Phenylalanine Analogues Research Articles

Synthesis of Enantiopure Unnatural Amino Acids by Metallaphotoredox Catalysis.

We describe herein a two-step process for the conversion of serine to a wide array of optically pure unnatural amino acids. This method utilizes a photocatalytic cross-electrophile coupling between a bromoalkyl intermediate and a diverse set of aryl halides to produce artificial analogues of phenylalanine, tryptophan, and histidine. The reaction is tolerant of a broad range of functionalities and can be leveraged toward the scalable synthesis of valuable pharmaceutical scaffolds via flow technology.

Multivalent Albumin-Neonatal Fc Receptor Interactions Mediate a Prominent Extension of the Serum Half-Life of a Therapeutic Protein.

Human serum albumin (HSA) has been used to extend the serum half-life of therapeutic proteins owing to its exceptionally long serum half-life via the neonatal Fc receptor (FcRn)-mediated recycling mechanism. In most cases, only one HSA molecule was conjugated to a therapeutic protein, leading to a limited extension of the serum half-life. In this study, we hypothesized that conjugation of multiple HSA molecules to a therapeutic protein significantly further extends the serum half-life via multivalent HSA-FcRn interactions. We chose urate oxidase (Uox), a tetrameric therapeutic protein used for the treatment of gout, as a model. In previous studies, only one HSA molecule was site-specifically conjugated to one Uox because of poor conjugation yield of the relatively slow bio-orthogonal chemistry, strain-promoted azide-alkyne cycloaddition (SPAAC). To increase the number of HSA molecules conjugated to one Uox, we employed the faster bio-orthogonal chemistry, inverse electron demand Diels-Alder reaction (IEDDA). We site-specifically introduced the phenylalanine analog with a fast-reacting tetrazine group (frTet) into position 174 of each subunit of Uox. We then achieved site-specific HSA conjugation to each subunit of Uox via IEDDA, generating Uox conjugated to four HSA molecules (Uox-HSA4), with a small portion of Uox conjugated to three HSA molecules (Uox-HSA3). We characterized Uox-HSA4 as well as Uox variants conjugated to one or two HSA molecules prepared via SPAAC (Uox-HSA1 or Uox-HSA2). The enzyme activity of all three Uox-HSA conjugates was comparable to that of unmodified Uox. We found out that an increase in HSA molecules conjugated to Uox (multiple albumin-conjugated therapeutic protein) enhanced FcRn binding and consequently prolonged the serum half-life in vivo. In particular, the conjugation of four HSA molecules to Uox led to a prominent extension of the serum half-life (over 21 h), which is about 16-fold longer than that of Uox-WT.

Experimental lipophilicity scale for coded and noncoded amino acid residues.

Among other features, the polarity of amino acid residues is the key parameter for understanding their role in proteins. The wide occurrence of protein modifications in nature and the advent of genetic code engineering techniques created a need for an experimental polarity value integrating both coded (canonical) and noncoded (noncanonical) residues on one universal scale. To address this issue, this work reports on a polarity scale based on the experimental lipophilicity of methyl esters of N-acetylamino acids. The derivatization of amino acids was performed in two steps under mild conditions that allowed conversion of a wide array of amino acids into analytical derivatives. The partitioning/distribution between octan-1-ol and water/buffer was measured using the intensity of the NMR signal as a characteristic for the concentration. The reference set of twenty coded amino acids generated log P values spanning 5.1 units: from tryptophan being the most hydrophobic to aspartate being the most hydrophilic. Furthermore, lipophilicity was measured for a set of analogues of phenylalanine, tyrosine, tryptophan, methionine, proline, and lysine that are typical in nature and/or laboratory practice. The polarity scale reported here will aid the rationalization of amino acid replacements in proteins, and will guide further efforts in experimental genetic code engineering.

Temporal Control of Efficient In Vivo Bioconjugation Using a Genetically Encoded Tetrazine-Mediated Inverse-Electron-Demand Diels-Alder Reaction.

