Synthesis of Nα-Fmoc protected derivatives of S-(2,3-dihydroxypropyl)-cysteine and their application in peptide synthesis

Acylated derivatives of S-(2,3-dihydroxypropyl)-cysteine (S-glycerylcysteine) form the N-terminus of structural and functional proteins of bacterial origin. Synthetic lipopeptides containing tripalmitoyl-S-glycerylcysteine are derived from bacterial lipoprotein and constitute potent immunoadjuvants activating both B-lymphocytes and macrophages. There is increasingly interest in conjugates consisting of tripalmitoyl-S-glycerylcysteine linked to appropriate viral and bacterial antigens, because of their capability of inducing antigen specific antibodies and T-helper and T-killer cell specific immune responses. A new convenient synthetic pathway for the preparation of these tripalmitoyl-S-glycerylcysteinyl peptides is described. The use of N_α-Fmoc-protected S-(2,3-dihydroxypropyl)-cysteine and its O,O′-bis acylated derivatives for the synthesis of triacyl-S-glycerylcysteinyl, O,O′-bis-acyl-5-glycerylcysteinyl and S-glycerylcysteinyl peptides of high diastereomeric purity by solid phase peptide synthesis or synthesis in solution is demonstrated.     

Synthetic lipopeptides: a novel class of anti-infectives

Lipopeptide daptomycin is one of the few recently approved antibiotics based on the novel mechanism of action. Recent advances in synthetic lipopeptides, driven by the biochemical and biophysical research, expanded their spectrum of antimicrobial activity and reduced their size to achieve economically viable production. Lipopeptides, consisting of a short peptide chain conjugated with an acyl chain, form a structurally defined conformation, which inserts into the bacterial membrane and dissipates its transmembrane potential. In addition to antimicrobial activity, synthetic lipopeptides also suppress inflammation through the neutralization of bacterial agonists of the innate immune response, synergize with conventional antibiotics and have improved proteolytic stability. Activities in animal models indicate that synthetic lipopeptides may surpass the natural lipopeptides as the perspective class of anti-infective agents.     

Synthesis of tritiated tuftsin and macrophage inhibitory tripeptide via acetylenic intermediates

Acetylenic analogues of tuftsin (Thr-Dah-Pro-Arg) and of a macrophage inhibitory tripeptide (Thr-Dah-Pro) have been synthesized by conventional procedures in solution (Dah = 2,6-diamino-4-hexynoic acid). These acetylenic derivatives are intermediates for the preparation of structurally unmodified, tritiated peptides. Catalytic tritiation of Thr-Dah-Pro-Arg and of Thr-Dah-Pro has afforded the radioactive tetra- and tripeptides with specific activities of 11.4 Ci/mmol and 37 Ci/mmol, respectively.     

正交设计法优化新型氮唑类抗真菌化合物关键中间体的合成工艺

目的 优化新型氮唑类抗真菌化合物关键中间体的合成工艺。方法 采用正交设计法,重点考察反应温度、投料比、反应时间及溶剂4个因素对收率的影响。结果 反应温度对反应收率的影响最为显著,其次是反应时间;投料比及溶剂对收率影响不明显。结论 新工艺的收率可达50%左右,反应杂质少,后处理简便。     

