Search Results (342)

This study reports the development of peptide-based hydrogels for the encapsulation and controlled release of peptide nucleic acids in drug delivery applications. Ultrashort aromatic peptides, such as Fmoc-FF, self-assemble into biocompatible hydrogels with nanostructured architectures. The functionalization of tripeptides (Fmoc-FFK and Fmoc-FFC) with lysine (K) or cysteine (C) enables electrostatic or covalent interactions with model PNAs engineered with glutamic acid or cysteine residues, respectively. Hydrogels were polymerized in situ in the presence of PNAs, and component ratios were systematically varied to optimize mechanical properties, loading efficiency, and release kinetics. The formulations obtained with a 1/10 ratio of Fmoc-FF(K or C)/Fmoc-FF provided an optimal balance between structural integrity and delivery performance. All hydrogel formulations demonstrated high stiffness (G′ > 19,000 Pa), excellent water retention, and minimal swelling under physiological conditions (ΔW < 4%). The release studies over 10 days showed that electrostatic loading enabled faster and higher release (up to 90%), while covalent bonding resulted in slower, sustained delivery (~15%). These findings highlight the tunability of the hydrogel system for diverse therapeutic applications. Full article

Because of the involvement of π-electron cyclic constituents in their side chains, the so-called aromatic residues give rise to a number of strong, narrow, and well-resolved lines spread over the middle wavenumber (1800–600 cm⁻¹) region of the Raman spectra of peptides and proteins. The number of characteristic aromatic markers increases with the structural complexity (Phe → Tyr → Trp), herein referred to as (F_i = 1, …, 6) in Phe, (Y_i = 1, …, 7) in Tyr, and (W_i = 1, …, 8) in Trp. Herein, we undertake an overview of these markers through the analysis of a representative data base gathered from the most structurally simple tripeptides, Gly-Xxx-Gly (where Xxx = Phe, Tyr, Trp). In this framework, off-resonance Raman spectra obtained from the aqueous samples of these tripeptides were jointly used with the structural and vibrational data collected from the density functional theory (DFT) calculations using the M062X hybrid functional and 6-311++G(d,p) atomic basis set. The conformation dependence of aromatic Raman markers was explored upon a representative set of 75 conformers, having five different backbone secondary structures (i.e., β-strand, polyproline-II, helix, classic, and inverse γ-turn), and plausible side chain rotamers. The hydration effects were considered upon using both implicit (polarizable solvent continuum) and explicit (minimal number of 5–7 water molecules) models. Raman spectra were calculated through a multiconformational approach based on the thermal (Boltzmann) average of the spectra arising from all calculated conformers. A subsequent discussion highlights the conformational landscape of conformers and the wavenumber dispersion of aromatic Raman markers. In particular, a new interpretation was proposed for the characteristic Raman doublets arising from Tyr (~850–830 cm⁻¹) and Trp (~1360–1340 cm⁻¹), definitely excluding the previously suggested Fermi-resonance-based assignment of these markers through the consideration of the interactions between the aromatic side chain and its adjacent peptide bonds. Full article

Focusing on the anti-aging mechanism and efficient utilization of anti-aging active ingredients in the skin is an excellent strategy to mitigate aging. In this study, ribose/collagen/decarboxylated carnitine hydrochloride/palmitoyl tripeptide-1 composite nanocarriers (RCDP NCs) were synthesized using transdermal drug delivery nanotechnology. The drug delivery of composite nanocarriers and the anti-aging mechanism of RCDP NCs were studied through transdermal behavior, cell uptake, cell proliferation, antioxidant enzyme activity, lipid oxidation product expression, β—galactosidase content, autophagy vesicle number, autophagy-related protein expression, and other indicators. The results showed that the composite nanocarriers on the skin could reach a dermal depth of 460.0 μm (4 h). The uptake of RCDP NCs by keratinocytes and fibroblasts increased by 47.37% and 89.11% (4 h), respectively. RCDP NCs promoted cell proliferation, enhanced the activities of the main antioxidant enzymes, and reduced the production of the lipid oxidation product malondialdehyde (MDA). Sequestosome-1 protein (p62) decreased, whereas both the ratio of microtubule-associated protein light chain 3 II/microtubule-associated protein light chain 3 I (LC3II/LC3I) and the number of autophagosomes increased, indicating that RCDP NCs promoted autophagy. The drug delivery nanotechnology in this study achieved better transdermal application of active ingredients, which could mitigate skin aging faster and more effectively. Full article

