Antiproliferative Properties of Vinyl Dipeptides: Synthesis and MCF-7 Cell Line Testing

Peptide mimics derived with close structure to peptide have vast utility because they are expected to interfere with biological targets while having superior drug-like properties if compared to peptides. In this work, novel vinyl dipeptides which are different in a double bond between the α-carbon of peptide and C1 of its side chain. Added to that, suitable substituents were selected to harness drug-like properties. The compounds were found to have moderate activities when tested against MCF-7 breast cancer cell line. For instance, the adamantyl analogue 2-(benzoylamino)-3-(2-furyl)-N-(1-adamantyl) propenamide (1c) and the heterocyclic analogue 2-(Benzoylamino)-3-(2-furyl)-N-[2-(5-cyanothia-zol-2-yl)] propenamide (1o) exhibited inhibition potency at 27.4 and 37.8 μM, respectively.

Systematic screening and structural characterization of dipeptides using offline 2D LC-LTQ-Orbitrap MS:A case study of Cordyceps sinensis

Cordyceps sinensis(C.sinensis)is a widely used and highly valuable traditional Chinese medicine.Several dipeptides have been detected in C.sinensis,but current scientific knowledge of its chemical makeup remains limited.In this study,an improved approach that integrates offline two-dimensional liquid chromatography(2D LC)separation,precursor ion list,library screening,and diagnostic ion filtering was established to systematically screen and characterize dipeptides in C.sinensis.Offline 2D LC integrating hydrophilic interaction LC and reverse phase separations was established to eliminate interference and identify the target dipeptides.A library containing the potential 400 dipeptides was created,and a precursor ion list with all theoretical precursor ions was adopted to trigger the MS/MS scan with high sensitivity.To identify dipeptides,the type and connection sequence of amino acids were determined according to the product ions.Ile and Leu residues were differentiated for the first time according to the characteristic ion at m/z 69.07.Ultimately,170 dipeptides were identified or tentatively characterized from C.sinensis,and most are reported for the first time in this species herein.In addition,the identified dipeptides were also applied for discrimination among the three Cordyceps species,and 11 markers were identified.The obtained results provide a deeper understanding of the chemical basis of C.sinensis.

DETERM INATION OF THE STABILITY CONSTANTS OF COMPLEXES OF HISTIDINE,SOME DIPEPTIDES AND TRIGLYCINE WITH Zn(Ⅱ)AND Cd(Ⅱ)USING SMALL-SCALE PH-METRIC TITRATIONS

A potentiometric study on the complexes of His,Gly-His,ALa-His,Gly-Gly and Gly—Gly—Gly with Zn(Ⅱ)and Cd(Ⅱ)has been reported.Small-scale potentiometric titrations were car- ried out to determine stabil ity constants of complexes at 25℃ with I=0.10 mol dm^(-3)(KNO_3).The com- puter programs SUPERQUAD were applied for data treatment with satisfactory results.

Asymmetric Reformatsky Reaction Induced by Dipeptides

For the first time, synthetic dipeptides were applied to the catalysis of asymmetric Reformatsky reaction. Review in this domain & factors influencing enantioselectivity were discussed.

Proline-based Amino Pyridine Dipeptides as Efficient Organocatalysts for Direct Aldol Reaction

A series of proline-based amino pyridine dipeptide organocatalysts was synthesized and applied in direct asymmetric intermolecular aldol reaction. These catalysts showed good solubility in organic solvents, good yields （73%--97%） and enantioselectivitives（74%--94%）. Among them, dipeptide organocatalyst（2） was found to be the most efficient one for the asymmetric aldol reaction between cyclohexanone and 4-nitrobeznaldehyde. After optimizing the catalytic reaction conditions, we found that the catalyst showed high yield（97%）, enantioselectivity（e.e., up to 92%） and anti-diastcreoselectivity（up to 95：5） at mild room temperature without any additives.

