Complementary roles and synergy of the Ephedra-Glycyrrhiza herb pair across murine models of respiratory symptoms and poly(I:C)-induced pneumonia

Background: The Ephedrae herba (Eh)-Glycyrrhizae Radix et Rhizoma(Grr) herb pair (EGP) is used for viral respiratory illness, but its advantage over single herbs and mechanistic basis remain unclear.

Purpose: To define the complementary roles and synergistic mechanisms of Eh and Grr within EGP and to assess short-term oral tolerability.

Methods: Anti-inflammatory, antipyretic, antitussive, and expectorant effects of Eh, Grr, and EGP were evaluated in four corresponding murine models, and synergy was quantified with the Bliss independence model. Single-cell RNA Sequencing and bioinformatics were used to implicate relevant cell types and pathways. Key findings were confirmed in Poly(I:C)-stimulated RAW 264.7 cells and lung tissue by ELISA, qPCR, Western blotting, and immunofluorescence. A 7-day oral study evaluated general condition, body weight, serum chemistry, organ indices, and histology.

Results: EGP improved fever, cough, sputum clearance, and pulmonary inflammation. Antitussive/expectorant effects were predominantly associated with Grr, antipyretic effects mainly with Eh, and both herbs contributed to anti-inflammatory activity. The combination showed synergistic anti-inflammatory effects, with greater interleukin-1β (IL-1β) suppression than either herb alone. p38 MAPK and NF-κB p65 phosphorylation was reduced, and co-inhibition of p38 MAPK and NF-κB ameliorated lung-injury indices and systemic cytokines beyond single inhibitors. No overt toxicity was observed under the 7-day oral dosing conditions at the tested doses.

Conclusions: EGP shows complementary roles in symptom control-Grr providing antitussive and expectorant effects and Eh antipyretic activity-and synergistic anti-inflammatory action centred on IL-1β, with good short-term oral tolerability in mice.

Ephedra; Glycyrrhiza; Herb pair; Il-1β; Synergy; Viral pneumonia.