OBJECTIVEA natural cyclic peptide previously isolated from Citrus medica was synthesized by coupling of tetrapeptide units Boc-Leu-Pro-Trp-Leu-OMe and Boc-Ile-Ala-Ala-Gly-OMe after proper deprotection at carboxyl and amino terminals followed by cyclization of linear octapeptide segment.

METHODSSolution phase technique was adopted for the synthesis of cyclooctapeptide-sarcodactylamide. Required tetrapeptide units were prepared by coupling of Boc-protected dipeptides viz. Boc-Leu-Pro-OH and Boc-Ile-Ala-OH with respective dipeptide methyl esters Trp-Leu-OMe and Ala-Gly-OMe. Cyclization of linear octapeptide unit was done by p-nitrophenyl ester method. The structure of synthesized cyclopolypeptide was elucidated by FTIR, 1H NMR, 13C NMR, FABMS spectral data and elemental analysis. The newly synthesized peptide was evaluated for different pharmacological activities including antimicrobial, anthelmintic and cytotoxic activities.

RESULTSSynthesis of sarcodactylamide was accomplished with >78% yield utilizing dicyclohexylcarbodiimide (DCC) as coupling agent. Newly synthesized peptide possessed potent cytotoxic activity against Dalton's lymphoma ascites (DLA) and Ehrlich's ascites carcinoma (EAC) cell lines, in addition to moderate anthelmintic activity against earthworms Megascoplex konkanensis, Pontoscotex corethruses and Eudrilus sp. Moreover, cyclopolypeptide displayed good antimicrobial activity against pathogenic fungi Candida albicans and Gram-negative bacteria Pseudomonas aeruginosa, in comparison to standard drugs griseofulvin and ciprofloxacin.

CONCLUSIONSolution phase technique employing DCC and triethylamine (TEA) as base proved to be effective for the synthesis of natural cyclooctapeptide. N-methyl morpholine (NMM) was found to be a better base for the cyclization of linear octapeptide unit in comparison to TEA and pyridine.

Animals ; Anti-Infective Agents ; chemical synthesis ; pharmacology ; Antineoplastic Agents ; chemical synthesis ; pharmacology ; Citrus ; chemistry ; Mice ; Peptides, Cyclic ; chemical synthesis ; pharmacology

Natural cyclopeptides are hot spots in chemical and pharmaceutical fields because of the wide spreading bio-resources, complex molecular structures and various bioactivities. Bio-producers of cyclopeptides distribute over almost every kingdom from bacteria to plants and animals. Many cyclopeptides contain non-coded amino acids and non-pepditic bonds. Most exciting characteristic of cyclopeptides is a range of interesting bioactivities such as antibiotics gramicidin-S (2), vancomycin (3) and daptomycin (4), immunosuppressive cyclosporin-A (1) and astin-C (8), and anti-tumor aplidine (5), RA-V (6) and RA-VII (7). Compounds 1-4 are being used in clinics; compounds 5-8 are in the stages of clinical trial or as a candidate for drug research. In this review, the progress in chemical and bioactive studies on these important natural bioactive cyclopeptides 1-8 are introduced, mainly including discovery, bioactivity, mechanism, QSAR and synthesis.
Animals ; Anti-Bacterial Agents ; chemical synthesis ; chemistry ; pharmacology ; Antineoplastic Agents ; chemical synthesis ; chemistry ; therapeutic use ; Cyclosporine ; chemistry ; pharmacology ; Daptomycin ; chemical synthesis ; chemistry ; pharmacology ; Depsipeptides ; chemical synthesis ; chemistry ; therapeutic use ; Gramicidin ; chemical synthesis ; chemistry ; pharmacology ; Humans ; Immunosuppression ; Immunosuppressive Agents ; chemical synthesis ; chemistry ; pharmacology ; Molecular Structure ; Neoplasms ; drug therapy ; Peptides, Cyclic ; chemical synthesis ; chemistry ; pharmacology ; therapeutic use ; Quantitative Structure-Activity Relationship ; Vancomycin ; chemical synthesis ; chemistry ; pharmacology

