Detection of NAD(P)H by fluorescent probe to reveal the protective effects of natural antioxidants on acute liver injury

Acute liver injury as a serious inflammatory liver disease has a high morbidity and mortality rate. For drug treatment for acute liver injury, the focus was mainly from oxidative stress and rarely from a reductive perspective over the past decades. Herein, a novel quinoline-malononitrile-based fluorescent probe (QM-NA) designed for high efficiency sensitive detection of NAD(P)H, a critical marker related to reductive stress. QM-NA exhibited high selectivity for NADPH as well as a fast "turn-on" fluorescence response (4 min) with a Stokes shift of 77 nm, a detection limit of 18 nM, and favorable biocompatibility for cell-based experiments. With QM-NA in hand, the fluorescence imaging of endogenous and exogenous NADPH at the cellular level was achieved. More importantly, in vivo experiments demonstrated QM-NA was successfully used to visualize the fluctuations of NADPH and evaluate the efficacy of three antioxidants for the first time in acute liver injury mice. These above results afford a novel strategy for the treatment of acute liver injury and this probe is expected to be a promising molecular tool to evaluate the efficacy of hepatoprotective drugs.