Solid-phase Peptide Synthesis Method Research Articles

Unveiling the Self-assembly and Therapeutic Efficacy of Antimicrobial Peptides SA4 Against Multidrug-Resistant A. baumannii.

Infections linked to Acinetobacter baumannii are one of the main risks of modern medicine. Biofilms formed by A. baumannii due to a protective extracellular polysaccharide matrix make them highly tolerant to conventional antibiotics and raise the possibility of antibiotic resistance. Antimicrobial peptides (AMPs) are gaining popularity due to their broad-spectrum actions and key properties of peptide self-assembly, making them a promising alternative to antibiotics. Here, we demonstrate that 12-residue synthetic self-assembled peptide SA4 nanostructures have enough antibacterial action to prevent the growth of mature bacterial biofilms. The SA4 peptide was successfully synthesized by using the solid-phase peptide synthesis method, and its self-assembly was prepared in water. The self-assembled peptide hydrogel formed nanotube structure was observed under a scanning electron microscope and further characterized to confirm their physical and molecular properties. The resulting hydrogel exhibits significant antibacterial activity against MDR A. baumannii strains (MDR-1 and MDR-2), responsible for many nosocomial infections. In addition, at various gel concentrations, this hydrogel has the potential to inhibit about 30-80% of biofilms formed by MDR strains. Furthermore, under a microscope, it has been observed that the rupture of the bacterial cell membrane and cell wall of A. baumannii cells is caused by peptide nanotubes generated by self-assemblies. Thus, peptide-based nanotubes present intriguing avenues for various biomedical applications. This is the first report of bacterial biofilm removal with SA4 peptide nanotubes, and offering a unique treatment for infections linked to biofilms.

Self-assembling peptides induced by eyes absent enzyme to boost the efficacy of doxorubicin therapy in drug-resistant breast cancer cells

Enzyme-induced self-assembly (EISA) is a recently developed nanotechnology technique in which small molecules are induced by cellular enzymes self-assembling into nanostructures inside cancer cells. This technique can boost the efficacy of chemotherapy drugs by avoiding drug efflux, inhibiting the cells’ DNA repair mechanisms, and targeting the mitochondria. In this work, we study the self-assembly of a short peptide and its fluorescence analogue induced by Eyes absent (EYA) tyrosine phosphatases to boost the efficacy of doxorubicin (DOX) therapy in drug-resistant types of breast cancer cells, MDA-MB-231 and MCF-7. The peptides Fmoc–FF–YP and NBD–FF–YP were synthesized with the solid-phase peptide synthesis (SPPS) method and analyzed with HPLC and MALDI-TOF. Dynamic light scattering was used to determine the size distribution of peptides exposed to the EYA enzyme in vitro. The presence of EYA enzymes in breast cancer cells was confirmed using the western blotting assay. The intracellular location of the peptide self-assembly was studied by imaging fluorescence NBD-tagged peptides. The efficacy of the peptide alone and with DOX was determined against MCF-7 and MDA-MB-231 using MTT and LIVE-DEAD assays. Nucleus and cytoplasm F-actin (Phalloidin) staining was used to determine cell morphology changes in response to the combination therapy of peptides/DOX. At an optimal concentration, the peptides are not toxic to the cells; however, they boost the efficacy of DOX against drug-resistant breast cancer cells. We used state-of-the-art computer-aided techniques to predict the molecular structure of peptides and their interactions with EYA. This study demonstrates an approach for incorporating non-cytotoxic components into DOX combination therapy, thereby avoiding increased systemic burden or adverse effects.

Development of Clarstatin, a Novel Drug Lead for the Therapy of Autoimmune Uveitis.

