Amino Carboxylic Acids Research Articles

Synthesis, Structures, optical properties and DFT studies of neodymium complexes containing octanoyl amino carboxylic acids

Amino acid rare-earth complexes are widely used due to their unique physical and chemical properties. In this study, three kinds of neodymium (III) complexes with octanoyl-aminocarboxylate ligands (abbr. Nd(oct-ala)3, Nd(oct-phe)3, Nd(oct-ser)3) were prepared by a chemical reaction method in methanol as the solvent. The chemical formulas and coordination modes of the neodymium complexes were determined by elemental analysis, 1H NMR and FT-IR. Additional analyses by X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that the neodymium complexes have lamellar irregular shapes and long-range disordered amorphous structures. The thermal performance of the complexes was determined by differential scanning calorimetry (DSC) and thermal gravimetry-differential thermal analysis (TG-DTA). Nd(oct-phe)3 and Nd(oct-ser)3 appeared glassy when heated. The solubility of the complexes in various organic reagents was also measured. The optical properties of the complexes were examined using UV–Vis absorption, polarizing microscopy observations, fluorescence spectra, quantum yield, and fluorescence lifetime. The luminescence properties of the complexes as a function of temperature were further observed by analysis of temperature-dependent emission spectra. The polarizing microscopy observations show that the three neodymium complexes exhibited the characteristic properties of thermotropic liquid crystals. UV–Vis, fluorescence spectroscopy, and quantum yield results show that they have excellent light absorption and luminescence properties. Temperature-dependent emission spectra show that the complexes have good luminescence properties in the temperature range of 25–160 °C. The powdered complexes and the complexed solutions in methanol were irradiated with 380 nm UV light, resulting in blue-violet light emission. A warm white-light device was constructed to further verify the luminescence of the complexes after combining with three kinds of rare-earth complexes (Nd(oct-phe)3, Eu(oct-phe)3, and Tb(oct-phe)3. The color rendering index (CRI) and color temperature (CCT) were measured. In addition, the density functional theory (DFT) was used to determine the geometric structures (Fig S1), and obtain 1H NMR, FT-IR spectra of the neodymium complexes (Fig S2, S3). Their structures were further examined by comparing the calculated with the experimental spectra. The results show that the ligands coordinate to the central Nd3+ through the bidentate chelation mode.

Transcriptional Programs and Regulators Underlying Age-Dependent and Dark-Induced Senescence in Medicago truncatula.

In forage crops, age-dependent and stress-induced senescence reduces forage yield and quality. Therefore, delaying leaf senescence may be a way to improve forage yield and quality as well as plant resilience to stresses. Here, we used RNA-sequencing to determine the molecular bases of age-dependent and dark-induced leaf senescence in Medicago truncatula. We identified 6845 differentially expressed genes (DEGs) in M3 leaves associated with age-dependent leaf senescence. An even larger number (14219) of DEGs were associated with dark-induced senescence. Upregulated genes identified during age-dependent and dark-induced senescence were over-represented in oxidation–reduction processes and amino acid, carboxylic acid and chlorophyll catabolic processes. Dark-specific upregulated genes also over-represented autophagy, senescence and cell death. Mitochondrial functions were strongly inhibited by dark-treatment while these remained active during age-dependent senescence. Additionally, 391 DE transcription factors (TFs) belonging to various TF families were identified, including a core set of 74 TFs during age-dependent senescence while 759 DE TFs including a core set of 338 TFs were identified during dark-induced senescence. The heterologous expression of several senescence-induced TFs belonging to NAC, WKRY, bZIP, MYB and HD-zip TF families promoted senescence in tobacco leaves. This study revealed the dynamics of transcriptomic responses to age- and dark-induced senescence in M. truncatula and identified senescence-associated TFs that are attractive targets for future work to control senescence in forage legumes.

Influence of the Type of Amino Acid on the Permeability and Properties of Ibuprofenates of Isopropyl Amino Acid Esters.

Modifications of (RS)-2-[4-(2-methylpropyl)phenyl] propanoic acid with amino acid isopropyl esters were synthesised using different methods via a common intermediate. The main reaction was the esterification of the carboxyl group of amino acids with isopropanol and chlorination of the amino group of the amino acid, followed by an exchange or neutralisation reaction and protonation. All of the proposed methods were very efficient, and the compounds obtained have great potential to be more effective drugs with increased skin permeability compared with ibuprofen. In addition, it was shown how the introduction of a modification in the form of an ion pair affects the properties of the obtained compound.

