Insights into the Vibrio Genus: A One Health Perspective from Host Adaptability and Antibiotic Resistance to In Silico Identification of Drug Targets.

The genus Vibrio comprises an important group of ubiquitous bacteria of marine systems with a high infectious capacity for humans and fish, which can lead to death or cause economic losses in aquaculture. However, little is known about the evolutionary process that led to the adaptation and colonization of humans and also about the consequences of the uncontrollable use of antibiotics in aquaculture. Here, comparative genomics analysis and functional gene annotation showed that the species more related to humans presented a significantly higher amount of proteins associated with colonization processes, such as transcriptional factors, signal transduction mechanisms, and iron uptake. In comparison, those aquaculture-associated species possess a much higher amount of resistance-associated genes, as with those of the tetracycline class. Finally, through subtractive genomics, we propose seven new drug targets such as: UMP Kinase, required to catalyze the phosphorylation of UMP into UDP, essential for the survival of bacteria of this genus; and, new natural molecules, which have demonstrated high affinity for the active sites of these targets. These data also suggest that the species most adaptable to fish and humans have a distinct natural evolution and probably undergo changes due to anthropogenic action in aquaculture or indiscriminate/irregular use of antibiotics.

New putative therapeutic targets against Serratia marcescens using reverse vaccinology and subtractive genomics.

The Gram-negative bacillus Serratia marcescens, a member of Enterobacteriaceae family, is an opportunistic nosocomial pathogen commonly found in hospital outbreaks that can cause infections in the urinary tract, bloodstream, central nervous system and pneumonia. Because S. marcescens strains are resistant to several antibiotics, it is critical the need for effective treatments, including new drugs and vaccines. Here, we applied reverse vaccinology and subtractive genomic approaches for the in silico prediction of potential vaccine and drug targets against 59 strains of S. marcescens. We found 759 core non-host homologous proteins, of which 87 are putative surface-exposed proteins, 183 secreted proteins, and 80 membrane proteins. From these proteins, we predicted seven candidates vaccine targets: a sn-glycerol-3-phosphate-binding periplasmic protein UgpB, a vitamin B12 TonB-dependent receptor, a ferrichrome porin FhuA, a divisome-associated lipoprotein YraP, a membrane-bound lytic murein transglycosylase A, a peptidoglycan lytic exotransglycosylase, and a DUF481 domain-containing protein. We also predicted two drug targets: a N(4)-acetylcytidine amidohydrolase, and a DUF1428 family protein. Using the molecular docking approach for each drug target, we identified and selected ZINC04259491 and ZINC04235390 molecules as the most favorable interactions with the target active site residues. Our findings may contribute to the development of vaccines and new drug targets against S. marcescens. Communicated by Ramaswamy H. Sarma.

Antidiarrhoeic effect and dereplication of the aqueous extract of Annona crassiflora (Annonaceae).

We investigated the antidiarrhoeic effect of the aqueous extract of Annona crassiflora leaves (AEAC). The AEAC decreased the diarrhoeic stools and enteropooling induced by castor oil, without altering total faecal output; moreover, the distance travelled by charcoal meal in the intestine was increased. Twenty-eight compounds were identified by LC-DAD-MS in the AEAC, including flavonoids, alkaloids and proanthocyanidins. In addition, two oligomeric series of condensed tannins of up to nine flavan-3-ol units were characterised by MALDI-MS. These data suggest that the antidiarrhoeic effect of the AEAC is related to its ability to inhibit intestinal secretion and/or to increase intestinal absorption. Moreover, the prokinetic effect of AEAC, together with its inhibitory effect on enteropooling induced by castor oil, explains why this extract decreased diarrhoeic faeces without altering the total faecal output. All these effects are in agreement with the pharmacological activity reported in the literature for many of the secondary metabolites identified.

Antidiarrhoeic effect of Eugenia dysenterica DC (Myrtaceae) leaf essential oil.

Essential oil from Eugenia dysenterica leaves was able to inhibit both the diarrhoea and enteropooling induced by castor oil; however, the distance travelled by charcoal meal in the intestine was not change. These data suggest that the antidiarrhoeic effect of the essential oil from E. dysenterica leaves is related to its ability to inhibit intestinal secretion and/or to increase intestinal absorption.

The gastroprotective effects of Eugenia dysenterica (Myrtaceae) leaf extract: the possible role of condensed tannins.

We applied a taxonomic approach to select the Eugenia dysenterica (Myrtaceae) leaf extract, known in Brazil as "cagaita," and evaluated its gastroprotective effect. The ability of the extract or carbenoxolone to protect the gastric mucosa from ethanol/HCl-induced lesions was evaluated in mice. The contributions of nitric oxide (NO), endogenous sulfhydryl (SH) groups and alterations in HCl production to the extract's gastroprotective effect were investigated. We also determined the antioxidant activity of the extract and the possible contribution of tannins to the cytoprotective effect. The extract and carbenoxolone protected the gastric mucosa from ethanol/HCl-induced ulcers, and the former also decreased HCl production. The blockage of SH groups but not the inhibition of NO synthesis abolished the gastroprotective action of the extract. Tannins are present in the extract, which was analyzed by matrix assisted laser desorption/ionization (MALDI); the tannins identified by fragmentation pattern (MS/MS) were condensed type-B, coupled up to eleven flavan-3-ol units and were predominantly procyanidin and prodelphinidin units. Partial removal of tannins from the extract abolished the cytoprotective actions of the extract. The extract exhibits free-radical-scavenging activity in vitro, and the extract/FeCl3 sequence stained gastric surface epithelial cells dark-gray. Therefore, E. dysenterica leaf extract has gastroprotective effects that appear to be linked to the inhibition of HCl production, the antioxidant activity and the endogenous SH-containing compounds. These pleiotropic actions appear to be dependent on the condensed tannins contained in the extract, which bind to mucins in the gastric mucosa forming a protective coating against damaging agents. Our study highlights the biopharmaceutical potential of E. dysenterica.

The aversive, anxiolytic-like, and verapamil-sensitive psychostimulant effects of pulegone.

We investigated the psychostimulant, rewarding, and anxiolytic-like effects of pulegone. Possible interactions between pulegone and menthol concerning their psychostimulant effect were also analyzed. General mouse activity after pulegone treatment, and the interacitons between pulegone and menthol, were determined in the open field. The anxiolytic-like activity, motor coordination and strength force were evaluated using the elevated plus maze (EPM), rotarod test and grasping test, respectively. The motivational properties of pulegone were evaluated by pairing the drug effects on the mice with the least preferred compartment (previously determined) of a conditioned place preference (CPP) apparatus. Pulegone increased mouse locomotor activity and immobilization time. Verapamil, but not diltiazem, haloperidol or picrotoxin, decreased the psychostimulation induced by pulegone. Pulegone also decreased grooming and rearing behaviors and caused motor incoordination and weakness at high doses. Pulegone increased the time spent by mice in the open arms of the EPM, and flumazenil pre-treatment did not alter this effect. Pulegone either produced no CPP or induced conditioned place aversion. The changes in mouse ambulatory activity caused by the association of pulegone with menthol were either lower than those predicted by the theoretical curve or not different from the predicted values. Therefore, pulegone induces a verapamil-sensitive psychostimulant effect that appears to independ on the opening of L-type calcium channels. Pulegone has negative reinforcing properties and seems to possess anxiolytic-like actions unrelated to the benzodiazepine site of the γ-aminobutyric acid type A (GABAA) receptor. Finally, pulegone might act in an addictive or synergic way with menthol.