Interaction of the carbon monoxide-releasing molecule Ru(CO)3Cl(glycinate) (CORM-3) with Salmonella enterica serovar Typhimurium: in situ measurements of carbon monoxide binding by integrating cavity dual-beam spectrophotometry

Abstract

Carbon monoxide (CO) is a toxic gas that binds to haems, but also plays critical signalling and cytoprotective roles in mammalian systems; despite problems associated with systemic delivery by inhalation of the gas, it may be employed therapeutically. CO delivered to cells and tissues by CO-releasing molecules (CO-RMs) has beneficial and toxic effects not mimicked by CO gas; CO-RMs are also attractive candidates as novel antimicrobial agents. Salmonella enterica serovar Typhimurium is an enteropathogen causing gastroenteritis in humans. Recent studies have implicated haem oxygenase-1 (HO-1), the protein that catalyses the degradation of haem into biliverdin, free iron and CO, in the host immune response to Salmonella infection. In several studies, CO administration via CO-RMs elicited many of the protective roles of HO-1 induction and so we investigated the effects of a well-characterized water-soluble CO-RM, Ru(CO)3Cl(glycinate) (CORM-3), on Salmonella. CORM-3 exhibits toxic effects at concentrations significantly lower than those reported to cause toxicity to RAW 264.7 macrophages. We demonstrated here, through oxyhaemoglobin assays, that CORM-3 did not release CO spontaneously in phosphate buffer, buffered minimal medium or very rich medium. CORM-3 was, however, accumulated to high levels intracellularly (as shown by inductively coupled plasma MS) and released CO inside cells. Using growing Salmonella cultures without prior concentration, we showed for the first time that sensitive dual-beam integrating cavity absorption spectrophotometry can detect directly the CO released from CORM-3 binding in real-time to haems of the bacterial electron transport chain. The toxic effects of CO-RMs suggested potential applications as adjuvants to antibiotics in antimicrobial therapy.

Heme Oxygenase-1 as a Modulator of Intestinal Inflammation Development and Progression

“…Furthermore, intestinal infections are an important factor in the development of IBD ( 51 ) and most of the evidence available to date supports the notion that HMOX1 promotes bacterial clearance, diminishing intestinal inflammation ( 90 ). Moreover, it has been demonstrated that CO can interact directly with heme groups of the bacterial electron transport chain, suggesting that HMOX1 has an effect in bacterial infections not only through the modulation of the immune response, but by the direct interaction with the pathogen ( 119 ). In another field, HMOX1 has also been associated with colorectal cancer, being suggested as a novel target for cancer therapy ( 106 ).…”

Host heme oxygenase‐1: Friend or foe in tackling pathogens?

“…That study further demonstrated that HMOX1‐derived CO induces bactericidal activity in mouse macrophages to protect them from Salmonella infection. However CO can directly inhibit the respiration of Salmonella and kill it in a concentration dependent manner . In contrast with the above‐cited studies, Mitterstiller et al, demonstrated reduced survival of Salmonella upon pharmacological inhibition of HMOX1 or upon its silencing.…”

Targeting heme oxygenase-1 and carbon monoxide for therapeutic modulation of inflammation

“…314–315 CORM3 was also shown to have antibacterial activity against E. coli , 313,318 and S. typhimurium after bacterial uptake of the drug. 316 Both CORM2 and CORM3 exerted antibacterial activity against antibiotic-resistant strains of H. pylori . 319 Recent advances using PhotoCORMs demonstrate photoactivatable toxicity of these compounds toward E. coli bacteria.…”