Enhancement of the Anti-Inflammatory Activity of NSAIDs by Their Conjugation with 3,4,5-Trimethoxybenzyl Alcohol.

The synthesis of derivatives of three nonspecific COX-1 and COX-2 inhibitors, ibuprofen, ketoprofen, naproxen is presented. These acids were connected via an amide bond with an amino acid (L-proline, L-tyrosine, and beta-alanine) used as a linker. The amino acid carboxylic group was esterified with 3,4,5 trimethoxybenzyl alcohol. The activity of the novel derivatives was examined in vivo on carrageenan-induced inflammation, and in vitro, as cyclooxygenase and lipoxygenase inhibitors. It was found that the new compounds were more potent anti-inflammatory agents than the parent drugs. Thus, the ibuprofen (21) and ketoprofen (16) derivatives reduced rat paw edema by 67 and 91% (the reduction by the relevant NSAIDs was 36 and 47%, respectively). They inhibited COX-2 more than the starting drugs (21 by 67%, ibuprofen 46%, 19 by 94%, ketoprofen 49%). Docking of compounds on the active sites of COX-1 and COX-2 reflects their in vitro activity. Thus, 19 adopts an unfavorable orientation for COX-1 inhibition, but it binds effectively in the binding pocket of COX-2, in agreement with the absence of activity for COX-1 and the high inhibition of COX-2. In conclusion, the performed structural modifications result in the enhancement of the anti-inflammatory activity, compared with the parent NSAIDs.

Characterizing of a new α-agarase AgaE from Thalassomonas sp. LD5 and probing its catalytically essential residues

A new α-agarase AgaE belonging to glycoside hydrolase (GH) family 96 was identified and cloned from marine bacterium Thalassomonas sp. LD5. AgaE consists of 926 amino acids with a theoretical molecular mass of 97 kDa. The optimum temperature and pH for recombinant AgaE were 35 °C and 7.0, respectively. In contrast to known α-agarases, the activity of AgaE does not depend on Ca2+, but on Na+. Thin-layer chromatography and 13C NMR analysis revealed that AgaE endohydrolytic of agarose to produce agarotetraose and agarohexaose as the final main products. Extensive site-directed mutagenesis studies on the conserved carboxylic amino acids of GH96 revealed two essential amino acids for AgaE, D779 and D781. Replacing D779 with G779 leads to complete inactivation of the enzyme, while D781G results in 70% loss of activity. Later studies showed that site D781 involved in the binding of Na+, and its mutation raised the optimal concentration of Na+ 4 times higher than that of the wild type. However, attempts to rescue the mutant's activities with sodium azide were failed. Kinetic parameters comparison of AgaE, AgaD, another α-agarase from LD5, and their mutants revealed that the former aspartic acid plays critical role in the catalysis.

Anti-adhesive membranes based on crosslinked carboxymethyl cellulose

In recent times, new anti-adhesion devices including devices based on carboxymethyl cellulose (CMC), which have “barrier” effect are being developed and actively introduced into surgical practice. The “barrier” should be completely resorbed after the time required to healing the morphofunctional integrity of the injured peritoneum, be economically available and easy to use (including laparoscopic technologies). But the time when the CMC is in the body is insufficient to prevent the formation of adhesions, particularly in the presence of non-absorbable rigid implants. The reactive functional groups in CMC allow to transform the CMC-macromolecule into a spatial structure. For this are required the using of bifunctional (bicarboxylic or aminocarboxylic) acids and the transform of a part of the carboxyl groups from the Na-form to the hardly soluble H-form, i.e., it is necessary to crosslink CMC-macromolecules. Adipic acid and glutaric acid, aminoacetic acid and amino capronic acid used are linking agents. The influence of modification parameters on the degree of polymers swelling in water is studied. As a result, to obtain membranes designed for the treatment of adhesive disease, it is recommended to use additives in CMC of bifunctional compounds.

A Photolabile Carboxyl Protecting Group for Solid Phase Peptide Synthesis.

A new kind of photolabile protecting group (PLPG) for carboxyl moieties was designed and synthesized as the linker between resin and peptide. This group can be used for the protection of amino acid carboxyl groups. The peptide was synthesized on Nph (2‐hydroxy‐3‐(2‐nitrophenyl)‐heptanoic acid)‐derivatized resins and could be cleaved under UV exposure, thus avoiding the necessity for harsh acid‐mediated resin cleavage. The PLPG has been successfully used for solid‐phase synthesis of peptides.

