In vitro evaluation on the safety of SFT gel.

<p>(<b>a</b>) MTT assay was used to determine the cell viability of epithelial line Caco-2 (left) or macrophage cell line RAW264.7 (right) after the treatment of different concentrations (3 nM, 30 nM and 300 nM) of SFT in PBS solution or corresponding gel versions (formulated with 0.015% HEC). (<b>b</b>) Production of IL-6 (left) and TNF-α (right) in macrophage cell line RAW264.7 was analyzed by CBA assay after incubation for 12 h with the above-mentioned three concentrations of SFT in PBS solutions or 0.015% HEC gel. Data represent means ±SD from triplicate experiments. Student's <i>t</i>-test was performed to determine the significance of difference between the PBS-treated group and each microbicide candidate or LPS-treated groups, *<i>p</i><0.05.