Identification of novel synthetic peptide showing angiogenic activity in human endothelial cells

Up- or Downregulation of Melanin Synthesis Using Amino Acids, Peptides, and Their Analogs

Harmonious synthesis and distribution of melanin in the skin contribute to the expression of beauty and the maintenance of health. When skin pigmentary disorders occur because of internal or external factors or, when there is a need to artificially increase or reduce the pigmentation level of the skin for aesthetic or therapeutic purposes, various pharmacological therapies are applied but the results are not always satisfactory. Studies have been conducted to improve the efficacy and safety of these treatment strategies. In this review, we present the latest studies regarding peptides and related compounds that may be useful in artificially increasing or reducing skin melanin levels. Certain analogs of α-melanocyte stimulating hormone (MSH) and oligopeptides with the sequences derived from the hormone were shown to promote melanin synthesis in cells and in vivo models. Various amino acids, peptides, their analogs, and their hybrid compounds with other chemical moieties were shown to inhibit tyrosinase (TYR) catalytic activity or downregulate TYR gene expression. Certain peptides were shown to inhibit melanosome biogenesis or induce autophagy, leading to decreased pigmentation. In vivo and clinical evidence are available for some compounds, including [Nle⁴-_D-Phe⁷]-α-MSH, glutathione disulfide, and glycinamide hydrochloride. For many other compounds, additional studies are required to verify their efficacy and safety in vivo and in clinical trials. The accumulating information regarding pro- and antimelanogenic activity of peptides and related compounds will lead to the development of novel drugs for the treatment of skin pigmentary disorders.

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.

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.

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.

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

In our previous studies, we showed that AmyI-1-18 and its single amino acid-substituted analogs have antimicrobial, anti-inflammatory, and anti-endotoxic activities and cause little or no hemolysis or cytotoxicity. In this study, we investigated the potential of these peptides to promote proliferation, angiogenesis (tube formation), and migration in human umbilical vein endothelial cells (HUVECs). Among five single amino acid-substituted analogs, [N3L]AmyI-1-18 induced cell proliferation in a concentration-dependent manner with similar efficacy to AmyI-1-18. In tube formation assays, AmyI-1-18 and [N3L]AmyI-1-18 had angiogenic activities at 1 μM and their effects were similar to those of LL-37. Moreover, scratch migration assays showed that AmyI-1-18, [N3L]AmyI-1-18, and LL-37 promote cell migration with optimum concentrations of 10, 1, and 0.1 μM, respectively. Subsequently, we performed tube formation assays using HUVECs pretreated with SU5416, which is an inhibitor of vascular endothelial growth factor (VEGF) receptors, and revealed that AmyI-1-18 and [N3L]AmyI-1-18 induce angiogenesis by activating VEGF receptors. Similarly, after pretreating HUVECs with mitomycin C, which inhibits cell proliferation, [N3L]AmyI-1-18 significantly contributed to wound closure in scratch migration assays. Moreover, enhancements of hydrophobicity following substitution of AmyI-1-18 asparagine with leucine led to greater increases in cell migration. The present data indicate that both peptides, particularly [N3L]AmyI-1-18, are candidates for use as wound healing agents.

The Safety Evaluation of a Potent Angiogenic Activator, Synthetic Peptide (SFKLRY-NH2) for the Skin Application

A novel synthetic hexapeptide (SFKLRY-NH₂) that displays angiogenic activity has been identified by positional scanning of a synthetic peptide combinatorial library (PS-SPCL). This study was carried out to investigate the irritation of the SFKLRY-NH₂ on the skin. The tests were performed on the basis of Korea Food and Drug Administration (KFDA) guidelines. In results, cell toxicity is not appeared for SFKLRY-NH₂ in HaCaT cells and B16F10 cells. SFKLRY-NH₂ induced no skin irritation at low concentration (10 μM), mild irritation at high concentration (10mM). We consider that this result is helpful for saying about the safety of SFKLRY-NH₂ in clinical use.