<b>Advances in understanding the functions and regulatory factors of secondary metabolites in</b> <i> <b>Reynoutria japonica</b> </i>

<i>Reynoutria japonica</i>, a perennial herb of the <i>Polygonaceae</i> family, is a traditional Chinese medicinal plant known for its diverse pharmacological activities and broad applications in medicine, agriculture, and related fields. This review explores the functions and regulatory mechanisms of its secondary metabolites by summarizing their types, bioactivities, and biosynthetic regulation. Additionally, it examines how factors such as plant age, medicinal organ, soil composition, and cultivation conditions influence the secondary metabolite profile. These insights support the clinical application and industrial development of <i>R. japonica</i>.