An online two-dimensional high-performance liquid chromatography-electrospray ionization (silica capillary tube with polyamide coating)-ion mobility spectrometry (HPLC-ESI-IMS) method was developed and applied to identify nine phenolic acids in seedling roots. The separation was performed by gradient elution consisting of methanol and 0.1% acetic acid (v/v) on a narrow diameter reverse C₁₈ column with ammonia as the sheath fluid. Ion mobility spectrometry (IMS) was employed to assist in the determination of the co-eluted compounds that were not separated by HPLC to achieve a highly selective and versatile two-dimensional analysis. Upon optimization of the mobile phase, sheath fluid and column flow rates, the resulting IMS spray voltage was 4.5 kV, and the drift tube temperature was 95 °C. Consequently, the HPLC-ESI-IMS technique enabled effective separation of coumaric acid, protocatechuic acid, chlorogenic acid, vanillic acid, caffeic acid, ferulic acid, sinapic acid, benzoic acid and salicylic acid according to their acquired mobility drift time differences. The limit of detection (LOD) ranged from 0.05 to 5 ng and the recovery of the spiked samples ranged from 85.10% to 100.51%. Collectively, this sensitive and efficient two-dimensional HPLC-ESI-IMS method developed in this study may be applicable for the isolation and identification of the phenolic acids secreted by the plant roots.

A novel on-line screening method for natural antioxidants was developed with a post-column cerium(IV) reduction reaction after high performance liquid chromatography (HPLC) separation. Under acidic conditions, Ce(IV) sulphate exhibits strong absorption at 320 nm and is reduced to Ce(III) by antioxidants in a post-column reaction coil (no absorbance at this wavelength). The reduction of absorbance at 320 nm affords a negative peak that corresponds to the retention time of an active constituent in the HPLC chromatogram. The proposed method demonstrated different selectivity versus a conventional HPLC-2,2-diphenyl-1-picrylhydrazyl (DPPH) method. This was used to detect the antioxidant constituents from the extract of Ziziphora clinopodioides Lam., which is an indigenous edible plant from north Xinjiang, China. Nine compounds were isolated as major antioxidant compounds by this method. All the isolated compounds were identified by ¹H NMR and ¹³C NMR; six of them were isolated from this plant for the first time.

Sonchus oleraceus L., a member of the Asteraceae family native to Eurasia, is a herbaceous plant whose young stems and leaves are consumed globally as a medicinal and edible wild vegetable; it is rich in flavonoids and exhibits various pharmacological activities, including anti-inflammatory and anti-tumor effects. This study optimized the extraction process of flavonoids from Xinjiang S. oleraceus using response surface methodology and evaluated the anti-inflammatory activity of luteoloside in vitro. Based on single-factor experiments and Box–Behnken design, the effects of ethanol concentration, extraction time, solid-to-liquid ratio, and extraction temperature on flavonoid yield were investigated. The optimal extraction conditions were determined as ethanol concentration 62%, extraction time 30 min, solid-to-liquid ratio 1:91 g/mL, and extraction temperature 64 °C, with a flavonoid yield of 21.64 mg/g. After purification via polyamide column chromatography, the luteoloside content was determined by HPLC to be 44.06 μg/g. Cytotoxicity assays revealed that a luteoloside concentration of 100 μmol/L reduced the viability of Oryctolagus cuniculus colon epithelial cells to approximately 80%. ELISA results demonstrated that luteoloside significantly inhibited the release of pro-inflammatory factors, including TNF-α, while promoting the expression of the anti-inflammatory factor IL-10. These findings indicate that luteoloside effectively alleviates LPS-induced cellular inflammation.