Rotundic acid (RA), an ursane-type pentacyclic triterpene acid isolated from the dried barks of Ilex rotunda Thunb. (Aquifoliaceae), possesses diverse bioactivities. To further study its pharmacokinetics, a simple and sensitive liquid chromatography with triple quadrupole mass spectrometry (LC-QqQ-MS/MS) method was developed and validated to quantify RA concentration in rat plasma and tissue using etofesalamide as an internal standard (IS). Plasma and tissue samples were subjected to one-step protein precipitation. Chromatographic separation was achieved on a ZORBAX Eclipse XDB-C₁₈ column (4.6 mm × 50 mm, 5 μm) under gradient conditions with eluents of methanol:acetonitrile (1:1, V/V) and 5 mM ammonium formate:methanol (9:1, V/V) at 0.5 mL/min. Multiple reaction monitoring transitions were performed at m/z 487.30 → 437.30 for RA and m/z 256.10 → 227.10 for IS in the negative mode. The developed LC-QqQ-MS/MS method exhibited good linearity (2–500 ng/mL) and was fully validated in accordance with U.S. Food and Drug Administration bioanalytical guidelines. Dose proportionality and bioavailability in rats were determined by comparing pharmacokinetic data after single oral (10, 20, and 40 mg/kg) and intravenous (10 mg/kg) administration of RA. Tissue distribution was studied following oral administration at 20 mg/kg. The results showed that the absolute bioavailability of RA after administration at different doses ranged from 16.1% to 19.4%. RA showed good dose proportionality over a dose range of 10–40 mg/kg. RA was rapidly absorbed in a dose-dependent manner and highly distributed in the liver. In conclusion, this study is the first to systematically elucidate the absorption and distribution characteristics of RA in rats, which can provide additional information for further development and evaluation of RA in drug metabolism and pharmacokinetic studies.

圆形酸 (RA)，一种从圆形冬青干树皮中分离出来的熊果烷型五环三萜酸。（水飞蓟科），具有多种生物活性。为了进一步研究其药代动力学，我们开发并验证了一种简单而灵敏的液相色谱三重四极杆质谱 (LC-QqQ-MS/MS) 方法，以使用依托非沙胺作为内标 (IS) 量化大鼠血浆和组织中的 RA 浓度。对血浆和组织样品进行一步蛋白质沉淀。色谱分离是在 ZORBAX Eclipse XDB-C ₁₈色谱柱 (4.6 mm × 50 mm, 5 μm) 上在梯度条件下使用甲醇:乙腈 (1:1, V / V ) 和 5 mM 甲酸铵:甲醇 (9 :1,V / V ) 在 0.5 毫升/分钟。对于 RA 和m/z ，在m/z 487.30 → 437.30 下进行多反应监测离子对256.10 → 227.10 用于负模式下的 IS。开发的 LC-QqQ-MS/MS 方法表现出良好的线性 (2–500 ng/mL)，并根据美国食品和药物管理局生物分析指南进行了充分验证。通过比较单次口服（10、20 和 40 mg/kg）和静脉内（10 mg/kg）RA 给药后的药代动力学数据来确定大鼠的剂量比例和生物利用度。在以 20 mg/kg 口服给药后研究组织分布。结果表明，RA在不同剂量给药后的绝对生物利用度范围为16.1%~19.4%。RA 在 10-40 mg/kg 的剂量范围内表现出良好的剂量比例。RA以剂量依赖的方式快速吸收并在肝脏中高度分布。综上所述，