Chemical Influence of Scutellaria baicalensis—Coptis chinensis Pair on the Extraction Efficiencies of Flavonoids and Alkaloids at Different Extraction Times and Temperatures
1
Department of Korean Medical Science, School of Korean Medicine, Pusan National University, Yangsan 50612, Republic of Korea
2
Division of Pharmacology, School of Korean Medicine, Pusan National University, Yangsan 50612, Republic of Korea
*
Author to whom correspondence should be addressed.
Separations 2023, 10(2), 131; https://doi.org/10.3390/separations10020131
Submission received: 30 January 2023
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Revised: 10 February 2023
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Accepted: 13 February 2023
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Published: 15 February 2023
Abstract
:The Scutellaria baicalensis—Coptis chinensis pair is an herbal combination used for the treatment of various heat-related diseases. During the extraction process, two herbs can mutually influence the extraction efficiency of the chemical constituents contained in each herb. The concentrations of five flavonoids from S. baicalensis and seven alkaloids from C. chinensis were compared in paired or single hot-water extracts at different temperatures (80, 90, and 100 °C) and extraction times (60, 90, and 120 min). Temperature- and time-dependent increases in marker compound concentrations were observed in both paired and single extracts, with the exception of baicalin, berberine, and coptisine in the paired extracts at 100 °C. However, the extractions of the compounds in the paired and single extracts were affected differently by the extraction conditions. Furthermore, the concentrations of most marker compounds in single extracts were 1.09–44.13 times those in paired extracts. The contents of baicalin, wogonoside, coptisine, and berberine, known to be easily aggregated by the flavonoid–alkaloid complex, were changed by 0.024–0.764-fold in the paired extract. The effect of extraction temperature and time on the formation of the flavonoid–alkaloid complex was not significant. The extraction efficiency of the flavonoids and alkaloids can be affected by the pair of S. baicalensis—C. chinensis, which is a primary factor in the chemical modification of two herb-containing herbal extracts.
1. Introduction
The roots of Scutellaria baicalensis Georgi (Lamiaceae) (SB) and the rhizomes of Coptis chinensis Franch. (Ranunculaceae) (CC) have been used to treat heat-induced disorders [1] and are a fundamental pair unit that constitutes diverse traditional herbal formulas [2,3,4,5]. The SB–CC pair also exhibits pharmacologically beneficial effects on diabetes mellitus by increasing intestinal disaccharidase activity [6], decreasing toll-like receptor expression [7], and regulating the gut microbiota [8]. Baicalin and berberine, for example, are chemical constituents extracted from the SB and CC and are known to play a significant role in these pharmacological effects [6,9].
The extraction efficiency of the constituents depends on the extracting conditions, such as temperature, time, sample/solvent ratio, and solvent composition. The extraction yields of the constituents are primarily influenced by the temperature, time, and apparatus [10,11,12]. Previous research on SB or CC has also compared different extraction parameters to maximize extraction yields by extracting methods, moisture content, molar ratio, temperature, and time [13,14,15].
The compatibility of the SB–CC pair is also a cause for concern, as their combination can alter the chemical or biological properties of a single SB or CC. The SB–CC combination, compared with single herbs, was found to have a more protective effect against ulcerative colitis and higher microbial diversity in the intestine [16]. A synergistic effect of SB–CC complex has also been observed in animal experiments on mice with irritable bowel syndrome that was better than the effects of the sum of berberine and baicalin [17]. Moreover, through proteomic analysis, the administration of SB–CC pair showed differently expressed protein profiling compared to their single herbs [18].
However, studies on how the extract conditions or herbal pair affect the extraction efficiencies of the marker compounds from SB or CC water extracts have not been reported. Nonetheless, it is thought that the same extraction parameters can have a different effect on the constituent extraction efficiencies of single herbs or their herbal pair.
Therefore, the chemical effects of time and temperature on the extraction efficiencies of twelve marker compounds from SB and CC are investigated using high-performance liquid chromatography and multiple regression analysis in both paired extracts of two herbs and their single extracts. Furthermore, the difference in the marker compound yields from each extract of SB or CC are compared to those of their paired extracts to determine the chemical influence of the herbal pair on the properties of the extracted solution.
2. Materials and Methods
2.1. Chemicals and Reagents
Acetonitrile and water (both HPLC grade) were purchased from J.T. Baker Inc. (Phillipsburg, NJ, USA). Chrysin 6-C-arabinoside 8-C-glucoside (1), magnoflorine (2), columbamine (4), epiberberine (5), jatrorrhizine (6), coptisine (7), wogonoside (8), palmatine (9), wogonin (11), and oroxylin A (12) (all purities ≥ 98%) were purchased from ChemFaces (Wuhan, Hubei, China). Baicalin (3, 95%), berberine (10, 98%), and trifluoroacetic acid (TFA) were purchased from Sigma-Aldrich (St. Louis, MO, USA). The chemical structures of the twelve marker compounds are shown in Figure S1 in the Supplementary File.
The roots of S. baicalensis Georgi (Yeosu, Republic of Korea) and the rhizomes of C. chinensis Franch. (Sichuan, China) were purchased from Kwangmyungdang Medicinal Herbs (Ulsan, Republic of Korea) and authenticated by the author (J.H. Kim). The voucher specimens (2022-PNUKM-SB01 and CC01) were deposited at the School of Korean Medicine, Pusan National University.
2.2. Sample Preparation
Sliced SB (20 g) and CC (20 g) were extracted separately for the single herbal extraction. The paired herbal extraction was obtained by extracting a total of 40 g of SB and CC with a 1:1 weight ratio. Both groups were extracted with 500 mL distilled water using a heating mantle (MS-DM; Misung Scientific Co., Ltd., Seoul, Republic of Korea) for 60, 90, and 120 min at 80 °C, 90 °C, and 100 °C, respectively. The extracts were cooled to room temperature (20 °C) and were filled up to 500 mL with distilled water. One milliliter of each decoction was centrifuged for 2 min at 13,000 rpm and filtered through a 0.2 μm syringe filter (BioFact, Daejeon, Korea). The filtrate (250 μL) was diluted with 750 μL of distilled water prior to the HPLC analysis.