Microalgae are a promising source of bioactive compounds, particularly proteins and peptides, with potential applications in skin health and the cosmetic industry. This study investigated the antioxidant and anti-aging properties of peptide fractions derived from Spirulina platensis and Chlorella vulgaris. Both microalgae were cultivated, and their proteins were subsequently extracted, enzymatically hydrolyzed with alcalase, and fractionated through ultrafiltration. Alkaline extraction yielded 82% protein from S. platensis and 72% from C. vulgaris. Enzymatic hydrolysis predominantly yielded <3 kDa peptides, which exhibited strong antioxidant activity reaching 78% for 2,2-diphenyl-1-picrylhidrazol (DPPH), 82% for 2,2′-azinobis-3-etilbenzothiazoline-6-sulfonic acid (ABTS), and 74% for ferric reducing antioxidant power (FRAP), with IC₅₀ values as low as 23.44 µg/mL for ABTS inhibition in C. vulgaris. These peptides also significantly inhibited skin-aging enzymes, showing 84% inhibition of elastase, 90% of collagenase, and 66% of tyrosinase. Mass spectrometry and GNPS molecular networking of the <3 kDa fraction identified several di- and tri-peptides, including Lys-Val, Val-Arg, His-Ile, Lys-Leu, Ile-Leu, and Leu-Phe, Tyr-Phe, and Leu-Gly-Leu, potentially contributing to these bioactivities. These findings suggest that the enzymatic hydrolysis of S. platensis and C. vulgaris proteins provides a sustainable and natural source of bioactive peptides for antioxidant and anti-aging applications in food, pharmaceutical, and cosmetic industries. Full article

Several D-amino acid residue-containing peptides (DAACPs) with antimicrobial, cardio-excitatory, and neuronal activities have been identified in various species. The L-Asn-D-Trp-L-Phe-NH₂ (N(dW)F) tripeptide, derived from Aplysia kurodai, exhibits cardiac activity in invertebrates. The chirality of the tryptophan residue at the second position in N(dW)F influences its conformation and biological characteristics. We demonstrated the chiral separation of N(dW)F and its diastereomer NWF using (S)-3,3′-diphenyl-1,1′-binaphthyl-20-crown-6-ether columns (CR-I(+)). A reduction in the ratio of acetonitrile and methanol in the mobile phase allowed the complete separation of N(dW)F and its diastereomer, improving the separation factor (α) from 0.96 to 6.28. Molecular dynamics simulations revealed that the interaction of N(dW)F with CR-I(−) was more favorable than with CR-I(+). These findings indicate that the structure of the CR-I column stereoselectively recognizes peptides and facilitates the separation of naturally occurring D-amino acid residue-containing tripeptides. Full article