Study of the Development of Carotid Artery Atherosclerosis upon Oxidative Stress using Infrared Spectroscopy and Scanning Electron Microscopy

In the present study, Fourier-transform infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) were used to investigate the formation and development of carotid artery atherosclerosis. The FTIR spectra showed that with the progression of atheromatic plaque formation, the collagen changed its native structure from ɑ-helix to random coil, amyloid, and cross-links. The infrared spectra and SEM analysis of carotid arteries showed that higher than 65% of the atheromatic plaque in patients with stenosis consisted of calcium carbonate, which lies inside foam cells. However, as the stenosis progresses, these deposits of calcium phosphate become more prevalent. A thorough analysis of the SEM images highlighted that mineral deposits preferred the carboxyl groups of amino acids. The intensity and shape changes in FT-IR spectra in the region of 1200-900 cm<sup>-1</sup> were related to elevated serum glucose and uric acid levels, the formation of advanced glycation end products (AGEs), and the involvement of free radicals during atherosclerosis.

Metabolic analysis of unripe papaya (Carica papaya L.) to promote its utilization as a functional food.

Papaya (Carica papaya L.) is widely cultivated in tropical and subtropical countries. While ripe fruit is a popular food item globally, the unripe fruit is only consumed in some Asian countries. To promote the utilization of unripe papaya based on the compositional changes of biological active metabolites, we performed liquid chromatography-Orbitrap-mass spectrometry-based analysis to reveal the comprehensive metabolite profile of the peel and pulp of unripe and ripe papaya fruits. The number of peaks annotated as phenolics and aminocarboxylic acids increased in the pulp and peel of ripe fruit, respectively. Putative carpaine derivatives, known alkaloids with cardiovascular effects, decreased, while carpamic acid derivatives increased in the peel of ripe fruit. Furthermore, the functionality of unripe fruit, the benzyl glucosinolate content, total polyphenol content, and proteolytic activity were detectable after heating and powder processing treatments, suggesting a potential utilization in powdered form as functional material.

Radiolysis generates a complex organosynthetic chemical network

The architectural features of cellular life and its ecologies at larger scales are built upon foundational networks of reactions between molecules that avoid a collapse to equilibrium. The search for life’s origins is, in some respects, a search for biotic network attributes in abiotic chemical systems. Radiation chemistry has long been employed to model prebiotic reaction networks, and here we report network-level analyses carried out on a compiled database of radiolysis reactions, acquired by the scientific community over decades of research. The resulting network shows robust connections between abundant geochemical reservoirs and the production of carboxylic acids, amino acids, and ribonucleotide precursors—the chemistry of which is predominantly dependent on radicals. Moreover, the network exhibits the following measurable attributes associated with biological systems: (1) the species connectivity histogram exhibits a heterogeneous (heavy-tailed) distribution, (2) overlapping families of closed-loop cycles, and (3) a hierarchical arrangement of chemical species with a bottom-heavy energy-size spectrum. The latter attribute is implicated with stability and entropy production in complex systems, notably in ecology where it is known as a trophic pyramid. Radiolysis is implicated as a driver of abiotic chemical organization and could provide insights about the complex and perhaps radical-dependent mechanisms associated with life’s origins.

Microbial engineering for the production of C2-C6 organic acids.

Covering: up to the end of 2020Organic acids, as building block compounds, have been widely used in food, pharmaceutical, plastic, and chemical industries. Until now, chemical synthesis is still the primary method for industrial-scale organic acid production. However, this process encounters some inevitable challenges, such as depletable petroleum resources, harsh reaction conditions and complex downstream processes. To solve these problems, microbial cell factories provide a promising approach for achieving the sustainable production of organic acids. However, some key metabolites in central carbon metabolism are strictly regulated by the network of cellular metabolism, resulting in the low productivity of organic acids. Thus, multiple metabolic engineering strategies have been developed to reprogram microbial cell factories to produce organic acids, including monocarboxylic acids, hydroxy carboxylic acids, amino carboxylic acids, dicarboxylic acids and monomeric units for polymers. These strategies mainly center on improving the catalytic efficiency of the enzymes to increase the conversion rate, balancing the multi-gene biosynthetic pathways to reduce the byproduct formation, strengthening the metabolic flux to promote the product biosynthesis, optimizing the metabolic network to adapt the environmental conditions and enhancing substrate utilization to broaden the substrate spectrum. Here, we describe the recent advances in producing C2-C6 organic acids by metabolic engineering strategies. In addition, we provide new insights as to when, what and how these strategies should be taken. Future challenges are also discussed in further advancing microbial engineering and establishing efficient biorefineries.

