The antimicrobial and anti-endotoxic peptide AmyI-1-18 from rice α-amylase and its [N3L] analog promote angiogenesis and cell migration

Antimicrobial peptides in bone regeneration: mechanism and potential

INTRODUCTION

Antimicrobial peptides (AMPs) are small-molecule peptides with a unique antimicrobial mechanism. Other notable biological activities of AMPs, including anti-inflammatory, angiogenesis, and bone formation effects, have recently received widespread attention. These remarkable bioactivities, combined with the unique antimicrobial mechanism of action of AMPs, have led to their increasingly important role in bone regeneration.

AREAS COVERED

In this review, on the one hand, we aimed to summarize information about the AMPs that are currently used for bone regeneration by reviewing published literature in the PubMed database. On the other hand, we also highlight some AMPs with potential roles in bone regeneration and their possible mechanisms of action.

EXPERT OPINION

The translation of AMPs to the clinic still faces many problems, but their unique antimicrobial mechanisms and other conspicuous biological activities suggest great potential. An in-depth understanding of the structure and mechanism of action of AMPs will help us to subsequently combine AMPs with different carrier systems and perform structural modifications to reduce toxicity and achieve stable release, which may be a key strategy for facilitating the translation of AMPs to the clinic.

Discovery of new functions of food proteins and their structural development for multifunctional applications

Proteins and peptides derived from various food sources are used in a variety of applications, including functional foods, pharmaceuticals, and cosmetics. The three-dimensional structure of proteins provides useful insights into their functions and essential information for the creation of proteins with new functions. In this review, a series of functional conversion technologies based on protein structural information derived from foods traditionally consumed in Japan, such as natto (fermented soybeans) and rice, are introduced. For natto, we first identified 2 types of Bacillus subtilis-derived endolytic and exolytic enzymes with different modes of action on soybean cell wall polysaccharides and then focused on the technology used to create an endolytic enzyme from an exolytic enzyme. By applying this technology, a method for creating novel bioactive peptides from rice seed proteins was established. The modified peptides created could provide diverse options for the production of substances such as pharmaceuticals and cosmetic materials.

Replacement in angiogenesis research: Studying mechanisms of blood vessel development by animal-free in vitro, in vivo and in silico approaches

Angiogenesis, the development of new blood vessels from pre-existing ones, is an essential process determining numerous physiological and pathological conditions. Accordingly, there is a high demand for research approaches allowing the investigation of angiogenic mechanisms and the assessment of pro- and anti-angiogenic therapeutics. The present review provides a selective overview and critical discussion of such approaches, which, in line with the 3R principle, all share the common feature that they are not based on animal experiments. They include in vitro assays to study the viability, proliferation, migration, tube formation and sprouting activity of endothelial cells in two- and three-dimensional environments, the degradation of extracellular matrix compounds as well as the impact of hemodynamic forces on blood vessel formation. These assays can be complemented by in vivo analyses of microvascular network formation in the chorioallantoic membrane assay and early stages of zebrafish larvae. In addition, the combination of experimental data and physical laws enables the mathematical modeling of tissue-specific vascularization, blood flow patterns, interstitial fluid flow as well as oxygen, nutrient and drug distribution. All these animal-free approaches markedly contribute to an improved understanding of fundamental biological mechanisms underlying angiogenesis. Hence, they do not only represent essential tools in basic science but also in early stages of drug development. Moreover, their advancement bears the great potential to analyze angiogenesis in all its complexity and, thus, to make animal experiments superfluous in the future.

