Fig. 1.

Staphylococcal biofilm inhibitory activities of norgestimate (NGM) and 17-deacetylnorgestimate (17DN). a Structures of NGM and 17DN. b MR23 biofilm-inhibitory activities of NGM and 17DN. Data are presented as the mean ± SD (standard deviation) (n = 3). The graphs represent the average absorbance of the crystal violet-stained biofilms formed on 96-well plates. Photographs of representative wells are shown below the graphs. c Effects of NGM and 17DN on the growth of MR23. Cells were cultured in BHI broth under shaking conditions, with or without 50 μM of the test compound. d Fluorescence microscopy of PIA in a SH1000 biofilm. PIA and DNA were stained using WGA-Alexa488 (WGA; upper panels) and DAPI (lower panels), respectively. Arrowheads indicate the filamentous structural PIA. Scale bars = 5 μm. e Dot blot assay of PIA. f Quantification of ECM proteins. Data are presented as the mean ± SD (n = 3). *p < 0.01. In d–f, cells were cultured under biofilm-forming conditions, with or without 50 μM of the test compound, or 20 μg/mL of DspB. SH1000, S. aureus SH1000; MR23, S. aureus MR23; SE4, S. epidermidis SE4. Cont. control, NGM norgestimate, 17DN 17-deacetylnorgestimate, DspB dispersin B