2.3. Chromatographic Conditions
An Agilent 1200 liquid chromatography system (Agilent Technologies, Palo Alto, CA, USA) with an autosampler, degasser, quaternary solvent pump, and diode array detector (DAD) was used for the quantitative analysis. Chemstation software was used to process the data (ver. B. 04. 03; Agilent Technologies, Inc., Santa Clara, CA, USA). The twelve marker compounds were separated on the ADME column (4.6 mm × 250 mm, 5 μm; Shiseido, Tokyo, Japan) at 30 °C. The flow rate was 1 mL/min, and the injection volume was 10 μL. The mobile phase comprised 0.1% TFA aqueous solution (A) and acetonitrile (B), and the gradient elution was applied as follows: 18–33% (B) for 0–50 min, 33–55% (B) for 50–60 min, 55–55% (B) for 60–62 min, and then re-equilibrated with 18% (B) until the end of the analysis. The detection wavelengths of the DAD were set as follows: 275 nm for chrysin 6-C-arabinoside 8-C-glucoside, magnoflorine, baicalin, wogonoside, wogonin, and oroxylin A; 345 nm for columbamine, jatrorrhizine, palmatine, and berberine; and 355 nm for epiberberine and coptisine.
2.4. Analytical Method Validation
For the calibration curves of the twelve marker compounds, stock solutions at a concentration of 1000 μg/mL were serially diluted to make seven working solutions. Within the linear ranges of concentrations, the correlation coefficients (r2) were used to assess the linearity of each calibration curve. The signal-to-noise (S/N) ratios of 3 and 10 were used to determine the limits of detections (LODs) and the limits of quantifications (LOQs).
The repeatability of the analytical methods was determined by analyzing a working solution three times in one day for intraday precision and analyzing it for three days in a row (interday precision). The precisions were expressed as a percentage of the relative standard deviation (RSD): RSD (%) = [(SD/mean) × 100].
The accuracy of the method used was determined by adding known concentrations of marker compounds to the water extracts and calculating the recoveries of the added concentrations as follows: Recovery (%) = [(detected concentration − initial concentration)/spiked concentration] × 100. The results of chromatographic conditioning and method validation are shown in Table S1 in the Supplementary File.
2.5. Statistical Analysis
Tukey’s test was used to compare differences in marker compound concentrations between the paired and single extracts, as well as between different extraction conditions (temperatures and times) in each of the paired or single extracts, with significance set at p < 0.05, p < 0.01, and p < 0.001.
Multiple regression analysis with two variables (extraction temperatures and times) and a response (the concentrations of the marker compounds) via a second-order polynomial model was used to determine the effects of extraction time and temperature on the concentrations of the marker compounds in both paired and single extracts. With significance at p < 0.05, p < 0.01, and p < 0.001, the regression coefficient was used to represent the influence of extraction time and temperature. The estimated second-order polynomial equations of the marker compounds were visualized using a 3-D response surface plot. Tukey’s test, multiple regression analysis, and 3-D plots were all performed using the open-source software R (ver. 4.1.2; The R Foundation for Statistical Computing, Vienna, Austria).
3. Results and Discussion
3.1. Differences of the Marker Compound Concentrations by Paired or Single Extraction
Extraction temperature and extraction time are the most influential factors in heat-mediated extraction [12,19]. It was hypothesized that various extraction temperatures and times could affect the extraction efficiencies of the marker compounds between a single herb and herbal pair differently.
The contents of chrysin 6-C-arabinoside 8-C-glucoside increased time-dependently in single extracts at 80 °C, peaking at 90 min and 90 °C. Baicalin content was highest at 120 min and 80 °C and at 90 min and 90 °C, compared to 60 min at each temperature. At 120 min, the contents of columbamine showed significant time-dependent increases at all temperatures, as well as temperature-dependent increases at 60 and 120 min. At 100 °C, epiberberine content was highest at 60 min and at 120 min at both 80 °C and 90 °C. Jatrorrhizine, coptisine, and berberine showed similar temperature-dependent increases in concentrations at 60 and 90 min, and jatrorrhizine and berberine showed maximum levels of concentrations at 120 min compared to 60 min at all temperatures. The contents of wogonoside were mostly proportional to temperature increase, especially at 100 °C, whereas the contents of palmatine increased in a temperature- and time-dependent manner in all extraction conditions. In all extraction times, both wogonin and oroxylin A showed significantly higher concentrations at 100 °C compared to those at 80 °C, with a significant time-dependent increase at 100 °C (Table 1).
The concentrations of chrysin 6-C-arabinoside 8-C-glucoside in the paired extracts were significantly proportional to the increase in extraction time at 80 °C and 90 °C, as well as proportional to the increase in temperature at 60 min, with the exception of the highest temperatures at 90 min and 120 min. Magnoflorine was found to have the highest concentrations at 100 °C with various extraction times; jatrorrhizine and wogonoside were highest at 60 and 120 min; palmatine was highest at 90 min and 120 min; and oroxylin A was highest at 60 min. Columbamine and epiberberine concentrations increased proportionally to the increase in extraction time at 80 °C and the increase in temperature at 60 min, respectively. The concentration of wogonin increased in direct proportion to the increase in temperature. The concentrations of coptisine and berberine were significantly proportional to the increase in temperature for all extraction times, with the highest concentrations at 90 min at 80 °C and 90 °C, and were inversely proportional to the increase in extraction time only at 100 °C (Table 2).
Although there were no significant differences in concentrations among the samples, the extraction time and temperature affected the concentrations of the marker compounds in the single extracts proportionally. These findings are consistent with previous reports that showed increasing the extraction temperature to 80–100 °C increased the contents of baicalin and wogonoside in boiled water extracts [20]. However, in the paired extracts, the positive proportionality between contents and conditions was not clearly observed: the temperature mostly affected the contents of the marker compounds positively, whereas the time provided peak contents in the middle of the extraction time for several cases at 80 °C and 90 °C. Moreover, the concentrations of chrysin 6-C-arabinoside 8-C-glucoside, baicalin, coptisine, and berberine showed negative proportionality with the increase in extraction time at the highest extraction temperature.
3.2. Influence of Extraction Conditions on the Marker Compound Extractions
Multiple regression analysis revealed differences in the effects of extraction temperature and time on the extraction of the marker compounds between the paired and single extracts, as shown in Table 3.
Temperature and time significantly affected the concentrations of chrysin 6-C-arabinoside 8-C-glucoside in the paired extracts by the first order, while extraction time significantly affected the concentrations of chrysin 6-C-arabinoside 8-C-glucoside in the single extracts by first and second order. Temperature influenced the concentrations of magnoflorine, jatrorrhizine, and palmatine in single extracts in a negative first order and a positive second order. The extraction times of baicalin and wogonoside in single extracts showed significant influences in the first (positive) and second (negative) orders, and the temperature in the second order positively affected the baicalin extraction. Extraction time was an influential factor in the concentrations of columbamine in the paired extracts in the first order, while the temperature was an influential factor in the single extracts in the second order, negative in the first order and positive in the second order.
Furthermore, both extraction time and temperature in the first and second orders had a significant impact on the concentrations of coptisine and berberine in the paired extracts. In contrast, the extraction time in the first order had a positive impact on two compounds in the single extracts, and the temperature in the second order had a positive impact on berberine.