Regulation of an Antimicrobial Peptide GL13K-Modified Titanium Surface on Osteogenesis, Osteoclastogenesis, and Angiogenesis Base on Osteoimmunology

Creating a pro-regenerative immune microenvironment around implant biomaterial surfaces is significant to osseointegration. Immune cells, especially macrophages that participate in the osseointegration, including osteogenesis, osteoclastogenesis, and angiogenesis, should be considered when testing biomaterials. In this study, we immobilized an antimicrobial peptide GL13K with immunomodulatory properties onto a titanium surface via silanization. The modified surfaces show good biocompatibility with bone mesenchymal stromal cells (BMSCs), human umbilical vein endothelial cells (HUVECs), and RAW264.7. By co-culturing BMSCs with RAW264.7, we found that the GL13K-coated titanium surfaces could promote late-stage osteogenesis as demonstrated by the upregulated expression of recombinant collagen type I alpha 1 (COL-1α1) and more extracellular matrix mineralization, while the early phase remained unchanged. The surfaces inhibited the osteoclastogenic differentiation of RAW264.7 cells by restraining nuclear factor-activated T cells, cytoplasmic 1 (NFATc1), the main factor of the receptor activator of nuclear factor-κ B, and the receptor activator of the nuclear factor-κ B ligand signaling pathway, from entering the nucleus and further reduced the expression of the activating osteoclastogenic tartrate-resistant acid phosphatase gene. Moreover, the GL13K-coated titanium surface demonstrated significant promotion of angiogenesis differentiation of HUVECs as indicated by the upregulated expression of essential angiogenesis function genes, including hypoxia-inducible factor-1α, endothelial nitric oxide synthase, kinase insert domain receptor, and vascular endothelial growth factor A (HIF-1α, eNOS, KDR, and VEGF-A). Taken together, these results demonstrated that the GL13K coating had properties of osteogenesis, angiogenesis, and anti-osteoclastogenesis via its immunomodulatory potential.

Identification and characterization of multifunctional cationic peptides from enzymatic hydrolysates of soybean proteins

In this study, we used the commercial soybean protein hydrolysate Hinute-DC6 as a novel starting material from which to purify and identify multifunctional cationic peptides. After fractionation, Hinute-DC6 was separated into 20 fractions with varying isoelectric points (pI) by ampholyte-free isoelectric focusing (autofocusing). Subsequently, we purified and identified the cationic peptides from fractions 19 and 20, which had pI values greater than 12, using reversed-phase high-performance liquid chromatography and matrix-assisted laser/desorption ionization-time-of-flight mass spectrometry. Of the 83 cationic peptides identified, 14 had high pI values and net charges greater than +2, and were chemically synthesized and assayed for various bioactivities, including hemolytic, antimicrobial, lipopolysaccharide (LPS)-neutralizing, and angiogenic activities. None of the 14 cationic peptides tested exhibited hemolytic activity toward mammalian red blood cells at concentrations up to 1000 μM. Five of the cationic peptides exhibited antimicrobial activities against at least one of four human-pathogenic microorganisms tested. In addition, in chromogenic LPS-neutralizing assays using Limulus amebocyte lysates, the 50% effective concentrations of these 14 peptides were between 0.069 and 5.2 μM. Tube-formation assays in human umbilical vein endothelial cells showed that each of the 14 cationic peptides exhibited significant angiogenic activities at 10 μM, with values similar to those of the positive control LL-37. Our results demonstrate that the 14 identified cationic peptides have multiple functions with negligible hemolytic activity. These data indicate that the cationic peptides isolated from Hinute-DC6 and fractions containing these cationic peptides have the potential to be used as multifunctional ingredients for healthcare applications.

Biofunctions of antimicrobial peptide-conjugated alginate/hyaluronic acid/collagen wound dressings promote wound healing of a mixed-bacteria-infected wound

