Revista Brasileira de Farmacognosia 28 (2018) 156–164 ww w.elsevier.com/locate/bjp Original Article Simultaneous determination of six bioactive components of total flavonoids of Scorzonera austriaca in rat tissues by LC-MS/MS: application to a tissue distribution study a,b a a a a Sixi Zhang , Yang Xie , Jing Wang , Yanmei Geng , Yu Zhou , a a,∗ Chengxin Sun , Guangshu Wang a School of Pharmaceutical Sciences, Jilin University, Changchun, PR China b Department of Pharmacy, The First Hospital of Jilin University, Changchun, PR China a b s t r a c t a r t i c l e i n f o Article history: A liquid chromatography-tandem mass spectrometry method was developed and validated for Received 1 September 2017 simultaneous determination of six bioactive constituents including vitexin, orientin, isoorientin, 2 -O- Accepted 5 January 2018 ␤ d - -xylopyranosyl isoorientin, 2 -O-␤-d-xylopyranosyl isovitexin, and 6-C-l-␣-arabipyranosyl vitexin Available online 21 February 2018 in rats’ various tissues using isoquercitrin as the internal standard. Biological samples were pretreated by protein precipitation with acetonitrile. Chromatographic separation was carried out on a C18 col- Keywords: umn with a gradient mobile phase consisting of acetonitrile and 0.1% aqueous formic acid. All analytes Scorzonera austriaca and internal standard were quantitated through electrospray ionization in negative ion selected reaction LC-MS/MS monitoring mode. The mass transitions were as follows: m/z 431 → 311 for vitexin, m/z 447 → 327 for Rat plasma orientin or isoorientin, m/z 579 → 459 for 2 -O-␤-d-xylopyranosyl isoorientin, m/z 563 → 293 for 2 -O-␤- Tissue distribution d -xylopyranosyl isovitexin, m/z 563 → 353 for 6-C-l-␣-arabipyranosyl vitexin, and m/z 463 → 300 for the internal standard, respectively. The lower limits of quantification for the six analytes in different tissue homogenates were 0.8–2.2 ng/ml. The validated assay was successfully applied to a tissue distribution study of the six components in rats after intravenous administration of total flavonoids of Scorzonera aus- triaca Willd; Asteraceae. The results of the tissue distribution study showed that the high concentrations of six components were mainly in the kidney. © 2018 Sociedade Brasileira de Farmacognosia. Published by Elsevier Editora Ltda. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Introduction components, and total flavonoids from S. austriaca elicit significant anti-HBV and hepatoprotective effects (Xie et al., 2015; Zhang Scorzonera austriaca Wild., Asteraceae, is a perennial herb et al., 2015). Based on the previous pharmacological researches, widely distributed in the northwestern regions of China and flavonoids (vitexin (1), orientin (2), isoorientin (3), 2 -O-␤-d- usually recommended for the treatments of fever, enteri- xylopyranosyl isoorientin (4), 2 -O-␤-d-xylopyranosyl isovitexin tis, pregnant vomiting, carbuncle, mastitis, and swelling (Li (5), or 6-C-l-␣-arabipyranosyl vitexin (6)) manifest a variety et al., 1992, 1997). Modern research found that the major of pharmacological properties, including anti-inflammatory, constituents of S. austriaca include flavonoids, sesquiterpenes, anti-tumor, antiplatelet, antithrombotic, neuroprotective, and car- triterpenes, and steroids (Li et al., 2004; Zhu et al., 2009; Wu et al., dioprotective effects (Wang et al., 2015; Lee and Bae, 2015; Liu et al., 2011). Flavonoids are generally regarded as the major bioactive 2016). ∗ Corresponding author. E-mail: [email protected] (G. Wang). https://doi.org/10.1016/j.bjp.2018.01.004 0102-695X/© 2018 Sociedade Brasileira de Farmacognosia. Published by Elsevier Editora Ltda. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/). S. Zhang et al. / Revista Brasileira de Farmacognosia 28 (2018) 156–164 157 Until now, there are several studies were reported the ␤ d determination of vitexin (1), orientin (2), isoorientin (3), 2 -O- - - decreasing A to 5% in 0.5 min, keeping constant for 5 min. The ␤ d xylopyranosyl isoorientin (4), 2 -O- - -xylopyranosyl isovitexin flow rate was 0.80 ml/min with a split ratio of 1:1 and the sam- l ␣ (5), or 6-C- - -arabipyranosyl vitexin (6) separately in biological ple injection volume was 10 ␮l. The total runtime was 20 min for samples with the method of HPLC, HPLC-MS/MS, and UPLC-MS/MS each sample run. (Li et al., 2008a,b; Yan et al., 2013; Huang et al., 2012). In our MS detection was performed on a TSQ Quantum Ultra triple previous investigations, we investigated the pharmacokinetic of quadrupole mass spectrometer (Thermo Scientific, San Jose, CA, these six flavonoid glycosides in rat plasma (Zhang et al., 2017). USA) equipped with an ESI source in the negative ionization mode. − However, simultaneous determination of tissue distributions of The [M–H] ions were used as the precursor for quantification in these six flavonoid glycosides in vivo has not been reported. Here, selected