Quantification of leonurine, a novel potential cardiovascular agent, in rat plasma by liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic study in rats

Leonurine (SCM‐198), an alkaloid from Herba Leonuri, has been suggested as a novel cardiovascular agent by pharmacology studies in preclinical stage. In present study, we report a simple, rapid and sensitive high‐performance liquid chromatography–tandem mass spectrometry method (HPLC‐MS/MS) for determination of leonurine in rat plasma. Leonurine and its internal standard (IS) n‐benzoyl‐l ‐arginine ethyl ester (BAEE) were extracted from plasma samples by one‐step protein precipitation with perchloric acid. Chromatographic separation was performed on an Agilent Zorbax SB‐C₁₈ column (150 × 2.1 mm, 5 µm) using an isocratic elution with acetonitrile–ammonium acetate buffer (10 mm , pH 4.0; 25:75, v/v) as mobile phase at a flow rate of 0.2 mL/min. Analytes were detected by tandem mass spectrometry in positive electrospray ionization (ESI) mode using multiple reaction monitoring (MRM) with the transitions of m/z 312.3 → 181.1 for leonurine and m/z 307.2 → 104.6 for IS. The calibration curves were linear over the range of 4–256 ng/mL with a lower limit of quantitation (LLOQ) of 4 ng/mL. The intra‐ and inter‐day assay precision (as relative standard deviation) were <15%, except which at LLOQ were <20%, with accuracy in the range 98.73‐105.42%. The validated HPLC‐MS/MS method was successfully applied to the pharmacokinetic study in rats following oral administration of leonurine. Copyright © 2011 John Wiley & Sons, Ltd.     

Polystyrene/graphene composite electrode fabricated by in situ polymerization for capillary electrophoretic determination of bioactive constituents in Herba Houttuyniae

A novel graphene/polystyrene composite electrode was developed for the enhanced amperometric detection of CE in this work. The composite electrode was fabricated on the basis of the in situ polymerization of a mixture of graphene and prepolymerized styrene in the bore of a piece of fused‐silica capillary under heat. SEM, XRD, and FTIR offered insights into the nature of the composite. The results indicated that graphenes were well dispersed and embedded throughout the PS matrix to form an interconnected conducting network. The performance of this unique graphene‐based detector has been demonstrated by separating and detecting rutin, isoquercitrin, quercitrin, and chlorogenic acid in Herba Houttuyniae (a traditional Chinese medicine) in combination with CE. The prepared graphene‐based CE detector offered significantly lower detection potential, yielded enhanced signal‐to‐noise characteristics, and exhibited high resistance to surface fouling and enhanced stability. It showed long‐term stability and reproducibility with a relative standard deviation of 3.1% for the peak current (n=15).     

白花蛇舌草中的汞和砷的氢化物发生-原子荧光光谱测定

一次性微波消解法,利用原子荧光光谱法（AFS）对白花蛇舌草中的砷和汞进行测定。结果指出,3个产地白花蛇舌草中砷、汞的相对标准偏差小于3%,加标回收率在95.0%—103.0%的范围内。本法简单、准确,适用于中药材有害重金属的含量检测。     

紫外光分光光度法测定淫羊藿中维生素C的含量

紫外光分光光度法测定淫羊藿中维生素C含量。测定波长为243nm;维生素C浸提剂为1.0%（V/V）盐酸溶液;维生素C浓度在2—50mg/L范围内与吸光度线性关系良好（r=0.9992,n=3）;回收率在97%—115%之间（n=3）;相对标准偏差都小于6.0%（n=3）;检出限（LOD）和定量限（LOQ）分别为1.33mg/L和4.04mg/L。人工栽培的箭叶淫羊藿、天平山淫羊藿和长蕊淫羊藿鲜叶中维生素C的含量不同。     

鸡骨草微量元素含量的测定

用电感耦合等离子体发射光谱仪测定了湛江人工栽培的鸡骨草中微量元素含量,发现其钙、镁、铁、锌等元素的含量都较丰富,并讨论了这些有益元素与人体健康的关系。     

Simultaneous determination of seven phenylethanoid glycosides in Cistanches Herba by a single marker using a new calculation of relative correction factor