HIV-1 fusion inhibitors are a new class of anti-HIV compounds, which block the entry of HIV into target cells through preventing the fusion between viral and cell plasma membrane and thus interrupt the initial steps of viral replication. T-20 (enfuvirtide), which has been clinically approved as the first fusion inhibitor of HIV-1 by U.S. FDA in 2003, can suppress replication of HIV variants with multi-drug resistance to reverse transcriptase and protease inhibitors. Peptides and small molecules display potent anti-HIV fusion activities by targeting gp41 thus inhibit its fusogenic function. In recent years, with the development of studies on the molecular mechanism of HIV membrane fusion process and the function of gp41, many new fusion inhibitors are found and some have been in advanced clinical trials. This review discusses recent progress in the development of HIV-1 fusion inhibitors targeting the gp41.
Anti-HIV Agents ; chemical synthesis ; chemistry ; pharmacology ; Drug Resistance, Multiple ; HIV Envelope Protein gp41 ; chemical synthesis ; chemistry ; pharmacology ; HIV Fusion Inhibitors ; chemical synthesis ; chemistry ; pharmacology ; HIV Infections ; drug therapy ; HIV-1 ; drug effects ; physiology ; Humans ; Peptide Fragments ; chemical synthesis ; chemistry ; pharmacology ; Peptides ; chemical synthesis ; chemistry ; pharmacology ; Recombinant Fusion Proteins ; chemical synthesis ; chemistry ; pharmacology ; Virus Replication ; drug effects ; alpha 1-Antitrypsin ; chemical synthesis ; chemistry ; pharmacology

As a key role in mussel defense system, Mytilin is an important antibacterial peptide isolated from the mussel serum. The structural and functional researches on Mytilin showed that the fragment connecting two beta-sheets in a stable beta-hairpin structure was probably required for antimicrobial activity. To elucidate the structural features and the antimicrobial activity of this fragment, we re-designed and synthesized two peptides corresponding to the main mimic structures of Mytilin-1 from Mytilus coruscus, we named these two peptides Mytilin Derived Peptide-1 and Mytilin Derived Peptide-2, respectively. Using a liquid growth inhibition assay, we evaluated their activity towards Gram-positive, Gram-negative bacteria and fungus. The results showed that both peptides can inhibit the growth of Gram-positive, Gram-negative bacteria and fungus. Besides, these two peptides showed high stability in heat water and human serum. These works laid the foundation for further research on the molecular mechanism of Mytilin and for further exploitation of antibacterial peptides with lower molecular mass and more stable structure.
Amino Acid Sequence ; Animals ; Anti-Infective Agents ; chemical synthesis ; pharmacology ; Antimicrobial Cationic Peptides ; chemical synthesis ; chemistry ; pharmacology ; Molecular Sequence Data ; Mytilus ; chemistry

Mytilin-derived-peptide-1 (MDP-1) and mytilin-derived-peptide-2 (MDP-2) are two truncated decapeptides with reversed sequence synthesized corresponding to the residues 20-29 of mytilin-1 (GenBank Accession No. FJ973154) from M. coruscus. The objective of this study is to characterize the structural basis of these two peptides for their antimicrobial activities and functional differences, and to investigate the inhibitory mechanism of MDPs on Escherichia coli and Sarcina lutea. The structures of MDP-1 and MDP-2 in solution were determined by 1H 2D NMR methods; the antibactericidal effects of MDPs on E. coli and S. lutea were observed by transmitted electron microscopy (TEM). Both MDP-1 and MDP-2 have a well-defined loop structure stabilized by two additional disulfide bridges, which resemble the-hairpin structure of mytilin-1 model. The surface profile of MDPs' structures was characterized by protruding charged residues surrounded by hydrophobic residues. TEM analysis showed that MDPs destroyed cytoplasmic membrane and cell wall of bacteria and the interface between the cell wall and membrane was blurred. Furthermore, some holes were observed in treated bacteria, which resulted in cell death. Structural comparison between MDP-1 and MDP-2 shows that the distribution of positively charged amino acids on the loop of MDPs is topologically different significantly, which might be the reason why MDP-2 has higher activity than MDP-1. Furthermore, TEM results suggested that the bactericidal mechanisms of MDPs against E. coli and S. lutea were similar. Both MDP-1 and MDP-2 could attach to the negatively charged bacterial wall by positively charged amino acid residues and destroy the bacteria membrane in a pore-forming manner, thus cause the contents of the cells to release and eventually cell death.
Animals ; Anti-Infective Agents ; chemical synthesis ; pharmacology ; Antimicrobial Cationic Peptides ; chemical synthesis ; chemistry ; pharmacology ; Cell Wall ; drug effects ; Escherichia coli ; drug effects ; Mytilus ; chemistry ; Sarcina ; drug effects

