Hispaglabridin B, a constituent of liquorice identified by a bioinformatics and machine learning approach, relieves protein-energy wasting by inhibiting forkhead box O1.

<bold>Background and Purpose: </bold>Liquorice is the root of Glycyrrhiza glabra, which is a popular food in Europe and China that has previously shown benefits for skeletal fatigue and nutrient metabolism. However, the mechanism and active ingredients remain largely unclear. The aim of this study was to investigate the active ingredients of liquorice for muscle wasting and elucidate the underlying mechanisms.<bold>Experimental Approach: </bold>RNA-Seq and bioinformatics analysis were applied to predict the main target of liquorice. A machine learning model and a docking tool were used to predict active ingredients. Isotope labelling experiments, immunostaining, Western blots, qRT-PCR, ChIP-PCR and luciferase reporters were utilized to test the pharmacological effects in vitro and in vivo. The reverse effects were verified through recombination-based overexpression.<bold>Key Results: </bold>The liposoluble constituents of liquorice improved muscle wasting by inhibiting protein catabolism and fibre atrophy. We further identified FoxO1 as the target of liposoluble constituents of liquorice. In addition, hispaglabridin B (HB) was predicted as an inhibitor of FoxO1. Further studies determined that HB improved muscle wasting by inhibiting catabolism in vivo and in vitro. HB also markedly suppressed the transcriptional activity of FoxO1, with decreased expression of the muscle-specific E3 ubiquitin ligases MuRF1 and Atrogin-1.<bold>Conclusions and Implications: </bold>HB can serve as a novel natural food extract for preventing muscle wasting in chronic kidney disease and possibly other catabolic conditions. [ABSTRACT FROM AUTHOR]