Design and synthesis of a novel peptide for selective detection of cancer cells

Using a minimalist approach, an 11‐residue peptide (Peptide 1 ) tagged with rhodamine fluorophore was designed and synthesized for selective detection of cancer cells. Peptide 1 contains RGD and NGR motifs to bind, respectively, integrins and aminopeptidase CD13, which are over expressed in cancer cells. Surface tension measurements revealed that peptide 1 possess surface‐active property owing to the overall hydrophobicity and cationic nature of the peptide. Peptide 1 displays cancer cell‐selective binding at ≤5.0 µM concentrations, while peptide 2 (randomized sequence of 1 ) shows non‐selective binding to normal and cancer cells. Fluorescence microscopy and FACS analysis demonstrated the intracellular localization of peptide 1 in three different cancer cell lines, confirming the role of RGD and NGR motifs. Cytotoxicity assay exhibited the viability of normal and cancer cells up to 100 µM concentrations of peptide 1 . Steady‐state fluorescence measurements disclosed the preferential interactions of the peptide 1 with anionic POPC/POPG bilayers rather than with zwitterionic POPC lipid bilayers. Circular dichroism studies showed minimal changes in the secondary structure of peptide 1 upon binding with the anionic lipid bilayers. Peptide 1 is largely unordered, non‐toxic, and useful for identification of cancer cells. Peptide 1 provides a template for designing drug‐loaded peptides for targeted delivery into cancer cells.     

Synthesis of new head-activator analogues and their application for improved radioimmunoassays

New analogues of head activator were produced for receptor and radioimmunoassay studies. The precursor molecules [(4′-I)Phe¹¹] head activator and [Tyr¹¹] head activator were synthesised for catalytic tritiation and iodination, respectively. With the tracer [(3,5-¹²⁵ I₂)Tyr¹¹] head activator the sensitivity range of the radioimmunoassay was 5–100 fmol.     

Synthesis of polyamide supports for use in peptide synthesis and as peptide-resin conjugates for antibody production

We have synthesized beaded, hydrophilic cross-linked, aminoalkyl polydimethylacrylamide supports upon which peptides have been assembled using standard Boc or Fmoc chemistry in automated equipment. The resins were prepared by the free radical-initiated co-polymerization of N,N-dimethylacrylamide, N,N′-bisacrylyl-1,3-diaminopropane, and a functional monomer which were contained in a reverse-phase, detergent-emulsified suspension. The functional monomers used were N-(2-(methylsulfonyl)ethyloxycarbonyl)-allyl-amine (MSC-allylamine), N-acrylyl-1,6-diaminohexane hydrochloride or N-methacrylyl-1,3-diaminopropane hydrochloride. The MSC protecting group was removed by treatment of the resin with methanolic base during workup. After coupling of N-α-t-butyloxycarbonyl-alanine (Boc-alanine), amino acid analyses gave resin loading capacities between 0.15 mmol/g and 1.4 mmol/g, depending on the concentration and composition of the functional monomer. The resulting polymers were highly swollen by polar solvents including aqueous buffers. Peptides were synthesized on these supports after attaching the first amino acid directly or through a cleavable ester linker. When the carboxyl-terminal amino acid was coupled as the 4-oxymethylbenzoic acid derivative, the peptide could be deprotected and remain attached to the hydrophilic polymer since the peptide-benzyl ester bond was stable to HF deprotection at 0° in the presence of 10% anisole and 1% ethanedithiol. The resulting peptidyl-resin could be swollen in aqueous buffers and injected into animals for the production of antibodies.     

N-甲酰羟胺类肽去甲酰酶抑制剂的合成及抗菌活性

目的 设计合成N-甲酰羟胺类肽去甲酰酶抑制剂,初步评价其体外抗菌活性.方法 以丙二酸二乙酯为起始原料,经多步反应合成目标化合物;采用对倍稀释法,测定目标化合物对金葡菌、表葡菌以及耐甲氧西林金葡菌、表葡菌的抑菌活性.结果与结论 合成了14个未见文献报道的目标化合物,其结构经1H-NMR、MS确证.体外试验表明:目标化合物均表现出一定的抗菌活性.     

β-Endorphin: Synthesis and properties of analogs with replacement of lysine residues by arginine

Human β-endorphin analogs, [Arg^{9,19,24,28,29}]-β-endorphin (I) and [Arg^24,28,29]-β-endorphin (II), have been synthesized by the solid-phase method. Peptide II had 86% of the analgesic potency and 216% of the receptor binding activity of the parent molecule. Peptide I had only 18% analgesic potency but its binding activity was more than three time greater than that of human β-endorphin.     