A novel series of bis-nicotine derivatives (3a-3i) were designed, synthesized and evaluated as bivalent anti-Alzheimer's disease agents. The pharmacological results indicated that compounds 3e-3i inhibited both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in the micromolar range (IC50, 2.28-117.86 micromol x L(-1) for AChE and 1.67-125 micromol x L(-1) for BChE), which was at the same potency as rivastigmine. A Lineweaver-Burk plot and molecular modeling study showed that these derivatives targeted both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. Besides, these compounds could significantly inhibit the self-induced Abeta aggregation with inhibition activity (11.85%-62.14%) at the concentration of 20 micromol x L(-1).
Acetylcholinesterase ; metabolism ; Amyloid beta-Peptides ; antagonists & inhibitors ; metabolism ; Binding Sites ; Butyrylcholinesterase ; metabolism ; Cholinesterase Inhibitors ; chemical synthesis ; chemistry ; pharmacology ; Nicotine ; analogs & derivatives ; chemical synthesis ; chemistry ; pharmacology

To simplify the macrocyclic fragment and to modify the zinc binding group of the natural product apicidin, two series of S-hexyl (heptyl) ethanethioate derivatives were designed and synthesized. Twenty-six compounds were synthesized and confirmed with 1H NMR, IR, MS and HR-MS spectrum, which were not reported. Take vorinostat as control, their antiporliferative activities against cancer cell lines, MCF-7 and HL-60, were tested with MTT assay or trypan blue staining method. Generally in both series it was found that, the chiral carbon atom at 7 position is not necessary, compounds II-1, II-3, II-6 and II-13 showed good activity on HL-60 cells in vitro, with the IC50 values less than 10 micromol x L(-1). II-7 and II-8 showed stronger activity against MCF-7 than Vorinostat, with the IC50 of 3.19 and 6.29 micromol x L(-1), respectively.
Antineoplastic Agents ; chemical synthesis ; chemistry ; pharmacology ; Cell Proliferation ; drug effects ; Drug Screening Assays, Antitumor ; HL-60 Cells ; Histone Deacetylase Inhibitors ; chemical synthesis ; chemistry ; pharmacology ; Humans ; Inhibitory Concentration 50 ; MCF-7 Cells ; Peptides, Cyclic ; chemical synthesis ; chemistry ; pharmacology ; Structure-Activity Relationship

OBJECTIVETo study the effect of the synthetic peptide RGDSY-CTTHWGFTLC on the biological behavior of breast cancer MCF-7 cells in vitro.

METHODSMCF-7 cells were incubated with different concentrations of the synthesized peptide RGDSY-CTTHWGFTLC (RGDSY-CTT), the positive control peptide CTTHWGFTLC (CTT), or the negative control peptide STTHWGFTLS (STT) in fibronectin-coated 96-well plates for different time lengths, and the changes in cell adhesion, invasiveness, proliferation, apoptosis and cell cycle were detected using Transwell chamber assay, MTT assay, and flow cytometry.

RESULTSIncubation of the cells with 50, 100 and 200 µg/ml of RGDSY-CTT caused a significant concentration- dependent inhibition of the cell adhesion (cell adhesion rates of 85.1%, 74.1% and 63.8%, respectively) with stronger effects than CTT (P<0.05). At 100 and 200 µg/ml, RGDSY-CTT significantly inhibited the invasion (with inhibition rate of 41.8% and 63.9%, respectively) of MCF-7 cells with an effect similar to that by CTT (P>0.05). At 50, 100 and 200 µg/ml, RGDSY-CTT concentration-dependently suppressed MCF-7 cell proliferation (with cell proliferation rates of 98.8%, 82.4% and 63.0%, respectively), and this inhibitory effect was stronger than that of CTT at 100 and 200 µg/ml (P<0.05). The results of flow cytometry also demonstrated a stronger apoptosis-inducing effect of RGDSY-CTT (76.7%) than that in CTT, STT and the blank control groups (P<0.05).