Moreover, the interactions between the extraction temperature and time on the concentrations were negatively significant to the concentrations of chrysin 6-C-arabinoside b-C-glucoside, baicalin, columbamine, coptisine, and berberine in the paired extracts, as seen in the interaction coefficients (temperature:time) [21]. These findings show that two variables, temperature and time, had a significant inverse relationship with the extraction efficiencies of those compounds when SB and CC were extracted together [22,23]. Significant interactions between the above two variables were observed as negative on chrysin 6-C-arabinoside b-C-glucoside but positive on wogonoside in single extracts.
With the exception of baicalin in the paired extracts, the correlation coefficient (r2) between the concentrations of the marker compounds and two variables (temperature and time), which ranged from 0.4264 to 0.9400 for adjusted r2, indicates better correlation and prediction among them when it is closer to 1 [24,25]. A 3-D response plot was used to visualize the predicted values of the second-order polynomial equation in the paired and single extracts (Figure 1 and Figure 2).
3.3. Influence of Herbal Pair on the Marker Compound Extractions
All marker compounds showed significantly higher concentrations in single extracts than in paired extracts at most extraction conditions: 1.09 (80 °C, 60 min)- and 1.12 (80 °C, 90 min)-fold for magnoflorine; 2.06–2.89-fold for baicalin; 3.01–3.84-fold for columbamine; 1.13–1.37-fold for epiberberine; 1.00–1.16-fold for jatrorrhizine; 11.71–19.53-fold for coptisine; 1.31–1.51-fold for wogonoside; 1.19–1.28-fold for palmatine; 27.31–44.13-fold for berberine; 2.04–2.96-old for wogonin; and 2.03–2.89-fold for oroxylin A, except for 0.90-fold for chrysin 6-C-arabinoside 8-C-glucoside (90 °C, 120 min) (Figure 3 and Figure 4).
Particularly, significant reductions in the concentrations of four major compounds, baicalin, wogonoside, coptisine, and berberine, were evident when SB and CC were paired.
As previously reported in studies, extracting herbal combination alleviates the extraction efficiency of single herbal medicines [26]. This phenomenon can be explained by a decrease in the mass transfer of herbal compounds to extract due to a restriction of solvent access or a change in the solubility of constituents, both caused by added herbal medicine [27,28]. In contrast, by increasing the solubility of herbal compounds, herbal combinations may promote the extraction of constituents from the paired herb [29,30]. However, there may be another reason for the reduced concentrations of marker compounds in the paired extracts of SB and CC. As reported [3], when the herbal pair of SB and CC were decocted together in boiling water and then cooled, the components from the composing herbs gradually aggregated in the decoction as precipitation formed.
In addition, precipitation from an herbal formula containing SB and CC consisted of flavonoids from SB (including baicalin and wogonoside) and alkaloids from CC (including coptisine, berberine, and palmatine) [31,32,33]. Those flavonoids and alkaloids exist as complexes, such as baicalin-berberine or wogonoside-berberine, and these complexes were formed by combining an ionized carboxylic group of glucuronic acid (negative ion by hydrogen loss) in baicalin or wogonoside with ionized nitrogen of berberine (positive ion) [34]. According to these findings, the formation of the chemical complex can cause components in the extracted solution to precipitate naturally, resulting in a reduction in the number of components in the supernatant. This can explain why the presence of flavonoids and alkaloids in the paired extracts is significantly lower than in a single SB or CC extract. In addition, there is a possibility that higher extraction temperature (especially at 100 °C) and longer extraction time may make flavonoids and alkaloids, such as chrysin 6-C-arabinoside 8-C-glucoside, baicalin, coptisine, and berberine, more participate in forming the precipitation, as shown in Table 2.
The extraction efficiencies of 12 marker compounds were affected differently by extraction time and temperature when in the SB and CC single and paired extracts. Furthermore, the SB–CC pair is thought to have significantly reduced the extraction of the marker compounds from each herbal medicine by either co-interaction between the herbs or the formation of a precipitate. The precipitates consisting of flavonoids and alkaloids may be potent factors that accelerate the decrease in concentrations of the marker compounds in the extracted solution. Thus, the composition and formation mechanism of the precipitation will be investigated further in order to understand the combined effect of the SB–CC pair.
4. Concluding Remarks
The chemical influence of the SB–CC pair on the extraction yields of the 12 marker compounds at various extraction times (60, 90, and 120 min) and temperatures (80 °C, 90 °C, and 100 °C) was investigated using validated HPLC analysis with multiple regression analysis. In most paired and single extracts, the extraction efficiencies of the marker compounds improved in response to temperature and time increases. In contrast, the yields of baicalin, berberine, and coptisine were inversely proportional to the extraction time at 100 °C in the paired extracts. With the exception of chrysin 6-C-arabinoside 8-C-glucoside and magnoflorine, the concentrations of the marker compounds were significantly reduced by the SB–CC pair in most extraction conditions, compared to single extracts, possibly because of the formation of flavonoid alkaloid–complexed precipitation. The influence of extraction temperature and time on the formation of the flavonoid–alkaloid complex was not significant. This study identifies the chemical characteristics of the SB–CC pair, which is differently influenced by the extraction time and temperature from a single SB or CC extracts.
Supplementary Materials
The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/separations10020131/s1, Figure S1: Chemical structures of the twelve marker compounds found in a water extract of the roots of Scutellaria baicalensis and the rhizomes of Coptis chinensis.; Figure S2: Chromatograms of the twelve marker compounds (A), the paired extract of S. baicalensis and C. chinensis (B), the single extract of S. baicalensis (C), and the single extract of C. chinensis (D) at a detection wavelength of 275 nm.; Table S1: Linear equations, correlation coefficients (r2), LOD, LOQ, and the values of analytical method validation of the marker compounds.
Author Contributions
Conceptualization, H.-Y.K. and J.-H.K.; validation, J.-H.K.; formal analysis, H.-Y.K.; investigation, H.-Y.K.; writing—original draft, J.-H.K.; writing—review and editing, H.-Y.K.; visualization, H.-Y.K. and J.-H.K.; supervision, J.-H.K.; project administration, J.-H.K. All authors have read and agreed to the published version of the manuscript.
Funding
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. 2021R1F1A1052550).
Data Availability Statement
The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.
Conflicts of Interest
The authors declare no conflict of interest.