Over the years, our research group developed dehydrodipeptides N-capped with aromatic moieties as protease-resistant efficacious hydrogelators, affording self-assembled hydrogels at low (critical) concentrations. Dehydrotripeptides, with different dipeptide sequences and (D,L) stereochemistry, open a wider chemical space for the development of self-assembled soft nanomaterials. In this work, a small library of N-succinylated dehydrotripeptides containing a C-terminal dehydrophenylalanine (∆Phe) residue and a scrambled dipeptide sequence with phenylalanine (Phe) and homophenylalanine (Hph) (L-Phe-L,D-Hph and L,D-Hph-L-Phe) was synthesized and characterized as a potential hydrogelator. Two pairs of diastereomeric tripeptides were synthesized, both as C-protected methyl esters and as deprotected dicarboxylic acids. Peptides with the sequence Hph-Phe-ΔPhe were obtained as a pair (D,L,Z)/(L,L,Z) of diastereomers. Their scrambled sequence analogues Phe-Hph-ΔPhe were obtained also as a diastereomeric (L,D,Z)/(L,L,Z) pair. The effect of stereochemistry (homo- vs. hetero-chirality) and sequence (Phe-∆Phe vs. Hph-∆Phe motif) on the self-assembly, biocompatibility, gelation and rheological properties of the hydrogels was studied in this work. Accessible, both as C-protected methyl esters and as dicarboxylic acids, N-succinylated dehydrotripeptides are interesting molecular architectures for the development of supramolecular nanomaterials. Interestingly, our results do not comply with the well-documented proposition that heterochiral peptides display much higher self-assembly propensity and gelation ability than their homochiral counterparts. Further studies will be necessary to fully understand the interplay between peptide sequence and homo- and hetero-chirality on peptide self-assembly and on the properties of their supramolecular materials. Full article

Bioactive peptides are promising therapeutic agents due to their antimicrobial and anticancer activities, although their lack of selectivity often limits clinical applications. This study demonstrates the optimal synthetic route for conjugating folic acid (FA) with the bioactive peptide Lunatin-1, aiming to improve selectivity for neoplastic cells. The synthesis combines solid-phase peptide synthesis (SPPS) and Cu(I)-catalyzed cycloaddition to link folic acid to Lunatin-1 via a triazole ring. Using the model tripeptide FIG-_NH2, key intermediates and the final product were characterized by high-performance liquid chromatography (HPLC), mass spectrometry (MALDI-ToF), Fourier-transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). Reaction yields and purity were optimized with FIG-_NH2, providing a reproducible synthesis pathway. Additionally, the results confirmed successful conjugation, with the FA-Trz-Luna product exhibiting molecular integrity and structural stability, as validated by spectral analyses. This study highlights a potential synthesis route for peptide-folate conjugates to be used as selective and multifunctional therapeutic agents, laying the groundwork for biological evaluations of their cytotoxicity and antimicrobial properties. Full article

Nowadays, large amounts of wastewater arise from various industrial applications. The discharge of wastewater into the environment represents a threat to the aquatic ecosystem and human health. Thus, in the present study, innovative double-network (DN) hydrogels with pH-sensitive features and applicability as adsorbents in the treatment of leather dye wastewater were prepared. The polyelectrolyte, poly(N,N-dimethylaminoethyl methacrylate (PDMAEMA), was obtained via the radical polymerization process, while the supramolecular structure was co-assembled through physical interactions. As a novelty, the double network was obtained through the interpenetration of the supramolecular network in the cross-linked polymeric one. The new hydrogels were physico-chemically and morphologically characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and in terms of thermogravimetric analysis (TGA), swelling degree measurements, and dye adsorption studies. The DN hydrogels present interconnected macropores and high thermal stability. The swelling capacity of the dual network gels highlights a superadsorbent behavior at pH 3. Furthermore, the dye adsorption study highlights the effects of several variables (pH, concentration dose of adsorbent) on the ability of the gels to adsorb an anionic dye. The adsorption kinetics of the anionic dyes fitted the pseudo-first-order model (PFO). The estimated maximum adsorption capacities for the anionic dyes was 451 mg g⁻¹ for PDMAEMA and 545 mg g⁻¹ for DN gel. Full article

