No abstract

The primary objective of this study was to ascertain the anti-biofilm and anti-virulence properties of sub-minimum inhibitory concentration (MIC) levels of eugenol against the standard strain PAO1 and two multi-drug resistant P. aeruginosa clinical isolates utilizing quorum sensing inhibition (QSI). Eugenol at 400 μM significantly reduced biofilm formation on urinary catheters and the virulence factors (VF) including extracellular polysaccharides, rhamnolipid, elastase, protease, pyocyanin, and pyoverdine (p < 0.001). Further, eugenol exhibited a marked effect on the production of QS signals (AIs) (p < 0.001) without affecting their chemical integrity. In silico docking studies demonstrated a stable molecular binding between eugenol and QS receptor(s) in comparison with respective AIs. Investigation on reporter strains confirmed the competitive binding of eugenol to a QS receptor (LasR) as the possible QSI mechanism leading to significant repression of QS associated genes besides the VF genes (p < 0.001). This study provides insights, for the first time, into the mechanism of the anti-virulence properties of eugenol.

Tamm-Horsfall protein (THP) is thought to protect against calcium oxalate monohydrate (COM) stone formation by inhibiting COM aggregation. Several studies reported that stone formers produce THP with reduced levels of glycosylation, particularly sialic acid levels, which leads to reduced negative charge. In this study, normal THP was treated with neuraminidase to remove sialic acid residues, confirmed by an isoelectric point shift to higher pH. COM aggregation assays revealed that desialylated THP (ds-THP) promoted COM aggregation, while normal THP inhibited aggregation. The appearance of protein aggregates in solutions at ds-THP concentrations ≥1 µg/mL in 150 mM NaCl correlated with COM aggregation promotion, implying that ds-THP aggregation induced COM aggregation. The aggregation-promoting effect of the ds-THP was independent of pH above its isoelectric point, but was substantially reduced at low ionic strength, where protein aggregation was much reduced. COM aggregation promotion was maximized at a ds-THP to COM mass ratio of ~0.025, which can be explained by a model wherein partial COM surface coverage by ds-THP aggregates promotes crystal aggregation by bridging opposing COM surfaces, whereas higher surface coverage leads to repulsion between adsorbed ds-THP aggregates. Thus, desialylation of THP apparently abrogates a normal defensive action of THP by inducing protein aggregation, and subsequently COM aggregation, a condition that favors kidney stone formation.

Objective:Aged garlic extract (AGE) has been proven to exhibit antioxidant, hypolipidemic, hypoglycemic and antidiabetic properties. However, its effect on diabetic nephropathy was unexplored. Therefore, the present study was designed to investigate the renoprotective effect of AGE in streptozotocin-induced diabetic rats.Materials and Methods:Albino Wistar rats were induced with diabetes by a single intraperitoneal injection of 45 mg/kg b.w. of streptozotocin. Commercially available AGE was supplemented orally at a dose of 500 mg/kg body weight/day. Aminoguanidine, which has been proven to be an anti-glycation agent was used as positive control and was supplemented at a dose of 1 g/L in drinking water. The serum and urinary biochemical parameters were analyzed in all the groups and at the end of 12 weeks follow up, the renal histological examination were performed using H & E and PAS staining.Results:The diabetic rats showed a significant change in the urine (P < 0.001) and serum (P < 0.01) constituents such as albumin, creatinine, urea nitrogen and glycated hemoglobin. In addition, the serum lipid profile of the diabetic rats were altered significantly (P < 0.05) compared to that of the control rats. However, the diabetic rats supplemented with aged garlic extract restored all these biochemical changes. The efficacy of the extract was substantiated by the histopathological changes in the kidney.Conclusion:From our results, we conclude that aged garlic extract has the ability to ameliorate kidney damage in diabetic rats and the renoprotective effect of AGE may be attributed to its anti-glycation and hypolipidemic activities.