人参皂苷Rb2在大鼠体内的药代动力学行为及代谢产物研究

建立快速高分离度液相色谱-四极杆飞行时间质谱联用方法(RRLC-Q-TOF-MS),分析人参皂苷Rb2在大鼠体内的药代动力学行为,并探索人参皂苷Rb2在大鼠体内的代谢过程.采用Agilent SB-C18色谱柱,流动相A为0.1％甲酸溶液,B为乙腈,流速为0.2 mL/min,进样量为5μL,二元线性梯度洗脱分离,采用电喷雾负离子模式进行质谱检测.方法的检出限(S/N=3)和定量限(S/N=10)分别为0.08 μg/mL和0.1 μg/mL,线性范围为0.10～ 1.26 μg/mL.结果表明,人参皂苷Rb2静脉注射后的体内代谢过程符合二室模型特征,血药浓度半衰期的α相(t1/2α)和β相(t1/2β)分别为(23.58±1.10)和(1306.55±147.23) min.通过对静脉注射人参皂苷Rb2的大鼠尿液和口服后的粪便样本进行分析,发现Rb2的代谢产物为M6,M2(C-Y),F2,C-K.     

人参多糖对人参皂苷Re体内代谢和体外转化的影响

利用快速分离液相色谱-四极杆飞行时间质谱联用仪(RRLC/Q-TOF-MS)研究了人参多糖对肠道菌群转化人参皂苷Re的影响;考察了人参皂苷Re的代谢产物Rg1在口服人参多糖大鼠体内的药代动力学,并与正常大鼠体内Rg1的药代动力学参数进行了比较.结果表明,体外肠道菌群转化人参皂苷Re的主要转化产物有人参皂苷Rg1,Rh1,Rg2,F1和原人参三醇(Protopanaxatriol,PPT),分别归属于3条转化路径;正常情况下,肠道菌群转化人参皂苷Re 48 h时,除了终产物PPT的存在,中间产物Rg1,Rg2和F1仍可被检测到,而加入人参多糖后,只检测到终产物PPT.当口服给药Re后,代谢产物Rg1的达峰时间(tmax)、最大血浆浓度(cmax)和血浆药物浓度-时间曲线下面积(AUC)分别为(11.6±6.1) h,(80.1±44.0) ng/m L和(549.3±209.4) ng·h/m L;当给予人参多糖14 d后,口服给药Re,代谢产物Rg1的tmax,cmax和AUC分别为(8.2±5.4) h,(98.2±50.6) ng/m L和(691.9±231.2) ng·h/m L.研究结果表明,人参多糖能促进人参皂苷Re转化为人参皂苷Rg1,进而提高胃肠道对人参皂苷Rg1的吸收,并可能增强人参的药理作用.     

人参皂苷Re在正常和中波紫外线辐射损伤模型大鼠体内药代动力学比较研究

建立了超高效液相色谱-三重四级杆质谱(UPLC-QQQ-MS)检测大鼠血浆中G-Re含量的方法,用于比较研究人参皂苷Re(Ginsenoside Re,G-Re)在正常大鼠和UVB辐射损伤模型大鼠体内的药代动力学行为。选用Ascentis~? Express C_(18)色谱柱(5.0 mm×3.0 mm,2.7μm),以0.1%甲酸-乙腈为流动相,梯度洗脱。电喷雾离子源(ESI)在负离子模式下,选择多反应监测模式(MRM)扫描,内标法定量,用于G-Re定量分析的离子为m/z 991.54/945.53/475.60。方法检出限为4.0 ng/m L,定量限为13.5 ng/m L,G-Re在15~20000 ng/m L范围内线性关系良好(r=0.999);日内和日间精密度、回收率、基质效应和稳定性均能满足药代动力学分析要求。结果表明,两组大鼠分别单次口服50 mg/kg G-Re后,体内代谢过程表现皆符合二室模型特征,正常组和模型组t_(1/2α)分别为(0.21±0.04)h和(0.69±0.07)h,t_(1/2β)分别为(17.08±0.53)h和(21.40±16.77)h,AUC_((0-t))分别为(321.91±2.27)"g/(L·h)和(474.99±194.96)"g/(L·h),AUC_((0-∞))分别为(332.44±1.66)"g/(L·h)和(518.64±231.39)"g/(L·h),除t_(1/2α)外,两组之间的药代动力学参数具有显著差异(p0.05)。本方法准确、灵敏、专属性强、稳定性好,可用于人参皂苷Re的体内药代动力学比较研究。     