An inverse-electron-demand Diels-Alder (IEDDA) reaction using genetically encoded tetrazine variants enables rapid bioconjugation for diverse applications in vitro and in cellulo. However, in vivo bioconjugation using genetically encoded tetrazine variants is challenging, because the IEDDA coupling reaction competes with rapid elimination of reaction partners in vivo. Here, we tested the hypothesis that a genetically encoded phenylalanine analogue containing a hydrogen-substituted tetrazine (frTet) would increase the IEDDA reaction rate, thereby allowing for successful bioconjugation in vivo. We found that the in vitro IEDDA reaction rate of superfolder green fluorescent protein (sfGFP) containing frTet (sfGFP-frTet) was 12-fold greater than that of sfGFP containing methyl-substituted tetrazine (sfGFP-Tet_v2.0). Additionally, sfGFP variants encapsulated with chitosan-modified, pluronic-based nanocarriers were delivered into nude mice or tumor-bearing mice for in vivo imaging. The in vivo-delivered sfGFP-frTet exhibited almost complete fluorescence recovery upon addition of trans-cyclooctene via the IEDDA reaction within 2 h, whereas sfGFP-Tet_v2.0 did not show substantial fluorescence recovery. These results demonstrated that the genetically encoded frTet allows an almost complete IEDDA reaction in vivo upon addition of trans-cyclooctene, enabling temporal control of in vivo bioconjugation in a very high yield.

The Impact of Halogenated Phenylalanine Derivatives on NFGAIL Amyloid Formation.

The hexapeptide hIAPP22–27 (NFGAIL) is known as a crucial amyloid core sequence of the human islet amyloid polypeptide (hIAPP) whose aggregates can be used to better understand the wild‐type hIAPP′s toxicity to β‐cell death. In amyloid research, the role of hydrophobic and aromatic‐aromatic interactions as potential driving forces during the aggregation process is controversially discussed not only in case of NFGAIL, but also for amyloidogenic peptides in general. We have used halogenation of the aromatic residue as a strategy to modulate hydrophobic and aromatic‐aromatic interactions and prepared a library of NFGAIL variants containing fluorinated and iodinated phenylalanine analogues. We used thioflavin T staining, transmission electron microscopy (TEM) and small‐angle X‐ray scattering (SAXS) to study the impact of side‐chain halogenation on NFGAIL amyloid formation kinetics. Our data revealed a synergy between aggregation behavior and hydrophobicity of the phenylalanine residue. This study introduces systematic fluorination as a toolbox to further investigate the nature of the amyloid self‐assembly process.

Synthesis and Inhibitory Studies of Phosphonic Acid Analogues of Homophenylalanine and Phenylalanine towards Alanyl Aminopeptidases.

A library of novel phosphonic acid analogues of homophenylalanine and phenylalanine, containing fluorine and bromine atoms in the phenyl ring, have been synthesized. Their inhibitory properties against two important alanine aminopeptidases, of human (hAPN, CD13) and porcine (pAPN) origin, were evaluated. Enzymatic studies and comparison with literature data indicated the higher inhibitory potential of the homophenylalanine over phenylalanine derivatives towards both enzymes. Their inhibition constants were in the submicromolar range for hAPN and the micromolar range for pAPN, with 1-amino-3-(3-fluorophenyl) propylphosphonic acid (compound 15c) being one of the best low-molecular inhibitors of both enzymes. To the best of our knowledge, P1 homophenylalanine analogues are the most active inhibitors of the APN among phosphonic and phosphinic derivatives described in the literature. Therefore, they constitute interesting building blocks for the further design of chemically more complex inhibitors. Based on molecular modeling simulations and SAR (structure-activity relationship) analysis, the optimal architecture of enzyme-inhibitor complexes for hAPN and pAPN were determined.

Chimeric design of pyrrolysyl-tRNA synthetase/tRNA pairs and canonical synthetase/tRNA pairs for genetic code expansion

An orthogonal aminoacyl-tRNA synthetase/tRNA pair is a crucial prerequisite for site-specific incorporation of unnatural amino acids. Due to its high codon suppression efficiency and full orthogonality, the pyrrolysyl-tRNA synthetase/pyrrolysyl-tRNA pair is currently the ideal system for genetic code expansion in both eukaryotes and prokaryotes. There is a pressing need to discover or engineer other fully orthogonal translation systems. Here, through rational chimera design by transplanting the key orthogonal components from the pyrrolysine system, we create multiple chimeric tRNA synthetase/chimeric tRNA pairs, including chimera histidine, phenylalanine, and alanine systems. We further show that these engineered chimeric systems are orthogonal and highly efficient with comparable flexibility to the pyrrolysine system. Besides, the chimera phenylalanine system can incorporate a group of phenylalanine, tyrosine, and tryptophan analogues efficiently in both E. coli and mammalian cells. These aromatic amino acids analogous exhibit unique properties and characteristics, including fluorescence, post-translation modification.

