HPLC Quantification of Nine Chemical Constituents from the Five Parts

Transcription

1 Journal of Chromatographic Science 2014;52: doi: /chromsci/bmt021 Advance Access publication April 10, 2013 Article HPLC Quantification of Nine Chemical Constituents from the Five Parts of Abutilon theophrasti Medic. Chunlian Tian, Miao Wang, Xiaokun Liu, Haiping Wang and Chunjie Zhao* Department of Pharmaceutical Analysis, School of Pharmacy, Shenyang Pharmaceutical University, No. 103 Wenhua Road Shenhe Dist , Shenyang Liaoning Prov., People s Republic of China *Author to whom correspondence should be addressed. zcjjljj@sina.com Received 16 March 2012; revised 26 February 2013 A method of reversed-phase high-performance liquid chromatography (RP-HPLC) was established for the simultaneous determination of gallic acid, protocatechuic acid, catechin, vanillic acid, caffeic acid, ferulic acid, rutin, quercetin and syriacusin A in the ethanolic extracts from the five parts (roots, stems, leaves, seeds and exocarps) of Abutilon theophrasti Medic. The nine components in the sample were extracted with 70% ethanol solution in an ultrasonic bath for 25 min and chromatographically separated on a C18 analytical column ( mm i.d., 5 mm) by gradient elution with water containing 0.1% (v/v) formic acid (ph 2.4) and acetonitrile as mobile phases, at a flow rate of 1.0 ml/min. The detection was conducted by ultraviolet-visible absorption. The proposed method showed good linearity between the peak area of each analyte and its concentration. Relative standard deviations of the instrumental intra-day and inter-day precision and method precision were less than 2.0, 3.5 and 2.0%. Recoveries were within the range of %. Limits of detection and quantification were mg/ml (signal-tonoise ratio: 3) and mg/ml (signal-to-noise ratio: 10), respectively. The proposed method was successfully applied to determine common phenols and flavonoids of Abutilon theophrasti Medic. The results indicated that the RP-HPLC system may provide a rapid method for the quality control of Abutilon theophrasti Medic. Introduction Abutilon theophrasti Medic. (Malvaceae) is widespread in China, except for the Tibetan Plateau, and cultivated in northeastern China, Vietnam, India, Japan, Europe and North America. Abutilon theophrasti Medic. has been demonstrated to have multiple pharmacological activities (1 2), such as expelling wind, detoxification and anti-inflammatory effectiveness; it is primarily used for rheumatic pains, arthralgia, bruises, sprains, dysentery, otitis media, tinnitus and deafness treatments. Phenolic compounds are widely found in plants in the form of simple phenols, phenolic acids, flavonoids, coumarins, lignans, lignins and tannins, which have intense antioxidant activity and play an important therapeutic role in antimicrobial, antiallergenic and anti-inflammatory activities. Syriacusin A, a naphthalene compound isolated from the roots of Abutilon theophrasti Medic., which inhibits lipid peroxidation with an IC 50 of 0.54 mg/ml, also shows cytotoxicity against seven human cancer cell lines with an ED 50 of mg/ml (3). Although Abutilon theophrasti Medic. has widely been used as a traditional Chinese medicines (TCM), its correlative research on chemical constituents has been rarely reported. Kaempferol, quercetin 3-O-b-glucopyranoside, p-hydroxybenzoic, p-coumaric, syringic, vanillic, luteolin, chrysoeriol, luteolin 7-O-b-glucopyranoside and other compounds have been isolated from Abutilon theophrasti by thin-layer chromatography (TLC), preparative paper chromatography, cellulose columns, Sephadex LH-20 and spectroscopic methods (4 8). In the roots, stems, leaves, seeds and exocarps of Abutilon theophrasti Medic., gallic acid, protocatechuic acid, catechin, vanillic acid, caffeic acid, ferulic acid, rutin, syriacusin A and quercetin (Figure 1) were generally found to be primary phenol components in an earlier report by Tian et al. (4). Several chromatographic methods, e.g., TLC (5), gas chromatography (GC) (9), high-performance liquid chromatography (HPLC) (10), capillary electrophoresis (CE) (11), GC mass spectrometry (MS) (12), HPLC MS (13) and CE MS (14) have been established for the qualitative and quantitative determination of the phenol and flavonoid components in food, plants and TCMs. Among the previously mentioned chromatographic methods, HPLC is the most popular; its primary advantage is that it can be coupled with many detectors, such as ultraviolet (UV), fluorescence detection (FD), diode array detection (DAD), evaporative light-scattering detection (ELSD) and MS, which provides more possibilities for detecting different types of constituents. Many extraction methods are used for active constituents in TCMs, which include immersion, percolation, decoction, reflux, ultrasonic and supercritical fluid extraction methods; the primary