高效液相色谱法测定竹节参中多种人参皂苷含量

建立了高效液相色谱法(HPLC)测定竹节参中人参皂苷Rg1、Re、Rb1、Rb2、Rg2、Rd含量的方法.运用二极管阵列检测器(DAD)峰纯度和光谱检索功能,结合保留时间定性,外标峰面积法定量.采用C18反相柱,以乙腈-水梯度洗脱测定了同一批竹节参总皂苷中人参皂苷Rg1、Re、Rd的含量分别为0.81%、0.15%、2.99%,回收率为93.46%~94.02%,含量及回收率的RSD均小于5%,该方法简便、灵敏,精密度及准确度在允许范围内,可作为竹节参皂苷提取物中多种人参皂苷的同时测定方法.     

人参皂苷Rb1在大鼠体内的药物代谢研究

人参皂苷Rb1是人参中的达玛烷型三萜皂苷类化合物, 具有多种生物活性. 对人参皂苷Rb1代谢产物的分析已有报道, 在大鼠尿液、粪便、胃和大肠中共检出了5种代谢产物. 本文采用高效液相色谱-飞行时间串联质谱进行人参皂苷Rb1的体内代谢研究, 通过口服和静脉给予药物, 在大鼠尿液中共检出了人参皂苷Rb1的14种代谢产物, 并系统分析和推断了这些代谢物的转化规律和可能结构.     

液相色谱-串联质谱法测定SD大鼠全血中新型亲环蛋白D抑制剂RN-0001浓度北大核心CSCD

建立了液相色谱-串联质谱法测定新型亲环蛋白D抑制剂RN-0001在SD大鼠全血中的浓度。样品前处理采用简单的蛋白沉淀法,色谱分离在Gemini C18110,色谱柱(50 mm×2 mm,5μm)上进行,以含10 mmol/L乙酸铵和0.1%甲酸的水溶液作为流动相A,含0.1%甲酸的甲醇溶液作为流动相B,在0.8 mL/min流速下梯度洗脱。待测物RN-0001和内标环孢菌素A的检测采用正离子电喷雾多反应监测模式,其检测离子对分别为m/z 645.4/156.2和m/z 601.8/156.1。RN-0001在30.0 ng/mL~30.0μg/mL浓度范围内线性关系良好(r 2>0.9961),定量下限为30.0 ng/mL,批内和批间的精密度小于5.2%,批内和批间准确度在-3.6%~6.7%之间。RN-0001基质样品在室温放置18 h,-80℃冰箱放置40天以及经过5次冻融循环后均稳定。SD大鼠尾静脉注射3 mg/kg的RN-0001注射液进行药代动力学研究,RN-0001的半衰期t 1/2为3.53 h,峰浓度C 0为9370 ng/mL,血药浓度-时间曲线下面积AUC 0-24 h为5300 h·ng/mL。结果表明,所建方法适用于RN-0001在SD大鼠体内的药代动力学研究。     