Current quantitative analysis of multi‐components by a single marker is usually performed by using liquid chromatography methods coupled with ultraviolet or mass spectrometry detection to afford the relative correction factors between reference standard and other components. However, low durability of the relative correction factors caused by different chromatographic system leading this approach lacking a high accuracy. In the present study, a simple but effective method was established by employing the absorption coefficient () to calculate the relative correction factors instead of peak area or height. The absorption coefficient, a fundamental constant of physics, has been widely used for qualitative and quantitative analysis in Pharmacopoeia all over the world. According to the absorbance coefficient ratio between echinacoside and other compounds, the content of seven phenylethanoid glycosides in Cistanche deserticola and Cistanches tubulosa were determined simultaneously. The low standard method difference on quantitative measurement of seven compounds in Cistanches Herba between our method and the external standard method proved the consistency of the two methods. Using an ultra high performance liquid system, these seven bioactive phenylethanoid glycosides were baseline separated in 8 min. All the data suggested that the method was accurate and reliable for the determination of multi‐components when authentic standard substances were unavailable.     

Simultaneous determination of nine flavonoids and qualitative evaluation of Herba Epimedii by high performance liquid chromatography with ultraviolet detection

A simple high performance liquid chromatographic method has been developed for the determination of nine flavonoids in Herba Epimedii, including quercetin-3-O-glucoside, epimedin A, hexandraside A, epimedin B, epimedin C, icariin, icariside I, icariside II, and icaritin. The chromatographic separation was performed on a Diamonsil C(18) column (5 microm, 250x4.6 mm) with gradient elution by acetonitrile-0.5% acetic buffer (adjusted to pH 5.00 with triethylamine). Methodological validation gave acceptable linearities (r(2) >0.9992) and recoveries (ranging from 98.9 to 102.4%). The limits of detection of these flavonoids ranged from 16.3 to 83.3 ng. The results indicated that the contents of flavonoids in Herba Epimedii varied significantly from habitat to habitat with contents ranging from 0.05 to 39.0 mg/g. Twenty five Herba Epimedii samples prepared from five different botanical materials were investigated by the established method, and the results showed the influence of the botanical material and the habitat on the quality of Herba Epimedii. The proposed method is simple, effective, and suitable for the evaluation of this traditional Chinese medicine.     

反相高效液相色谱法分离测定墨旱莲中的鳢肠醛

对墨旱莲中的有效成分鳢肠醛进行了分离和结构鉴定,并对其含量进行了分析。色谱条件:Kromasil C18柱(200 mm×4.6 mm,5 μm),流动相为乙腈-0.1%磷酸水溶液(体积比为65∶35),流速为1.0 mL/min,柱温为30 ℃,检测波长为365 nm,进样量为10 μL。结果表明,鳢肠醛的峰面积与其质量浓度有良好的线性关系(r=0.9993)。方法的加样回收率为96.7%～100.0%。该方法简便、快速、准确,可作为墨旱莲质量控制的一个有效方法。     

麻黄与桂枝混合汤剂的红外光谱

测试了单味药麻黄、桂枝及麻黄+桂枝混合汤剂红外光谱,标示其吸收峰,并确认其归属。在麻黄+桂枝汤剂中保留了麻黄、桂枝单味药物汤剂中的某些成分,见麻黄+桂枝光谱1 205和1 074 cm-1处等;麻黄、桂枝光谱中的某些成分并未在麻黄+桂枝光谱中出现,见麻黄+桂枝光谱1 394和678 cm-1处等;在麻黄+桂枝汤剂光谱中,出现了新的吸收峰,见麻黄+桂枝光谱757和1 407 cm-1处等。同时,因吸收峰位置有所改变,说明各基团在麻黄、桂枝、麻黄+桂枝汤剂中所处的化学环境不同。在麻黄+桂枝汤剂中可能新生成了麻黄、桂枝单味药物汤剂中所没有的化学成分。麻黄+桂枝汤剂所包含的药物成分并非是单味麻黄、桂枝汤剂所含药物成分的简单相加。文章在研究麻黄+桂枝混合汤剂红外光谱的基础上提出了方剂光谱学的概念。     

秦巴山区中草药钮子七中微量元素的测定

用ICP-AES测定了秦巴山区独有的中草药钮子七中的2种常量营养性元素(钙、镁)和5种微量元素(铜、铬、铁、锌、锰)含量。钙4790.66μg.g-1、镁55.32μg.g-1、铜18.44μg.g-1、铬2.1μg.g-1、铁264.50μg.g-1、锌56.71μg.g-1、锰17.83μg.g-1,回收率均在96.2%—100.5%之间,结果表明,此方法简便、可靠,具有良好的精确度和准确性。并初步讨论了中草药钮子七中有益元素与治疗疾病的关系,并与中药材汉三七中微量元素含量相比较,二者微量元素含量略有差异。