Молочна продуктивність кіз зааненської породи за згодовування органічної кормової добавки гумінової природи

The results of the study of Saanen goats milk productivity while feeding humic origin organic feed supplement of «VitaHum» are presented in the paper. Studying milk productivity of different goat breeds, as well as using balanced rations of biologically active feed supplements for therapeutic and prophylactic properties and improving metabolic processes and body functions, are important issues for animal breeding industry, since goat husbandry in Ukraine is in a state of formation. «VitaHum» is completely different from existing biologically active peat supplements on the market because it is received not as a result of peat hydrolysis by alkalis or acids, but by a natural way of chelation. It does not contain humic acids sodium salts with alkali residues with which no reaction had taken place, but residues of amino acids, peptides, carboxylic acids and other useful substances in pure «natural» organic form. This feed supplement meets European standards of organic products. It was found that with the industrial technology of the animal management and feeding with mixed diets when using humic origin feed supplement «VitaHum» during the entire lactation period, milk yield was increased by 15.9% or 137.3 kg, milk protein content by 0.11 abs. percent. However, the goats from the control group had the advantage in milk fat content by 0.09 abs. percent (P > 0.999). The maximum average daily milk yield of 3.55 kg was observed in the second experimental group of goats, which received feed supplements «VitaHum» in addition to the main diet. However, as a result of a significant advantage in milk yield from goats of the experimental group, a noticeably higher amount of both milk protein and milk fat mass fraction was obtained by 5.94 kg and 4.63 kg, respectively. Analysis of the qualitative milk composition of the experimental goats showed that the percentage of milk solids non-fat (MSNF) was in the range of 8.45–8.58%, and the content of somatic cells in the milk of control group animals was higher by 7.05%. The qualitative milk composition was quite satisfactory for this breed of goats, as the milk fat mass fraction was 3.94–4.03% and protein one 3.52–3.63%. The ratio of fat and protein at the level of 1.15–1.09 units indicated a good physiological state of the digestive system of the Saanen breed goats.

Research on Targeted Acidizing Technology in Long Horizontal Section of Carbonate Reservoir

The upper layer of Oil field A is developed by horizontal linear well pattern with long well segment. After completion, there is relatively serious formation damage, and the tested epidermal factor is up to 6.21 on average. Due to the length of horizontal well section and the serious vertical heterogeneity of formation, some strata were over-acidized in the early stage, so it was very difficult to distribute acid evenly. For this reason, the low contribution layer of horizontal section was determined by using amino carboxylic acid system and coiled tubing hydrojet acidification process, combined with reservoir characteristics, and the spindle-type acid distribution method was adopted to optimize nozzle combination parameters to predict construction displacement and ground construction pressure. The laboratory experiment was carried out to compare with the conventional acid system for core displacement experiment. The acid could form acid-etch wormhole, effectively extend the acid-action distance, and achieve the purpose of slow and deep penetration.

138 Analytical Methods for Organometallic Chelation Testing

Abstract Chelated minerals have increasingly captured the attention of scientists, manufacturers, and consumers in nutritional markets during the past five decades, due to their enhanced bioavailability compared to traditional ionic metal compounds. A wide variety of organic ligands bind to metal ions to form complexes that are generally referred to as chelates, including amino acids, peptides, proteins and carboxylic acids. Chemical reactions used to synthesize mineral chelates are affected by a number of factors that can alter the extent of chelation in manufactured products, such as pH, temperature, concentration, solvation, competing ions and ligands, and other variables. Qualitative and quantitative determination of chelation can be a daunting challenge, especially for dilute micronutrient minerals in complex matrices. Measuring chelation between metals and their ligands specifically focuses on the attractive forces between them. Analytical methods to determine the extent of chelation rely on a wide array of spectroscopic and electrochemical techniques. Very few standard methods of analysis exist to quantitatively measure the extent of chelation in nutritional products. A variety of these methods will be reviewed and compared for their potential use as standard methods of analysis.