A New Metal Tag for Highly Selective and Sensitive Analyses of Amino Acids and Dipeptides by HPLC/ICP-MS

We have developed a novel metal tag, bis(ethylenediamine)-4'-methyl-4-carboxybipyridine-ruthenium N-succinimidyl ester (ECRS) for sensitive analysis of amino acids using high performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICP-MS). ECRS is a functional reagent, containing an ester group at one end that can be activated to bind to amino group and a chelated ruthenium at the other. The activated ester was reacted briefly with amino groups under weakly alkaline conditions. The ruthenium was detected sensitively by ICP-MS. ECRS was reacted with 17 proteinogenic amino acids in borate buffer. The derivatives were separated by reversed phase HPLC and identified by quadrupole-based ICP-MS. ECRS was suitable for speciation;low molecular weight compounds containing amino groups. We have thus established a quantitative analytical method for amino acids and dipeptides. The detection limits of branched amino acids (signal-to-noise ratio of 3) were 1.5 nmol·L-1 in the standard solution (100 amol per injection).

Inhibition of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase enzyme by dipeptides identified in dry-cured ham

High cholesterolemia is a key risk factor for the development of cardiovascular diseases,which are the main cause of mortality in developed countries.Most therapies are focused on the modulation of its biosynthesis through 3-hydroxy-3-methylglutaryl-coenzyme A reductase(HMG-CoAR)inhibitors.In this sense,food-derived bioactive peptides might act as promising health alternatives through their ability to interact with crucial enzymes involved in metabolic pathways,avoiding the adverse effects of synthetic drugs.Dry-cured ham has been widely described as an important source of naturally-generated bioactive peptides exerting ACEI-inhibitory activity,antioxidant activity,and anti-inflammatory activity between others.Based on these findings,the aim of this work was to assess,for the first time,the in vitro inhibitory activity of HMG-CoAR exerted by dipeptides generated during the manufacturing of dry-cured ham,previously described with relevant roles on other bioactivities.The in vitro inhibitory activity of the dipeptides was assessed by measuring the substrate consumption rate of the 3-hydroxy-3-methylglutaryl CoA reductase in their presence,with the following pertinent calculations.Further research was carried out to estimate the possible interactions of the most bioactive dipeptides with the enzyme by performing in silico analysis consisting of molecular docking approaches.Main findings showed DA,DD,EE,ES,and LL dipeptides as main HMG-CoAR inhibitors.Additionally,computational analysis indicated statin-like interactions of the dipeptides with HMG-CoAR.This study reveals,for the first time,the hypocholesterolemic potential of dry-cured ham-derived dipeptides and,at the same time,converges in the same vein as many reports that experimentally argue the cardiovascular benefits of dry-cured ham consumption due to its bioactive peptide content.

Influence of peptide bond on photosensitized oxidation of tryptophan, tyrosine and histidine dipeptides

IN photodynamic therapy, the damage of protein results from the photooxidation of one ormore of only five amino acid residues (tryptophanyl, tyrosyl, histidyl, methionyl and cys-teinyl). These five amino acids are also readily photooxidized in their monomeric states. How-ever, the reaction kinetics and mechanisms of free amino acids and bound amino acid residuesin proteins are somewhat different. For example, Tassin found that the incorporation of tryp-tophan into a peptide linkage dramatically altered its susceptibility to photooxidation as well

Theoretical Study on the Cyclization Mechanism of Dipeptides

Cyclization is an important chemical reaction for the dipeptides containing N-alkyl groups. The cyclization mechanism has been examined by theoretical calculations. Our calculation results indicate that the most favorable mechanism is the piperidine-catalyzed stepwise mechanism, in which piperidine acts as a proton shuttle. The attack of the N-terminal amino nitrogen at the C-terminal carbonyl carbon along with the proton transfer is the rate-limiting step. The effect of the alkyl substituent on the amide N on the eyclization reaction was then examined. Finally, the influence of the solvation effect, electronic effect and steric effect on the cyclization was investigated. It is found that all of these effects contribute to the cyclization.

