Rapid Intrabacterial Hydrolysis for Activating Antibiotics against Gram-negative Bacteria

<div>Antimicrobial drug resistance demands novel approaches for improving the efficacy of antibiotics, especially against Gram-negative bacteria. Here we report that conjugating a diglycine (GG) to a prodrug of antibiotics drastically accelerates intrabacterial hydrolysis of ester bond for regenerating the antibiotics against E. coli. Specifically, the attachment of GG to chloramphenicol succinate (CLsu) generates a novel conjugate (CLsuGG), which exhibits about an order of magnitude higher inhibitory efficacy than CLsu against E. coli. This work, for the first time, illustrates that dipeptide conjugation modulates intrabacterial hydrolysis for increasing antibiotic efficacy and reducing adverse drug effects.</div>

Rapid Intrabacterial Hydrolysis for Activating Antibiotics against Gram-negative Bacteria

<div>Antimicrobial drug resistance demands novel approaches for improving the efficacy of antibiotics, especially against Gram-negative bacteria. Here we report that conjugating a diglycine (GG) to a prodrug of antibiotics drastically accelerates intrabacterial hydrolysis of ester bond for regenerating the antibiotics against E. coli. Specifically, the attachment of GG to chloramphenicol succinate (CLsu) generates a novel conjugate (CLsuGG), which exhibits about an order of magnitude higher inhibitory efficacy than CLsu against E. coli. This work, for the first time, illustrates that dipeptide conjugation modulates intrabacterial hydrolysis for increasing antibiotic efficacy and reducing adverse drug effects.</div>

Preparation of anti-chloramphenicol rabbit antibody

Chloramphenicol (CAP) is a broad-spectrum antibiotic of high toxicity on human therefore it is being strictly controlled in food. We are interested in the development of a method of effective extraction of CAP in food based on the immunological principle using specific anti-CAP antibody combining with LC/MS/MS for the analysis of the residual CAP in food meeting the international standard. In this article, we reported experimental results on the preparation of anti-CAP rabbit antibody. Conjugative antigen between CAP and the carrier protein, bovine serum albumin, BSA (CAP-BSA) was successfully synthesized from chloramphenicol succinate and BSA with a BSA conjugating efficiency of more than 70 %, and the presence of CAP in the conjugative antigen was confirmed by ELISA method. The CAP-BSA antigen could cause good immune response in rabbit by the first antigen injection and induce the increasing production of anti-CAP antibody in rabbit serum from the third antigen injection which reached maximal value after the fifth injection. Anti-CAP antibody was purified from rabbit anti-serum in two steps: i) Removing of albumin and other non antibody proteins by 35–37 % saturated ammonium sulphate; ii) Elimination of anti-BSA antibody by the Sepharose-BSA specific affinity chromatography column. The ability of the purified anti-CAP antibody to interact and bind with CAP molecules in CAP-spiked sample was proved using a Sepharose-Anti-CAP antibody chromatography column which was made by conjugating the purified anti-CAP antibody with Sepharose beads.