Synthesis of novel N-substitutedphenyl-6-oxo-3-phenylpyridazine derivatives as cyclooxygenase-2 inhibitors

Some novel non-ulcerogenic N-substitutedphenyl-6-oxo-3-phenylpyridazines as COX-2 inhibitors have been developed (Supplementary material Appendix 1 ). The novel aldehyde 3 was prepared by reacting 6-phenylpyridazin-3(2H)-one with 4-fluorobenzaldehyde. The aldehyde 3 was reacted with different hydrazines and thiazolidin-4-ones to obtain the novel N-substitutedphenyl-6-oxo-3-phenylpyridazine derivatives. These were assessed for their anti-inflammatory potential and gastric ulcerogenic effects. The molecular docking investigations were also undertaken. The spectroscopic data were coherent with the allocated structures of the compounds. The compounds 4a (IC₅₀ = 17.45 nm; p < .05), 4b (IC₅₀ = 17.40 nm; p < .05), 5a (IC₅₀ = 16.76 nm; p < .05), and 10 (IC₅₀ = 17.15 nm; p < .05) displayed better COX-2 inhibitory activity than celecoxib (IC₅₀ = 17.79 nm; p < .05). These findings were consistent with the molecular docking investigations of 4a , 4b , 5a , and 10 . The in vivo anti-inflammatory profile of 4a , 4b , 5a , and 10 was also superior to celecoxib and indomethacin. The compounds 4b , 5a , and 10 revealed no gastric ulcerogenic effects, wherein the compound 4a produced almost negligible gastric ulcerogenic effects than celecoxib and indomethacin. The compounds 4a , 4b , 5a , and 10 have been postulated as promising non-ulcerogenic COX-2 inhibitors.     

芳酰基硫脲类克鲁斯氏锥体虫半胱氨酸蛋白酶小分子抑制剂的合成及活性研究

目的：通过设计、合成芳酰基硫脲类化合物发现新的克鲁斯氏锥体虫半胱氨酸蛋白酶小分子抑制剂。方法：通过芳酰基硫代异氰酸酯和取代苯胺的反应合成芳酰基硫脲类化合物，化合物的结构经HRMS(EI)和^1H-NMR光谱确证。结果：共合成了20个芳酰基硫脲类化合物，化合物的体外抑制克鲁斯氏锥体虫半胱氨酸蛋白酶的活性测定结果表明：所合成的化合物均有一定的抑制克鲁斯氏锥体虫半胱氨酸蛋白酶的活性，其中化合物Id和In的活性高于对照药tf-175的活性。结论：这类化合物有可能开发成新的抗南美锥体虫病的化疗药物。     

Synthesis of a cyclic analogue of the C-loop region of epidermal growth factor,containing 1-aminocyclopropane-1-carboxylic acid

We report the synthesis of a cyclic analogue of epidermal growth factor sequence 33–42 with substitution of 1-aminocyclopropane-1-carboxylic acid for glycine at position 39 (N-acetyl-Cys-Val-Ile-Gly-Tyr-Ser-ACPCA-Asp-Arg-Cys-NH₂). The analogue was synthesised by solid-phase methods, using t-Boc chemistry and acid-labile side-chain protecting groups. The use of the 4-methoxybenzyl protecting group for C- and N-terminal cysteine residues resulted in the spontaneous formation of the desired intramolecular disulfide bond after HF deprotection.     