We describe the design, synthesis, and activity of a potent thiourea-bridged backbone cyclic peptidomimetic known as Clarstatin, comprising a 5-amino acid sequence (Q/D)1-(R/K)2-X3-X4-A5-(Gln/Asp)1-(Arg/Lys)2-AA3-AA4-Ala5-based on a motif called "shared epitope (SE)", specifically present in specific alleles of the HLA-DRB1 gene. This SE binds to a particular site within the proline reach domain (P-domain) of the cell surface-calreticulin (CS-CRT). CS-CRT is a multifunctional endoplasmic reticulum (ER) calcium-binding protein that is located on the cell surface of T cells and triggers innate immune signaling, leading to the development of inflammatory autoimmune diseases. The development of Clarstatin was based on the parent peptide W-G-D1-K2-S3-G4-A5- derived from the active region of the SE. Following the design based on the cycloscan method, the synthesis of Clarstatin was performed by the Fmoc solid phase peptide synthesis (SPPS) method, purified by HPLC to 96% homogeneity, and its structure was confirmed by LC-MS. Clarstatin reduced calcium levels in Jurkat lymphocyte cultures, ameliorated uveitis in vivo in the experimental autoimmune uveitis (EAU) mice model, and was safe upon acute toxicity evaluation. These findings identify Clarstatin as a promising lead compound for future drug development as a novel class of therapeutic agents in the therapy of uveitis.

Synthesis, Characterization, and In vitro Evaluation of Short Cationic Peptides for Gene Delivery Vehicle Candidate

Background: Amongst gene delivery vehicles, peptide-based vectors have drawn the intensive attraction of experts globally due to their simplicity and many advantages due to ease in design, biocompatibility, and safety. Rationally designed peptides are capable of condensing DNA molecules efficiently and facilitating gene expression in the target cells. Objective: This study aims to design, synthesize and evaluate short cationic peptides composed of several positively charges amino acids of lysine (K) and arginine (R) for gene delivery vehicle candidates. Methods: The short cationic peptides of PKKKRKV (P1), CHSPKKKRKV (P2), and YGRKKRRQRRR (P3) were synthesized using a solid-phase method on 2-chlorotrityl chloride resin. The crude peptides were purified using RP-HPLC and characterized by HR-TOF-ESI-MS and 1H-NMR. The capability of the peptides to condense DNA was evaluated by ethidium bromide exclusion assay. Cytotoxicity study of the peptides was carried out in HEK-293T, CHO-K1, and HepG2 cells using MTT assay. Gene expression facilitated by the peptides was determined in the HEK-293T. Results: The peptides were successfully synthesized with high purity (> 90%) and in a high consistency with the synthetic products, as shown by the spectroscopic data. Physicochemical and biological evaluation showed that the cationic peptides are capable of condensing DNA molecule and have low cytotoxicity to the cells of HEK-293T, CHO-K1, and HepG2. Moreover, the cationic peptides facilitated gene delivery of green fluorescence protein more efficiently compared to PLL. Conclusion: The short cationic peptides rich in lysine and arginine have been successfully synthesized using solid-phase peptide synthesis method. They were found to be capable of condensing DNA, have low cytotoxicity, and facilitate gene delivery. However, structure modification or formulation of cationic peptide with lipid components to form cationic liposome is still needed to enhance transgene expression by these peptides.

Preparation of Mucin Glycopeptides by Organic Synthesis.

Mucins are sugar-rich glycoproteins. Glycoprotein sugar moieties are structurally diverse, making it difficult to obtain naturally pure glycoproteins. Chemical synthesis is a powerful tool for obtaining target or designed compounds. Automated peptide synthesizers are commercially available, and many use the solid-phase peptide synthesis (SPPS) method. In addition, some of these synthesizers apply microwave irradiation to obtain higher reaction yields, thereby enabling the synthesis of 40 to 50 amino acid residual glycopeptides. Theoretically, glycopeptides can be synthesized using methods similar to those used for peptide synthesis, but glycosylated amino acid synthons are less stable than amino acid synthons and are also very expensive. Therefore, they are not suitable for use in large excess amounts. Many of oligosaccharide-linked amino acid synthons are not commercially available, so they must be specially prepared, and they also require careful handling that demands specific organic synthesis experience and techniques. However, monosaccharide-linked amino acid synthons are commercially available and are relatively easy to handle. Here, as an entry into glycopeptide synthesis, we describe a typical glycopeptide synthesis procedure for a 27 amino acid residual MUC1 repeating unit with monosaccharides.

Solid-Phase Synthesis of Caged Luminescent Peptides via Side Chain Anchoring.