References
- Muluye, R.A.; Bian, Y.; Alemu, P.N. Anti-inflammatory and antimicrobial effects of heat-clearing Chinese herbs: A current review. J. Tradit. Complement. Med. 2014, 4, 93–98. [Google Scholar] [CrossRef] [Green Version]
- Wu, T.Y.; Chang, F.R.; Liou, J.R.; Lo, I.W.; Chung, T.C.; Lee, L.Y.; Chi, C.C.; Du, Y.C.; Wong, M.H.; Juo, S.H.H.; et al. Rapid HPLC quantification approach for detection of active constituents in modern combinatorial formula, San-Huang-Xie-Xin-Tang (SHXXT). Front. Pharmacol. 2016, 20, 374. [Google Scholar] [CrossRef] [Green Version]
- Wang, J.; Zheng, D.; Xu, N.; Zhang, C.; Wang, Y.; Sun, X.; Zhang, Z. Attribution and identification of absorbed components by HPLC-DAD-ESI-MS after oral administration of Erhuang decoction. J. Anal. Sci. Technol. 2020, 11, 38. [Google Scholar] [CrossRef]
- Huang, J.; Guo, W.; Cheung, F.; Tan, H.Y.; Wang, N.; Feng, Y. Integrating network pharmacology and experimental models to investigate the efficacy of Coptidis and Scutellaria containing Huanglian Jiedu decoction on hepatocellular carcinoma. Am. J. Chin. Med. 2020, 48, 161–182. [Google Scholar] [CrossRef]
- Wang, Q.; Kuang, Y.; Song, W.; Qian, Y.; Qiao, X.; Guo, D.A.; Ye, M. Permeability through the Caco-2 cell monolayer of 42 bioactive compounds in the TCM formula Gegen-Qinlian Decoction by liquid chromatography tandem mass spectrometry analysis. J. Pharm. Biomed. Anal. 2017, 146, 206–213. [Google Scholar] [CrossRef] [PubMed]
- Liu, S.Z.; Deng, Y.X.; Chen, B.; Zhang, X.J.; Shi, Q.Z.; Qiu, X.M. Antihyperglycemic effect of the traditional Chinese Scutellaria–Coptis herb couple and its main components in streptozotocin-induced diabetic rats. J. Ethnopharmacol. 2013, 145, 490–498. [Google Scholar] [CrossRef] [PubMed]
- Zhang, C.H.; Sheng, J.Q.; Sarsaiya, S.; Shu, F.X.; Liu, T.T.; Tu, X.Y.; Ma, G.Q.; Xu, G.L.; Zheng, H.X.; Zhou, L.F. The anti-diabetic activities, gut microbiota composition, the anti-inflammatory effects of Scutellaria–Coptis herb couple against insulin resistance-model of diabetes involving the toll-like receptor 4 signaling pathway. J. Ethnopharmacol. 2019, 237, 202–214. [Google Scholar] [CrossRef] [PubMed]
- Zhang, B.; Yue, R.; Chen, Y.; Huang, X.; Yang, M.; Shui, J.; Peng, Y. The herbal medicine Scutellaria-Coptis alleviates intestinal mucosal barrier damage in diabetic rats by inhibiting inflammation and modulating the gut microbiota. Evid.-Based Complement. Altern. Med. 2020, 2020, 4568629. [Google Scholar] [CrossRef]
- Zhang, C.H.; Yu, R.Y.; Liu, Y.H.; Tu, X.Y.; Tu, J.; Wang, Y.S.; Xu, G.-L. Interaction of baicalin with berberine for glucose uptake in 3T3-L1 adipocytes and HepG2 hepatocytes. J. Ethnopharmacol. 2014, 151, 864–872. [Google Scholar] [CrossRef]
- Vergara-Salinas, J.R.; Pérez-Jiménez, J.; Torres, J.L.; Agosin, E.; Pérez-Correa, J.R. Effects of temperature and time on polyphenolic content and antioxidant activity in the pressurized hot water extraction of deodorized thyme (Thymus vulgaris). J. Agric. Food Chem. 2012, 60, 10920–10929. [Google Scholar] [CrossRef]
- Yim, H.S.; Chye, F.Y.; Rao, V.; Low, J.Y.; Matanjun, P.; How, S.E.; Ho, C.W. Optimization of extraction time and temperature on antioxidant activity of Schizophyllum commune aqueous extract using response surface methodology. J. Food Sci. Technol. 2013, 50, 275–283. [Google Scholar] [CrossRef] [PubMed] [Green Version]
- Kim, J.H. Extraction time and temperature affect the extraction efficiencies of coumarin and phenylpropanoids from Cinnamomum cassia bark using a microwave-assisted extraction method. J. Chromatogr. B Biomed. Appl. 2017, 1063, 196–203. [Google Scholar] [CrossRef] [PubMed]
- Teng, H.; Choi, Y.H. Optimization of extraction of bioactive alkaloids and antioxidants from Rhizome Coptidis (Coptis chinensis Franch) by using response surface methodology. Food Sci. Biotechnol. 2012, 21, 799–806. [Google Scholar] [CrossRef]
- Li, L.; Zhang, D.; Wang, Y.; Liu, F.; Xu, Y.; Bao, H. Effective extraction of palmatine and berberine from Coptis chinensis by deep eutectic solvents-based ultrasound-assisted extraction. J. Anal. Methods Chem. 2021, 2021, 9970338. [Google Scholar] [CrossRef]
- Li, H.; Luo, S.L.; Su, J.; Ke, H.; Wang, W.; Yang, B. Optimization of extraction conditions for flavonoid composition and antioxidant activity of Radix Scutellariae. Anal. Lett. 2015, 48, 1234–1244. [Google Scholar] [CrossRef]
- Liu, D.; Zhao, R.; Wu, Y.; Wang, Y.; Yang, R.; Ke, X. Variation in the efficacy of anti-ulcerative colitis treatments reveals the conflict between precipitating compatibility of traditional Chinese medicine and modern technology: A case of Scutellaria-Coptis. Front. Pharmacol. 2022, 20, 819851. [Google Scholar] [CrossRef]
- Li, L.; Cui, H.; Li, T.; Qi, J.; Chen, H.; Gao, F.; Tian, X.; Mu, Y.; He, R.; Lv, S.; et al. Synergistic effect of berberine-based Chinese medicine assembled nanostructures on diarrhea-predominant irritable bowel syndrome in vivo. Front. Pharmacol. 2020, 11, 1210. [Google Scholar] [CrossRef]
- Miao, Q.; Zhao, Y.Y.; Miao, P.P.; Chen, N.; Yan, X.H.; Guo, C.E.; Chen, H.Y.; Zhang, Y.J. Proteomics approach to analyze protein profiling related with ADME/Tox in rat treated with Scutellariae Radix and Coptidis Rhizoma as well as their compatibility. J. Ethnopharmacol. 2015, 173, 241–250. [Google Scholar] [CrossRef]