Stereoselective interactions of chiral dipeptides on amylose based chiral stationary phases

Dipeptides are stereo-specifically involved in several biological functions that are challenging to separate enantiomerically. Elution order of enantiomers is an important issue in chiral chromatography. Amylose tris-(3,5-dimethylphenylcarbamate) chiral stationary phase(CSP) is the best and most-widely-used CSP in chiral separations, but experimental data of enantiomeric separation of dipeptides on this CSP is lacking. Simulation studies were conducted to determine the order of elution and the chiral recognition mechanism of didpetides on this CSP. Results indicated that the docking energy of SR-enantiomers were higher than SS-antipodes. The range of docking energies for SR-enantiomers was -7.44 to -5.92 kcal/mol with CSP, but -7.15 to -5.87 kcal/mol for SS-stereoisomers. Therefore it is predicted that SS-enantiomer will elute first, followed by SR-antipode. Furthermore, hydrogen bondings, van der Waal's interactions and electrostatic interactions were observed among SR- and SSenantiomers and chiral grooves of CSP. The number of hydrogen bonds was one in each enantiomer binding except S-Ala-R-Tyr, which contained two hydrogen bonds. No hydrogen bond was found in S-Ala-R-Trp, S-Leu-S-Trp, and S-Leu-S-Tyr dipeptides bindings. The chiral recognition mechanisms dictate different strengths of stereoselective bindings of the enantiomers on CSP.

Dock-able linear and homodetic di, tri, tetra and pentapeptide library from canonical amino acids: SARS-CoV-2 Mpro as a case study

Peptide-based therapeutics are increasingly pushing to the forefront of biomedicine with their promise of high specificity and low toxicity.Although noncanonical residues can always be used,employing only the natural 20 residues restricts the chemical space to a finite dimension allowing for comprehensive in silico screening.Towards this goal,the dataset comprising all possible di-,tri-,and tetra-peptide combinations of the canonical residues has been previously reported.However,with increasing computational power,the comprehensive set of pentapeptides is now also feasible for screening as the comprehensive set of cyclic peptides comprising four or five residues.Here,we provide both the complete and prefiltered libraries of all di-,tri-,tetra-,and penta-peptide sequences from 20 canonical amino acids and their homodetic(N-to-C-terminal)cyclic homologues.The FASTA,simplified molecular-input line-entry system(SMILES),and structure-data file(SDF)-three dimension(3D)libraries can be readily used for screening against protein targets.We also provide a simple method and tool for conducting identity-based filtering.Access to this dataset will accelerate small peptide screening workflows and encourage their use in drug discovery campaigns.As a case study,the developed library was screened against severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)main protease to identify potential small peptide inhibitors.

Three previously undescribed metabolites from Cordyceps cicadae JXCH-1,an entomopathogenic fungus

Three previously undescribed compounds,cordycicadione(1),cordycicadin F(2),and 7-hydroxybassiatin(3),were isolated from the cultures of Cordyceps cicadae JXCH1,an entomopathogenic fungus.Their structures and relative configurations were elucidated primarily by NMR spectroscopic analysis.The absolute configurations of 1 and 2 were determined by ECD calculations.Single-crystal X-ray diffraction method was adopted to determine the absolute configuration of 3.Compound 2 is a polycyclic polyketide with an unusual enol ether moiety and a spiro ring.The compounds obtained in this study were subjected to screening their inhibition against the proliferation of the human lung cancer cell line A549 and the production of nitric oxide in murine macrophages RAW264.7.

A Dipeptide Isolated from Aster tataricus L.f

从紫菀AastertataricusL.f的根及根茎中分离鉴定出6个化合物，分别为auraniamideacetate;shionone,triedelm,epitrriedelanol,triedel-3-ene和stigmasterol.其中aurantiamideacetate和triedel-3-ene为首次从菊科植物中分得。

Peptide-based enteral formula improves tolerance and clinical outcomes in abdominal surgery patients relative to a whole protein enteral formula

AIM To compare a dipeptide- and tripeptide-based enteral formula with a standard enteral formula for tolerance and nutritional outcomes in abdominal surgery patients.METHODS A retrospective study was performed to assess the differences between a whole-protein formula(WPF) and a dipeptide- and tripeptide-based formula(PEF) in clinical outcomes.Seventy-two adult intensive care unit(ICU) patients with serum albumin concentrations less than 3.0 g/d L were enrolled in this study.Patients were divided into two groups(WPF group = 40 patients,PEF group = 32 patients).The study patients were fed for at least 7 d,with ≥ 1000 m L of enteral formula infused on at least 3 of the days.RESULTS The mean serum albumin level on postoperative day(POD) 10,prealbumin levels on POD-5 and POD-10,and total lymphocyte count on POD-5 were significantly higher in the PEF group compared to those in the WPF group(P < 0.05).The average maximum gastric residual volume of the PEF patients during their ICU stays was significantly lower than that for WPF patients.CONCLUSION Dipeptide- and tripeptide-based enteral formulas are more efficacious and better tolerated than wholeprotein formulas.

