Ginsenoside compound K inhibited the gelation of GGGGCC repeats and regulated co-aggregation with arginine-rich poly-dipeptides in C9orf72-related ALS.

GGGGCC repeat expansion in C9orf72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). It produces toxic RNA repeats and poly-dipeptides, leading to abnormal phase separation and deposition in nerve cells. In particular, repeat RNAs form gels that induce cellular toxicity. Thus, they are potential therapeutic targets. Ginsenoside compound K (CK) is the major metabolite of Panax ginseng, a traditional Chinese medicine commonly used for the treatment of neurodegenerative diseases. In this study, CK significantly inhibited the gelation of GGGGCC repeats both in vitro and in vivo. Moreover, it reduced the co-aggregation of RNA and arginine-rich poly-dipeptides via electrostatic interactions. Further investigation suggested that CK preferentially interacts with G-quadruplex monomers formed by GGGGCC repeats rather than with complex multimers, thereby inhibiting the formation of toxic RNA foci. These results elucidate the mechanism of action of CK in C9orf72-related ALS/FTD. Thus, this study provides new avenues for the potential application of ginsenoside in the treatment of neurodegeneration.