https://www.selleckchem.com/products/Y-27632.html Novel polymyxin derivatives are often classified either as having direct activity against Gram-negative pathogens or as compounds inactive in their own right, which through permeabilization of the outer membrane act as potentiators of other antibiotics. Here, we report the systematic investigation of the influence of lipophilicity on microbiological activity (including against strains with reduced susceptibility to polymyxins), potentiation of rifampicin, and in vitro toxicity within a series of next-generation polymyxin nonapeptides. We demonstrate that the lipophilicity at the N-terminus and amino acids 6 and 7 in the cyclic peptide core is interchangeable and that the activity, ability to potentiate, and cytotoxicity all appear to be primarily driven by overall lipophilicity. Our work also suggests that the characterization of a polymyxin molecule as either a direct acting compound or a potentiator is more of a continuum that is strongly influenced by lipophilicity rather than as a result of fundamentally different modes-of-action. The aim was to investigate the efficacy of citric acid and ethylenediaminetetraacetic acid (EDTA)-based treatments on smear layer removal and blood clot formation and stabilization. After scaling and root planing, 126 root samples were divided into seven groups treated with deionized water; saline; citric acid solution; Ultradent Citric Acid gel; EDTA solution; EDTA-based PrefGel; or untreated. Each group was divided into three subgroups I for the evaluation of smear layer removal and surface wettability, II and III for the evaluation of blood clot formation and stabilization in static or dynamic rinsing conditions. Conditioning agent treatments increased surface wettability with respect to untreated samples (Ultradent 45 ± 1 degrees, P = 6.2 × 10-3; EDTA 36 ± 5 degrees, P = 8.9 × 10-7; PrefGel 47 ± 7 degrees, P = 3.2 × 10-2). Smear layer removal (30% to 60% with respect to untre