Royal jelly and medical grade honey are traditionally used in treating wounds and infections, although their effectiveness is often variable and insufficient. To overcome their limitations, we created novel amphiphiles by modifying the main reparative and antimicrobial components, queen bee acid (hda) and 10-hydroxyl-decanoic acid (hdaa), through peptide bonding with specific tripeptides. Our molecular design incorporated amphiphile targets as being biocompatible in wound healing, biodegradable, non-toxic, hydrogelable, prohealing, and antimicrobial. The amphiphilic molecules were designed in a hda(hdaa)-aa1-aa2-aa3 structural model with rational selection criteria for each moiety, prepared via Rink/Fmoc-tBu-based solid-phase peptide synthesis, and structurally verified by NMR and LC–MS/MS. We tested several amphiphiles among those containing moieties of hda or hdaa and isoleucine–leucine–aspartate (ILD-amidated) or IL-lysine (ILK-NH₂). These tests were conducted to evaluate their prohealing and antimicrobial hydrogel properties. Our observation of their hydrogelation and hydrogel-rheology showed that they can form hydrogels with stable elastic moduli and injectable shear-thinning properties, which are suitable for cell and tissue repair and regeneration. Our disc-diffusion assay demonstrated that hdaa-ILK-NH₂ markedly inhibited Staphylococcus aureus. Future research is needed to comprehensively evaluate the prohealing and antimicrobial properties of these novel molecules modified from hda and hdaa with tripeptides. Full article

Hijiki (Hizikia fusiformis) is a seaweed native to warm-temperate and subtropical regions that has a high edible value and economic value, with a production of about 2 × 10⁵ tons/year. Current research has clearly shown that the pharmacological activities of active ingredients from hijiki have covered a broad spectrum of areas, including antioxidant, hypoglycemic, antiviral, anticoagulant, anti-inflammatory, intestinal flora modulation, anti-aging, antineoplastic and antibacterial, and anti-Alzheimer’s disease areas. However, no studies have reported on the production of antioxidant peptides from hijiki proteins. The objectives of this study were to optimize the preparation process and explore the cytoprotective function and mechanisms of antioxidant peptides from hijiki protein. The results indicated that papain is more suitable for hydrolyzing hijiki protein than pepsin, trypsin, alkaline protease, and neutral protease. Under the optimized parameters of an enzyme dosage of 3%, a material–liquid ratio of 1:30, and an enzyme digestion time of 5 h, hijiki hydrolysate with a high radical scavenging activity was generated. Using ultrafiltration and serial chromatographic methods, ten antioxidant oligopeptides were purified from the papain-prepared hydrolysate and identified as DGPD, TIPEE, TYRPG, YTPAP, MPW, YPSKPT, YGALT, YTLLQ, FGYGP, and FGYPA with molecular weights of 402.35, 587.61, 592.64, 547.60, 532.53, 691.77, 523.57, 636.73, 539.58, and 553.60 Da, respectively. Among them, tripeptide MPW could regulate the Keap1/Nrf2 pathway to significantly ameliorate H₂O₂-induced oxidative damage of A549 cells by increasing cell viability and antioxidant enzyme (SOD, CAT, and GSH-Px) activity, decreasing ROS and MDA levels, and reducing the apoptosis rate. Molecular docking experiments show that HFP5 (MPW) exerts its inhibitory effect mainly through hydrogen bonds and hydrophobic interactions with the Kelch domain of the Keap1 protein, eventually facilitating the translocation of Nrf2 to the nucleus. Therefore, antioxidant peptides from hijiki can be applied to develop algae-derived health foods for treating diseases associated with oxidative stress. Full article

Cosmetically active compounds (CACs), both of lipophilic and hydrophilic origin, have difficulty reaching the deeper layers of the skin, and this shortcoming significantly reduces their efficacy. One such CAC that occurs naturally in the human body and displays many beneficial properties (via reducing fine lines and wrinkles, tightening skin, improving its elasticity, etc.) is the glycyl-L-histidyl-L-lysine tripeptide complex of copper (GHK–Cu). GHK–Cu is a fairly hydrophilic compound with limited permeation through the lipophilic stratum corneum. On the other hand, liposomes capable of encapsulating GHK–Cu may improve its permeation potential. The present review discusses various issues related to obtaining insight into the permeation of CACs through the skin. Methods for studying the transport of CACs encapsulated by liposomes and free GHK–Cu across the skin barrier are summarized. An analysis of the literature data reveals that the transport of liposomes containing GHK–Cu received little attention. This research gap gives an impetus to the methodological developments for assessing the effect of liposomes on GHK–Cu transportation and trafficking. Full article

