Comparative Study of the Flavonoid Content in Radix Scutellaria from Different Cultivation Areas in China

Scutellariabaicalensis Georgi, an important perennial herb, is widely distributed and used all over the world. The root of S. baicalensis (Radix Scutellaria) is rich in flavonoids with a variety of bioactive effects and is widely used in clinic. The different geographical and climatic conditions of different cultivated areas of S. baicalensis lead to the differences of the main components in Radix Scutellaria. The main objective of this study was to evaluate the difference of flavonoid content in Radix Scutellaria from different cultivated areas in China. The mobile phase system, elution gradient, detection wavelength, and other chromatographic conditions for high-performance liquid chromatography-diode array detection (HPLC-DAD) determination of 8 flavonoids in Radix Scutellaria were optimized. The contents of flavonoids in 38 samples of Radix Scutellaria collected from seven main genuine cultivated areas were determined, and the correlation between the content, cultivated area, and the biological activities of Radix Scutellaria was compared. The results implied that baicalin, wogonoside, and baicalein were the three main flavonoids with the highest contents in Radix Scutellaria. The content of flavonoids in different cultivated areas was very different, which had significant regionality and was closely related to the natural conditions of various places. The antioxidant and antitumor activities of the extract of Radix Scutellaria were closely related to the content of flavonoids, and high contents of baicalin, wogonoside, and baicalein positively improved biological activities.


Introduction
Scutellaria baicalensis Georgi (Chinese skullcap) is a perennial herb belonging to genus Scutellaria (Labiatae). Te traditional Chinese medicine Radix Scutellaria refers to the dry root of S. baicalensis and is one of the bulk medicinal materials commonly used all over the world [1,2]. Radix Scutellaria had the efects of clearing away heat and dampness, purging fre and detoxifying, stopping blood gas, and calming fetus and had been used clinically for more than 2000 years in China [1][2][3][4][5]. Radix Scutellariae had also played an important role in Qingfei Paidu Decoction in the National Diagnosis Treatment Protocol for COVID -19 in China [6,7].
S. baicalensis has strong adaptability to the environment, is widely distributed and commonly used throughout the world, and is also the traditional herbal medicine in China, Mongolia, North Korea, and Japan [2][3][4]. S. baicalensis is geographically widespread in almost all provinces and regions of China, mainly in Hebei, Henan, Gansu, Inner Mongolia, Shaanxi, Shanxi, Shandong, and other places [11,12,[21][22][23]. S. baicalensis mostly grows in the warm, cool, semi-humid, and semi-arid environment of middle and high mountains or plateau grassland with good sunshine. Te diversity of growth environment and the diferent geographical and climatic conditions of diferent cultivated areas lead to the diferences of the main components in Radix Scutellaria [12,24,25]. As an important industrial crop, S. baicalensis is widely cultivated in China, among which Gansu, Hebei, Henan, Shandong, Shaanxi, Shanxi, and Gansu are the genuine producing areas of S. baicalensis [11,12,23].
HPLC is a very widely used analytical method with the advantages of simple operation, high efciency, and high sensitivity and is widely used in a variety of natural active substance content determination [26][27][28]. In this study, a method for simultaneous determination of 8 main favonoids in Radix Scutellaria was established to evaluate the content diferences of main favonoids in Radix Scutellaria collected from diferent production areas and diferent planting environments. Te principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed to select the key indexes afecting the quality of Radix Scutellaria, and the quality evaluation system of Radix Scutellaria was preliminarily established. Te study provided research reference for the utilization of Radix Scutellaria and the evaluation of the quality of genuine medicinal materials and reference basis for the quality control and evaluation of S. baicalensis and related products. (Table 1), collected from diferent regions of China, was identifed as the dry root of the medicinal plant Scutellaria baicalensis Georgi by Professor Dingxu Li, School of Agriculture, Henan University of Science and Technology. Te geographical and climatic information of diferent cultivated areas is shown in Table S1.

Preparation of the Samples.
Te samples of Radix Scutellaria from diferent cultivated areas were dried in an oven at 80°C to constant weight and then were crushed with a highspeed pulverizer and sieved with 80 meshes. All samples were kept in sealed bags at room temperature for further research.

Preparation of Sample Solution.
Te sample powder (4.0 g) of Radix Scutellaria was accurately weighed and was placed in a 250 mL Soxhlet refux device and extracted with 100 mL methanol solution in a constant temperature water bath at 85°C for 4 hours under refux. Te extract solution was cooled to room temperature, and then fxed the volume in a 100 mL volumetric fask with methanol. Te solution was fltered by 0.45 μm organic microporous flter membrane, and then the fltrate was collected for HPLC analysis.