加压毛细管电色谱-微流蒸发光散射检测器联用系统的构建及其应用

构建微流蒸发光散射检测器(μELSD)与加压毛细管电色谱(pCEC)联用系统,测定中药提取物注射用血塞通(冻干)中三七皂苷R1、人参皂苷Rg1,Re,Rb1、Rd考察系统的实用性和稳定性。用C18毛细管色谱柱,通过对流动相体系、梯度洗脱条件、雾化载气流速、蒸发温度、施加电压等参数的优化,确定了注射用血塞通(冻干)5种成分含量测定的最佳测定参数。最佳测定参数如下,流动相A为15 mmol/L甲酸-三乙胺乙腈溶液(pH=7.0),流动相B为15 mmol/L甲酸-三乙胺溶液(pH=7.0);梯度洗脱条件:0~10 min,19%A;10~30 min,22%A;30~35 min,36%A;35~45 min,40%A。雾化载气流速2 L/min;蒸发温度120℃;施加电压+8 kV。5种成分线性范围为8.6~146.9 ng(三七皂苷R1)、6.9~189.7 ng(人参皂苷Rg1)、6.8~171.4 ng(人参皂苷Re)、9.4~156.1 ng(人参皂苷Rb1)、7.5~180.5 ng(人参皂苷Rd),5种成分回收率都在95%~105%之间。实验表明,构建的pCEC-μELSD联用系统能用于药物中有效成分的含量测定。μELSD的构建为毛细管液相色谱、毛细管电色谱和毛细管电泳分离技术提供了一种全新的检测手段。     

免疫亲和柱净化-超高效液相色谱-三重四极杆质谱法高灵敏测定尿液和血浆中3种鹅膏毒肽

建立了超高效液相色谱-三重四极杆质谱高灵敏测定尿液和血浆中α-鹅膏毒肽、β-鹅膏毒肽和γ-鹅膏毒肽的方法。经过免疫亲和柱净化,尿液样品浓缩20倍、血浆样品浓缩10倍,以Kinetex Biphenyl色谱柱(100 mm×2.1 mm, 1.7 μm)作为分析柱,甲醇-0.005%(v/v)甲酸水溶液作为流动相进行梯度洗脱分离,电喷雾电离、负离子、多反应监测模式下检测,外标法定量。3种鹅膏毒肽的线性范围为0.1~200 ng/mL,相关系数(r)>0.999。尿液和血浆中3种鹅膏毒肽的基质效应和提取回收率分别为92%~108%和90%~103%,变异系数均小于13%。尿液中3种鹅膏毒肽的准确度为-9.4%~8.0%,重复性和中间精度分别为3.0%~14%和3.5%~18%,当取样量为2.00 mL时,方法的检出限均为0.002 ng/mL;血浆中3种鹅膏毒肽的准确度为-13%~8.0%,重复性和中间精度分别为3.9%~9.7%和5.5%~12%,当取样量为1.00 mL时,方法的检出限均为0.004 ng/mL。该法操作简单、灵敏、准确,已在中毒患者摄入野生蘑菇后138 h的尿液中检出0.0067 ng/mL α-鹅膏毒肽和0.0059 ng/mL β-鹅膏毒肽。该法已成功解决中毒患者尿液和血浆中超痕量鹅膏毒肽的检测难题,对于疑似中毒病人的早诊断、早治疗、降低死亡率都具有非常重要意义,也为今后开展此类毒素毒理作用及机体代谢规律的研究提供了可靠的技术支撑。     

液相色谱-质谱联用技术结合多探针底物法研究人参皂苷Rb1的体外代谢

以奥美拉唑、 苯妥英、 卡马西平和非那西丁为检测肝药酶细胞色素P450酶(CYP450)亚型的专属探针药物, 通过原型药物减少量测定法考察药物体外代谢的变化, 评价人参皂苷Rb1对CYP450不同亚型酶的作用. 结果表明, P2C9, P2C19和P3A4实验组与对照组差异不显著, P1A2实验组与对照组差异显著, 表明人参皂苷Rb1能诱导P1A2亚型酶的活性, 促进底物与酶反应, 加快底物的代谢, 而对P2C9, P2C19和P3A4三个亚型酶有弱的诱导或无诱导作用. 根据快速分离液相色谱-质谱联用(RRLC-MS/MS)检测结果推断, 人参皂苷Rb1在CYP450酶中的代谢产物可转化为人参皂苷Rb1氧化产物(Rb1+O)及人参皂苷Rd和F2.     