Phosphonic Acid Analogs of Fluorophenylalanines as Inhibitors of Human and Porcine Aminopeptidases N: Validation of the Importance of the Substitution of the Aromatic Ring.

A library of phosphonic acid analogs of phenylalanine substituted with fluorine, chlorine and trifluoromethyl moieties on the aromatic ring was synthesized and evaluated for inhibitory activity against human (hAPN) and porcine (pAPN) aminopeptidases. Fluorogenic screening indicated that these analogs are micromolar or submicromolar inhibitors, both enzymes being more active against hAPN. In order to better understand the mode of the action of the most active compounds, molecular modeling was used. It confirmed that aminophosphonic portion of the enzyme is bound nearly identically in the case of all the studied compounds, whereas the difference in activity results from the placement of aromatic side chain of an inhibitor. Interestingly, both enantiomers of the individual compounds are usually bound quite similarly.

Structure-based design, synthesis, and evaluation of the biological activity of novel phosphoroorganic small molecule IAP antagonists

SummaryOne of the strategies employed by novel anticancer therapies is to put the process of apoptosis back on track by blocking the interaction between inhibitor of apoptosis proteins (IAPs) and caspases. The activity of caspases is modulated by the caspases themselves in a caspase/procaspase proteolytic cascade and by their interaction with IAPs. Caspases can be released from the inhibitory influence of IAPs by proapoptotic proteins such as secondary mitochondrial activator of caspases (Smac) that share an IAP binding motif (IBM). The main purpose of the present study was the design and synthesis of phosphorus-based peptidyl antagonists of IAPs that mimic the endogenous Smac protein, which blocks the interaction between IAPs and caspases. Based on the structure of the IAP antagonist and recently reported thiadiazole derivatives, we designed and evaluated the biochemical properties of a series of phosphonic peptides bearing the N-Me-Ala-Val/Chg-Pro-OH motif (Chg: cyclohexylglycine). The ability of the obtained compounds to interact with the binding groove of the X-linked inhibitor of apoptosis protein baculovirus inhibitor of apoptosis protein repeat (XIAP BIR3) domain was examined by a fluorescence polarization assay, while their potential to induce autoubiquitination followed by proteasomal degradation of cellular IAP1 was examined using the MDA-MB-231 breast cancer cell line. The highest potency against BIR3 was observed among peptides containing C-terminal phosphonic phenylalanine analogs, which displayed nanomolar Ki values. Their antiproliferative potential as well as their proapoptotic action, manifested by an increase in caspase-3 activity, was examined using various cell lines.

Linker and N-Terminal Domain Engineering of Pyrrolysyl-tRNA Synthetase for Substrate Range Shifting and Activity Enhancement.

The Methanosarcina mazei pyrrolysyl-tRNA synthetase (PylRS)⋅tRNAPyl pair can be used to incorporate non-canonical amino acids (ncAAs) into proteins at installed amber stop codons. Although engineering of the PylRS active site generates diverse binding pockets, the substrate ranges are found similar in charging lysine and phenylalanine analogs. To expand the diversity of the ncAA side chains that can be incorporated via the PylRS⋅tRNAPyl pair, exploring remote interactions beyond the active site is an emerging approach in expanding the genetic code research. In this work, remote interactions between tRNAPyl, the tRNA binding domain of PylRS, and/or an introduced non-structured linker between the N- and C-terminus of PylRS were studied. The substrate range of the PylRS⋅tRNAPyl pair was visualized by producing sfGFP-UAG gene products, which also indicated amber suppression efficiencies and substrate specificity. The unstructured loop linking the N-terminal and C-terminal domains (CTDs) of PylRS has been suggested to regulate the interaction between PylRS and tRNAPyl. In exploring the detailed role of the loop region, different lengths of the linker were inserted into the junction between the N-terminal and the C-terminal domains of PylRS to unearth the impact on remote effects. Our findings suggest that the insertion of a moderate-length linker tunes the interface between PylRS and tRNAPyl and subsequently leads to improved suppression efficiencies. The suppression activity and the substrate specificity of PylRS were altered by introducing three mutations at or near the N-terminal domain of PylRS (N-PylRS). Using a N-PylRS⋅tRNAPyl pair, three ncAA substrates, two S-benzyl cysteine and a histidine analog, were incorporated into the protein site specifically.