Alanyl-glutamine dipeptide inhibits hepatic ischemiareperfusion injury in rats

AIM： To investigate the protective effect and mechanism of alanyl-glutamine dipeptide （Ala-GIn） against hepatic ischemia-reperfusion injury in rats. METHODS： Rats were divided into group C as normal control Group （/7=16） and group G as alanyl-glutamine pretreatment 07=16）. Rats were intravenously infused with 0.9% saline solution in group C and Ala-GIn -enriched （2% glutamine） 0.9% saline solution in group G via central venous catheter for three days. Then all rats underwent hepatic warm ischemia for 30 min followed by different periods of reperfusion. Changes in biochemical parameters, the content of glutathione （GSH） and the activity of superoxide dismutase （SOD） in liver tissue, Bcl-2 and Bax protein expression and morphological changes of liver tissue were compared between both groups. RESULTS： One hour after reperfusion, the levels of liver enzymes in group G were significantly lower than those in group C （P〈0.05）. Twenty-four hours after reperfusion, the levels of liver enzymes in both groups were markedly recovered and the levels of liver enzyme in group G were also significantly lower than those in group C （P〈0.01）. One and 24 h after reperfusion, GSH content in group G was significantly higher than that in group C （P 〈0.05）. There was no statistical difference in activities of SOD between the two groups. One and 24 h after reperfusion, the positive expression rate of Bcl-2 protein was higher in group G than in group C （P〈0.05） and the positive expression rate of Bax protein was lower in group G than in group C （P〈0.05）. Histological and ultrastructural changes of liver tissue were inhibited in group C compared to group G. CONCLUSION： Our results suggest that Ala-GIn pretreatment provides the rat liver with significant tolerance to warm ischemia-reperfusion injury, which may be mediated partially by enhancing GSH content and regulating the expression of Bcl-2 and Bax proteins in the liver tissue.

In-silico Prediction of the Sweetness of Aspartame Analogues from QSPR Analysis

The extensive utilization of the low-energy dipeptide sweetener aspartame in foods leads to various studies on searching for new sweeteners in series. However, the real mechanistic cause of their sweetness power is still not completely known owing to their complex interactions with human sweet receptor, which may be different from that of other sweeteners to some extent. In this contribution, predictive quantitative structure-property relationship(QSPR) models have been developed for diverse aspartame analogues using Materials Studio 5.0 software. The optimal QSPR model(r2 = 0.913, r2 CV = 0.881 and r2 pred = 0.730) constructed by the genetic function approximation method has been validated by the tests of cross validation, randomization, external prediction and other statistical criteria, which shows that their sweetness power is mainly governed by their electrotopological-state indices(SssCH and SsNH), spatial descriptors(Shadow length: LX, ellipsoidal volume and Connolly surface occupied volume) and topological descriptors(Chi(3): cluster and Chi(0)(valence modified)), which partially supports both multipoint attachment theory proposed by Nofre and Tinti et al. and B-X theory proposed by Kier et al.. Present exploited results provide the key structural features for the sweetness power of aspartame analogues, supplement the mechanistic understanding of the sweet perception, and would be also helpful for the design of potent sweetener analogs prior to their synthesis.

Carnosine concentration and expression profiles of carnosine related genes in Mytilus after beta-alanine injection