A novel bioconjugated reduced graphene oxide-based nanocomposite for sensitive electrochemical detection of cadmium in water

Herein, construction of an ecofriendly SnO2 nanoparticles@bioconjugated reduced graphene oxide’ nanocomposite was reported, which was prepared through carbodiimide coupling between carboxyl groups of amino acid ‘l-proline’ and amino-functionalized reduced graphene oxide (H2N-rGO) followed by its anchoring to SnO2 nanoparticles. Furthermore, prepared nanocomposite modified electrode was applied for the selective and sensitive detection of cadmium (II) in water sample. Synergistic effect of SnO2 and bioconjugated reduced graphene oxide greatly enhanced the electrocatalytic efficiency of the electrode. Quantification of Cd (II) was recorded in a linear range of 0.001−0.4 ppm with limit of detection 1 × 10−4 ppm and high sensitivity 67.43 μA/ppm. Finally, real sample analysis was also performed using tap water and ground water samples with excellent recovery results.

Synthesis and Properties of Two Amino Carboxylic Acid Gemini Surfactants

AbstractThe number of hydrophilic and hydrophobic groups of a surfactant has a great influence on its property. Two Gemini surfactants, N,N″‘‐didodecyl‐N,N',N″,N″‘‐tetrapropionate triethylenetetramine and N,N'‐didodecyl‐N,N'‐dipropionate ethylenediamine (referred as DTPTT and DDPED), were prepared by Michael addition reaction of the didodecyl secondary amines with methyl acrylate. The didodecyl secondary amines were synthesized by nucleophilic substitution reaction of triethylenetetramine or ethylenediamine with bromododecane. The DTPTT and DDPED surfactants were characterized by mass spectrometry and proton nuclear magnetic resonance spectrometry. The surface activities of the DTPTT and DDPED aqueous solutions were studied by surface tension measurements. The surface tension and critical micelle concentration (cmc) of DDPED is smaller than that of DTPTT. The DDPED can reduce the surface tension of water to approximate 34 mN m−1 at concentration levels of 10−5 mol L−1. The aggregation behavior of the DTPTT and DDPED aqueous solution were studied by dynamic light scattering and transmission electron microscopy. Both surfactants can form spherical vesicles at a solution of about 3–5 times cmc of the Gemini surfactants. The foam property was determined by nitrogen blowing method. The DTPTT has relatively good foaming ability and DDPED has excellent foam stability. The foam volume of DDPED barely change within 1000s. The emulsion stability of the Gemini surfactants was determined by separation time of water from the emulsion. The emulsion stability of DDPED is equivalent to Tween 80. The DDPED Gemini surfactant with two hydrophilic carboxylic groups has better surface activity, foam stability, and can be used as an O/W emulsifier.

Denatured M13 Bacteriophage-Templated Perovskite Solar Cells Exhibiting High Efficiency.

The M13 bacteriophage, a nature‐inspired environmentally friendly biomaterial, is used as a perovskite crystal growth template and a grain boundary passivator in perovskite solar cells. The amino groups and carboxyl groups of amino acids on the M13 bacteriophage surface function as Lewis bases, interacting with the perovskite materials. The M13 bacteriophage‐added perovskite films show a larger grain size and reduced trap‐sites compared with the reference perovskite films. In addition, the existence of the M13 bacteriophage induces light scattering effect, which enhances the light absorption particularly in the long‐wavelength region around 825 nm. Both the passivation effect of the M13 bacteriophage coordinating to the perovskite defect sites and the light scattering effect intensify when the M13 virus‐added perovskite precursor solution is heated at 90 °C prior to the film formation. Heating the solution denatures the M13 bacteriophage by breaking their inter‐ and intra‐molecular bondings. The denatured M13 bacteriophage‐added perovskite solar cells exhibit an efficiency of 20.1% while the reference devices give an efficiency of 17.8%. The great improvement in efficiency comes from all of the three photovoltaic parameters, namely short‐circuit current, open‐circuit voltage, and fill factor, which correspond to the perovskite grain size, trap‐site passivation, and charge transport, respectively.

Dissecting Amino Acid Osmolytes: Is a Zwitterion Required for Increasing Protein Thermal Stability?

