Surface activities and thermodynamic properties of novel cationic surfactants with hydroxymethyl group

<p>A new series of cationic surfactants, <i>N</i>–alkyl–<i>N,N</i>–dimethyl–<i>N</i>–(<i>p</i>–(hydroxymethyl) benzyl) ammonium chlorides (<i>p</i>-DHBA<i>-m</i>), were synthesized and the structures were characterized by ¹HNMR, ¹³CNMR, FT–IR and ESI–MS. The surface activities, thermodynamic properties and aggregation behaviors of <i>p</i>-DHBA<i>-m</i> in aqueous solutions were respectively studied by means of surface tension, isothermal titration calorimetry and steady-state fluorescence methods. Thermodynamic parameters show that the micellization is an entropy-driven process. According to the fluorescence quenching method, the micelle aggregation numbers (<i>N</i>_agg) of <i>p</i>-DHBA-<i>m</i> were calculated and found that the increase of temperature or the elongation of alkyl chain length could lead to the reduction of the <i>N</i>_agg, respectively.</p

Clotrimazole inhibits OSCC cells proliferation.

<p>OSCC cells (CAL27, SCC25, and UM1) were treated with clotrimazole (0–80 µM) for 24 h, 48 h and 72 h, and cell viability was detected using a Cell Counting Kit-8 assay. The results presented as mean ± standard deviation values for three independent experiments.</p

Clotrimazole slows the growth of human OSCC xenograft tumors in nude mice.

<p>A total of 5×10⁶ CAL27 cells/mouse were injected subcutaneously into the back next to the right front limb. When a tumor became palpable, clotrimazole (150 mg/kg/body) was administered intraperitoneally for 2 weeks, 6 times per week, control mice treated with equal volume of peanut oil. (A) Representative photographs of the gross tumors from nude mice treated with clotrimazole or peanut oil. (B) Graphs represent the average tumor volumes of CAL27 xenografts in mice from the control and clotrimazole-treated groups. (C) Graphs represent the average weight of tumors from the control and clotrimazole-treated groups. (D) PCNA expression in tumor tissues was assessed by IHC. The bar graph shows PCNA labeling index (PCI) in twelve tumors per each experimental group. PCI (%)  = positive tumor cells/total tumor cells×100%. (E) Cleaved caspase-3 expression in tumor tissues was assessed by IHC. The bar graph shows cleaved caspase-3 labeling index (CI) in twelve tumors per each experimental group. CI (%)  =  positive tumor cells/total tumor cells ×100%. *<i>P</i><0.05; ** <i>P</i><0.01 compared with control nude mice.</p

Clotrimazole induces G₀/G₁ cell cycle arrest in OSCC cells.

<p>OSCC cells were exposed to various concentrations of clotrimazole (0, 30 and 40 µM) for 24 h. Cell cycle distributions were analyzed by flow cytometry with PI staining. *<i>P</i><0.05, **<i>P</i><0.01 as compared with the CAL27 control cells; # <i>P</i><0.01 as compared with the SCC25 control cells; ‡<i>P</i><0.01 as compared with the UM1 control cells.</p

Clotrimazole inhibits colony formation of OSCC cells.

<p>OSCC cells (CAL27, SCC25, and UM1) grown in 6-well plates (1000 cells/well) were incubated with various concentrations of clotrimazole (0, 10, 20 and 30 µM) for two weeks. Cell colonies were stained and counted as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098885#s2" target="_blank">Methods</a> section. The results presented as mean ± standard deviation values for three independent experiments. *<i>P</i><0.05; **<i>P</i><0.01 compared with solvent control.</p