reaction monitoring (SRM) mode. The optimized tube lens a rapid liquid chromatography-tandem mass spectrometry (LC- and collision energy for six analytes and IS are shown in Table 1. MS/MS) method has been developed for the determination of 1, Other parameters of MS analysis were as follows: spray voltage ◦ 2, 3, 4, 5, or 6 in rat tissues after intravenous administration of total 3.0 kV, vaporizer temperature 300 C, sheath gas (nitrogen) pres- flavonoids of S. austriaca. sure, 35 AU; auxiliary gas (nitrogen) pressure, 10 AU; and capillary ◦ TM temperature, 270 C. Xcalibur 2.2 Software was used for acquir- Materials and methods ing and processing data. Preparation of standard and quality control (QC) samples Chemicals and reagents Mixed stock solution containing 200 ␮g/ml of 1 and 2, 80 ␮g/ml Standard substances of 1, 2, 3, 4, 5, and 6 were previously iso- of 3, 220 ␮g/ml of 4, 5, and 6 was prepared in methanol. The stock lated from Scorzonera austriaca Wild., Asteraceae, in our laboratory, solution of the six analytes was diluted with methanol to make and identified by MS and NMR spectra. Total flavonoids of S. aus- a series of composited standard solutions. The stock solution of triaca were prepared as previously described (Zhang et al., 2017), the IS was diluted to a concentration of 200 ng/ml with methanol and the contents of the six components in the total flavonoids as working solution. The samples of standard calibration curves of S. austriaca were assayed by LC-MS/MS as described in Zhang were prepared by spiking 10 ␮l of the above working solutions et al. The internal standard (IS) isoquercitrin (7) was purchased into 190 ␮l of blank tissue homogenate. The concentrations were from the National Institute for the Control of Pharmaceutical and in the range of 2–2000 ng/ml for 1 and 2, 0.8–800 ng/ml for 3, Biological Products (Beijing, China). Acetonitrile and methanol of 2.2–2200 ng/ml for 4, 5, and 6, respectively. QC samples at low, mid- HPLC grade were purchased from Tedia company (Fairfield, OH, dle and high concentrations (4, 50 and 1600 ng/ml for 1 and 2; 1.6, USA). HPLC grade formic acid was obtained from Tianjin Kemiou 20 and 640 ng/ml for 3; 4.4, 55 and 1760 ng/ml for 4, 5, and 6) were Chemical Reagent Co., Ltd. (Tianjin, China). Deionized water was also prepared by the same operation listed above. All standards purchased from Wahaha Co., Ltd. (Hangzhou, China). ◦ were stored at −20 C before analysis. LC-MS/MS conditions Sample preparation ® Chromatographic separation was conducted on a Diamonsil The tissue homogenate sample (50 ␮l) was mixed with 150 ␮l C18 column (4.6 × 250 mm, 5.0 ␮m ID) preceded by a Thermo acetonitrile containing 200 ng/ml isoquercitrin (7). The mixture Universal Filter 4.6/4 mm HPLC precolumn. The gradient elution was then vortex-mixed for 40 s and centrifugation at 14,850 × g ◦ consisted of acetonitrile (mobile phase A) and 0.1% aqueous formic for 10 min at 8 C. The supernatant was transferred into another acid (mobile phase B) was set as follows: starting at 5% A–95%B, clean eppendorf tube and evaporated to dryness under a nitrogen ◦ increasing A to 20% in 5 min, maintaining 20% A for 9.5 min; then stream in a water bath at 45 C. Finally, the residue was dissolved Table 1 MS/MS parameters for quantifications of six analytes and Internal Standard. Analyte Precursor to product ion (m/z) transition Tube lens (V) Collision energy (eV) Vitexin 431 → 311 88 25 Orientin or isoorientin 447 → 327 80 25 2 -O-␤-d-xylopyranosyl isoorientin 579 → 459 102 50 2 -O-␤-d-xylopyranosyl isovitexin 563 → 293 89 38 6-C-l-␣-arabipyranosyl vitexin 563 → 353 109 38 Internal standard 463 → 300 80 30 158 S. Zhang et al. / Revista Brasileira de Farmacognosia 28 (2018) 156–164 ␮ in 80 l of acetonitrile-water (20:80, v/v) with vortex-mixing for and on three consecutive days, respectively. Extraction recovery 20 s, and centrifugation process was repeated. An aliquot of 10 ␮l was assessed by comparing the responses of extracted QC samples was injected into the LC-MS/MS system for analysis. with those of post-extraction blank tissue homogenates spiked with equivalent concentrations using six replicates. The matrix effect was calculated by comparing the peak areas obtained from Method validation samples where the extracted matrix was spiked with standard solutions to those obtained from the pure reference standard According to the FDA bioanalytical method validation guide solutions at the same concentration. Stability studies in different (U.S. Food and Drug Administration, 2001), the LC-MS/MS method tissue homogenate samples were performed at three QC levels was validated in terms of selectivity, sensitivity, linearity, precision under different storage conditions: Short-term temperature and accuracy, matrix effect and extraction recovery, carryover stability was determined by analyzing QC samples left at room and stability.