method is solvent extraction. Compared to the previously mentioned extraction methods, the ultrasonic extraction method is regarded as an important method, with simple operation procedures, a short extraction time and less solvent use. However, the majority of previously reported studies on the assay of Abutilon theophrasti Medic. (4 8) focused on the identification of phenols and flavonoid components. Little is known about the quantitative research of chemical constituents from the Abutilon theophrasti Medic. In previous research (4), the phenolic compounds in 70% ethanolic extracts from the five parts (roots, stems, leaves, seeds and exocarps) of Abutilon theophrasti Medic. were screened and identified by reversed-phase (RP) HPLC electrospray ionization (ESI) quadrupole (Q) time of flight (TOF) MS. This study primarily reports an ultrasonic extraction method coupled with an RP-HPLC system for the simple and rapid determination of the major phenols and flavonoids components in the roots, stems, leaves, seeds and exocarps of Abutilon theophrasti Medic. The optimized method is helpful for quality control and to understand the usage and functions of the herb and its # The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please journals.permissions@oup.com

2 Figure 1. Structures of the nine compounds: gallic acid (A); protocatechuic acid (B); catechin (C); vanillic acid (D); caffeic acid (E); ferulic acid (F); rutin (G); quercetin (H); syriacusin A (I). products in research into its antioxidant, antimicrobial, antiallergenic and anti-inflammatory activities. Materials and Methods Apparatus and reagents RP-HPLC analysis was conducted on an Agilent 1100 series chromatograph (Agilent Technologies, Palo Alto, CA) consisting of ChemStation software (version A.09.03), a G1379A degasser, a G1311A QuatPump, a G1313A autosampler (ALS), a G1316A Colcom and a G1314A variable wavelength UV detector (VWD). The nuclear magnetic resonance (NMR) spectra were measured by a Bruker Avance II 300 spectrometer (Bruker Daltonics, Bremen, Germany), with [ 2 H 1 ] chloroform (CDCl3) as solvent. RP-HPLC separation was performed on a Diamonsil C18 analytical column ( mm i.d., 5 mm; Dalian Zhonghuida, China). HPLC-grade acetonitrile and methanol were purchased from Caledon Laboratories (Georgetown, Ontario, Canada). Ultrapure water was purchased from Hangzhou Wahaha Group. Formic acid was of chromatographic grade (Dima Technology, Beijing, China). Standards of gallic acid, protocatechuic acid, catechin, vanillic acid, caffeic acid, ferulic acid, rutin and quercetin (HPLC purity. 98.0%) were purchased from National Institutes for Food and Drug Control, except syriacusin A (HPLC purity. 98.5%), which was separated from the root of Abutilon theophrasti Medic. The structures of the nine compounds are provided in Figure 1. Sample preparation The five parts (roots, stems, leaves, seeds and exocarps) of Abutilon theophrasti Medic. were collected from Jilin province in China (Number ) and authenticated by Professor Jingming Jia of Shenyang Pharmaceutical University. Ten, 10, 0.5, 10 and 2.5 g of the finely ground powder from the roots, stems, leaves, seeds and exocarps, respectively, were accurately weighed and extracted in a two-step extraction (each for 30 min) with 200, 200, 10, 200 and 50 ml of 70% ethanol solution by ultrasound. The extracts were filtered and the filtrate was dried by vacuum rotary evaporation to yield a solid residue. The residue was dissolved with 5 ml of HPLC grade methanol and filtered through a 0.45 mm membrane filter before analysis, yielding crude extracts of the five parts. RP-HPLC separation procedure The five crude extracts were separately analyzed on the Diamonsil C18 column. The column temperature was set at 308C. The detection wavelength was 268 nm. The mobile phases A and B consisted of water containing 0.1% (v/v) formic acid ( ph 2.4) and acetonitrile, respectively. The gradient program was as follows: from 5 to 15% B in 10 min, 15 to 19% in 16 min and 19 to 70% in 29 min. A 10 min re-equilibration time was used after each analysis. The flow rate was 1.0 ml/min and 20 ml of the sample solution was injected in each run. Method validation Calibration curves A stock solution containing nine reference compounds was prepared and diluted to appropriate concentrations (six points) to construct the calibration curves. Each concentration of the mixed standard solution was injected in duplicate and the calibration curves were constructed by plotting the peak area versus the concentration of each analyte. The concentration HPLC Quantification of Nine Chemical Constituents from the Five Parts of Abutilon theophrasti Medic. 259

