Antimicrobial activity and mechanism of action of Nu-3, a protonated modified nucleotide

Annals of Clinical Microbiology and Antimicrobials

Research

Shanping Cao¹  Ming Wang¹  Lun-Quan Sun² 

[1] College of Veterinary Medicine, China Agricultural University, No.2 Yuanmingyuan West Road, 100193, Beijing, China;Xiangya Hospital and Center for Molecular Medicine, Central South University, 410078, Changsha, China;

关键词: Minimum Inhibitory Concentration;    Francisella Tularensis;    Brucella Abortus;    BrdU Incorporation Assay;    Green Florescence;   

DOI  :  10.1186/1476-0711-10-1

 received in 2010-09-11, accepted in 2011-01-14,  发布年份 2011

来源: Springer

【 摘 要 】

Background"Nubiotics" are synthetic oligonucleotides and nucleotides with nuclease-resistant backbones, and are fully protonated for enhanced ability to be taken up by bacterial cells. Nu-3 [butyl-phosphate-5'-thymidine-3'-phosphate-butyl], one of the family members of Nubiotics was efficacious in the treatment of burn-wound infections by Pseudomonas aeruginosa in mice. Subsequent studies revealed that Nu-3 had a favorable toxicological profile for use as a pharmaceutical agent. This study evaluated the antibacterial activity of Nu-3 in vitro and its efficacy as a topical antibiotic. In addition, we investigated the possible mechanisms of Nu-3 action at the levels of DNA synthesis and bacterial membrane changes.MethodsAntimicrobial minimum inhibitory concentrations (MIC) experiments with Nu-3 and controls were measured against a range of Gram-positive and Gram-negative bacteria, including some hospital isolates according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Analysis of the killing kinetics of Nu-3 was also performed against two strains (Staphylococcus aureus cvcc 2248 and Pseudomonas aeruginosa cvcc 5668). The mouse skin suture-wound infection model was used to evaluate the antibacterial activity of Nu-3. We used a 5-Bromo-2'-deoxy-uridine Labeling and Detection Kit III (Roche, Switzerland) to analyze DNA replication in bacteria according to the manufacturer's instruction. The BacLight™ Bacterial Membrane Potential Kit (Invitrogen) was used to measure the bacterial membrane potential in S. aureus.ResultsNu-3 had a wide antibacterial spectrum to Gram-positive, Gram-negative and some resistant bacteria. The MIC values of Nu-3 against all tested MRSA and MSSA were roughly in a same range while MICs of Oxacillin and Vancomycin varied between the bacteria tested. In the mouse model of skin wound infection study, the treatment with 5% Nu-3 glycerine solution also showed comparable therapeutic effects to Ciprofloxacin Hydrochloride Ointment. While Nu-3 had no effect on DNA synthesis of the tested bacteria as demonstrated in a BrdU assay, it could cause bacterial cell membrane depolarization, as measured using a BacLight™ Bacterial Membrane Potential Kit.ConclusionsThese results provide additional experimental data that are consistent with the hypothesis that Nu-3 represents a new class of antibacterial agents for treating topical infections and acts via a different mechanism from conventional antibiotics.

【 授权许可】

Unknown   
© Cao et al; licensee BioMed Central Ltd. 2011. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.