Apparatus and Chromatographic
Conditions. An agilent 1100 high performance liquid chromatograph series system equipped with a quaternionic pump (G1311A), a diode array detector (DAD, G1315A/B), an online vacuum degassing device (G1322A), a column temperature box (G1316A), and an automatic sampler (G1313A) was employed in the determination. Te chromatographic column was Agilent Zorbax Eclipse SB-AQ-C18 (250 mm × 4.6 mm, 5 μm). Mobile phase was acetonitrile (A)-0.1% phosphoric acid (B) with the gradient elution of 0 min (A, 30%) ⟶ 5 min (A, 35%) ⟶ 10 min (A, 40%) ⟶ 15 min (A, 50%) ⟶ 22 min (A, 50%) ⟶ 35 min (A, 30%). Te fow rate was 1.0 mL·min −1 with the detection wavelength of 280 nm, the column temperature of 30°C, and the injection volume of 10 μL. Te separated compounds were identifed by comparing the retention time of the test sample with the reference sample. Based on the peak area corresponding to each component, the identifed favonoids were quantitatively analyzed by the external standard method according to the standard correction curve.
where Y is the content of sample; A x is the peak area of test article; A R is the peak area of control article; D is the dilution multiple of test article; C R is the concentration of control sample (mg·mL −1 ); m is the amount of test sample (g); and V is the volume of test sample (mL).

Method Validation Parameters.
Te contents of 8 favonoids in Radix Scutellaria were determined by HPLC, and the linear relationship and linear range, stability, precision, repeatability, and sample recovery of the established method were evaluated. Te calibration curve of each compound was constructed with the mixed reference standard solution containing 8 favonoids, and the mixed reference standard solution was analyzed with the increase of gradient concentration of the reference standard solutions to investigate the linear range and calculate the regression parameters. Te least squares method was used to calculate the regression equation between the chromatographic peak area (y) and the concentration (x) of 8 favonoids, and the correlation coefcient (R 2 ) was used to refect the correlation degree between the peak area and the concentration [12]. Te methodological investigation of the determination method was further carried out through the determination of repeatability, stability, precision, and sample recovery according to the method of literature [9,12,29]. In order to verify the repeatability of the determination method, six diferent sample solutions prepared in parallel of Radix Scutellaria sample from the same origin (HQ-1) were analyzed, and the contents and relative standard deviation (  International Journal of Analytical Chemistry scutellarin (0.677 mg·mL −1 ), baicalin (1.214 mg·mL −1 ), scutellarein (0.261 mg·mL −1 ), wogonoside (0.704 mg·mL −1 ), baicalein (0.603 mg·mL −1 ), wogonin (0.232 mg·mL −1 ), chrysin (0.107 mg·mL −1 ), and oroxylin A (0.077 mg·mL −1 ), which were added to the known content of Radix Scutellaria samples, respectively. Te favonoids were extracted, the contents of the 8 favonoids were determined under the chromatographic conditions above, and recovery and RSD values were calculated. Te limit of detection (LOD) and limit of quantifcation (LOQ) were determined by continuously diluting the reference standard solution until the signal-to-noise ratio (S/N) was about 3 or 10, respectively.

Determination of Total Flavonoids.
Te contents of total favonoids (TFs) in Radix Scutellaria from diferent location of cultivated areas were determined by UV spectrophotometry reported in literature [21]. Te samples of Radix Scutellaria were extracted by the method described in Section 2.4, and the powder of Radix Scutellaria extract was obtained by vacuum concentration and weighed. Te dried powder of Radix Scutellaria extract (5 mg) was weighed accurately and dissolved in methanol and then transferred into a 25 mL volumetric fask, and then methanol was added to obtain the test solution with a mass concentration of 0.2 mg·mL −1 . 0.8 ml of 0.1 mol·L −1 aluminum trichloride solution and 1 mL of 1 mol·L −1 potassium acetate solution were added into the test solution and then mixed well. After bathing in water at 20°C for 20 min, the absorbance of prepared test solution was measured at the wavelength of 415 nm, and methanol was used as the blank control. Te rutin solution of 0.005, 0.01, 0.02, 0.03, 0.04, and 0.05 mg·mL −1 was used as abscissa, and the corresponding absorbance was used as ordinate to determine the regression curve. Te regression equation was obtained as y � 0.06553x + 0.00031 (where x is absorbance and y is the concentration of rutin standard solution, in mg·mL −1 ) with R 2 of 0.9997. Te total favonoid content was calculated according to the calibration curve and the method reported in literature [21].

