applied sciences Article Development and Validation of a HPLC–PDA Method for the Simultaneous Determination of Berberine, Palmatine, Geniposide, and Paeoniflorin in Haedoksamul-tang Beom-Geun Jo 1, Kyung-Hwa Kang 2,* and Min Hye Yang 1,* 1 College of Pharmacy, Pusan National University, Busan 46241, Korea; [email protected] 2 Department of Physiology, College of Korean Medicine, Dongeui University, Busan 47227, Korea * Correspondence: [email protected] (K.-H.K.); [email protected] (M.H.Y.); Tel.: +82-51-890-3309 (K.-H.K.); +82-51-510-2811 (M.H.Y.); Fax: +82-51-853-4036 (K.-H.K.); +82-51-513-6754 (M.H.Y.) Received: 11 July 2020; Accepted: 6 August 2020; Published: 7 August 2020 Abstract: Haedoksamul-tang (HST) is a traditional medical prescription comprising eight medicinal herbs: Angelica gigas, Cnidium officinale, Coptis japonica, Gardenia jasminoides, Paeonia lactiflora, Phellodendron amurense, Rehmannia glutinosa, and Scutellaria baicalensis. HST is used to treat blood circulation disorders and has anti-inflammatory, hemostatic, and anticonvulsant effects. In this study, a high-performance liquid chromatography/photodiode array detector (HPLC–PDA) method was developed and validated for the simultaneous determination of four marker compounds in HST, namely, berberine, palmatine, geniposide, and paeoniflorin. Four standard solutions and HST sample solutions were analyzed using a reverse-phase SunFire®C column (4.6 250 mm, 18 × 5 µm) using a 0.05% aqueous formic acid/methanol gradient. The column temperature, flow rate, injection volume, and wavelengths used were 28 2 °C, 1.0 mL/min, 10.0 µL, and 230 nm and 240 nm, ± respectively. Calibration curves of the four marker compounds showed good linearity (r2 0.9994), ≥ and limits of detection (LODs) and quantification (LOQs) were in the ranges 0.131–0.296 µg/mL and 0.398–0.898 µg/mL, respectively. Ranges of intra- and inter-day precisions and accuracies values were 96.74–102.53% and 97.95–100.83%, respectively, and relative standard deviation (RSD) values were all <4%. Recoveries averaged 92.33–116.72% with RSD values <5%. Quantitative analysis for the four marker compounds showed geniposide (10.77 mg/g) was most abundant in HST. Keywords: Haedoksamul-tang; traditional medical prescription; HPLC-PDA; geniposide 1. Introduction Haedoksamul-tang (HST), also known as Onchungeum in Korea, Wen-Qing-Yin in China, and Unsei-in in Japan, is a traditional medical prescription comprising Hwangryunhaedok-tang (HHT) and Samul-tang (SMT). According to the Donguibogam (principles and practice of eastern medicine), HST has been traditionally used to treat abnormal uterine bleeding and abdominal pain in women or to treat flooding accompanied by a yellowish complexion, stomach aches, and alternating chills [1]. According to several studies, HST exhibits diverse therapeutic effects on inflammation [2–7], atopic dermatitis [8–11], blood stasis [12,13], Behcet’s syndrome [14,15], hyperlipidemia [16], and oxidative stress [17–20]. HST consists of eight medicinal herbs: Angelica gigas (Apiaceae), Cnidium officinale (Umbelliferae), Coptis japonica (Ranunculaceae), Gardenia jasminoides (Rubiaceae), Paeonia lactiflora (Paeoniaceae), Phellodendron amurense (Rutaceae), Rehmannia glutinosa (Orobanchaceae), and Scutellaria baicalensis Appl. Sci. 2020, 10, 5482; doi:10.3390/app10165482 www.mdpi.com/journal/applsci Appl. Sci. 2020, 10, 5482 2 of 9 (Lamiaceae). The major components of the eight medicinal herbs in HST are: flavones (e.g., baicalin, wogonin, and baicalein) from Scutellaria baicalensis [21], alkaloids (e.g., berberine, palmatine, coptisine, jatrorrhizine, and epiberberine) from Coptis japonica [22], alkaloids (e.g., palmatine, phellodendrine, magnoflorine, and berberine) from Phellodendron amurense [23], iridoids (e.g., geniposide, genipin, genipin-1-β gentiobioside, and geniposidic acid) from Gardenia jasminoides [24], iridoids (e.g., catalpol) from Rehmannia glutinosa [25], coumarins (e.g., decursin, decursinol, decursinol angelate, and nodakenin) from Angelica gigas [26], monoterpenoids (e.g., paeoniflorin, albiflorin, benzoylpaeoniflorin, and oxypaeoniflorin) and phenols (e.g., paeonol and (+)-catechin) from Paeonia lactiflora [27], and phthalides (e.g., senkyunolideA, Z-ligustilide, and Z-butylidenephthalide) and ferulic acid from Cnidium officinale [28]. Qualitative and quantitative analyses of HHT and SMT by high-performance liquid chromatography (HPLC) using photodiode array (PDA) detectors have been previously reported [29–32]. Recently, a method for simultaneous quantification of six biomarkers (berberine, baicalin, ferulic acid, geniposide, hydorxymethoxylfurfural, and paeoniflorin) in HST by high-performance liquid chromatography/diode array detector (HPLC-DAD) was developed [33]. However, analysis results depended on geographic sources and cultivation environments, and the analysis data was inadequate for standardizing HST quality. In the present study, we devised and validated a HPLC-PDA method for the simultaneous determination of four biomarkers in HST (berberine from Coptis japonica, palmatine from Phellodendron amurense, geniposide from Gardenia jasminoides, paeoniflorin from Paeonia lactiflora). 