- Beaufils, N.; Boucher, J.; Peydecastaing, J.; Rigal, L.; Vilarem, G.; Villette, M.J.; Candy, L.; Pontalier, P.Y. The effect of time and temperature on the extraction of xylose and total phenolic compounds with pressurized hot water from hardwood species used for pulp and paper production in the South of France. Bioresour. Technol. Rep. 2021, 16, 100832. [Google Scholar] [CrossRef]
- Li, J.; Wang, R.; Sheng, Z.; Wu, Z.; Chen, C.; Ishfaq, M. Optimization of baicalin, wogonoside, and chlorogenic acid water extraction process from the roots of Scutellariae Radix and Lonicerae japonicae Flos using response surface methodology (RSM). Processes 2019, 7, 854. [Google Scholar] [CrossRef]
- Dalal, D.K.; Zickar, M.J. Some common myths about centering predictor variables in moderated multiple regression and polynomial regression. Organ. Res. Methods 2012, 15, 339–362. [Google Scholar] [CrossRef]
- Shanock, L.R.; Baran, B.E.; Gentry, W.A.; Pattison, S.C.; Heggestad, E.D. Polynomial regression with response surface analysis: A powerful approach for examining moderation and overcoming limitations of difference scores. J. Bus. Psychol. 2010, 25, 543–554. [Google Scholar] [CrossRef]
- Aguinis, H.M.; Gottfredson, R.K. Best-practice recommendations for estimating interaction effects using moderated multiple regression. J. Organ. Behav. 2010, 31, 776–786. [Google Scholar] [CrossRef]
- Taylor, R. Interpretation of the correlation coefficient: A basic review. J. Diagn. Med. Sonogr. 1990, 6, 35–39. [Google Scholar] [CrossRef]
- Zhao, L.C.; He, Y.; Deng, X.; Yang, G.L.; Li, W.; Liang, J.; Tang, Q.L. Response surface modeling and optimization of accelerated solvent extraction of four lignans from Fructus Schisandrae. Molecules 2012, 17, 3618–3629. [Google Scholar] [CrossRef] [PubMed] [Green Version]
- Cui, X.; Shen, Y.M.; Jiang, S.; Qian, D.W.; Shang, E.X.; Zhu, Z.H.; Duan, J.A. Comparative analysis of the main active components and hypoglycemic effects after the compatibility of Scutellariae Radix and Coptidis Rhizoma. J. Sep. Sci. 2019, 42, 1520–1527. [Google Scholar] [CrossRef]
- Kim, J.H.; Ha, W.R.; Park, J.H.; Lee, G.; Choi, G.; Lee, S.H.; Kim, Y.S. Influence of herbal combinations on the extraction efficiencies of chemical compounds from Cinnamomum cassia, Paeonia lactiflora, and Glycyrrhiza uralensis, the herbal components of Gyeji-tang, evaluated by HPLC method. J. Pharm. Biomed. Anal. 2016, 129, 50–59. [Google Scholar] [CrossRef]
- Qu, H.J.; Lin, K.W.; Li, X.L.; Ou, H.Y.; Tan, Y.F.; Wang, M.; Wei, N. Chemical constituents and anti-gastric ulcer activity of essential oils of Alpinia officinarum (Zingiberaceae), Cyperus rotundus (Cyperaceae), and their herbal pair. Chem. Biodivers. 2021, 18, e2100214. [Google Scholar] [CrossRef]
- Cao, G.; Li, Q.; Cai, H.; Tu, S.; Cai, B. Investigation of the chemical changes from crude and processed Paeoniae Radix Alba-Atractylodis Macrocephalae Rhizoma herbal pair extracts by using Q exactive high-performance benchtop quadrupole-orbitrap LC-MS/MS. Evid.-Based Complement. Altern. Med. 2014, 2014, 170959. [Google Scholar] [CrossRef] [Green Version]
- Yin, G.; Cheng, X.; Tao, W.; Dong, Y.; Bian, Y.; Zang, W.; Tang, D. Comparative analysis of multiple representative components in the herb pair Astragali Radix-Curcumae Rhizoma and its single herbs by UPLC-QQQ-MS. J. Pharm. Biomed. Anal. 2018, 148, 224–229. [Google Scholar] [CrossRef]
- Kim, M.J.; Kim, N.S.; Kim, Y.I.; Kim, D.K.; Yang, J.H. Improvement of hydrolysis and bioavailability of coprecipitated product of Coptidis rhizoma and Scutellariae radix by β-glucuronidase. J. Kor. Pharm. Sci. 2003, 33, 91–97. [Google Scholar]
- Zhang, C.; Zhao, R.; Yan, W.; Wang, H.; Jia, M.; Zhu, N.; Zhu, Y.; Zhang, Y.; Wang, P.; Lei, H. Compositions, formation mechanism, and neuroprotective effect of compound precipitation from the traditional Chinese prescription Huang-Lian-Jie-Du-Tang. Molecules 2016, 21, 1094. [Google Scholar] [CrossRef] [PubMed] [Green Version]
- Wang, H.; Li, T.; Xiang, H.; Zhang, X.; Fang, K.; Wu, G.; Yan, M.; Xue, N.; Chen, M.; Xie, T.; et al. Origin and formation mechanism investigation of compound precipitation from the traditional Chinese prescription Huang-Lian-Jie-Du-Tang by isothermal titration calorimetry. Molecules 2017, 22, 1456. [Google Scholar] [CrossRef] [PubMed]
- Wang, J.R.; Tanaka, T.; Zhang, H.; Kouno, I.; Jiang, Z.H. Formation and conformation of baicalin–berberine and wogonoside– berberine complexes. Chem. Pharm. Bull. 2012, 60, 706–711. [Google Scholar] [CrossRef]
Figure 1.
Response surface plots for the twelve marker compounds in a single extract of S. baicalensis or C. chinensis at various extraction temperatures and times. Color red is the lowest condition while color purple is the highest condition of parameters in 3D plot.
Figure 1.
Response surface plots for the twelve marker compounds in a single extract of S. baicalensis or C. chinensis at various extraction temperatures and times. Color red is the lowest condition while color purple is the highest condition of parameters in 3D plot.
Figure 2.
Response surface plots for the twelve marker compounds in S. baicalensis and C. chinensis single paired extract at various extraction temperatures and times. Color red is the lowest condition while color purple is the highest condition of parameters in 3D plot.
Figure 2.
Response surface plots for the twelve marker compounds in S. baicalensis and C. chinensis single paired extract at various extraction temperatures and times. Color red is the lowest condition while color purple is the highest condition of parameters in 3D plot.
Figure 3.
