Targeting the Achilles’ Heel of Multidrug-Resistant Staphylococcus aureus by the Endocannabinoid Anandamide

Abstract

Antibiotic-resistant Staphylococcus aureus is a major health issue that requires new therapeutic approaches. Accumulating data suggest that it is possible to sensitize these bacteria to antibiotics by combining them with inhibitors targeting efflux pumps, the low-affinity penicillin-binding protein PBP2a, cell wall teichoic acid, or the cell division protein FtsZ. We have previously shown that the endocannabinoid Anandamide (N-arachidonoylethanolamine; AEA) could sensitize drug-resistant S. aureus to a variety of antibiotics, among others, through growth arrest and inhibition of drug efflux. Here, we looked at biochemical alterations caused by AEA. We observed that AEA increased the intracellular drug concentration of a fluorescent penicillin and augmented its binding to membrane proteins with concomitant altered membrane distribution of these proteins. AEA also prevented the secretion of exopolysaccharides (EPS) and reduced the cell wall teichoic acid content, both processes known to require transporter proteins. Notably, AEA was found to inhibit membrane ATPase activity that is necessary for transmembrane transport. AEA did not affect the membrane GTPase activity, and the GTPase cell division protein FtsZ formed the Z-ring of the divisome normally in the presence of AEA. Rather, AEA caused a reduction in murein hydrolase activities involved in daughter cell separation. Altogether, this study shows that AEA affects several biochemical processes that culminate in the sensitization of the drug-resistant bacteria to antibiotics.

Anti-Bacterial and Anti-Biofilm Activities of Anandamide against the Cariogenic Streptococcus mutans

“…After incubation, the samples were stained with 10 µg/mL Alexafluor 647 -conjugated anionic Dextran 10,000 (Invitrogen Live Technologies Corporation, Eugene, OR, USA) for 20 min at 37 °C in 95% air/5% CO 2 . Fluorescence intensity was analyzed by flow cytometry (LRS-Fortessa flow cytometer, BD Biosciences, San Jose, CA, USA) using the 640 nm laser excitation, and the fluorescence was collected using the 670 nm filter [ 13 ].…”

“…RNA extraction was performed as previously described in Sionov et al [ 13 ], with slight modifications. An overnight culture of S. mutans was diluted to an OD of 0.1 in BHI containing 2% sucrose, and the bacteria were incubated for 4 h in the absence or presence of 12.5 µg/mL AEA or 0.125% ethanol.…”

“…Gene expression is expressed in relative values, with the expression level of the control sample set to 1 for each gene. The assays were performed in triplicate and repeated three times [ 13 ].…”

“…Additionally, endocannabinoids were found to have anti-microbial effects. For example, N-arachidonoyl ethanolamine (anandamide, AEA) was found to have anti-microbial and anti-biofilm activities against methicillin-sensitive and methicillin-resistant Staphylococcus aureus [ 10 , 11 , 12 , 13 ]. Fornelos et al [ 14 ] observed that AEA prevented the growth of Streptococcus salivarius and Enterococcus faecalis when applying 17–35 µg/mL (50–100 µM) AEA.…”

Synthesis and Antibacterial Activity Evaluation of Biphenyl and Dibenzofuran Derivatives as Potential Antimicrobial Agents against Antibiotic-Resistant Bacteria

“…To defuse the antibacterial resistance crisis, medicinal chemists are devoting their resources to innovate antibacterial drugs without pre-existing resistance against human bacterial pathogens by uncovering new molecular structures and utilizing unique modes of action and hybrid antibacterial drugs strategies [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Natural products can be regarded as a group of privileged structures that have been evolutionarily selected to interact with various biological targets; therefore, they are always an abundant source for antibacterial drug development [ 25 , 26 , 27 ].…”