The synthesis of caged luminescent peptide substrates remains challenging, especially when libraries of the substrates are required. Most currently available synthetic methods rely on a solution-phase approach, which is less suited for parallel synthesis purposes. We herein present a solid-phase peptide synthesis (SPPS) method for the synthesis of caged aminoluciferin peptides via side chain anchoring of the P1 residue. After the synthesis of a preliminary test library consisting of 40 compounds, the synthetic method was validated and optimized for up to >100 g of resin. Subsequently, two separate larger peptide libraries were synthesized either having a P1 = lysine or arginine residue containing in total 719 novel peptide substrates. The use of a more stable caged nitrile precursor instead of caged aminoluciferin rendered our parallel synthetic approach completely suitable for SPPS and serine protease profiling was demonstrated using late-stage aminoluciferin generation.

Total Chemical Synthesis of the SARS-CoV-2 Spike Receptor-Binding Domain.

SARS-CoV-2 and its global spread have created an unprecedented public health crisis. The spike protein of SARS-CoV-2 has gained significant attention due to its crucial role in viral entry into host cells and its potential as both a prophylactic and a target for therapeutic interventions. Herein, we report the first successful total synthesis of the SARS-CoV-2 spike protein receptor binding domain (RBD), highlighting the key challenges and the strategies employed to overcome them. Appropriate utilization of advanced solid phase peptide synthesis and cutting-edge native chemical ligation methods have facilitated the synthesis of this moderately large protein molecule. We discuss the problems encountered during the chemical synthesis and approaches taken to optimize the yield and the purity of the synthetic protein molecule. Furthermore, we demonstrate that the chemically synthesized homogeneous spike RBD efficiently binds to the known mini-protein binder LCB1. The successful chemical synthesis of the spike RBD presented here can be utilized to gain valuable insights into SARS-CoV-2 spike RBD biology, advancing our understanding and aiding the development of intervention strategies to combat future coronavirus outbreaks. The modular synthetic approach described in this study can be effectively implemented in the synthesis of other mutated variants or enantiomer of the spike RBD for mirror-image drug discovery.

Synthesis and glutathione peroxidase (GPx)-like activity of selenocystine (SeC) bioconjugates of biotin and lipoic acid.

The conjugation of active biomolecules provides insight into their bioreactivity, leading to many applications in biotechnology and materials science. Herein, we report L-selenocystine (SeC) bioconjugates of lipoic acid (universal antioxidant) and biotin (Vitamin-H). The SeC-bioconjugates, SeC-Biotin (1) and SeC-Lipoic acid (2) were synthesized using solid phase peptide synthesis (SPPS) method and were characterized by multinuclear 1D (1H, 13C, 77Se) and 2D (1H-1H COSY and 1H-13C TOCSY) NMR spectroscopy, ESI-MS spectrometry, and RP-HPLC. The GPx-like enzyme mimicking activity of the SeC-bioconjugates 1 and 2 has been investigated through the coupled reductase assay method for the catalytic reductions of hydrogen peroxide into water. A significant enhancement in GPx-like enzymatic activity was observed for both novel bioconjugates SeC-Biotin (1) and SeC-Lipoic acid (2) as compared to diphenyl diselenide (Ph2Se2), L-selenocystine (SeC), biotin, lipoic acid, and ebselen.

Sintesis Senyawa Heksapeptida Siklik Analog Pipecolisporin (Pro-Lys-Pip-Trp-

Pipecolisporin compounds isolated from the fungus Nigrospora oryzae from theroots of Triticum sp. is one of the compounds that has potential as an antimalarial with its activity against Plasmodium falciparum of 3.21 μM. The modification of the amino acid sequence to Pro-Lys-Pip-Trp-β-Ala-Phe aims to determine the best arrangement of pipecolisporin analogues as antimalarials. Analogues of pipecolisporin linear hexapeptide compounds were synthesized using the solid phase peptide synthesis (SPPS) method with the use of buffers in the form of 2-chlorotrityl chloride resins, Fmoc and Boc protective groups, and DIC, Oxyma, Dipea coupling reagent solutions. The synthesis results were obtained as much as 9 mg and then characterized using mass spectroscopy with a peak m/z of 959.5246 [M]. Analogues of linear pipecolisporin hexapetide compounds were successfully cyclized using the solution phase peptide synthesis (LPPS) method with the use of DIPEA, HATU, DCM reagent solutions. The synthesis results were characterized using mass spectroscopy with an m/z peak of 743.78 [M+H]+.
 Senyawa pipecolisporin hasil isolasi jamur Nigrospora oryzae dari akar Triticum sp. merupakan salah satu senyawa yang berpotensi sebagai antimalaria dengan aktivitasnya terhadap Plasmodium falciparum sebesar 3,21 μM. Modifikasi urutan asam amino menjadi Pro-Lys-Pip-Trp-