Biosynthesis of Amino Acid Derived α-Pyrones by an NRPS-NRPKS Hybrid Megasynthetase in Fungi.

A nonribosomal peptide synthetase (NRPS)-nonreducing polyketide synthase (NRPKS) hybrid enzyme (AnATPKS) from Aspergillus niger was shown to produce amino acid derived α-pyrone natural products (pyrophen and campyrone B). Biochemical characterization of the NRPS module in vitro reveals that the adenylation domain is promiscuous toward a variety of substituted phenylalanine analogues. Using precursor feeding and heterologous expression of AnATPKS and an associated O-methyltransferase (AnOMT), we were able to access a library of substituted pyrophen analogues. Our study paves the way for future combinatorial biosynthesis of diverse α-pyrone natural products using NRPS-NRPKS hybrids.

2D-IR studies of cyanamides (NCN) as spectroscopic reporters of dynamics in biomolecules: Uncovering the origin of mysterious peaks.

Cyanamides (NCN) have been shown to have a larger transition dipole strength than cyano-probes. In addition, they have similar structural characteristics and vibrational lifetimes to the azido-group, suggesting their utility as infrared (IR) spectroscopic reporters for structural dynamics in biomolecules. To access the efficacy of NCN as an IR probe to capture the changes in the local environment, several model systems were evaluated via 2D IR spectroscopy. Previous work by Cho [G. Lee, D. Kossowska, J. Lim, S. Kim, H. Han, K. Kwak, and M. Cho, J. Phys. Chem. B 122(14), 4035-4044 (2018)] showed that phenylalanine analogues containing NCN show strong anharmonic coupling that can complicate the interpretation of structural dynamics. However, when NCN is embedded in 5-membered ring scaffolds, as in N-cyanomaleimide and N-cyanosuccinimide, a unique band structure is observed in the 2D IR spectrum that is not predicted by simple anharmonic frequency calculations. Further investigation indicated that electron delocalization plays a role in the origins of the band structure. In particular, the origin of the lower frequency transitions is likely a result of direct interaction with the solvent.

Amino acid chalcogen analogues as tools in peptide and protein research

The chalcogen elements oxygen, sulfur, and selenium are essential constituents of side chain functions of natural amino acids. Conversely, no structural and biological function has been discovered so far for the heavier and more metallic tellurium element. In the methionine series, only the sulfur-containing methionine is a proteinogenic amino acid, while selenomethionine and telluromethionine are natural amino acids that are incorporated into proteins most probably because of the tolerance of the methionyl-tRNA synthetase; so far, methoxinine the oxygen analogue has not been discovered in natural compounds. Similarly, the chalcogen analogues of tryptophan and phenylalanine in which the benzene ring has been replaced by the largely isosteric thiophene, selenophene, and more recently, even tellurophene are fully synthetic mimics that are incorporated with more or less efficiency into proteins via the related tryptophanyl- and phenylalanyl-tRNA synthetases, respectively. In the serine/cysteine series, also selenocysteine is a proteinogenic amino acid that is inserted into proteins by a special translation mechanism, while the tellurocysteine is again most probably incorporated into proteins by the tolerance of the cysteinyl-tRNA synthetase. For research purposes, all of these natural and synthetic chalcogen amino acids have been extensively applied in peptide and protein research to exploit their different physicochemical properties for modulating structural and functional properties in synthetic peptides and rDNA expressed proteins as discussed in the following review.

Phenylalanine Monitoring via Aptamer-Field-Effect Transistor Sensors.