超高效液相色谱-三重四极杆质谱联用方法测定血浆和尿液中的α-龙葵碱、α-卡茄碱和茄啶

建立了超高效液相色谱-三重四极杆质谱联用方法,检测血浆和尿液中的α-龙葵碱、α-卡茄碱和茄啶。样品经2%(v/v,下同)甲酸水溶液等量稀释,再经混合型阳离子交换固相萃取柱(MCX SPE)净化,以0.1%甲酸乙腈溶液和含0.05%甲酸的5 mmol/L乙酸铵水溶液作为流动相进行梯度洗脱,在UPLC BEH C18色谱柱上实现分离,正离子电喷雾串联质谱多反应监测(ESI-MS/MS MRM)方式检测,基质匹配外标法定量。一次进样分析时间为5.5min。血浆和尿液中3种待测物的线性范围均为0.3~100 ng/mL,相关系数为0.997~0.999;样品的检出限为0.1 ng/mL,定量限为0.3 ng/mL;血浆和尿液中的平均加标回收率分别为82%~112%和96%~114%,相对标准偏差为4.0%~16%和2.7%~17%(n=6)。方法简单、准确、灵敏,适用于马铃薯中毒检测。     

Simultaneous determination of notoginsenoside R1 and ginsenoside Re in rat plasma by ultra high performance liquid chromatography with tandem mass spectrometry and its application to a pharmacokinetic study

A rapid and high sensitive ultra high performance liquid chromatography with tandem mass spectrometry method for the simultaneous determination of notoginsenoside R1 and ginsenoside Re in rat plasma was developed. The analytes and internal standard, digoxin, were extracted from rat plasma via protein precipitation with methanol and separated on an Phenomenex Gemini C₁₈ column within 2 min. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique, operating in multiple reaction monitoring and positive ion mode. The precursor to product ion transitions monitored for notoginsenoside R1, ginsenoside Re, and internal standard were m/z 955.5→775.5, 969.6→789.1, and 803.6→283.1, respectively. The assay was validated with linear range of 1.9–380 ng/mL for notoginsenoside R1 and 0.5–100 ng/mL for ginsenoside Re. The intra‐ and interday precisions (RSD%) were within 8.96% for each analyte. The absolute recoveries were greater than 93% for R1 and 96% for Re. Each analyte was stable during all sample storage, preparation, and analytic procedures. The method was successfully applied to a pharmacokinetic study of Xuesaitong dispersible tablets in eight rats.     

Comparative pharmacokinetics of the main active components in normal and ulcerative colitis rats after oral administration of Zingiberis Rhizoma–Ginseng Radix et Rhizoma herb pair and its single herb extracts by LC–MS/MS

Zingiberis Rhizoma and Ginseng Radix et Rhizoma are usually used together for the treatment of ulcerative colitis in clinical practices. However, their compatibility mechanism remains unclear. In this study, a rapid and sensitive liquid chromatography with tandem mass spectrometry method was developed for simultaneous quantification of ginsenoside Re, ginsenoside Rg1, ginsenoside Rb1, and 6-gingerol in rat plasma after oral administration of Zingiberis Rhizoma–Ginseng Radix et Rhizoma herb pair and its single herb extracts. The calibration curves exhibited good linearity, with correlation coefficients of more than 0.993. The precision deviations of intra- and interday analysis were within 10.66%, and accuracy error ranged from −12.74 to 11.56%. The average recoveries of analytes were higher than 76.60% and the matrix effects were minimal. Thus, the validated method was successfully applied to a pharmacokinetic study of four ingredients in normal and ulcerative colitis rat plasma. The results indicated that the pharmacokinetic parameters of four analytes in normal and model groups showed significant differences. The larger exposure (the mean AUC_0-t of ginsenoside Re, ginsenoside Rg1, ginsenoside Rb1, and 6-gingerol were increased by 50.93, 141.90, 3.68, and 37.25%, respectively) and slower elimination (the CLz/F of ginsenoside Re, ginsenoside Rg1, and 6-gingerol were decreased by 52.94, 83.64, and 32.18%, respectively) were observed in ulcerative colitis rats. Furthermore, compared with single herbs, the analytes in rat plasma after oral administration of combined extracts presented relatively high systemic exposure levels with AUC_0-t > 2000 h·ng/mL and C_max > 200 ng/mL. Collectively, the differences of pharmacokinetic characteristics revealed the synergistic effect of Zingiberis Rhizoma–Ginseng Radix et Rhizoma herb pair, which provided a valuable and reliable basis for its clinical application in the treatment of ulcerative colitis.     