The increase in severe infections caused by antibiotic drug resistance and the decrease in the number of new antibacterial drugs approved for use in the last few decades are driving the need for the development of new antimicrobial strategies. Antimicrobial peptides (AMPs) are a potential new class of antimicrobial drugs that are expected to solve the problem of global antibiotic drug resistance. Herein, the AMP Tet213 was immobilised onto the substrates of alginate (ALG), hyaluronic acid (HA), and collagen (COL) to form the ALG/HA/COL-AMP wound dressing. This wound dressing exhibited a high degree of swelling and the appropriate porosity, mechanical properties, and biodegradability. The Tet213-immobilised ALG/HA/COL dressings exhibited antimicrobial activity against three pathogenic bacterial strains (Gram-negative E. coli and Gram-positive MRSA and S. aureus) and facilitated the proliferation of NIH 3T3 fibroblast cells. In addition, the ALG/HA/COL-AMP antimicrobial dressings promoted wound healing, re-epithelialisation, collagen deposition, and angiogenesis. Moreover, the wound-healing effects of ALG/HA/COL-AMP surpassed the gauze and ALG/HA/COL compared to commercially available silver-based dressings (Aguacel Ag). These results suggest that the Tet213-conjugated ALG/HA/COL wound dressing, with its multiple biological activities, is a promising wound-dressing material.

Chemical profiling and pharmaco-toxicological activity of Origanum sipyleum extracts: Exploring for novel sources for potential therapeutic agents

The phytochemical, antiradical, and enzyme inhibition profile of three solvent extracts (ethyl acetate, methanol, water) of Origanum sipyleum were assessed. We also performed a pharmacological study in order to explore protective effects induced by extracts in inflamed colon. LC-MS analysis revealed that the extracts contained different classes of phenolics. The aqueous extract showed the highest antioxidant and acetylcholinesterase (AChE) inhibitory effects. Total phenol and flavonoid contents were highest in aqueous and ethyl acetate extract, respectively. All extracts were effective in reducing colon pro-oxidant and pro-inflammatory biomarkers. The extracts revealed also able to inhibit fungal and bacterial species involved in ulcerative colitis, including Candida albicans, Candida tropicalis, Staphylococcus aureus, and Staphylococcus thyphimurium. Finally, we also showed the antiproliferative effects exerted by the EA extracts on human colon cancer HCT116 cell line. Concluding, our results indicated that O. sipyleum extracts displayed promising therapeutic properties which warrants further validation. PRACTICAL APPLICATIONS: The present phytochemical and biological studies, including antioxidant, anti-inflammatory, and antimicrobic assessments, showed significant protective effects exerted by O. sipyleum extracts in an experimental model of ulcerative colitis. The results are intriguing and suggest potential applications O. sipyleum extracts as sources of natural agents for the management of clinical symptoms related to ulcerative colitis, characterized by increased burden of oxidative stress and microbiome dysbiosis.

Identification and characterization of multifunctional cationic peptides from traditional Japanese fermented soybean Natto extracts

In this study, we investigated the lipopolysaccharide (LPS)-neutralizing and angiogenic activities of cationic peptides derived from the traditional Japanese fermented product Natto, which is made by fermenting cooked soybeans using Bacillus subtilis. Initially, we prepared 20 fractions of Natto extracts with various isoelectric points (pI's) using ampholyte-free isoelectric focusing (autofocusing). Cationic peptides were then purified from fractions 19 and 20, whose pH values were greater than 12, using reversed-phase high-performance liquid chromatography, and were identified using matrix-assisted laser/desorption ionization-time-of-flight mass spectroscopy. Among the 13 identified cationic peptides, seven (KFNKYGR, FPFPRPPHQK, GQSSRPQDRHQK, QRFDQRSPQ, ERQFPFPRPPHQK, GEIPRPRPRPQHPE, and EQPRPIPFPRPQPR) had pI's greater than 9.5, positive net charges, and differing molecular weights. These peptides were then chemically synthesized and applied to chromogenic LPS-neutralizing assays using Limulus amebocyte lysates, and 50% effective (neutralizing) concentrations of 2.6-5.5 μM were demonstrated. In addition, tube formation assays in human umbilical vein endothelial cells revealed angiogenic activities for all but one (GEIPRPRPRPQHPE) of these seven cationic peptides, with increases in relative tube lengths of 23-31% in the presence of peptides at 10 μM. Subsequent experiments showed negligible hemolytic activity of these peptides at concentrations of up to 500 μM in mammalian red blood cells. Collectively, these data demonstrate that six cationic peptides from Natto extracts, with the exception of GEIPRPRPRPQHPE, have LPS-neutralizing and angiogenic activities but do not induce hemolysis.

