CDSF is a novel DSF-family signal. (A) High resolution ESI-MS analysis of CDSF showing a molecular weight of 209.1555 dalton (peak a). The internal control was indicated as peak b. (B) The 1 H NMR spectra of CDSF. (C) The 13 C NMR spectra of CDSF. The NMR analyses were conducted at room temperature (CDCl3, 125MHz).