A UFLC‐MS/MS method with a switching ionization mode for simultaneous quantitation of polygalaxanthone III,four ginsenosides and tumulosic acid in rat plasma: application to a comparative pharmacokinetic study in normal and Alzheimer's disease rats

A fast, sensitive and reliable ultra fast liquid chromatography‐tandem mass spectrometry (UFLC‐MS/MS) method has been developed and validated for simultaneous quantitation of polygalaxanthone III (POL), ginsenoside Rb1 (GRb1), ginsenoside Rd (GRd), ginsenoside Re (GRe), ginsenoside Rg1 (GRg1) and tumulosic acid (TUM) in rat plasma after oral administration of Kai‐Xin‐San, which plays an important role for the treatment of Alzheimer's disease (AD). The plasma samples were extracted by liquid–liquid extraction using ethyl acetate–isopropanol (1:1, v/v) with salidrdoside as internal standard (IS). Good chromatographic separation was achieved using gradient elution with the mobile phase consisting of methanol and 0.01% acetic acid in water. The tandem mass spectrometric detection was performed in multiple reaction monitoring mode on 4000Q UFLC‐MS/MS system with turbo ion spray source in a negative and positive switching ionization mode. The lower limits of quantification were 0.2–1.5 ng/ml for all the analytes. Both intra‐day and inter‐day precision and accuracy of analytes were well within acceptance criteria (±15%). The mean absolute extraction recoveries of analytes and IS from rat plasma were all more than 60.0%. The validated method has been successfully applied to comparing pharmacokinetic profiles of analytes in normal and AD rat plasma. The results indicated that no significant differences in pharmacokinetic parameters of GRe, GRg1 and TUM were observed between the two groups, while the absorption of POL and GRd in AD group were significantly higher than those in normal group; moreover, the GRb1 absorbed more rapidly in model group. The different characters of pharmacokinetics might be caused by pharmacological effects of the analytes. Copyright © 2013 John Wiley & Sons, Ltd.     

UPLC–MS/MS simultaneous determination of seven active ingredients of Yaobitong capsule in rat plasma and its integrated pharmacokinetic application

A reliable and sensitive UPLC–MS/MS method was first established and validated for the simultaneous determination of seven active ingredients of Yaobitong capsule in rat plasma: ginsenoside Rg1, ginsenoside Rb1, osthole, tetrahydropalmatine, paeoniflorin, albiflorin, and ferulic acid. And this method was further applied for the integrated pharmacokinetic study of Yaobitong capsule in rats after oral administration. Plasma samples (100 μL) were precipitated with 300 μL of methanol using carbamazepine as internal standard. Chromatographic separation was achieved using an Aquity UPLC BEH C18 column (100 × 2.1 mm, 1.7 μm), with the mobile phase consisting of 0.1% formic acid and acetonitrile. The method was validated using a good linear relationship (r ≥ 0.991), and the lower limit of quantification of the analytes ranged from 0.5 to 40 ng/mL. In the integrated pharmacokinetic study, the weight coefficient was calculated by the ratio of AUC_0–∞ of each component to the total AUC_0–∞ of the seven active ingredients. The integrated pharmacokinetic parameters C_max, T_max, and t_1/2 were 81.54 ± 9.62 ng/mL, 1.00 ± 0.21 h, and 3.26 ± 1.14 h, respectively. The integration of pharmacokinetic parameters showed a shorter t_1/2 because of fully considering the contribution of the characteristics of each active ingredient to the overall pharmacokinetics.     

