OBJECTIVE  To optimize the extraction process of volatile oil from Bupleuri Radix and Cinnamomi Ramulus Decoction(BCD), and analyze its composition, and evaluate the role of volatile oil in the antiviral activity of the BCD.

METHODS The extraction process was optimized through single-factor experiments and response surface methodology. The volatile oil was then qualitatively analyzed using GC-MS. Subsequently, 36 Balb/c mice were randomly divided into 6 groups: blank control group, model group, oseltamivir group(19.5 mg·kg⁻¹·d⁻¹), water extract group, volatile oil group, and water extract+volatile oil group(each traditional Chinese medicine intervention group received the same dosage of 24.7 g·kg⁻¹·d⁻¹). With the exception of the blank control group, the other groups of mice were infected with H1N1 influenza virus via nasal drip to replicate the influenza mouse model. Medication was administered after weight loss. The general physiological indicators of mice were observed, and organs such as the thymus, spleen, and lungs were collected and weighed at the conclusion of the experiment, and the organ index was calculated. viral load and cytokines in lung tissue were determined by RT-qPCR.

RESULTS The optimal extraction process was as follows: Collecting a distillate volume that was 8 times the amount of herbal materials, adding water volume equivalent to15 times the amount of herbal materials, and soaking for 4 h. GC-MS analysis revealed that the volatile oil of BCD primarily consists of 41 components, including cinnamaldehyde, palmitic acid, and 2-methoxycinnamaldehyde. Pharmacodynamic results demonstrated that both the water extract and volatile oil of BCD were effective in improving weight loss and reducing the viral load in the lungs of mice infected with influenza virus. Notably, the volatile oil+water extract group exhibited superior effects in reducing the viral load in the lungs of influenza-infected mice and inhibiting the mRNA expression of cytokines IFN-γ, TNF-α, and IL-6 compared to the water extract alone.

CONCLUSION  The volatile oil may have a synergistic effect in the intervention of BCD on influenza virus infection in mice. The optimized process for extracting volatile oils is stable and feasible, which contributes to the advancement and utilization of volatile oils from BCD.