Abstract P320: Novel Alpha-calcitonin Gene Related Peptide Agonist Analogs In The Treatment Of Cardiovascular Disease

Alpha-calcitonin gene related peptide (α-CGRP) is a potent vasodilator and protects against heart failure and hypertension in various animal models; however, rapid clearance of the peptide from the circulation makes it difficult to use as a therapeutic agent. Recently, we have synthesized two α-CGRP agonist analogs linked with two n-methoxyethylglycine (NMEG) peptoid molecules at either end: 1)- α-CGRP with NMEG molecules at the N-terminal end (N-ter NMEG), and 2)- α-CGRP with NMEG molecules at the C-terminal end (C-ter NMEG). Bioactivity and toxicity of modified peptides were evaluated in in vitro and in vivo conditions. Peptide-peptoid hybrids, N-ter NMEG and C-ter NMEG, were synthesized using a solid-phase peptide synthesis method with a >98% purity. To test the in vitro cell viability of the analogs, rat H9C2 cardiac myocyte cells were treated with 1 μM, 3 μM, and 10 μM concentrations of N-ter NMEG and C-ter NMEG peptides for 4 days followed by an MTT assay. Our in vitro results demonstrated that neither α-CGRP analogs were toxic to H9C2 cells. To test the bioactivity of these peptides, blood pressure (BP) was measured in wild-type C57BL6 mice using a tail-cuff BP analysis system. A bolus dose of 1.2, 3.6, and 12 (in mg/kg b.wt./mouse) of either peptide was injected subcutaneously (n= 4 mice/dose) followed by BP measurement at increasing time points. Our results demonstrate that there is a variance in the bioactivity of the two peptides. Subcutaneous delivery of N-ter NMEG reduced BP similar to the native peptide. After ten minutes of N-ter NMEG delivery, the BP (in mmHg ±SD) at a dose of 1.2 mg/kg was 76 ±5 (baseline BP= 118 ±15), at a dose of 3.6 mg/kg was 79 ±7 (baseline BP= 113 ±9), and at a dose of 12 mg/mg was 83 ±12 (baseline BP= 104 ±6). In contrast, C-ter NMEG administration did not reduce BP at any peptide concentration tested. In summary, in this study we determined that the α-CGRP analog N-ter NMEG, but not C-ter NMEG, is bioactive. Furthermore, N-ter NMEG showed no toxic effects on H9C2 cardiac myocytes in an in vitro viability assay. These results demonstrate that the analog N-ter NMEG is an effective α-CGRP agonist and a promising candidate molecule to treat cardiac diseases.

Development of the efficient preparation method for thermoresponsive elastin-like peptides using liquid-phase synthesis combined with fragment condensation strategy.

Elastin-like peptides (ELPs) are synthetic peptides that mimic the characteristic hydrophobic amino acid repeat sequences of elastin and exhibit temperature-dependent reversible self-assembly properties. ELPs are expected to be used as temperature-responsive biomolecular materials across diverse industrial and research fields, and there is a requirement for a straightforward method to mass-produce them. Previously, we demonstrated that phenylalanine-containing ELP analogs, namely, (FPGVG)n , can undergo coacervation with short chains (n = 5). The Fmoc solid-phase peptide synthesis method is one strategy used to synthesize these short ELPs. However, owing to its low reaction efficiency, an efficient method for preparing ELPs is required. In this study, efficient preparation of ELPs was investigated using a liquid-phase synthesis method with a hydrophobic benzyl alcohol support (HBA-tag). Because HBA-tags are highly hydrophobic, they can be easily precipitated by the addition of poor solvents and recovered by filtration. This property allows the method to combine the advantages of the simplicity of solid-phase methods and the high reaction efficiency of liquid-phase methods. By utilizing liquid-phase fragment condensation with HBA-tags, short ELPs were successfully obtained in high yield and purity. Finally, the temperature-dependent response of the ELPs generated through fragment condensation was assessed using turbidity measurements, which revealed a reversible phase transition. Consequently, the ELPs exhibited a reversible phase transition, indicating successful synthesis of ELPs via fragment preparation with tags. These findings provide evidence of the potential for mass production of ELPs using this approach.

