Compositions and methods for analyzing intracellular BoNT protease activity, and especially BoNTB, BoNTG, BoNTD, andor BoNTF protease activity are provided. Specifically, the compounds of the formula I upregulate the expression of the enzyme endothelial NO synthase and can be applied in conditions in which an increased expression of said enzyme or an increased NO level or the normalization of a decreased NO level is desired. Furthermore, a latch in the phase-domain \u0394\u03a3 modulator provides a bit stream by sampling one or more bits of the filtered demodulated phase error, where an average value of the bit stream represents the phase.