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1.
J Am Chem Soc ; 144(51): 23614-23621, 2022 12 28.
Artigo em Inglês | MEDLINE | ID: mdl-36530144

RESUMO

We have developed a new concept for reversible peptide stapling that involves macrocyclization between two amino groups and decyclization promoted via dual 1,4-elimination. Depending on the trigger moiety, this strategy could be employed to selectively deliver peptides to either intracellular or extracellular targets. As a proof of concept, a peptide inhibitor targeting a lysine-specific demethylase 1 (LSD1) was temporarily cyclized to enhance its stability and ability to cross the cell membrane. Once inside the cells, the biologically active linear peptide was released under reducing environment. Moreover, we have developed reversibly stapled peptides using antimicrobial peptides (RStAMPs) whose bioactive helical conformation can be temporarily destabilized by stapling the peptide backbone. The resulting helix-distorted RStAMPs are nontoxic and highly resistant to protease hydrolysis, while at the infection site, RStAMPs can be rapidly activated by the overproduced H2O2 through the dual 1,4-elimination. The latter restored the helical structure of the native peptide and its antimicrobial activity. This work illustrates a highly valuable macrocyclization strategy for the peptide community and should greatly benefit the field of peptide delivery.


Assuntos
Peróxido de Hidrogênio , Peptídeos , Peptídeos/farmacologia , Peptídeos/química , Conformação Molecular
2.
Eur J Med Chem ; 221: 113488, 2021 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-33991963

RESUMO

Naturally occurring cyclic antimicrobial peptides (AMPs) such as tyrocidine A (Tyrc A) and gramicidin S (GS) are appealing targets for the development of novel antibiotics. However, their therapeutic potentials are limited by undesired hemolytic activity and relatively poor activity against Gram-negative bacteria. Inspired by polycationic lipopeptide polymyxin B (PMB), the so called 'last-resort' antibiotic for the treatment of infections caused by multidrug-resistant Gram-negative bacteria, we synthesized and biologically evaluated a series of polycationic analogues derived from Tyrc A. We were able to obtain peptide 8 that possesses 5 positive charges exhibiting potent activities against both Gram-negative and Gram-positive bacteria along with totally diminished hemolytic activity. Intriguingly, antibacterial mechanism studies revealed that, rather than the 'pore forming' model that possessed by Tyrc A, peptide 8 likely diffuses membrane in a 'detergent-like' manner. Furthermore, when treating mice with peritonitis-sepsis, peptide 8 showed excellent antibacterial and anti-inflammatory activities in vivo.


Assuntos
Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Polimixina B/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Tirocidina/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Linhagem Celular , Relação Dose-Resposta a Droga , Farmacorresistência Bacteriana/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Polimixina B/química , Relação Estrutura-Atividade , Tirocidina/síntese química , Tirocidina/química
3.
ChemMedChem ; 15(12): 1089-1100, 2020 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-32233075

RESUMO

Gramicidin S (GS), one of the most widely investigated antimicrobial peptides (AMPs), is known for its robust antimicrobial activity. However, it is restricted to topical application due to undesired hemolytic activity. With the aim of obtaining nontoxic GS analogues, we describe herein a molecular approach in which the native GS ß-turn region is replaced by synthetic ß,γ-diamino acids (ß,γ-DiAAs). Four ß,γ-DiAA diastereomers were employed to mimic the ß-turn structure to afford GS analogues GS3-6, which exhibit diminished hemolytic activity. A comparative structural study demonstrates that the (ßR,γS)-DiAA is the most-stable ß-turn mimic. To further improve the therapeutic index (e. g., high antibacterial activity and low hemolytic activity) and to extend the molecular diversity, GS5 and GS6 were used as structural scaffolds to introduce additional hydrophobic or hydrophilic groups. We show that GS6K, GS6F and GS display comparable antibacterial activity, and GS6K and GS6F have significantly decreased toxicity. Moreover, antibacterial mechanism studies suggest that GS6K kills bacteria mainly through the disruption of the membrane.


Assuntos
Antibacterianos/farmacologia , Gramicidina/análogos & derivados , Gramicidina/farmacologia , Antibacterianos/síntese química , Antibacterianos/toxicidade , Bactérias/efeitos dos fármacos , Linhagem Celular , Membrana Celular/efeitos dos fármacos , Eritrócitos/efeitos dos fármacos , Gramicidina/toxicidade , Hemólise/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Estereoisomerismo
4.
Vet Parasitol ; 158(4): 360-3, 2008 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-19022581

RESUMO

Acquisition of Toxoplasma gondii infections is mainly through ingestion of parasite-contaminated food. T. gondii oocyst distribution in the living environment of human and livestock is directly linked to the prevalence of the parasite infection in humans and domestic animals. In this study, we investigated the sero-prevalence of T. gondii infection in free-range as well as caged chicken in northeast China. The purpose of this study was to investigate the potential prevalence of T. gondii oocysts in the environments. Sera of 308 free-range chickens and 210 caged chickens collected in three areas in northeast China were tested for anti-T. gondii antibodies with ELISA assays. The infection rates of free-range and caged chickens were 34.7% and 2.8% respectively, indicating that the parasite is widely distributed in the environment and poses threatens to the health of people living in those areas.


Assuntos
Galinhas/sangue , Doenças das Aves Domésticas/epidemiologia , Toxoplasma , Toxoplasmose Animal/epidemiologia , Criação de Animais Domésticos , Animais , Anticorpos Antiprotozoários/sangue , Antígenos de Protozoários , China/epidemiologia , Ensaio de Imunoadsorção Enzimática , Doenças das Aves Domésticas/sangue , Doenças das Aves Domésticas/parasitologia , Sensibilidade e Especificidade , Estudos Soroepidemiológicos , Toxoplasmose Animal/sangue
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