Syntheses,characterization and application of cross‐linked polystyrene−ethyleneglycol acrylate resin (CLPSER) as a novel polymer support for polypeptide syntheses

Abstract: Cross‐linked polystyrene?ethyleneglycol acrylate resin (CLPSER) was developed for the solid‐phase synthesis of peptide by introducing a cross‐linker, O,O′‐bis(2‐acrylamidopropyl)polyethylene glycol₁₉₀₀ (Acr₂PEG), into polystyrene. The cross‐linker was prepared by treating acryloyl chloride with O,O′‐bis(2‐aminopropyl) polyethylene glycol₁₉₀₀[(NH₂)₂PEG] in the presence of diisopropylethylamine. The copolymer was prepared either by bulk or inverse suspension copolymerization of Acr₂PEG₁₉₀₀ and styrene using sorbitan monolaurate as the suspension stabilizer, and a mixture of ammonium peroxodisulfate and benzoyl peroxide as the radical initiators. The resin was characterized using gel‐phase ¹³C NMR, infrared (KBr) spectroscopic techniques and the morphological features of the resin were investigated using scanning electron microscopy photographs. CLPSER showed excellent swelling in a broad range of solvents and was found to be chemically inert to various reagents and solvents used in solid‐phase peptide synthesis. To demonstrate the usefulness of the new resin in polypeptide synthesis, the support was derivatized with an ‘internal reference’ amino acid (norleucine) and a handle 4‐(4‐hydroxymethyl‐3‐methoxy)butyric acid. The new resin was compared with commercial supports such as Merrifield and Sheppard resins by synthesizing an acyl carrier protein (65?74) fragment under the same experimental conditions. HPLC profiles revealed the high efficiency of the newly developed support. Resin capability in peptide synthesis was further demonstrated by the solid phase synthesis of a 25‐residue peptide from the E2/NS1 region hepatitis C viral polyprotein.     

Synthesis, molecular docking, and biological evaluation of novel triazole derivatives as antifungal agents

Twenty-eight novel triazole derivatives (compounds 1a-v, 2a-f) have been synthesized for structure–activity relationship studies as antifungal agents. The compounds were designed on the basis of the structure of fluconazole and molecular modeling of the active site of the cytochrome P450 14α-demethylase (CYP51). All of them are reported for the first time. Their chemical structures are characterized by ¹H NMR, ¹³C NMR, LC-MS, and elemental analysis. The antifungal activities have been evaluated in vitro by measuring the minimal inhibitory concentrations (MICs). Compounds 1a-v exhibited higher activity against nearly all fungi tested except Aspergillus fumigatus (A. fum) than fluconazole (FCZ). The computational molecular docking experiments indicated that the inhibition of CYP51 involves a coordination bond with iron of the heme group, a hydrophilic H-bonding region, a hydrophobic region, and a narrow hydrophobic binding cleft.     

Synthesis and structure-activity relationship of alpha-sulfonylhydroxamic acids as novel,orally active matrix metalloproteinase inhibitors for the treatment of osteoarthritis

The matrix metalloproteinases (MMPs) are a family of zinc-containing endopeptidases that play a key role in both physiological and pathological tissue degradation. These enzymes are strictly regulated by endogenous inhibitors such as tissue inhibitors of MMPs and alpha(2)-macroglobulins. Overexpression of these enzymes has been implicated in various pathological disorders such as arthritis, tumor metastasis, cardiovascular diseases, and multiple sclerosis. Developing effective small-molecule inhibitors to modulate MMP activity is one approach to treat these degenerative diseases. The present work focuses on the discovery and SAR of novel N-hydroxy-alpha-phenylsulfonylacetamide derivatives, which are potent, selective, and orally active MMP inhibitors.     

Carbopeptides: carbohydrates as potential templates for de novo design of protein models

Abstract: De novo design of proteins has evolved into a powerful approach for studying the factors governing protein folding and stability. Among the families of structures frequently studied is the ‘four‐helix bundle’ in which four α‐helical peptide strands, linked by loops, form a hydrophobic core. Assembly of protein models on a template has been suggested as a way to reduce the entropy of folding. Here we describe the potential use of a carbohydrate as such a template. The monosaccharide d ‐galactose was per‐O‐acylated with (N^β‐Fmoc‐βAla)₂O to give a penta‐substituted derivative, which was converted to the corresponding glycosyl bromide and used for the glycosylation of 4‐hydroxymethylbenzoic acid pentafluorophenyl ester (HMBA‐OPfp). The β‐glycosidic carbohydrate template (N^β‐Fmoc‐βAla)₄‐β‐d ‐Galp‐(1‐O)‐MBA‐OPfp thus obtained was coupled to a PAL‐PEG‐PS resin and simultaneously extended at the four arms to yield, after cleavage from the solid support, a carbopeptide with four identical peptide strands. Extension of this concept to, for example, synthesis of novel multiple antigenic peptides (MAPs) and synthesis of carbohydrate clusters can be easily envisioned. The ability to efficiently synthesize such structures sets the stage for further studies to test whether the carbohydrate templates do indeed nucleate folding.     