2. Materials and Methods 2.1. Plant Materials and Chemicals Scutellaria baicalensis was purchased from Hyunjin pharmaceutical Corp., Coptis japonica from Miryung herb medicine Ltd., Gardenia jasminoides, Phellodendron amurense, and Rehmannia glutinosa from Taechang pharmaceutical Corp., Angelica gigas, Cnidium officinale, and Paeonia lactiflora from Jechen traditional herbal market. All herbal materials were authenticated by Professor Eun Ju Jeong of the Department of Agronomy and Medicinal Plant Resources at Gyeongnam National University of Science and Technology (Jinju, South Korea). Voucher specimens (PNU-0028~PNU-0035) were deposited at the College of Pharmacy, Pusan National University. Geniposide was isolated from G. jasminoides by column chromatography in our laboratory and used as a reference standard. The structure of geniposide was determined by nuclear magnetic resonance (NMR) [34], and their purities by HPLC ( 98.0%). Other reference standards: berberine ≥ ( 98.0%), palmatine ( 98.0%), and paeoniflorin ( 98.0%) were purchased from ChemFaces Biochemical ≥ ≥ ≥ Co., Ltd. (Wuhan, China). Water, acetonitrile, methanol (Honeywell Burdick and Jackson, Muskegon, MI, USA), and formic acid (DAEJUNG Chemicals & Metals Co., Ltd., Siheung-si, Korea) were of HPLC grade. 2.2. Preparation of Haedoksamul-Tang (HST) Extract The eight herbal materials (100 g of each) were mixed and crushed for HST extraction, and then extracted for 3 h in 8 L of distilled water using an ultrasonic extractor. The extract was passed through filter paper (Advantec, Tokyo, Japan), concentrated under vacuum at 50 ◦C, and freeze-dried. The lyophilized HST extract was sieved to a particle size of <0.425 mm with a standard sieve and 117.6 g of HST (hereafter referred to as HST) was obtained (yield, 14.7%). 2.3. Preparation of Samples and Standard Solutions Sample solutions contained HST (40.0 mg) dissolved in distilled water at a concentration of 20.0 mg/mL, and then sonicated for 10 min at room temperature and filtered through a 0.5 µm polytetrafluoroethylene (PTFE) syringe filter (13JP050AN, Advantec, Tokyo, Japan) prior to injection. Appl. Sci. 2020, 10, 5482 3 of 9 Appl. Sci. 2020, 10, x 3 of 9 StandardStandard stockstock solutionssolutions of thethe fourfour referencereference standardsstandards (Figure(Figure1 ),1), berberine, berberine, palmatine,palmatine, geniposide,geniposide, and and paeoniflorin paeoniflorin,, were were prepared prepared at concentrations at concentrations of 500.0 of 500.0μg/mL,µg 500.0/mL, μg/mL, 500.0 µ 1000.0g/mL, 1000.0μg/mL,µ gand/mL, 1000.0 and 1000.0 μg/mLµ,g respectively,/mL, respectively, in methanol. in methanol. All solutions All solutions were were stored stored in a refrigerator in a refrigerator at 4 at°C 4 until◦C until required required for analysis. for analysis. Figure 1.1. Chemical structures of standard compounds.compounds. 2.4. High-Performance Liquid Chromatography–Photodiode Array (HPLC–PDA) Equipment and Chromatographic2.4. High-Performance Conditions Liquid Chromatography–Photodiode Array (HPLC–PDA) Equipment and Chromatographic Conditions Simultaneous analysis of the berberine, palmatine, geniposide, and paeoniflorin in HST was Simultaneous analysis of the berberine, palmatine, geniposide, and paeoniflorin in HST was performed using a Waters Alliance system (Waters Corporation, Milford, MA 01757, USA) consisting performed using a Waters Alliance system (Waters Corporation, Milford, MA 01757, USA) consisting of an e 2695 separation module and a 2998 photodiode array (PDA) detector. All chromatographic of an e 2695 separation module and a 2998 photodiode array (PDA) detector. All chromatographic data were recorded and analyzed using Empower three chromatography data software. The four data were recorded and analyzed using Empower three chromatography data software. The four components were separated using a reverse-phase SunFire® C18 column (100 Å, 4.6 250 mm ID, components were separated using a reverse-phase SunFire® C18 column (100 Å, 4.6 × ×250 mm ID, 5 5 µm particle size, Waters), which was maintained at 28 2 °C. The mobile phase consisted of 0.05% μm particle size, Waters), which was maintained at 28 ± 2 ℃. The mobile phase consisted of 0.05% (v/v) formic acid in water (A) and methanol (B); solvents were degassed prior to analysis. The optimum (v/v) formic acid in water (A) and methanol