Host-Dependent Medicinal Quality of Taxilli Herba: A Comprehensive Review on Chemical Profiles and Bioactivities

Taxilli Herba (Sangjisheng) is a hemi-parasitic medicinal plant whose quality is intrinsically linked to its host species. While previous reviews have extensively summarized its chemical constituents and pharmacological activities, a systematic understanding of how host trees dictate its quality and safety remains largely fragmented. This review bridges this gap by proposing a "host-governed quality paradigm." By integrating historical records with modern scientific findings, we critically evaluate the molecular mechanisms underlying host-parasite interactions and their impact on medicinal quality. We highlight that host species influence Taxilli Herba across three critical dimensions: (i) chemical composition, comprising both intrinsic bioactive compounds and host-derived metabolites; (ii) toxicity profile, where even hosts lacking cardiac glycosides may pose potential safety hazards; and (iii) pharmacological activity, where host identity modulates therapeutic potency and traditional medicinal properties (e.g., "cold" vs. "warm" nature). Importantly, we highlight that the cardiac glycoside test specified in the current Chinese Pharmacopoeia is insufficient to ensure the safety of Sangjisheng derived from diverse hosts. To address these challenges, we propose a host-governed quality paradigm comprising four pillars: (1) mechanistic studies on host-parasite interactions; (2) revision of pharmacopeial standards to restrict approved sources; (3) promotion of standardized cultivation using safe host species (e.g., Morus alba); and (4) stringent quality control for edible and medicinal applications. This framework aims to ensure the safety, efficacy, and sustainable use of Sangjisheng in clinical practice.