Amino acids are an important class of osmolytes that demonstrate the ability to stabilize certain proteins under acute thermal stress. However, little consensus exists on what structural aspects produce this phenomenon. It has been proposed that the stabilizing nature of amino acids emerges from their zwitterionic nature at neutral pH, but little evidence has supported this view, especially in regards to the breadth of its applicability to proteins of varying structure and composition. In this report, we structurally dissect the amino acids L‐alanine and β‐alanine to determine functional group contributions to protein‐stabilizing activity on two structurally dissimilar proteins: human C‐reactive protein (CRP) and human myoglobin. The stabilizing effects of the osmolytes (and their structural derivatives) were quantified by Differential Scanning Fluorimetry (DSF) in three metrics: protein melting temperature (Tm), standard free energy change (ΔGo), and “m”‐values. Our results indicate that the zwitterionic theory holds for myoglobin, as removal of either the carboxylate or amino moiety from the amino acid abrogated all thermal stabilizing effects. Furthermore, substitution of the carboxylate group with a hydroxyl group did not restore protein‐stabilizing activity, arguing for the zwitterionic requirement for amino acid‐mediated thermal stabilization. However, the results with CRP were significantly different from those observed with myoglobin. In the case of CRP, the amino acid carboxylate proved to be the dominant stabilizing group, as compounds lacking the amino group conferred greater thermal stability than the complete amino acids. These results affirm that the zwitterionic theory is limited in its ability to describe amino acid‐mediated effects on protein thermal stability and suggests that the nature of the interactions between amino acid osmolytes and proteins is highly dependent on protein structure. These results may have significant implications for the development of chemistries to stabilize diverse protein targets in biospecimens for diagnostic applications.Support or Funding InformationCalifornia State University Program for Education and Research in Biotechnology (CSUPERB)Chevron Biotechnology Applied Research EndowmentBill and Linda Frost Fund

Analyses of energy metabolism and stress defence provide insights into Campylobacter concisus growth and pathogenicity

Campylobacter concisus is an emerging enteric pathogen that is associated with inflammatory bowel disease. Previous studies demonstrated that C. concisus is non-saccharolytic and hydrogen gas (H2) is a critical factor for C. concisus growth. In order to understand the molecular basis of the non-saccharolytic and H2-dependent nature of C. concisus growth, in this study we examined the pathways involving energy metabolism and oxidative stress defence in C. concisus. Bioinformatic analysis of C. concisus genomes in comparison with the well-studied enteric pathogen Campylobacter jejuni was performed. This study found that C. concisus lacks a number of key enzymes in glycolysis, including glucokinase and phosphofructokinase, and the oxidative pentose phosphate pathway. C. concisus has an incomplete tricarboxylic acid cycle, with no identifiable succinyl-CoA synthase or fumarate hydratase. C. concisus was inferred to use fewer amino acids and have fewer candidate substrates as electron donors and acceptors compared to C. jejuni. The addition of DMSO or fumarate to media resulted in significantly increased growth of C. concisus in the presence of H2 as an electron donor, demonstrating that both can be used as electron acceptors. Catalase, an essential enzyme for oxidative stress defence in C. jejuni, and various nitrosative stress enzymes, were not found in the C. concisus genome. Overall, C. concisus is inferred to have a non-saccharolytic metabolism in which H2 is central to energy conservation, and a narrow selection of carboxylic acids and amino acids can be utilised as organic substrates. In conclusion, this study provides a molecular basis for the non-saccharolytic and hydrogen-dependent nature of C. concisus energy metabolism pathways, which provides insights into the growth requirements and pathogenicity of this species.

P-Toluenesulfonyl Chloride Catalysed Facile Synthesis of O-benzyl-l-amino Acids and Their In Vitro Evaluation

Protection and subsequent deprotection of amino acid functional groups play a key role in regioselective peptide synthesis. For protection, carboxylic acid functional groups are often benzylated using p-toluenesulfonic acid catalysed Fischer-Speier esterification reaction. Such reaction involves in situ water formation, which requires subsequent separation by azeotropic distillation for forward shift of equilibrium. To eliminate the need of this corresponding step requiring additional set-up, current study investigated p-toluenesulfonyl chloride as a reasonable alternative catalyst for facile benzylation of selected mono- and di- carboxylic amino acids. Literature reports that p-toluenesulfonyl chloride not only has a better shelf life but also demonstrates better safety in case of accidental systemic absorption over p-toluenesulfonic acid. As the O-benzyl-l-amino acids are often retained without deprotection to constitute the pharmaceutical peptide systems, synthesized compounds were investigated for their biocompatibility using in vitro cytotoxicity assays.