A Systematic Investigation into the Influence of Net Charge on the Biological Distribution of Radiometalated Peptides Using [68Ga]Ga-DOTA-TATE Derivatives.

Recently, several radiometalated peptides have been approved for clinical imaging and/or therapy (theranostics) of several types of cancer; nonetheless, the primary challenge that most of these peptides confront is significant renal uptake and retention, which is often dose limiting and can cause nephrotoxicity. In response to this, numerous methods have been employed to reduce the uptake of radiometalated peptides in the kidneys, and among these is adding a linker to modulate polarity and/or charge. To better understand the influence of net charge on the biodistribution of radiometalated peptides, we selected the clinically popular construct DOTA-TATE (NETSPOT/LUTATHERA) as a model system. We synthesized derivatives using manual solid-phase peptide synthesis methods including mechanical and ultrasonic agitation to effectively yield the gold standard DOTA-TATE and a series of derivatives with different net charges (+2, +1, 0, -1, -2). Dynamic PET imaging from 0 to 90 min in healthy female mice (CD1) revealed high accumulation and retention of activity in the kidneys for the net-neutral (0) charged [68Ga]Ga-DOTA-TATE and even higher for positively charged derivatives, whereas negatively charged derivatives exhibited low accumulation and fast renal excretion. Ex vivo biodistribution at 2 h post injection demonstrated a significant retention of [68Ga]Ga-DOTA-TATE (∼74 %ID/g) in the kidneys, which increased as the net positive charge per molecule increased to +1 and +2 (∼272 %ID/g and ∼333 %ID/g, respectively), but the -1 and -2 net charged molecules exhibited lower renal uptake (∼15 %ID/g and 16 %ID/g, respectively). Interestingly, the net -2 charged [68Ga]Ga-DOTA-(Glu)2-PEG4-TATE was stable in blood serum but had much higher healthy organ uptake (lungs, liver, spleen) than the net -1 compound, suggesting instability in vivo. Although the [68Ga]Ga-DOTA-PEG4-TATE derivative with a net charge of 0 also showed a decrease in kidney uptake, it also showed instability in blood serum and in vivo. Despite the superior pharmacokinetics of the net -1 charged [68Ga]Ga-DOTA-Glu-PEG4-TATE in healthy mice with respect to kidney uptake and overall profile, dynamic PET images and ex vivo biodistribution in male mice (NSG) bearing AR42J (SSTR2 overexpressing) subcutaneous tumor xenografts showed significantly diminished tumor uptake when compared to the gold standard [68Ga]Ga-DOTA-TATE. Taken together, these findings indicate unambiguously that kidney uptake and retention are significantly influenced by the net charge of peptide-based radiotracers. In addition, it was illustrated that the negatively charged peptides had substantially decreased kidney uptake, but in this instantiation the tumor uptake was also impaired.

Highly Efficient, Non-Covalent Functionalization of CVD-Graphene via Novel Pyrene-Based Supporter Construct

Ultra-thin two-dimensional (2D) materials have attained huge interest for biosensing applications because of their strong electrostatic coupling with target molecules such as spike proteins and DNA. One such 2D material is graphene, which is extremely thin and flexible and has a strong non-covalent interaction with the supporting constructs needed to detect biomolecules. This work aimed to develop a way to efficiently functionalize the surface of 2D material using a pyrene-based supporter construct to detect the target protein. For this purpose, high-quality, pristine graphene was grown via the chemical vapor deposition (CVD) method and transferred over the Si/SiO2 substrate for its functionalization using our engineered pyrene–lysine-based supporter construct (PLB). The construct was synthesized using the solid-phase peptide synthesis (SPPS) method and utilized to functionalize the graphene-channel-based field-effect transistor (FET) device via non-covalent π−π stacking interaction. The optimum concentration of the functionalized PLB was evaluated via atomic force microscopy (AFM), Raman spectroscopy, and real-time electrical measurements. The characterization techniques successfully provide an overview of the effect of the concentration of PLB used for functionalization. Moreover, the performance was tested and compared in terms of the percentage response of the device generated after the detection of various concentrations of the streptavidin protein. This research could be useful in determining how to functionalize any 2D material by designing a supporter construct without material degradation and owing to over-stacking or bypassing surface screening effects.

