of natural antimicrobial peptide templates could provide an accelerated path to overcoming obstacles en-route to their possible clinical applications. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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Review

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Review
Bioactive Nutrients and Nutrigenomics in Age-Related Diseases
by Tania Rescigno, Luigina Micolucci, Mario F. Tecce and Anna Capasso
Molecules 2017, 22(1), 105; https://doi.org/10.3390/molecules22010105 - 08 Jan 2017
Cited by 57 | Viewed by 15849
Abstract
The increased life expectancy and the expansion of the elderly population are stimulating research into aging. Aging may be viewed as a multifactorial process that results from the interaction of genetic and environmental factors, which include lifestyle. Human molecular processes are influenced by [...] Read more.
The increased life expectancy and the expansion of the elderly population are stimulating research into aging. Aging may be viewed as a multifactorial process that results from the interaction of genetic and environmental factors, which include lifestyle. Human molecular processes are influenced by physiological pathways as well as exogenous factors, which include the diet. Dietary components have substantive effects on metabolic health; for instance, bioactive molecules capable of selectively modulating specific metabolic pathways affect the development/progression of cardiovascular and neoplastic disease. As bioactive nutrients are increasingly identified, their clinical and molecular chemopreventive effects are being characterized and systematic analyses encompassing the “omics” technologies (transcriptomics, proteomics and metabolomics) are being conducted to explore their action. The evolving field of molecular pathological epidemiology has unique strength to investigate the effects of dietary and lifestyle exposure on clinical outcomes. The mounting body of knowledge regarding diet-related health status and disease risk is expected to lead in the near future to the development of improved diagnostic procedures and therapeutic strategies targeting processes relevant to nutrition. The state of the art of aging and nutrigenomics research and the molecular mechanisms underlying the beneficial effects of bioactive nutrients on the main aging-related disorders are reviewed herein. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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Review
Impact of Bee Venom Enzymes on Diseases and Immune Responses
by Md. Sakib Hossen, Ummay Mahfuza Shapla, Siew Hua Gan and Md. Ibrahim Khalil
Molecules 2017, 22(1), 25; https://doi.org/10.3390/molecules22010025 - 27 Dec 2016
Cited by 56 | Viewed by 14621
Abstract
Bee venom (BV) is used to treat many diseases and exhibits anti-inflammatory, anti-bacterial, antimutagenic, radioprotective, anti-nociceptive immunity promoting, hepatocyte protective and anti-cancer activity. According to the literature, BV contains several enzymes, including phospholipase A2 (PLA2), phospholipase B, hyaluronidase, acid phosphatase and α-glucosidase. Recent [...] Read more.
Bee venom (BV) is used to treat many diseases and exhibits anti-inflammatory, anti-bacterial, antimutagenic, radioprotective, anti-nociceptive immunity promoting, hepatocyte protective and anti-cancer activity. According to the literature, BV contains several enzymes, including phospholipase A2 (PLA2), phospholipase B, hyaluronidase, acid phosphatase and α-glucosidase. Recent studies have also reported the detection of different classes of enzymes in BV, including esterases, proteases and peptidases, protease inhibitors and other important enzymes involved in carbohydrate metabolism. Nevertheless, the physiochemical properties and functions of each enzyme class and their mechanisms remain unclear. Various pharmacotherapeutic effects of some of the BV enzymes have been reported in several studies. At present, ongoing research aims to characterize each enzyme and elucidate their specific biological roles. This review gathers all the current knowledge on BV enzymes and their specific mechanisms in regulating various immune responses and physiological changes to provide a basis for future therapies for various diseases. Full article
(This article belongs to the Special Issue Bioactive Natural Peptides As A Pipeline For Therapeutics)
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