3 range for each constituent was as follows: gallic acid, mg/ml; protocatechuic acid, mg/ml; catechin, mg/ml; vanillic acid, mg/ml; caffeic acid, mg/ml; ferulic acid, mg/ml; rutin, mg/ml; quercetin, mg/ml; syriacusin A, mg/ml. Limits of detection quantification Sensitivity was evaluated by determining the limit of detection (LOD) and the limit of quantification (LOQ). The stock solution containing nine reference compounds was diluted to a series of appropriate concentrations and an aliquot of the diluted solutions was injected into HPLC for analysis. The values of LOD and LOQ under the present chromatographic conditions were determined at a signal-to-noise ratio (S/N) of approximately 3 and 10, respectively. Precision, accuracy, repeatability and stability Intra-day and inter-day variations were chosen to determine the precision of the developed method. For the intra-day variability test, the mixed standard solutions were analyzed for six replicates within one day, whereas for the inter-day variability test, the solutions were examined in duplicate for three consecutive days. Variations were expressed by relative standard deviation (RSD). The recovery was used to evaluate the accuracy of the method. A known amount of standards was added to a certain amount (80, 100 and 120% of the expected value) of each constituent in the sample. The mixture was extracted and analyzed using the previously described method. Three replicates were performed for the test. To confirm the repeatability, six replicates of the same samples were extracted and analyzed as described previously. The RSD value was calculated as a measurement of method repeatability. A stability study was performed with the same sample solutions after storage at room temperature for 2, 4, 6, 8 and 12 h. Variations were expressed as RSDs. Statistical analysis One-way analysis of variance (ANOVA), performed by SPSS (version 13.0) software package for Windows (SPSS Inc., Chicago, IL), was used to estimate the overall significance. A probability level of 5% ( p 0.05) was considered to be significant. Separation procedure of syriacusin A Syriacusin A (4) was separated by silica gel and Sephadex LH-20 columns. Figure 1 shows the structural formulae of Syriacusin A. Results and Discussion Preparation of samples Considering the literature (15 17) about the determination of phenol compounds from different foods and plants, experimental experience and preliminary studies to efficiently release nine analytes from complex matrices, four factors were investigated, which were closely connected with extraction capacities (Table I), including concentrations of ethanol, quantity of ethanol, extraction time, and the times of extraction. For the comprehensive analysis of the nine analytes, it was found that Table I Selected Factors and Levels Levels Factors A B C D Concentration of alcohol Quantitation of solvent Extraction time Extraction time (times*) (min) (times) *Times: volume of solvent (ml) / weight of sample (g). 0% alcohol, 20 times solvent, extraction for 30 minutes and 2 times (A 3 B 3 C 2 D 2 ) of the extraction process exhibited the best performance. There is a significant difference in Factor A for the nine compounds, but the other three factors have no significant difference. Optimization of HPLC condition Because of baseline drift with methanol, acetonitrile was selected as the organic phase of the mobile phase. Considering the symmetry factor and resolution, water containing 0.1% (v/v) formic acid (ph 2.4) was optimized as the aqueous phase from 0, 0.05 and 0.1% (v/v) formic acid and 0.05, 0.1 and 0.2% (v/v) acetic acid. For better separation and quantitative determination in this study, the gradient elution procedures were improved, but the composition of the mobile phase was the same as in the study by Tian et al. (4). The detection wavelength of 268 nm was chosen by comparing 254, 268, 346 and 450 nm. Chromatograms of the standard solution and samples of roots, stems, leaves, seeds and exocarps of Abutilon theophrasti Medic. at a wavelength of 268 nm are shown in Figure 2. Method validation Calibration, LOD and LOQ Calibration graphs corresponding to gallic acid, protocatechuic acid, catechin, vanillic acid, caffeic acid, ferulic acid, rutin, quercetin and syriacusin A have shown good linearity function responses, indicated by a determination coefficient (r) value The LOD of the nine compounds varied from to mg/ml and the LOQ ranged from to mg/ml (Table II). Precision, accuracy, repeatability and stability RSD values corresponding to the instrumental intra-day and inter-day precision are listed in Table II. They were less than 2.0 and 3.5%, respectively. The results of the recovery for accuracy are shown in Table III. The overall recoveries ranged from 87.3 to 100.8% and the RSD ranged from 0.87 to 3.4%. The reproducibility of the quantification of the nine analytes, expressed as the RSD, was less than 2.0%. It was also found that the analytes in the sample solution were stable for 12 h with RSD of %. 260 Tian et al.