Pharmacokinetics and bioavailability study of ginsenoside Rk1 in rat by liquid chromatography/electrospray ionization tandem mass spectrometry

Ginsenoside Rk1 (Rk1) exhibited various potent biological activities. However, its pharmacokinetic profile in vivo remains unclear. In the present study, a simple and sensitive liquid chromatography tandem mass spectrometry method was developed and validated for determination of Rk1 in rat plasma and applied in a pharmacokinetic study. The sample was precipitated with acetonitrile and separated on a Zorbax Eclipse XDB C18 column (50 × 2.1 mm, 1.8 μm). The mobile phase was composed of 0.1% formic acid in water and acetonitrile at a flow rate of 0.4 mL/min. Rk1 and internal standard (ginsenoside Rg3) were quantitatively monitored with precursor‐to‐product ion transitions of m/z 765.4 → 441.5 and m/z 783.5 → 621.4, respectively. The assay was linear over the concentration range of 5–1000 ng/mL (r > 0.99) with the LLOQ of 5 ng/mL. Other parameters including intra‐ and inter‐day precision and accuracy, extraction recovery and matrix effect were within the acceptable limits. The analyte was stable under the tested storage conditions. The validated method has been successfully applied to a pharmacokinetic study of Rk1 in rat plasma after intravenous (5 mg/kg) and oral (25 mg/kg, 50 mg/kg) administration. After oral administration, Rk1 could be detected in blood at 30 min and reached the highest concentration at 4.29~4.57 h. Our results demonstrated that Rk1 showed low clearance, moderate half‐life (3.09–3.40 h) and low bioavailability (2.87–4.23%). The study will provide information for the further application of Rk1.     

Determination of pseudo‐ginsenoside GQ in human plasma by high performance liquid chromatography–tandem mass spectrometry

A specific, sensitive and rapid method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC‐MS/MS) was developed for the determination of pseudo‐ginsenoside GQ in human plasma. Liquid–liquid extraction was used to isolate the analyte from biological matrix followed by injection of the extracts onto a C₈ column with isocratic elution. Detection was carried out on a triple quadrupole tandem mass spectrometer (API‐4000 system) in multiple reaction monitoring mode using negative electrospray ionization. The mobile phase consisted of methanol–10 mm ammonium acetate (90:10, v/v) and the flow rate was 0.3 mL/min. The method was validated over the concentration range of 5.0–5000.0 ng/mL for plasma. Inter‐ and intra‐day precisions (relative standard deviation) were all within 15% and the accuracy (relative error) was ≤9.4%. The lower limit of quantitation was 5.0 ng/mL. The pseudo‐ginsenoside GQ was stable after 8 h at room temperature, 24 h at autosampler and three freeze–thaw cycles (from ?30 to 25 °C). The method was successfully applied to the pharmacokinetic study of pseudo‐ginsenoside GQ in healthy Chinese volunteers. Copyright © 2013 John Wiley & Sons, Ltd.     

A rapid and sensitive LC–MS/MS method for analysis of iguratimod in human plasma: Application to a pharmacokinetic study in Chinese healthy volunteers