Carnosine and its analogues are histidine-containing dipeptides(HCDs)playing diverse functions in vertebrates.However,the distribution and the metabolism of carnosine in invertebrates are still unknown.In this study,Mytilus coruscus,a shellfish with important economic value in China,was selected for the investigation of HCD content and the expression profiling of carnosine-related genes in various mussel tissues.Quantification of HCD by amino acids analyzer revealed a low concentration of anserine in muscular tissues in Mytilus,indicating the presence of HCD even in an invertebrate.mRNA expression of five carnosine metabolic-related genes was profiled in various tissues,and the results highlighted the relative higher expression level of these genes in muscular tissues.Considering the fact that beta-alanine supplementation can increase the HCD content in vertebrates,a beta-alanine injection was performed and the changes of HCD concentration and the mRNA expression of carnosine related genes were investigated in five mussel tissues.The results revealed the increase of HCD concentration,as well as the up-regulated expression level of related genes,in tested tissues of beta-alanine injected mussels.Transcriptomic analysis for the whole soft tissue of mussel before and after beta-alanine injection were performed,and 3569 differential expression genes(DEGs)were identified in the beta-alanine injected group when compared to their expression levels in the control.These data indicated the complex eff ects of betaalanine on M.coruscus metabolism,and those DEGs enriched in pathways of cancers,muscle contraction,and tyrosine metabolism highlighted the possible functions of beta-alanine in cell proliferation,sports,and melanogenesis,respectively.

In silico identification and characterization of common epitope-based peptide vaccine for Nipah and Hendra viruses

Objective: To explore a common B-and T-cell epitope-based vaccine that can elicit an immune response against encephalitis causing genus Henipaviruses, Hendra virus(He V) and Nipah virus(Ni V). Methods: Membrane proteins F, G and M of He V and Ni V were retrieved from the protein database and subjected to different bioinformatics tools to predict antigenic B-cell epitopes. Best B-cell epitopes were then analyzed to predict their T-cell antigenic potentiality. Antigenic B-and T-cell epitopes that shared maximum identity with He V and Ni V were selected. Stability of the selected epitopes was predicted. Finally, the selected epitopes were subjected to molecular docking simulation with HLA-DR to confirm their antigenic potentiality in silico. Results: One epitope from G proteins, one from M proteins and none from F proteins were selected based on their antigenic potentiality. The epitope from the G proteins was stable whereas that from M was unstable. The M-epitope was made stable by adding flanking dipeptides. The 15-mer G-epitope(VDPLRVQWRNNSVIS) showed at least 66% identity with all Ni V and He V G protein sequences, while the 15-mer M-epitope(GKLEFRRNNAIAFKG) with the dipeptide flanking residues showed 73% identity with all Ni V and He V M protein sequences available in the database. Molecular docking simulation with most frequent MHC class-II(MHC II) and class-I(MHC I) molecules showed that these epitopes could bind within HLA binding grooves to elicit an immune response. Conclusions: Data in our present study revealed the notion that the epitopes from G and M proteins might be the target for peptide-based subunit vaccine design against He V and Ni V. However, the biochemical analysis is necessary to experimentally validate the interaction of epitopes individually with the MHC molecules through elucidation of immunity induction.

ALTERATION IN ENTEROCYTE GENE EXPRESSION MAY EXPLAIN STRUCTURAL AND FUNCTIONAL CHANGES FOLLOWING GLUTAMINE SUPPLEMENTED PARENTERAL NUTRITION

Following extensive bowel resection, the intestinal tract undergoes a variety of adaptive responses to enhance bowel function. The purpose of this study was to determine the effect of glutamine-supplemented parenteral nutrition on mucosal cellularity and gut function. In addition, enterocyte gene expression of two relevant systems was also characterized and related to the structural and functional changes that occurred. Male Wistar rats underwent a 60% small bowel resection and jugular vein catheterization and were randomized into two groups. The control group (n = 10) received a standard intravenous nutritional solution and the study group (n = 10) received a similar solution but enriched with alanylglutamine dipeptide. After 7 days blood was taken for amino acid analysis, and bowel was harvested to determine mucosal morphology and expression of mucosal cell glutaminase and IGF-I mRNA. Mesentery lymphnodes were cultured to determine the presence of bacteria and thus access bacteria translocation. Serum glutamine concentration and mucosal architecture were maintained in the study group compared to the controls. Seventy percent of lymphnodes were cultured positive in control vs. only 20% in the study group (P

Novel Efficient Method for Synthesis of N_(1,4)-Disubstituted-1,4-benzodiazepine-2,5-diones

A novel and efficient method was developed for the liquid-phase synthesis of Nj,4-disubstitutedbenzodiazepine-2,5-diones with 2-chloro-5-nitrobenzoic acid as initiating material via 4 step reactions containing esterifieation, ＂Ulmn reaction＂, acylation, alkylation and cyclization. The reaction conditions were mild and the overall yields of the products ranged from 45% to 71%.