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Quorum sensing (QS) is a cell-to-cell communication process that controls bacterial collective behaviors. The QS network regulates and coordinates bacterial virulence factor expression, antibiotic resistance and biofilm formation. Therefore, inhibition of the QS system is an effective strategy to suppress the bacterial virulence. Herein, we identify a phosphate ester derivative of chrysin as a potent QS inhibitor of the human pathogen Pseudomonas aeruginosa (P. aeruginosa) using a designed luciferase reporter assay. In vitro biochemical analysis shows that the chrysin derivative binds to the bacterial QS regulator LasR and abrogates its DNA-binding capability. In particular, the derivative exhibits higher anti-virulence activity compared to the parent molecule. All the results reveal the potential application of flavone derivative as an anti-virulence compound to combat the infectious diseases caused by P. aeruginosa. [ABSTRACT FROM AUTHOR]

Abstract: A series of phosphorylated flavonoids were synthesized and investigated in vitro as inhibitors of pancreatic cholesterol esterase (CEase) and acetylcholinesterase (AChE). The results showed that most of the synthesized compounds exhibited nanomolar potency against CEase, much better than the parent flavonoids. Furthermore, these phosphorylated flavonoids demonstrated good to high selectivity for CEase over AChE, which only showed micromolar potency inhibition of AChE. The most selective and potent inhibitor of CEase (3e) had IC50 value of 0.72 nM and 11800-fold selectivity for CEase over AChE. The structure–activity relationships revealed that the free hydroxyl group at position 5 and phosphate group at position 7 of the phosphorylated flavonoids are favorable to the inhibition of CEase. The inhibition mechanism and kinetic characterization studies indicated that they are irreversible competitive inhibitors of CEase. [Copyright &y& Elsevier]

Highlights: [•] Phosphorylated flavonoids were screened as inhibitors of porcine liver CE. [•] Six tested compounds showed potency against CE with IC50 values below 5.0nM. [•] These compounds demonstrated similar levels of inhibition toward CEase and CE. [•] They were identified as irreversible competitive inhibitors of CE. [Copyright &y& Elsevier]

Abstract: Due to the importance of pancreatic cholesterol esterase (CEase) as a potential target in atherosclerosis and for the development of hypocholesterolemic agents, there are increasing interests in designing and synthesizing CEase inhibitors. In the present study, we prepared forty-five isocoumarin phosphorus analogues (i.e., phosphaisocoumarins) and investigated the inhibition of these compounds on the CEase. The results showed that some phosphaisocoumarins could act as potent inhibitors of CEase. The most potent inhibitors, compounds 9d, 10a and 12e give IC50 values of 4.8 μM, 2.3 μM and 1.9 μM, respectively. The inhibition mechanism and kinetic characterization studies indicate that they are reversible competitive inhibitors. [Copyright &y& Elsevier]