Changes in the contents of the marker compounds in the paired (black) or single extract (gray) of S. baicalensis and C. chinensis at various extraction times (60 min, 90 min, and 120 min). (A) Chrysin 6-C-arabinoside 8-C-glucoside; (B) magnoflorine; (C) baicalin; (D) columbamine; (E) epiberberine; (F) jatrorrhizine; (G) coptisine; (H) wogonoside; (I) palmatine; (J) berberine; (K) wogonin; (L) oroxylin A. Significance at *** p < 0.001, ** p < 0.01, or * p < 0.05.
Figure 3.
Changes in the contents of the marker compounds in the paired (black) or single extract (gray) of S. baicalensis and C. chinensis at various extraction times (60 min, 90 min, and 120 min). (A) Chrysin 6-C-arabinoside 8-C-glucoside; (B) magnoflorine; (C) baicalin; (D) columbamine; (E) epiberberine; (F) jatrorrhizine; (G) coptisine; (H) wogonoside; (I) palmatine; (J) berberine; (K) wogonin; (L) oroxylin A. Significance at *** p < 0.001, ** p < 0.01, or * p < 0.05.
Figure 4.
Changes in the contents of the marker compounds in the paired (black) or single extract (gray) S. baicalensis and C. chinensis at various extraction temperatures (80 °C, 90 °C, and 100 °C). (A) Chrysin 6-C-arabinoside 8-C-glucoside; (B) magnoflorine; (C) baicalin; (D) columbamine; (E) epiberberine; (F) jatrorrhizine; (G) coptisine; (H) wogonoside; (I) palmatine; (J) berberine; (K) wogonin; (L) oroxylin A. Significance at *** p < 0.001, ** p < 0.01, or * p < 0.05.
Figure 4.
Changes in the contents of the marker compounds in the paired (black) or single extract (gray) S. baicalensis and C. chinensis at various extraction temperatures (80 °C, 90 °C, and 100 °C). (A) Chrysin 6-C-arabinoside 8-C-glucoside; (B) magnoflorine; (C) baicalin; (D) columbamine; (E) epiberberine; (F) jatrorrhizine; (G) coptisine; (H) wogonoside; (I) palmatine; (J) berberine; (K) wogonin; (L) oroxylin A. Significance at *** p < 0.001, ** p < 0.01, or * p < 0.05.
Table 1.
The mean concentrations of the marker compounds in the single extracts of S. baicalensis or C. chinensis.
Table 1.
The mean concentrations of the marker compounds in the single extracts of S. baicalensis or C. chinensis.
| Compound | Temperature | Time | ||
|---|---|---|---|---|
| 60 Min | 90 Min | 120 Min | ||
| Chrysin 6-C-arabinoside 8-C-glucoside | 80 °C | 40.625 ± 3.428 | 46.416 ± 0.736 d | 48.320 ± 1.985 eee |
| 90 °C | 41.557 ± 1.199 | 47.792 ± 1.189 dd | 43.521 ± 0.878 | |
| 100 °C | 44.022 ± 1.810 | 46.007 ± 1.460 | 46.731 ± 0.724 | |
| Magnoflorine | 80 °C | 52.783 ± 1.552 | 55.370 ± 0.505 | 58.735 ± 1.414 |
| 90 °C | 51.708 ± 2.354 | 54.190 ± 3.166 | 60.912 ± 3.405 | |
| 100 °C | 56.648 ± 3.523 | 62.910 ± 4.382 c | 63.877 ± 3.001 | |
| Baicalin | 80 °C | 924.320 ± 145.968 | 1088.679 ± 51.385 | 1126.509 ± 36.244 e |
| 90 °C | 950.606 ± 58.115 | 1143.521 ± 34.794 d | 1033.981 ± 31.679 | |
| 100 °C | 1077.343 ± 61.543 | 1180.799 ± 30.917 | 1200.941 ± 36.866 | |
| Columbamine | 80 °C | 33.294 ± 0.205 | 36.594 ± 1.144 | 38.023 ± 0.905 ee |
| 90 °C | 33.575 ± 1.501 | 36.617 ± 1.133 | 40.755 ± 2.342 eee | |
| 100 °C | 38.075 ± 0.228 bb | 39.750 ± 0.634 | 45.431 ± 1.896 bbb,cc,eee,ff | |
| Epiberberine | 80 °C | 95.780 ± 0.830 | 103.358 ± 4.597 | 109.247 ± 5.093 e |
| 90 °C | 95.480 ± 2.699 | 104.958 ± 5.612 | 113.973 ± 1.507 eee | |
| 100 °C | 109.044 ± 4.300 b,c | 111.594 ± 2.816 | 113.425 ± 6.051 | |
| Jatrorrhizine | 80 °C | 21.241 ± 0.615 | 22.939 ± 0.263 | 23.720 ± 1.056 ee |
| 90 °C | 21.050 ± 0.677 | 23.237 ± 0.700 d | 24.740 ± 0.528 eee | |
| 100 °C | 23.559 ± 0.216 bb,cc | 24.924 ± 0.348 b | 25.771 ± 0.632 b,ee | |
| Coptisine | 80 °C | 105.643 ± 1.240 | 114.155 ± 3.274 | 121.410 ± 2.724 ee |
| 90 °C | 103.974 ± 3.273 | 118.021 ± 2.872 d | 125.534 ± 3.639 eee | |
| 100 °C | 118.958 ± 5.247 b,cc | 129.212 ± 8.629 bb | 124.364 ± 1.824 | |
| Wogonoside | 80 °C | 204.398 ± 7.265 | 228.672 ± 4.270 d | 236.058 ± 8.624 ee |
| 90 °C | 214.309 ± 7.757 | 245.387 ± 6.973 dd | 240.145 ± 10.003 | |
| 100 °C | 245.493 ± 12.946 bbb,cc | 257.508 ± 3.553 bbb | 267.452 ± 10.475 bbb,c | |
| Palmatine | 80 °C | 90.987 ± 0.368 | 99.845 ± 1.989 ddd | 105.568 ± 2.727 eee |
| 90 °C | 91.047 ± 3.611 | 100.356 ± 2.184 ddd | 109.630 ± 0.484 eee | |
| 100 °C | 101.956 ± 1.603 bbb,ccc | 108.150 ± 0.591 bb,cc | 117.262 ± 0.658 bbb,cc,eee,fff | |
| Berberine | 80 °C | 382.550 ± 0.705 | 412.910 ± 9.617 | 438.538 ± 2.199 ee |
| 90 °C | 380.456 ± 12.640 | 427.644 ± 9.018 dd | 458.198 ± 17.486 eee | |
| 100 °C | 431.040 ± 19.987 bb,cc | 471.017 ± 23.083 bb,c,d | 471.948 ± 5.875 e | |
| Wogonin | 80 °C | 5.422 ± 0.170 | 6.225 ± 0.091 | 6.430 ± 0.035 |
| 90 °C | 6.347 ± 0.214 | 7.446 ± 0.351 | 7.687 ± 0.331 e | |
| 100 °C | 8.082 ± 0.283 bbb,cc | 8.450 ± 0.438 bbb | 10.491 ± 1.133 bbb,ccc,eee,fff | |
| Oroxylin A | 80 °C | 2.221 ± 0.112 | 2.499 ± 0.088 | 2.575 ± 0.173 |
| 90 °C | 2.607 ± 0.110 | 2.768 ± 0.226 | 2.941 ± 0.067 | |
| 100 °C | 3.023 ± 0.124 bb | 3.095 ± 0.107 b | 3.748 ± 0.405 bbb,cc,ee,ff | |
Concentrations were represented as ‘mean concentration ± standard deviation’. Difference of the contents in the extract prepared at 80 °C vs. 90 °C, Difference of the contents in the extract prepared at 80 °C vs. 100 °C, with significance at bbb p < 0.001, bb p < 0.01, or b p < 0.05. Difference of the contents in the extract prepared at 90 °C vs. 100 °C, with significance at ccc p < 0.001, cc p < 0.01, or c p < 0.05. Difference of the contents in the extract prepared in 60 min vs. 90 min, with significance at ddd p < 0.001, dd p < 0.01, or d p < 0.05. Difference of the contents in the extract prepared in 60 min vs. 120 min, with significance at eee p < 0.001, ee p < 0.01, or e p < 0.05. Difference of the contents in the extract prepared in 90 min vs. 120 min, with significance at fff p < 0.001, ff p < 0.01, or f p < 0.05.