Synthesizing Cylic Peptides with Antioxidant Properties using Solid Phase Peptide Synthesis as an Alternative to Natural Product Isolation from Pork

Tetrapeptides Ser-Leu-Tyr-Ala and Tyr-Leu-Tyr-Ala are two derivates that have been successfully isolated from the pork and synthesized using Solid Phase Peptide Synthesis (SPPS) method. Tetrapeptide Gly-Ala-Trp-Ala has also been successfully isolated from the Sardinella aurita fish found in Atlantic Ocean using SPPS. This study aims to synthesize tetrapeptide Ser-Leu-Tyr-Ala, Tyr-Leu-Tyr-Ala and Gly-Ala-Trp-Leu using the SPPS method, and to find the antioxidant properties of the synthesized tetrapeptides using DPPH test. The three tetrapeptides have been synthesized using 2-chlorotritilchloride resin as solid phase, Fmoc group protection, and coupling reagent HBTU/HOBt. HR-TOF-MS with m/z was [M+H]+ 453,23 and [2M+H]+ 905,49 for Ser- Leu-Tyr-Ala, [M+H]+114,61 for Tyr-Leu-Tyr-Ala and [M+H]+ 446,23 for Gly-Ala-Trp-Leu. The antioxidant properties of Ser-Leu-Tyr- Ala had an IC50 value of 11130,04 mg/ml, while the antioxidant properties of Tyr-Leu-Tyr-Ala had an IC50 value of 4319,522 mg/ml.
 Keywords: solid phase peptide synthesis, antioxidant

Practical Synthetic Method for Ogipeptin Derivatives

AbstractIn synthesizing novel derivatives of the natural cyclic peptides the ogipeptins, we established a simple and practical solid-phase peptide synthesis and macrocyclization method. By using this method, it became possible to obtain skeleton-modified ogipeptin derivatives with dehydroxylation of the β-hydroxy-α,γ-diaminobutyric acid, replacement of the (Z)-dehydrobutyrine residue, or replacement of the arginine residue.

Kinetic study of aza-amino acid incorporation into peptide chains: Influence of the steric effect of the side chain

Aza-peptides are peptidomimetics developed to avoid drawbacks connected with peptide instability in drugs. However, information concerning their bioactivity is quite limited due to the absence of efficient synthetic strategies to these compounds by SPPS (solid-phase peptide synthesis) method. Herein, we investigate, the effect of steric hindrance of various aza-amino acids (AzGly, AzAla, AzLeu, AzVal) on their reactivity with the N-terminus of amino acids in the synthesis of model aza-peptide H-AzAA-Ala-Phe-NH2 using BTC (Bis(trichloromethyl) carbonate) as an activator for aza-amino acid precursor. The results of kinetic measurements showed that this method could be used for aza-amino acid incorporation into peptide regardless of the structure of the preceding amino acid. However, for effective coupling of AzGly, DSC (N,N′-Disuccinimidyl carbonate) is the preferable activator.

Functionalized Peptide-Based Nanoparticles for Targeted Cancer Nanotherapeutics: A State-of-the-Art Review.

Cancer mortality is increasing at an alarming rate across the globe. Albeit, many therapeutics are available commercially, they are not effective and have no cure up to today. Moreover, the knowledge gap in cancer therapy persists, representing a potential blind spot for the innovation of effective anticancer therapeutics. This review presents an update on current advancements in nanopeptide therapeutics. Herein, a detailed exploration of peptide-functionalized nanoparticles for the development of nanotherapeutics was carried out. Different approaches that include self-assembly nanostructures, solid phase peptide synthesis, ligand exchange, chemical reduction, and conjugation methods for assembling peptides for functionalizing nanodrugs are also highlighted. An outlook on biomedical applications is also reviewed. Additionally, a comprehensive discussion on targeted cancer cell therapy and mechanism of action are provided. The present review reflects the functional novelty of nanodrugs to improve stability, accessibility, bioavailability, and specificity toward cancerous cells. Finally, it summarizes the current challenges and future perspectives on the formulation of these nanodrugs.

