Pachypodanthine inhibits virulence markers of Yersinia enterocolitica at sub-inhibitory concentration

DI MARCO, N.; LUCERO ESTRADA C.; PUNGITORE C. R.

Salta

Congreso; XIV PABMB Congress (Panamerican Association of Biochemistry and Molecular Biology) y XV Reunión Anual SAIB (Sociedad Argentina de Investigaciones Bioquímicas y de Biología Molecular); 2019

SAIB

Most bacteria live as heterogeneous congregations of surface associated microorganisms encapsulated within a self-produced polymer matrixcalled biofilms. This matrix protects cells in biofilms from the detrimental effects of chemical insults and harsh environmental conditions. Anestimated 80% of all bacterial infections are biofilm related. Within biofilms, cells use a communication system known as quorum sensing (QS)to coordinate and cooperate for a joint behavior. QS in Gram-negative bacteria is coordinated by acil homoserin lactones (AHLs) using theLuxI/LuxR-type system, corresponding to AHLs synthase and the response regulator, respectively. Aporphinoid alkaloids are abundantsecondary metabolites in plants and represent one of the most widespread classes of compounds endowed with multiple and variedpharmacological properties. Various aporphinoids were described as antimicrobials but no reports have been found on their inhibiting biofilmabilities. Recently, we have demonstrated the antimicrobial activity of an aporphinoid alkaloid named pachypodanthine against Yersiniaenterocolitica (Ye) with MIC value of 100 μM. Inhibiting biofilm formations could be a novel therapeutic against antimicrobial resistanceproblems. Focusing on this ?antipathogenesis? therapy and considering that plants provide unlimited opportunities for new drugs, the aim of thiswork was to examine a set of aporphinoid alkaloids as possible Ye biofilm inhibitors at sub-inhibitory concentrations. The strain used was YeCLC001 bio-serotype 1A/O:7,8-8-8,19: isolated from pork sausage in our laboratory. Minimum biofilm inhibitory concentration (MBIC) wasassayed by crystal violet technique. The QS technique was performed using the biosensor Chromobacterium violaceum CV026. Expression ofQS Ye genes (luxI: yenI and luxR: yenR homologues) was analyzed by RT-PCR and scanning electron microscopy (SEM) was performed aftercoating biofilm with gold. Results revealed that pachypodanthine inhibited Ye biofilm formation at 12.5 μM, suggesting that it behaved as biofilm formation inhibitor at sub-inhibitory concentrations. In addition, QS was clearly affected, because AHLs production was inhibited by55.17 ± 4.87 %, yenI gene was overexpressed and yenR gene expression was reduced. Biofilm morphology changes were observed by SEM,including monolayer cells added to the surface with a mixture of sparse palisade distribution, randomized cells with irregular edges, andheterogeneous bacillus length and thickness. We concluded that pachypodanthine behaves as biofilm formation and QS inhibitor at subinhibitoryconcentrations against Ye. The advantage of this alternative approach is that these new anti-microbials could be able to inhibitvirulence rather than growth. Consequently, the problems of resistance associated with many bactericidal or bacteriostatic drugs could beavoided.