Table 2.
The mean concentrations of the marker compounds in the paired extracts of S. baicalensis and C. chinensis.
Table 2.
The mean concentrations of the marker compounds in the paired extracts of S. baicalensis and C. chinensis.
| Compound | Temperature | Time | ||
|---|---|---|---|---|
| 60 Min | 90 Min | 120 Min | ||
| Chrysin 6-C-arabinoside 8-C-glucoside | 80 °C | 42.979 ± 1.721 | 45.801 ± 0.301 d | 46.842 ± 1.089 ee |
| 90 °C | 43.633 ± 1.219 | 47.437 ± 0.291 dd | 48.270 ± 0.683 eee | |
| 100 °C | 46.605 ± 0.670 b,cc | 45.272 ± 0.621 | 44.788 ± 1.185 cc | |
| Magnoflorine | 80 °C | 47.083 ± 2.607 | 50.738 ± 1.846 | 56.980 ± 2.518 |
| 90 °C | 53.791 ± 6.382 | 59.867 ± 2.934 | 60.033 ± 3.182 | |
| 100 °C | 60.148 ± 4.973 b | 67.069 ± 5.333 bb | 70.173 ± 2.892 b | |
| Baicalin | 80 °C | 448.536 ± 42.954 | 458.085 ± 42.282 | 449.980 ± 17.525 |
| 90 °C | 435.675 ± 50.632 | 479.909 ± 44.931 | 479.288 ± 18.777 | |
| 100 °C | 522.052 ± 46.350 | 462.883 ± 48.275 | 414.866 ± 5.970 | |
| Columbamine | 80 °C | 10.097 ± 0.360 | 11.767 ± 0.236 d | 12.470 ± 0.451 eee |
| 90 °C | 11.169 ± 0.652 | 10.809 ± 0.726 | 11.204 ± 0.376 | |
| 100 °C | 11.184 ± 0.358 | 11.802 ± 0.559 | 11.846 ± 0.465 | |
| Epiberberine | 80 °C | 70.078 ± 6.390 | 80.740 ± 2.475 | 83.819 ± 2.849 |
| 90 °C | 84.766 ± 3.794 a | 84.357 ± 5.561 | 83.031 ± 6.051 | |
| 100 °C | 85.078 ± 2.234 b | 93.444 ± 4.014 | 93.419 ± 8.087 | |
| Jatrorrhizine | 80 °C | 18.344 ± 0.210 | 19.920 ± 1.948 | 20.984 ± 1.301 |
| 90 °C | 21.024 ± 1.559 | 22.069 ± 0.937 | 23.042 ± 1.831 | |
| 100 °C | 20.785 ± 0.476 b | 23.418 ± 0.999 | 25.109 ± 1.191 e | |
| Coptisine | 80 °C | 6.115 ± 0.212 | 7.420 ± 0.128 dd,ff | 6.215 ± 0.352 |
| 90 °C | 6.170 ± 0.265 | 8.075 ± 0.286 ddd,fff | 6.615 ± 0.527 | |
| 100 °C | 10.155 ± 0.316 bbb,ccc,d,eee | 9.187 ± 0.176 bbb,ccc | 8.483 ± 0.216 bbb,ccc | |
| Wogonoside | 80 °C | 156.208 ± 4.720 | 160.761 ± 2.859 | 161.743 ± 3.883 |
| 90 °C | 162.507 ± 2.888 | 172.477 ± 2.425 | 170.679 ± 3.829 | |
| 100 °C | 175.403 ± 1.426 bb | 170.966 ± 8.131 | 184.174 ± 8.246 bb | |
| Palmatine | 80 °C | 73.373 ± 1.975 | 78.377 ± 4.610 | 81.476 ± 4.359 |
| 90 °C | 80.246 ± 5.047 | 81.691 ± 2.293 | 87.902 ± 4.467 | |
| 100 °C | 79.361 ± 1.092 | 90.961 ± 5.473 b,d | 95.889 ± 3.575 bb | |
| Berberine | 80 °C | 9.744 ± 0.379 | 11.797 ± 0.222 ddd,ff | 9.937 ± 0.571 |
| 90 °C | 11.808 ± 0.403 aaa | 13.058 ± 0.556 a,ddd,fff | 11.128 ± 0.549 | |
| 100 °C | 15.783 ± 0.474 bbb,ccc,ee | 15.157 ± 0.201 bbb,ccc | 13.984 ± 0.170 bbb,ccc | |
| Wogonin | 80 °C | 2.659 ± 0.098 | 3.016 ± 0.269 | 2.910 ± 0.120 |
| 90 °C | 2.953 ± 0.125 | 3.198 ± 0.071 | 3.405 ± 0.376 | |
| 100 °C | 3.808 ± 0.358 bbb,cc | 3.430 ± 0.240 | 3.550 ± 0.178 | |
| Oroxylin A | 80 °C | 1.062 ± 0.045 | 1.185 ± 0.065 | 1.199 ± 0.047 |
| 90 °C | 1.259 ± 0.111 | 1.219 ± 0.063 | 1.303 ± 0.101 | |
| 100 °C | 1.489 ± 0.180 bb | 1.301 ± 0.135 | 1.297 ± 0.061 | |
Concentrations were represented as ‘mean concentration ± standard deviation’. Difference of the contents in the extract prepared at 80 °C vs. 90 °C, with significance at aaa p < 0.001, or a p < 0.05. Difference of the contents in the extract prepared at 80 °C vs. 100 °C, with significance at bbb p < 0.001, bb p < 0.01, or b p < 0.05. Difference of the contents in the extract prepared at 90 °C vs. 100 °C, with significance at ccc p < 0.001, cc p < 0.01. Difference of the contents in the extract prepared in 60 min vs. 90 min, with significance at ddd p < 0.001, dd p < 0.01, or d p < 0.05. Difference of the contents in the extract prepared in 60 min vs. 120 min, with significance at eee p < 0.001, ee p < 0.01, or e p < 0.05. Difference of the contents in the extract prepared in 90 min vs. 120 min, with significance at fff p < 0.001, ff p < 0.01.
