Exploring resveratrol dimers as virulence blocking agents – Attenuation of type III secretion in Yersinia pseudotuberculosis and Pseudomonas aeruginosa

Abstract

Bacterial infections continue to threaten humankind and the rapid spread of antibiotic resistant bacteria is alarming. current antibiotics target essential bacterial processes and thereby apply a strong selective pressure on pathogenic and non-pathogenic bacteria alike. one alternative strategy is to block bacterial virulence systems that are essential for the ability to cause disease but not for general bacterial viability. We have previously show that the plant natural product (-)-hopeaphenol blocks the type iii secretion system (T3SS) in the Gram-negative pathogens Yersinia pseudotuberculosis and Pseudomonas aeruginosa. (-)-Hopeaphenol is a resveratrol tetramer and in the present study we explore various resveratrol dimers, including partial structures of (-)-hopeaphenol, as T3SS inhibitors. To allow rapid and efficient assessment of T3SS inhibition in P. aeruginosa, we developed a new screening method by using a green fluorescent protein reporter under the control of the ExoS promoter. Using a panel of assays we showed that compounds with a benzofuran core structure i.e. viniferifuran, dehydroampelopsin B, anigopreissin A, dehydro-δ-viniferin and resveratrol-piceatannol hybrid displayed significant to moderate activities towards the T3SS in Y. pseudotuberculosis and P. aeruginosa.

A Brief Updated Review of Advances to Enhance Resveratrol’s Bioavailability

“…However, due to the complex core structure of this compound (i.e., multiple fused rings and various stereocenters) synthetic synthesis of the compound is challenging. Sundin et al [ 49 ] investigated the inhibitory effects of natural (dihydro)benzofuran RES dimers of T3SS that target Yersinia pseudotuberculosis and Pseudomonas aeruginosa and compared it to (-)-hopeaphenol. The dimers were found to have superior activity compared to the parent compound and were thus recommended as leads for drug discovery and potential clinical development.…”

Identification of Small Molecules Blocking the Pseudomonas aeruginosa Type III Secretion System Protein PcrV

“…Compounds with two times higher binding to PcrV than to the deactivated control protein CAII were considered as potential binders, while the best binders had more than five times higher binding to PcrV than to CAII, as exemplified in Figure 2 . The screening resulted in 395 potential PcrV binders that were tested for biological activity in an infection assay at 100 µM [ 35 ].…”

“…The cell viability assay was performed essentially as described before [ 35 ]. J774 cells were seeded in 96-well micro-titer plates (Nunc), 100 µL/well, to a final number of 50,000 cells/well in Dulbecco’s modified Eagle’s medium (DMEM) with glutamax (Merck) supplemented with 10% fetal calf serum (FCS) and 3 µg/mL gentamicin and incubated for 16-18 h. Overnight cultures of the P. aeruginosa strains PAK and PAK pcrV [ 10 ] were grown in Luria Broth (LB) on a rotary shaker at 220 rpm at 37 °C.…”

“…The T3SS of P. aeruginosa and other gram-negative pathogens have been explored as targets for the development of virulence-blocking antibacterial agents [ 30 , 31 ]. A number of synthetic and natural compounds have been demonstrated to block the T3SS of P. aeruginosa , resulting in attenuation of infection in vitro and in vivo [ 32 , 33 , 34 , 35 , 36 , 37 ]. However, most of these compounds have been identified by phenotypic screening and the mode of action at the molecular level remains unknown.…”

“…Since PcrV is present on the exterior of the bacterium, the challenge of entry into the bacterial cell and the action of efflux pumps are circumvented. Importantly, the T3SS in P. aeruginosa is essential to block macrophage phagocytosis and the anti-PcrV antibody was demonstrated to successfully protect the macrophage from infection [ 35 , 39 ]. Later, many monoclonal and polyclonal anti-PcrV antibodies were shown to protect against P. aeruginosa infection in a variety of animal models [ 39 , 40 , 41 , 42 , 43 ] and anti-PcrV antibodies have been advanced to clinical trials [ 18 , 44 , 45 ].…”