Wound healing activity and mechanism of action of antimicrobial and lipopolysaccharide-neutralizing peptides from enzymatic hydrolysates of rice bran proteins

In our previous study, we identified multifunctional cationic peptides from enzymatic hydrolysates of rice bran proteins (RBPs) that have antimicrobial and lipopolysaccharide-neutralizing activities. In this study, we investigated the potential of the peptides RBP-LRR, RBP-EKL, and RBP-SSF to promote proliferation, angiogenesis (tube formation), and migration in human umbilical vein endothelial cells (HUVECs). To determine mechanisms of wound healing actions, angiogenic and migration-promoting activities of these peptides were evaluated following pretreatments of HUVECs with specific inhibitors. In these experiments, the cationic peptides RBP-LRR, RBP-EKL, and RBP-SSF induced cell proliferation at low concentrations of 0.1 μM or 1 μM. Moreover, the three cationic peptides had angiogenic activities at concentrations more than 1 μM in tube formation assays, and their effects were similar to those of LL-37. Subsequent scratch migration assays exhibited that RBP-LRR, RBP-EKL, and RBP-SSF promote wound closure at optimum concentrations of 10, 10, and 0.1 μM, respectively. In further studies, we performed tube formation assays using HUVECs pretreated with SU5416, which inhibits vascular endothelial growth factor (VEGF) receptors, and suggested the possibility that the three cationic peptides induce angiogenesis by activating VEGF receptors. In corresponding scratch migration assays using HUVECs, pretreatment with the proliferation inhibitor mitomycin C did not alter the effects of RBP-LRR and RBP-EKL, and significant contribution to wound closure were mediated by cell migration regardless of proliferation rates. In contrast, RBP-SSF contributed to wound closure exclusively by promoting cell proliferation. The present data indicate that RBP-LRR, RBP-EKL, and RBP-SSF are candidates for use as wound healing agents.

Crocus sativus by-products as sources of bioactive extracts: Pharmacological and toxicological focus on anthers

Multiple studies revealed the potential application of high quality saffron byproducts as cheap sources of bioactive compounds endowed with antioxidant activity. In the present study, we analyzed the total fatty acids of the anthers, and explored the pharmacological and toxicological potential of anthers, by evaluating genotoxic and protective effects in multiple cell lines, brine shrimps and isolated rat tissues. The phytochemical analyses showed that anthers are rich in long chain fatty acids most of which are unsaturated (80.51%). Particularly, anther water extract revealed to be well tolerated by multiple cell lines, and able to modulate reactive oxygen species (ROS) levels, without exerting either genotoxic or cytotoxic effects. The same extract was also able to blunt lipopolysaccharide (LPS)-induced nitrite and malondialdehyde (MDA) in isolated rat tissues. On the other hand, considering the concomitant null effect on HCT116 cell migration, in wound healing experimental paradigm, our findings suggest the efficacy of water anther extract as protective agent without any direct reverting effects on lesioned tissues. Concluding, the promising results, deriving from the pharmacological and toxicological evaluations, support the valorization of saffron anthers as a strategy to optimize and develop the productive chain of Abruzzo saffron.

Cationic peptides from enzymatic hydrolysates of soybean proteins exhibit LPS-neutralizing and angiogenic activities