Table 3.
The coefficients of multiple regression analysis of the marker compounds in the paired or the single extract of S. baicalensis and C. chinensis.
Table 3.
The coefficients of multiple regression analysis of the marker compounds in the paired or the single extract of S. baicalensis and C. chinensis.
| Compound | Extraction | Regression Coefficient (Significance at *** p < 0.001, ** p < 0.01, or * p < 0.05) | ||||||
|---|---|---|---|---|---|---|---|---|
| Intercept | Temp. | Time | Temp.:Time | Temp.:Temp. | Time:Time | Adjusted r2 | ||
| Chrysin 6-C-arabinoside 8-C-glucoside | Pair | −88.5300 | 2.3610 * | 0.5933 *** | −0.0047 *** | −0.0107 | −0.0007 | 0.5352 *** |
| Single | 66.7608 | −1.5171 | 0.9644 *** | −0.0041 * | 0.0106 | −0.0029 ** | 0.5407 *** | |
| Magnoflorine | Pair | 36.7900 | −0.7422 | 0.3738 | 0.0001 | 0.0080 | −0.0013 | 0.7567 *** |
| Single | 253.3000 * | −4.8310 * | 0.0377 | 0.0011 | 0.0278 * | −0.0001 | 0.6449 *** | |
| Baicalin | Pair | −823.4690 | 18.8697 | 9.5140 | −0.0905 * | −0.0556 | −0.0095 | 0.0723 |
| Single | 3738.7794 | −91.4914 | 25.2441 ** | −0.0655 | 0.5706 * | −0.0949 ** | 0.6086 *** | |
| Columbamine | Pair | 33.9548 | −0.7038 | 0.1716 * | −0.0014 * | 0.0047 | −0.0001 | 0.4264** |
| Single | 151.7000 ** | −2.7230 * | −0.1977 | 0.0022 | 0.0155 * | 0.0006 | 0.8629 *** | |
| Epiberberine | Pair | −11.3266 | 0.3454 | 1.0811 | −0.0045 | 0.0038 | −0.0031 | 0.5148 *** |
| Single | 166.7000 | −2.978 | 0.9791 | −0.0076 | 0.0227 | −0.0005 | 0.6690 *** | |
| Jatrorrhizine | Pair | −38.3800 | 1.1540 | −0.0256 | 0.0014 | −0.0062 | −0.0003 | 0.6899 *** |
| Single | 59.8904 * | −1.1041 * | 0.1373 | −0.0002 | 0.0068 * | −0.0004 | 0.8428 *** | |
| Coptisine | Pair | 54.6919 ** | −1.4890 ** | 0.3137 *** | −0.0015 * | 0.0098 *** | −0.0010 *** | 0.8442 *** |
| Single | 198.0029 | −4.3063 | 1.7775 ** | −0.0086 | 0.0311 | −0.0042 | 0.7167 *** | |
| Wogonoside | Pair | 76.6400 | 1.2430 | −0.1946 | 0.0027 | −0.0035 | 0.0004 | 0.6422 *** |
| Single | 437.9281 | −9.55309 | 3.0117 ** | −0.0081 | 0.0665 | −0.0102 * | 0.8170 *** | |
| Palmatine | Pair | 66.0000 | −0.0102 | −0.3256 | 0.0070 | −0.0004 | −0.0007 | 0.7169 *** |
| Single | 327.1000 *** | −6.0480 *** | 0.2234 | 0.0006 | 0.0362 *** | 0.0000 | 0.9400 *** | |
| Berberine | Pair | 28.5085 | −0.9508 * | 0.3913 *** | −0.0017 ** | 0.0074** | −0.0014 *** | 0.9322 *** |
| Single | 957.1066 | −19.1585 | 4.1149 * | −0.0126 | 0.1257 * | −0.0112 | 0.8258 *** | |
| Wogonin | Pair | −0.2535 | −0.0035 | 0.0407 | −0.0004 | 0.0004 | 0.0000 | 0.5820 *** |
| Single | 30.0000 | −0.5978 | −0.0859 | 0.0012 * | 0.0036 | 0.0000 | 0.8786 *** | |
| Oroxylin A | Pair | −2.048 | 0.0444 | 0.0181 | −0.0003 | 0.0000 | 0.0000 | 0.4874 ** |
| Single | 8.4160 | −0.1441 | −0.0330 | 0.0003 | 0.0009 | 0.0001 | 0.8078 *** | |
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Kim, H.-Y.; Kim, J.-H. Chemical Influence of Scutellaria baicalensis—Coptis chinensis Pair on the Extraction Efficiencies of Flavonoids and Alkaloids at Different Extraction Times and Temperatures. Separations 2023, 10, 131. https://doi.org/10.3390/separations10020131
AMA Style
Kim H-Y, Kim J-H. Chemical Influence of Scutellaria baicalensis—Coptis chinensis Pair on the Extraction Efficiencies of Flavonoids and Alkaloids at Different Extraction Times and Temperatures. Separations. 2023; 10(2):131. https://doi.org/10.3390/separations10020131
Chicago/Turabian StyleKim, Han-Young, and Jung-Hoon Kim. 2023. "Chemical Influence of Scutellaria baicalensis—Coptis chinensis Pair on the Extraction Efficiencies of Flavonoids and Alkaloids at Different Extraction Times and Temperatures" Separations 10, no. 2: 131. https://doi.org/10.3390/separations10020131
APA StyleKim, H. -Y., & Kim, J. -H. (2023). Chemical Influence of Scutellaria baicalensis—Coptis chinensis Pair on the Extraction Efficiencies of Flavonoids and Alkaloids at Different Extraction Times and Temperatures. Separations, 10(2), 131. https://doi.org/10.3390/separations10020131
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