Determination of the amino acid phenylalanine is important for lifelong disease management in patients with phenylketonuria, a genetic disorder in which phenylalanine accumulates and persists at levels that alter brain development and cause permanent neurological damage and cognitive dysfunction. Recent approaches for treating phenylketonuria focus on injectable medications that efficiently break down phenylalanine but sometimes result in detrimentally low phenylalanine levels. We have identified new DNA aptamers for phenylalanine in two formats, initially as fluorescent sensors and then, incorporated with field-effect transistors (FETs). Aptamer-FET sensors detected phenylalanine over a wide range of concentrations (fM to mM). para-Chlorophenylalanine, which inhibits the enzyme that converts phenylalanine to tyrosine, was used to induce hyperphenylalaninemia during brain development in mice. Aptamer-FET sensors were specific for phenylalanine versus para-chlorophenylalanine and differentiated changes in mouse serum phenylalanine at levels expected in patients. Aptamer-FETs can be used to investigate models of hyperphenylalanemia in the presence of structurally related enzyme inhibitors, as well as naturally occurring amino acids. Nucleic acid-based receptors that discriminate phenylalanine analogs, some that differ by a single substituent, indicate a refined ability to identify aptamers with binding pockets tailored for high affinity and specificity. Aptamers of this type integrated into FETs enable rapid, electronic, label-free phenylalanine sensing.

Copper(ii) complexes with alloferon analogues containing phenylalanine H6F and H12F stability and biological activity lower stabilization of complexes compared to analogues containing tryptophan.

Copper(ii) complex formation processes between alloferon 1 (Allo1) (H1 GVSGH6 GQH9 GVH12G) analogues where the phenylalanine residue is introduced in the place of His residue H6F and H12F have been studied by potentiometric, UV-visible, CD and EPR spectroscopic, and MS methods. For the phenylalanine analogues of alloferon 1, complex speciation has been obtained for a 1 : 1, 2 : 1 and 3 : 1 metal-to-ligand molar ratio. At physiological pH and in 1 : 1 metal-to-ligand molar ratio the phenylalanine analogues of alloferon 1 form a CuL complex similar to that of alanine analogues with the 4N{NH2,N1Im,2NIm} coordination mode. The stability of the complexes of the phenylalanine analogues is higher in comparison to those of alanine analogues, but lower in comparison to those containing tryptophan. Injection of Allo12F into insects induced prominent apoptotic changes in all hemocytes. The presence of apoptotic bodies only in the insect hemolymph testifies to the fact that Allo12F is an extremely pro-apoptotic peptide.

New fluoroethyl phenylalanine analogues as potential LAT1-targeting PET tracers for glioblastoma

The use of O-(2-[18F]fluoroethyl)-l-tyrosine ([18F]FET) as a positron emission tomography (PET) tracer for brain tumor imaging might have some limitations because of the relatively low affinity for the L-type amino acid transporter 1 (LAT1). To assess the stereospecificity and evaluate the influence of aromatic ring modification of phenylalanine LAT1 targeting tracers, six different fluoroalkylated phenylalanine analogues were synthesized. After in vitro Ki determination, the most promising compound, 2-[18F]-2-fluoroethyl-l-phenylalanine (2-[18F]FELP), was selected for further evaluation and in vitro comparison with [18F]FET. Subsequently, 2-[18F]FELP was assessed in vivo and compared with [18F]FET and [18F]FDG in a F98 glioblastoma rat model. 2-[18F]FELP showed improved in vitro characteristics over [18F]FET, especially when the affinity and specificity for system L is concerned. Based on our results, 2-[18F]FELP is a promising new PET tracer for brain tumor imaging.

New ACE Inhibitor Designed from Nicotianamine and Its Docking Pose Prediction Using the Gold Program

Hypertension is currently one of the most serious health issues worldwide. Nicotianamine, a non-peptide-type amino acid trimer, is ubiquitously present in higher plants and plays a role as an internal metal transporter. It is known that nicotianamine inhibits ACE activity and that oral treatment with the compound improves hypertension. However the mode of action remains unclear, due to lack of crystallographic data. Although a structure-activity relationship study of nicotianamine has the potential to uncover the details of the inhibition profile, the azetidine-2-carboxylic acid moiety in nicotianamine has become a critical barrier for further biochemical research due to limited commercial supply and difficulties with structural modification. In this paper, ten nicotianamine analogs without azetidine-2-carboxylic acid moiety were prepared and their inhibition of angiotensin I-converting enzyme was investigated. Among these analogs, a phenylalanine analog, (2S,3′S,3″S)-N-{3′-(3″-amino-3″-carboxypropylamino)-3′-carboxypropyl}phenylalanine, displayed the most potent activity. The inhibition activity of the compound corresponded to that of captopril. These results suggested a possibility of structural modification of nicotianamie to develop antihypertensive drugs. Molecular docking studies with Gold were also performed to predict the binding poses of nicotianamine and its analog, suggesting that nicotianamine and its analogs combine a plausible allosteric site in an area away from the catalytic site in ACE.