Synthesis,Characterization, and Biological Evaluation of 99mTc(CO)3‐Labeled Peptides for Potential Use as Tumor Targeted Radiopharmaceuticals

During the past decade, several peptides containing Arg‐Gly‐Asp sequence have been conjugated with different chelating agents for labeling with various radionuclides for the diagnosis of tumor development. In this study, we report the synthesis of two tetrapeptides (Asp‐Gly‐Arg‐His and Asp‐Gly‐Arg‐Cys) and one hexapeptide [Asp‐Gly‐Arg‐D‐Tyr‐Lys‐His] by changing the amino acid sequence of the Arg‐Gly‐Asp motif. Peptide synthesis was initiated from aspartic acid. Aspartic acid placed at C‐terminal end of the peptide chain can be conjugated with different drug molecules facilitating their transport to the site of action. The peptides were synthesized in excellent yield and labeled using freshly prepared [^99mTc(CO)₃(H₂O)₃]⁺ intermediate. A complexation yield of over 97% was achieved under mild conditions even at low ligand concentrations of 10^?2 m . Radiolabeled peptides were characterized by HPLC and were found to be substantially stable in saline, in His solution as well as in rat serum and tissue (kidney, liver) homogenates. Internalization studies using Ehrlich ascites carcinoma cell line showed rapid and significant internalization (30–35% at 30 min of incubation attaining maximum value of about 40–60% after 2–4 h incubation). A good percentage of quick internalization was also observed in α_vβ₃‐receptor‐positive B16F10 mouse melanoma cell line (14–16% after 30 min of incubation and 25–30% after 2–4 h incubation). Imaging and biodistribution studies were performed in Swiss albino mice bearing Ehrlich ascites tumor in right thigh. Radiolabeled peptides exhibited fast blood clearance and rapid elimination through the urinary systems. ^99mTc(CO)₃‐tetra‐Pep2 exhibited remarkable localization at tumor site (1.15%, 1.17%, and 1.37% ID/g at 2, 4, and 6 h p.i., respectively) which could be due to slow clearance of the radiolabeled peptide from blood in comparison with the other two radiolabeled peptides. However, ^99mTc(CO)₃‐hexa‐Pep exhibited the highest tumor to muscle and tumor to blood ratios among the three. The preliminary results with these amino acid–based peptides are encouraging enough to carry out further experiments for targeting tumor.     

Synthesis of biologically active gels for the treatment and prophylaxis of soft tissue and bone damage

A method for the synthesis of combined calcium-, phosphorus-, and silicon-containing hydrogels from silicon glycerates was developed, along with methods for preparing glycerohydrogels based on these hydrogels using different types of hydroxyapatite (powder, suspension, colloidal solution) to create pharmaceutical formulations for local and external application with wound-healing and osteoplastic actions. Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 43, No. 1, pp. 41–43, January, 2009.     

Synthesis of Ac-Asp-Gly-Ser and Ac-Asp-Pro-Leu-Gly-NH2

The syntheses of Ac-Asp-Gly-Ser and Ac-Asp-Pro-Leu-Gly-NH₂ are described. The two peptides were prepared in solution by stepwise elongation using the DCC method with additives (HOSu or HOBt). The push-pull method was also used in the synthesis of Ac-Asp-Gly-Ser. A racemization test of the amino acids in this peptide has been performed.