A rapid, sensitive and reproducible LC–MS/MS method was developed and validated to determine iguratimod in human plasma. Sample preparation was achieved by protein precipitation with acetonitrile. Chromatographic separation was operated on an Ultimate® XB‐C₁₈ column (2.1 × 50 mm, 3.5 μm, Welch) with a flow rate of 0.400 mL/min, using a gradient elution with acetonitrile and water which contained 2 mm ammonium acetate and 0.1% formic acid as the mobile phase. The detection was performed on a Triple Quad™ 5500 mass spectrometer coupled with an electrospray ionization interface under positive‐ion multiple reaction monitoring mode with the transition ion pairs of m/z 375.2 → 347.1 for iguratimod and m/z 244.3 → 185.0 for agomelatine (the internal standard), respectively. The method was linear over the range of 5.00–1500 ng/mL with correlation coefficients ≥0.9978. The accuracy and precision of intra‐ and inter‐day, dilution accuracy, recovery and stability of the method were all within the acceptable limits and no matrix effect or carryover was observed. As a result, the main pharmacokinetic parameters of iguratimod were as follows: C_max, 1074 ± 373 ng/mL; AUC_0–72, 13591 ± 4557 ng h/mL; AUC_0–∞, 13,712 ± 4613 ng h/mL; T_max, 3.29 ± 1.23 h; and t_1/2, 8.89 ± 1.23 h.     

LC‐MS/MS method for the determination of pitolisant: application to rat pharmacokinetic and brain penetration studies

A simple and sensitive LC‐MS/MS method was developed and validated for the quantitation of pitolisant, an H₃ receptor antagonist/inverse agonist. Acetonitrile protein precipitation technique was used to prepare rat blood and brain tissue homogenate samples by using aripiprazole as internal standard (IS). Chromatographic separation was performed by using Xbridge column (2.1 × 50 mm, 3.5 µm) with a gradient elution program. The mobile phase consists of ammonium formate (10 mm ) with 0.2% formic acid and acetonitrile. Multiple reaction monitoring mode was used in positive polarity with a transition of m/z 296.3 → 98.2 for the pitolisant and m/z 448.2 → 285.3 for the IS. The calibration curves were linear in the range of 0.1–100 ng/mL in both the blood and brain homogenate samples. This method was applied to quantify samples obtained from the pharmacokinetic and brain penetration studies in male wistar rats. Mean maximum concentration, area under the curve from zero to infinity and half‐life of the pitolisant were found to be 3.4 ± 1.7 ng/mL, 5 ± 4 ng h/mL and 1.9 ± 0.3 h, respectively, after a 3 mg/kg oral dose. The mean calculated concentrations in the brain were found to be 38, 60 and 52 ng/g at 0.5, 1 and 2 h, respectively. Copyright © 2013 John Wiley & Sons, Ltd.     

Simultaneous determination of the bioactive components in rat plasma by UPLC‐MS/MS and application in pharmacokinetic studies after oral administration of radix Scutellariae extract

A highly sensitive and rapid ultraperformance liquid chromatography–tandem mass spectrometry (UPLC‐MS/MS) method has been developed and validated for simultaneous quantification of the four main bioactive compounds, i.e. baicalin, baicalein, wogonoside and wogonin, in rat plasma after oral administration of Radix Scutellariae extract. Clarithromycin was used as an internal standard (IS). Plasma samples were processed by protein precipitation with methanol. The separation was performed on an Acquity BEH C₁₈ column (100 × 2.1 mm, 1.7 μm) at a flow rate of 0.4 mL/min, using 0.1% formic acid–acetonitrile as mobile phase. The MS/MS ion transit ions monitored were 447.5 → 270.1 for baicalin, 270.1 → 168.1 for baicalein, 461.2 → 284.0 for wogonoside, 284.2 → 168.1 for wogonin and 748.5 → 158.1 for IS. Method validation was performed according to US Food and Drug Administration guidelines and the results met the acceptance criteria. The lower limit of quantification (LLOQ) achieved was 1.13 ng/mL for baicalin, 1.23 ng/mL for baicalein, 0.82 ng/mL for wogonoside and 0.36 ng/mL for wogonin. The calibration curves obtained were linear (r > 0.99) over the concentration range ~ 1–1000 ng/mL. The intra‐ and inter‐day precision was <15% and the accuracy was within ±14.7%. After validation, this method was successfully applied to a pharmacokinetic study of Radix Scutellariae extract.