Downregulation of NT5C3 gene expressions by elastin-like polypeptide gemcitabine conjugate for ovarian cancer therapy

Due to the undesirable side effects and lack of target specificity of existing anticancer drugs the newer drug delivery system with target specificity and undesirable side effects are, therefore, essential today. Given that sensitive polymers, peptides, dendrimers and hydrogels have been widely investigated as carriers for controlled release and target specificity, it is still a challenge to overcome the cumbersome problems faced in cancer treatment. Elastin like – polypeptide is genetically designed as VPGXG, ‘n’ times where ‘X’ can be any amino acid except proline. In the present study, the peptide VPGVG and VPGVG gemcitabine conjugate were synthesized using solid phase peptide synthesis method and the successful synthesis and conjugation of gemcitabine were confirmed by Fourier Transform Infrared spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR) and Liquid Chromatography Mass Spectrometry (LCMS) studies. The isoelectric point calculator, differential scanning calorimetry, in vitro drug release studies revealed the thermosensitive and pH sensitive nature of the peptide. The in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and gene expression studies have been performed to evaluate the tumor targeting potential of VPGVG gemcitabine conjugate. We conclude that the peptide VPGVG can be used with certain advantages over naturally occurring long Elastin Like Polypeptides for targeting anticancer drugs to intra-cellular space.

Structural Design and Synthesis of Novel Cyclic Peptide Inhibitors Targeting Mycobacterium tuberculosis Transcription.

Tuberculosis (TB) remains one of the deadliest infectious diseases in the world. Although several established antitubercular drugs have been found, various factors obstruct efforts to combat this disease due to the existence of drug-resistance (DR) TB strains, the need for lengthy treatment, and the occurrence of side effects from drug–drug interactions. Rifampicin (RIF) is the first line of antitubercular drugs and targets RNA polymerase (RNAP) of Mycobacterium tuberculosis (MTB). Here, RIF blocks the synthesis of long RNA during transcription initiation. The efficacy of RIF is low in DR-TB strains, and the use of RIF leads to various side effects. In this study, novel cyclic peptides were computationally designed as inhibitors of MTB transcription initiation. The designed cyclic peptides were subjected to a virtual screening to generate compounds that can bind to the RIF binding site in MTB RNAP subunit β (RpoB) for obtaining a new potential TB drug with a safe clinical profile. The molecular simulations showed that the cyclic peptides were capable of binding with RpoB mutants, suggesting that they can be possibility utilized for treating DR-TB. Structural modifications were carried out by acetylation and amidation of the N- and C-terminus, respectively, to improve their plasma stability and bioavailability. The modified linear and cyclic peptides were successfully synthesized with a solid-phase peptide synthesis method using Fmoc chemistry, and they were characterized by analytical HPLC, LC-ESI-MS+, and 1H NMR.

Design and Synthesis of certain Novel Peptides for Dual Selective Activity of Specific Cells

Cancer and the multi-resistant diseases that plague people today must be controlled to lower mortality rates. With the low susceptibility to resistance, the design and synthesis of peptide assembling was a superior alternative upgrading source for future chemotherapeutic medications. This paradigm first appeared in the pharmaceutical industry. It has been demonstrated that specific peptides exhibit dual functions as antibacterial and anticancer peptides (ACPs). Using a minimalized approach, a 10-residue peptide P1 and Rhodamine tagged peptide P2 were designed and synthesized using solid phase peptide synthesis method (SPPS) for selective activity against microbial and cancer cell lines. Peptide P1 contains RGD sequence has a net charge of +2 and peptide P2 has net charge of -4. The peptide P1 and P2 are characterized by using spectroscopic techniques. Circular dichroism studies showed changes in the secondary structure of peptide 1 and peptide 2 with buffer. Cytotoxicity assay exhibited the viability of normal and cancer cells up to 5 ?g concentrations of peptide 1.Thus, Peptide 1 acts on therapeutic properties like antibacterial and anticancer. Both peptide activities are checked against gram-positive and gram-negative bacteria at lower concentration. We can ensure the toxicity level of designed both peptides. Peptide P1 and peptide P2 sequence are non-toxic and recognition of selective activity against cancer cells.