Stereoselective deconjugation of macrocyclic α,β-unsaturated esters by sequential amidation and olefin transposition: application to enantioselective phase-transfer catalysis.

The stereoselective synthesis of chiral macrocycles bearing two aliphatic amide functional groups is reported. After the amidation mediated by TBD, a guanidine derivative, the olefin transposition step is performed with a slight excess of t-BuOK. The products are afforded in moderate to good combined yields (up to 59%) and with an excellent syn diastereoselectivity (dr > 49 : 1). Introducing enantiopure α-branched substituents was possible and it resulted in mixtures of diastereomers, which could be tested as phase-transfer catalysts using the formation of a phenylalanine analog as a test reaction (up to 43% ee). A clear matched-mismatched situation was observed in the two diastereomeric series.

76 - Decreased proteasome cleavage rates at nitrotyrosine sites in proteins and peptides

Oxidative post-translational modifications to proteins can lead to conformationally altered and/or dysfunctional proteoforms. Removal of moderately oxidized proteins is mainly carried out by the proteasome while highly modified proteins are no longer degradable. However, in the case of proteins modified by nitration of tyrosine residues to 3-nitrotyrosine (NO2Y), the role of the proteasome remains to be established. For this purpose, degradation assays and mass spectrometry analyses were performed using isolated proteasome and purified fractions of native cytochrome c (cyt c) and tyrosine nitrated proteoforms (NO2-cyt c). While cyt c pre-treated under mild conditions with hydrogen peroxide is preferentially degraded by the proteasome, NO2Y74- and NO2Y97-cyt c are less degradable. Peptide mapping analysis confirmed a decreased chymotrypsin-like cleavage at NO2Y sites. Degradation yields by the other two proteasome active sites remained the same in the unmodified and NO2-cyt c. Additionally, studies with the proteasome substrate N-suc-LLVY-AMC (Y-AMC) and its NO2Y-containing analog, N-suc-LLVNO2Y-AMC (NO2Y-AMC) were performed. Comparison of both substrates showed a significantly decreased proteasome activity towards NO2Y-AMC either using the isolated proteasome or cell lysates. Moreover, NO2Y-AMC degradation rates were largely blunted by increasing the reaction pH, suggesting an inhibitory influence of the additional negative charge contained in NO2Y-AMC secondary to nitration. The mechanism of slowing of proteasome activity in NO2Y-contaning peptides was further substantiated in studies using the phenylalanine and nitro-phenylalanine peptide analog substrates. Finally, degradation rates of Y-AMC and NO2Y-AMC with proteinase K were the same, demonstrating the selective inability of the proteasome to readily cleave at nitrotyrosine sites.

Potential Antileishmanial Activity of a Triazole‐Based Hybrid Peptide against Leishmania major

AbstractThe dipeptides 1–4 with a triazole containing synthetic amino acid and Leu/ Phe/ Val/ Gly have been designed and synthesized as a potent antileishmanial agent. The 1‐(2‐Amino‐phenyl)‐1H‐[1, 2,3] triazole‐4‐carboxylic acid was synthesized using click chemistry approach. From X‐ray crystallography, the peptide 1 containing a Leu residue at C‐terminus adopts kink like structure but there is no intramolecular hydrogen bond. So, the hydrogen bonding sites are free and allowed for intermolecular interaction with the guests. The phenylalanine analogue 2 where the phenyl and triazole rings are perpendicular to each other also form supramolecular column‐like structure through π‐π stacking interaction. The incorporation of a triazole containing synthetic amino acid at the N‐terminus enhances its anti‐parasites activity. The properties such as lipophilicity and cytotoxicity, are relevant factors for the design of new antileishmanial agent. IC50 value were calculated for dipeptides 1–4 using normal growth inhibition strategy. For dipeptide 1, IC50 value is 11μg/ml and the Phe containing dipeptide 2 exhibits IC50 21.17μg/ml on Leishmania major promastigotes. But the Val and Gly containing dipeptides 3 and 4 have IC50 values 138.23 μg/ml and 21.75 μg/ml respectively. The higher lipophilicity of dipeptide 1 is likely to improve the chances of reaching this intracellular parasite. The experimental result show that the triazole‐based dipeptide 1 is promising as antileishmanial agent.