Table 1.

Synergistic Mechanisms of Astragalus–Atractylodes Saposhnikovia in Yupingfeng San (YPFS)

Herb	Major Active Constituents	Key Targets/Pathways	Immuno-inflammatory Effects	Synergistic Role in Formula
Astragalus (Huangqi)	Flavonoids (eg., calycosin), saponins (astragaloside IV), polysaccharides	NF-κB, JAK/STAT, PI3K-Akt	Enhances T and NK cell activity; promotes Th1 response; inhibits IL-6, TNF-α	Principal herb: initiates immune activation and provides anti-inflammatory foundation
Atractylodes (Baizhu)	Sesquiterpenes (eg., atractylenolide I–III), polysaccharides	TLR4/MyD88, NF-κB	Suppresses inflammatory cascade; protects intestinal barrier; reduces IL-1β; increase ZO-1	Assistant herb: stabilizes internal environment and enhances immune tolerance
Saposhnikovia (Fangfeng)	Coumarins (eg., cimicifugin), chromones	MAPK, NF-κB, STAT3	Inhibits Th2 polarization; reduces IgE, IL-4, IL-13; anti-allergic effects	Adjuvant herb: prevents excessive immune activation and controls inflammation
YPFS (Combination)	Multi-component system (flavonoids, coumarins, polysaccharides)	PI3K-Akt, NF-κB, JAK-STAT, TLR4/MyD88	Bidirectional immunoregulation; balances Th1/Th2 and Th17/Treg; improves immune microenvironment	Multi-target synergy: integrates immune activation, anti-inflammation, and barrier protection, superior to single herbs