4 Figure. 2 Chromatograms of Abutilon theophrasti Medic. at a wavelength of 268 nm: standard solution (A); root sample (B); stem sample (C); leaf sample (D); seed sample (E); exocarp sample (F). Peaks: gallic acid (1), protocatechuic acid (2), catechin (3), vanillic acid (4), caffeic acid (5), ferulic acid (6), rutin (7), quercetin (8) and syriacusin A (9). Retention times in Figure 2A are as follows: 5.74 min (1), 8.82 min (2), min (3), min (4), min (5), min (6), min (7), min (8) and min (9). Table II Calibration, LOD, LOQ, Precision, Accuracy, Repeatability and Stability of the Nine Analytes Compounds Calibration curves* Correlation coefficient (r) SD of calibration curves Linear range LOD LOQ Intra-day precision Inter-day precision Repeatability Gallic acid Y ¼ 49.63X Protocatechuic Y ¼ 12.84X acid Catechin Y ¼ 8.596X Vanillic acid Y ¼ 56.14X Caffeic acid Y ¼ 36.05X Ferulic acid Y ¼ 31.14X Rutin Y ¼ 30.66X Quercetin Y ¼ 12.99X Syriacusin A Y ¼ 24.28X *Y ¼ ax þ b, where Y is the response (peak area), a is the slope, b is the intercept and C is the concentration of the nine analytes. Stability Sample assay The validated method was developed for the simultaneous determination of nine components from the roots, stems, leaves, seeds and exocarps of Abutilon theophrasti Medic. The results of quantitative analyses are shown in Table IV. Samples of the leaves showed high percentages of rutin, catechin, caffeic acid, ferulic acid, rutin and quercetin, whereas gallic acid, protocatechuic acid, vanillic acid and syriacusin A were rich in the exocarp samples, but the contents of the compounds were lower in the seeds. The results indicate a wide distribution of the nine compounds within the organs of the plant, which may explain the differences in antioxidant activities (18, 19). HPLC Quantification of Nine Chemical Constituents from the Five Parts of Abutilon theophrasti Medic. 261

5 Table III Results of Recovery and Repeatability Tests (n ¼ 3) Compounds Background Added (mg/ ml) Found Recovery Structural identification of Syriacusin A Syriacusin A (4) was identified by ESI-Q-TOF-MS, 1 H-NMR (CDCl 3, 300 MHz) and 13 C-NMR (CDCl 3, 300 MHz). Concluding Remarks Although some studies have been conducted over the past few decades regarding the chemical compositions and biological activities of Abutilon theophrasti Medic., few studies have focused on the assay of the primary metabolites, such as phenols and flavonoids. In this work, an RP-HPLC method was developed for the simultaneous determination of nine common phenols, flavonoids and a naphthalene compound from the roots, stems, leaves, RSD Gallic acid Protocatechuic acid Catechin Vanillic acid Caffeic acid ND* Ferulic acid Rutin Quercetin Syriacusin A *Not detected. Table IV Contents of the Nine Compounds in Real Samples* Compounds Roots Stems Leaves Seeds Exocarps Gallic acid ND ND ND Protocatechuic acid Catechin Vanillic acid ND Caffeic acid ND ND ND Ferulic acid ND Rutin , Quercetin Syriacusin A *Mean + SD (n ¼ 3). Not detected. seeds and exocarps of Abutilon theophrasti Medic., which is widely applied for rheumatic pains, dribbling urination, otitis media and other diseases. The chromatographic conditions were optimized carefully, including the formic acid concentration, the ph value, the detection