CONCLUSIONSRGDSY-CTT can inhibit cell invasion, suppress adhesion and proliferation, and induce apoptosis in MCF-7 cells.

Apoptosis ; drug effects ; Cell Adhesion ; Cell Proliferation ; drug effects ; Female ; Humans ; MCF-7 Cells ; Peptides, Cyclic ; chemical synthesis ; pharmacology

A novel peptide, named BF2-X, was designed based on the structure-activity analysis of an analogue of Buforin II, named BF2-A. The BF2-X was a hybrid peptide containing the N-terminal residues 5 to 13 of BF2-A and three repeats of the C-terminal regular alpha-helical motif RLLR, and the residues 8 valine were replaced by leucine. The results of bioinformatics analysis had showed that compared with BF2-A, the helicity, positive charge, hydrophobicity rate and C-terminal amphipathy of BF2-X had remarkably enhanced. Both peptides showed a random coil structure in an aqueous solution, while displaying a typical alpha-helical structure in 50% trifluoroethanol solution (a membrane mimic condition). BF2-X exhibited higher alpha-helical contents than BF2-A in hydrophobic environment. BF2-X displayed potent antimicrobial activities against a broad spectrum of microorganisms. And BF2-X showed stronger antimicrobial activities against bacteria tested than parent peptide BF2-A. These results suggest that the alpha-helical content was directly correlated with the enhanced antibacterial activity. Both peptides had no hemolytic action on mouse erythrocyte.
Amino Acid Sequence ; Animals ; Anti-Bacterial Agents ; chemical synthesis ; chemistry ; pharmacology ; Antimicrobial Cationic Peptides ; chemical synthesis ; chemistry ; pharmacology ; Bacteria ; drug effects ; Circular Dichroism ; Hemolysis ; drug effects ; Hydrophobic and Hydrophilic Interactions ; Mice ; Protein Structure, Secondary ; Proteins ; chemical synthesis ; chemistry ; pharmacology ; Structure-Activity Relationship

The purpose of this study is to investigate the penetration effects and mechanism of N-arginine chitosan (ACS). This novel transdermal enhancer with a mimetic structure of cell-penetration peptides was synthesized by introducing hydrophilic arginine groups to the amino-group on chitosan's side chain. The structure of ACS was confirmed by FT-IR, 1H NMR and element analysis. In addition, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) was used to study the protein conformation and the water content of stratum corneum, and the result suggested that ACS can change the orderly arrangement of the molecules in the stratum corneum, making the stack structure of keratin become loose. And ACS can increase the water content of the stratum corneurn. Inverted fluorescence microscope and flow cytometry were used to examine penetration effect of ACS on Hacat cell. The result confirmed that the uptake of ACS was enhanced with increased substitution degree of arginine by 4-8 folds compared to chitosan. In vitro penetration studies on three electrical types of drugs were carried out using three model drugs of negatively charged aspirin, positively charged terazosin and neutral drug isosorbide mononitrate by the method of Franz diffusion cells. The results showed that ACS has obviously penetration of the negatively charged drug aspirin, and certain penetration of neutral drug issorbide mononitrate, but inhibition of positively charged terazosin. In vivo imaging technology research results show that the ACS can significantly enhance the fluorescence intensity of morin, which is the auto-fluorescence anionic drug. These obtained results suggested that ACS, as a promising transdermal enhancer, can change the structure of the keratinocytes and analog penetrating peptides promote absorption, but have certain selectivity for the drug.
Administration, Cutaneous ; Animals ; Arginine ; chemical synthesis ; chemistry ; pharmacology ; Aspirin ; administration & dosage ; pharmacokinetics ; Cell Line ; Cell Survival ; drug effects ; Cell-Penetrating Peptides ; chemical synthesis ; chemistry ; pharmacology ; Chitosan ; chemical synthesis ; chemistry ; pharmacology ; Drug Carriers ; Humans ; Isosorbide Dinitrate ; administration & dosage ; analogs & derivatives ; pharmacokinetics ; Keratinocytes ; cytology ; Male ; Mice ; Prazosin ; administration & dosage ; analogs & derivatives ; pharmacokinetics ; Skin Absorption ; drug effects