Development of a UPLC‐MS/MS Method for Bioanalysis of Ethoxysanguinarine and Its Application in Pharmacokinetic Study of Ethoxysanguinarine Nanoemulsion

Ethoxysanguinarine (ETSG), a benzophenanthridine alkaloid, exhibits diverse biological activities, including antibacterial, antifungal, anti-inflammatory, antioxidant, and anti-tumor effects. Despite these properties, limited research exists on ETSG in vivo pharmacokinetics due to its poor solubility and low bioavailability. In this study, we developed a rapid and specific UPLC-MS/MS method for ETSG bioanalysis. Sample preparation involved one-step protein precipitation using methanol and phellodendrine as an internal standard (IS). The Waters HSS T3 column (2.1 * 50 mm, 1.8 μM) employed a gradient elution with mobile phases A (2 mmol/L ammonium formate aqueous solution-formic acid [99.8:0.2, v/v]) and B (methanol-formic acid [99.8:0.2, v/v]). Mass analysis via Waters Q-mass spectrometer utilized positive scan mode and multiple reaction monitoring. ETSG and IS were detected at m/z 332.0 → 274.0 and 342.0 → 177.0, respectively, within 7.0 min. The method demonstrated excellent precision, accuracy, recovery, and stability, with a linear calibration curve (1.1-560 ng/mL) and strong correlation coefficient (0.9984). Successful pharmacokinetic evaluation in Sprague-Dawley rats included intravenous ETSG administration and intragastric ETSG nanoemulsion/suspension. This method enables steroidal saponin analysis from ETSG in biological samples.