In this study, we prepared fractions containing multifunctional cationic peptides by separating the commercial soybean protein hydrolysate Hinute-AM into 20 fractions. These fractions contained peptides with various isoelectric points (pI), as indicated by ampholyte-free isoelectric focusing (autofocusing). Thus, we purified and identified the cationic peptides from fractions 19 and 20, which had pH values greater than 10, using reversed-phase high-performance liquid chromatography and matrix-assisted laser/desorption ionization-time-of-flight mass spectroscopy. Among 19 identified cationic peptides, NKNAKPPSPR, PGKKNAIV, KSGPGMSPR, NVSKPPRVV, RKVGAGGRKPLG, and LPCVIGGVPKRV had high pI values and were included as chemically synthesized peptides in assays of various functions, including lipopolysaccharide (LPS)-neutralizing and angiogenic activities. Chromogenic LPS-neutralizing assays using Limulus amebocyte lysates showed that 50% effective concentrations of these six peptides were between 1.63 and 2.65 μM, and were higher than that (0.12 μM) of polymyxin B. Moreover, in tube-formation assays in human umbilical vein endothelial cells, all of the six cationic peptides except LPCVIGGVPKRV exhibited angiogenic activities similar to those of the positive control LL-37. In addition, the six identified cationic peptides had no hemolytic activity at concentrations up to 500 μM in mammalian red blood cells. Our results demonstrate that five of the identified cationic peptides, excluding LPCVIGGVPKRV, have multiple functions and little or no hemolytic activity. These data indicate that fractions containing cationic peptides from Hinute-AM have the potential to be used as dietary supplements and functional ingredients in food products.

Multiple pharmacognostic characterization on hemp commercial cultivars: Focus on inflorescence water extract activity

One of the most promising economic perspectives of hemp production chain is female inflorescence valorization, despite there being actually no chemical composition or biological data from water fraction. In this context, the focus of this study is the evaluation of protective effects related to hemp water flower extracts from four commercial cultivars (Futura 75, Kc virtus, Carmagnola Cs and Villanova). We evaluated the phytochemical profile through validated spectrophotometric and HPLC methods. Then, we studied the biological activity on C2C12 and HCT116 cell lines, and in an ex vivo experimental model of ulcerative colitis, constituted by isolated LPS-stimulated colon. Particularly, we assayed the blunting effects induced by hemp water extract treatment on LPS-induced levels of nitrites, malondialdehyde (MDA), prostaglandin (PG)E₂ and serotonin (5-HT). All tested cultivars displayed similar total phenolic and flavonoid profile. However, Futura 75 water extract displayed a better antioxidant and anti-inflammatory profile. Considering this, Futura 75 extract activity has been subsequently assayed on bacterial and fungal species involved in ulcerative colitis, finding a significant inhibition on C. albicans and selected Gram positive and negative bacterial strains. Concluding, our results support the potential efficacy of hemp inflorescence water extracts in managing the clinical symptoms related to ulcerative colitis.

Protective effects of Cotoneaster integerrimus on in vitro and ex-vivo models of H2 O2 -induced lactate dehydrogenase activity in HCT116 cell and on lipopolysaccharide-induced inflammation in rat colon

The present study evaluated the biological potential of methanol and aqueous extracts of the twigs and fruits of Cotoneaster integerrimus Medik. Lethality bioassays performed on Artemia salina showed that aqueous and methanol C. integerrimus extracts were non-toxic in the concentration range (0.1-20 mg/ml), with a LC50 ≥ 2.5 mg/ml, for each single extract. The protective effect of the extracts was assessed in vitro against hydrogen peroxide-induced lactate dehydrogenase (LDH) activity and tumor necrosis factor (TNF)α gene expression in colon cancer HCT116 cell line. All the extracts downregulated (H₂ O₂ )-induced TNFα gene expression, in HCT116. By contrast, it was observed that the lipopolysaccharide (LPS)-induced increase in colon nitrite, prostaglandin E₂ , and 8-iso-PGF_2α levels were counteracted mostly by the methanol twig extract. The present study showed protective effects induced by C. integerrimus in vitro and ex vivo, thus supporting potential application in the management of chronic inflammatory diseases. PRACTICAL APPLICATIONS: In the present study, protective effects of C. integerrimus are highlighted using in vitro and ex-vivo models of hydrogen peroxide-induced LDH activity in HCT116 cell and on LPS-induced inflammation in rat colon. Based on our results, this edible and traditionally used species could be considered as a valuable source of natural agents to combat inflammatory diseases, particularly ulcerative colitis. Results amassed herein advocates for further bioprospection of this species that could open new avenues for the development of nutraceuticals and functional foods geared toward the management of chronic inflammatory diseases.