wavelength and the programmed gradient elution; thus, favorable peak symmetry and resolution were achieved within 55 min. The developed method was successfully applied to the qualitative and quantitative assay of chemical constituents from the five parts of Abutilon theophrasti Medic. The method proved to be rapid, simple and routinely manageable, and it may provide technical support for quality appraisal and pharmacological and clinical research. References 1. Fu, C.D., Hong, Y.F.; Research on chemical composition of Abutilon theophrasti Medic.; Foreign Medical Science, (1993); 15: Gu, G.Y., Jiang, Y.; Research on chemical composition and pharmacological action of Abutilon indicum and Abutilon; Modern Pharmacy and Clinic, (2009); 24: Yoo, I.D., Yun, B.S., Lee, I.K., Voo, I.J., Choung, D.H., Han, K.H.; Three naphthalenes from root bark of hibiscus syriacus; Phytochemistry, (1998); 47: Tian, C.L., Wang, M., Shen, C.H., Zhao, C.J; Accuracy mass screening and identification of phenolic compounds from the five parts of Abutilon theophrasti Medic. by reverse phase high performance liquid chromatography-electrospray ionization quadrupole-time of flight mass spectrometry; Journal of Separation Science, (2012); 35: Sikorska, M., Matlawska, I.; Polyphenolic compounds from Abutilon grandiflorum leaves; Acta Poloniae Pharmaceutica Drug Research, (2008), 65: Matlawska, I., Sikorska, M.; Flavonoid compounds in the flowers of Abutilon indicum (L.) sweet (Malvaceae); Acta Poloniae Pharmaceutica Drug Research, (2002); 59: Matlawska, I., Sikorska, M.; Flavonoid from Abutilon theophrasti flowers; Acta Poloniae Pharmaceutica Drug Research, (2005); 62: Hussain, M., Zahra, D.N., Hussain, S.M.S., Ahmed, E., Ahmad, I., Malik, A., et al.; Structure determination of new steroids from Abutilon pakistanicum by NMR techniques; Magnetic Resonance in Chemistry, (2008); 46: Liu, C.Y., Hu, C.C., Chen, J.L., Liu, K.T.; Metallomesogens as stationary phases for the separation of phenols by gas chromatography; Analytica Chimica Acta, (1999); 384: Yang, L., Wang, Z.T., Xu, L.S.; Simultaneous determination of phenols (bibenzyl, phenanthrene, and fluorenone) in Dendrobium species by high-performance liquid chromatography with diode array detection; Journal of Chromatography A, (2006); 1104: Lee, I.S.L., Boyce, M.C., Breadmore, M.C.; A rapid quantitative determination of phenolic acids in Brassica oleracea by capillary zone electrophoresis; Food Chemistry, (2011); 127: Minuti, L., Pellegrino, R.; Determination of phenolic compounds in wines by novel matrix solid-phase dispersion extraction and gas chromatography/mass spectrometry; Journal of Chromatography A, (2008); 1185: Maldini, M., Montoro, P., Pizza, C.; Phenolic compounds from Byrsonima crassifolia L. bark: Phytochemical investigation and quantitative analysis by LC-ESI MS/MS; Journal of Pharmaceutical and Biomedical Analysis, (2011); 56: Sawalha, S.M.S., Roma n, D.A., Carretero, A.S., Gutiérrez, A.F.; Quantification of main phenolic compounds in sweet and bitter orange peel using CE MS/MS; Food Chemistry, (2009); 116: Simirgiotis, M.J., Schmeda-Hirschmann, G.; Determination of phenolic composition and antioxidant activity in fruits, rhizomes and leaves 262 Tian et al.

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