Whey proteins have anti-fatigue activity, but there are few studies that have reported the ameliorative effects of branched-chain amino acid (BCAA) oligopeptides from whey proteins on fatigue in mice. The purposes of this study were to establish a process for the preparation of BCAA oligopeptides from whey protein and to investigate the anti-fatigue activity of BCAA oligopeptides. Whey proteins were hydrolyzed by trypsin and flavourzyme and purified by ethanol precipitation and reversed-phase high performance liquid chromatography (RP-HPLC). Fraction D’ was found to contain the highest content of BCAAs and a high proportion of low-molecular-weight peptides (<1 kDa; content: 81.48%). Subsequently, mass spectrometry identified 15 BCAA oligopeptides in Fraction D’, including three dipeptides, six tripeptides, two tetrapeptides, and four pentapeptides. In addition, animal experiments showed that BCAA oligopeptides significantly prolonged the residence time on the rod and swimming time of mice. Further studies showed that BCAA oligopeptides remarkably reduced serotonin (5-hydroxytryptamine, 5-HT) synthesis in the brain by down-regulating the plasma-free tryptophan (F-Trp)/BCAA ratio, thereby alleviating fatigue. Therefore, BCAA oligopeptides can be used as an auxiliary functional dietary molecule in functional products to exert anti-fatigue activity by regulating 5-HT synthesis. Full article

Tyrosinase is a key enzyme responsible for the formation of melanin (a natural skin pigment with ultraviolet-protection properties). However, some people experience melanin overproduction, so new, safe, and biocompatible enzyme inhibitors are sought. New tripeptide tyrosinase inhibitors were developed using molecular modeling. A combinatorial library of tripeptides was prepared and docked to the mushroom tyrosinase crystal structure and investigated with molecular dynamics. Based on the results of calculations and expert knowledge, the three potentially most active peptides (CSF, CSN, CVL) were selected. Their in vitro properties were examined, and they achieved half-maximal inhibitory concentration (IC₅₀) values of 136.04, 177.74, and 261.79 µM, respectively. These compounds attach to the binding pocket of tyrosinase mainly through hydrogen bonds and salt bridges. Molecular dynamics simulations demonstrated the stability of the peptid–tyrosinase complexes and highlighted the persistence of key interactions throughout the simulation period. The ability of these peptides to complex copper ions was also confirmed. The CSF peptide showed the highest chelating activity with copper. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay confirmed that none of the test tripeptides showed cytotoxicity toward the reconstructed human epidermis. Our results indicated that the developed tripeptides were non-toxic and effective tyrosinase inhibitors. They could be applied as raw materials in skin-brightening or anti-aging cosmetic products. Full article

Angiotensin-converting enzyme (ACE) inhibitory peptides exhibit antihypertensive effects by inhibiting ACE activity, and the study of the interaction between ACEs and inhibitory peptides is important for exploring new therapeutic strategies. In this study, the ACE-inhibitory peptide isolated from casein hydrolysate with the amino acid sequence Leu–Leu–Tyr (LLY) exhibited high ACE-inhibitory activity and stability, which holds significant implications for biochemistry and pharmaceutical applications. Furthermore, systematic investigations were conducted on the interaction between ACE and LLY through various approaches. The Lineweaver–Burk plot indicated the non-competitive inhibition pattern of LLY, suggesting that it binds to the enzyme at the non-active site, and the results were further validated by a molecular docking study. Additionally, multispectral experiments and atomic force microscopy were conducted to further elucidate the underlying mechanism of peptide activity. The findings indicated that LLY could induce a conformational change in ACE, thereby inhibiting its activity. This study contributes to a deeper understanding of the mechanism of action of ACE-inhibitory peptides and bears important significance for drug development in hypertension. Full article