Data Analysis.
In the study, PCA and HCA were employed to select the key indexes afecting the quality of Radix Scutellaria, and the quality evaluation system of Radix Scutellaria was preliminarily established [32][33][34][35]. Te study provided research reference for the utilization of Radix Scutellaria and the evaluation of the quality of genuine medicinal materials.
Tree parallel experiments were conducted in each experimental group, and the experimental results were expressed as mean ± standard deviation (SD). One-way analysis of variance (ANOVA) was used to compare the data between the treatments.

Optimization of Extraction Conditions.
As conventional organic solvents, methanol and ethanol were widely used as the solvents in the extraction of favonoids due to the high polarity of favonoids in Radix Scutellaria [9,12]. Te efects of ultrasonic extraction, Soxhlet extraction, and refux extraction on the yields of total favonoids from S. baicalensis were compared with those using methanol and ethanol as extraction solvent. Te results revealed that the extraction yield of total favonoids by methanol (10.75%) was signifcantly higher than that of ethanol (6.88%) under the ultrasonic extraction. Te methanol thus was more suitable for the extraction of favonoids from Radix Scutellaria in this study. Te yield of total favonoids by Soxhlet extraction (13.06%) was higher than that by refux extraction (11.73%) and ultrasonic extraction (10.75%) with methanol used as extraction solvent. It may be that the solubility of favonoids in solvent has a certain saturation in the extraction process, and the extraction rate of ultrasonic extraction and refux extraction will not be improved when reaching saturation. While Soxhlet extraction method makes use of the principle of solvent refux and siphon, the favonoids can be extracted by pure solvent every time, so the extraction efciency is higher. Te results are consistent with those reported in the literature [36,37]. Terefore, the Soxhlet extraction method with methanol as the extraction solvent was used to extract favonoids from samples of Radix Scutellaria.
In the experiment, the maximum absorption wavelengths of 8 favonoids were scanned in the wavelength range of 200-400 nm. Among them, scutellarin and scutellarein were well absorbed at 335 nm, and baicalin, baicalein, wogonoside, wogonin, and oroxylin A had the maximum absorption at 280 nm, and the maximum absorption wavelength of chrysin was 250 nm. Te results of the selected absorption wavelength were close to the detection wavelengths of 262 nm, 278 nm, and 340 nm reported in the literature [9][10][11][12]. Te HPLC chromatograms at the wavelengths of 335 nm, 280 nm, and 250 nm were combined, and wavelength of 280 nm was selected in the study for the stable baseline and good resolution ( Figure 2).

HPLC Method Validation.
Te determination method was evaluated through the verifcation of linearity, precision, repeatability, stability, and sample recovery. Te linear range, regression equation, and R 2 of 8 favonoids were obtained as shown in Table 2. Te results implied that the method had a good linear relationship and a wide linear range and could be used for the quantitative analysis of favonoids in Radix Scutellaria. Under the same conditions, the same sample was evaluated for 6 times, and the values of RSD of scutellarin, baicalin, scutellarein, baicalein, wogonoside, wogonin, chrysin, and oroxylin A were calculated to be 1.53%, 0.21%, 0.31%, 0.30%, 0.25%, 0.22%, 0.23%, and 0.24%, respectively, indicating that the precision of the instrument was good. Te RSD values of the eight components measured after being placed at room temperature for 0, 2, 4, 8, 12, 16, and 24 hours were 1.54%, 0.84%, 0.77%, 0.73%, 0.62%, 0.93%, 0.98%, and 0.92%, respectively, which revealed that the prepared solution has good stability within 24 hours. Six sample solutions were extracted in parallel under the same conditions for determination, and the RSD values were 1.41%, 0.65%, 0.77%, 0.75%, 0.71%, 0.76%, 0.96%, and 0.99%, respectively, and the results implied that the method has good repeatability. Te average recovery of the 8 compounds was 99.066-100.433% with the RSD of 0.619-1.763%, which indicated that the method had good sample recovery (Table S2). Te LOD and LOQ were determined, and the results are shown in Table 2.
Te results suggested that the precision, stability, repeatability, and sample recovery of this method met the analysis requirements, and the method had the characteristics of fast, accurate, reliable, and strong specifcity. Terefore, the method was suitable for the content determination of favonoids in Radix Scutellaria and could also provide a scientifc basis for the quality evaluation and effective quality control of Radix Scutellaria.

Method
Application. An HPLC method was established for the simultaneous determination of 8 main favonoids in the extracts of 38 Radix Scutellaria samples from seven cultivated areas. Te chromatograms of the mixed control and representative sample at the detection wavelength of 280 nm are shown in Figure 2. Te results revealed that the eight favonoids were completely separated from each other and the baseline was stable. Te retention time of all the compounds to be analyzed was within 25 min, and the test time was much smaller than that (30-50 minutes) reported in the literature [9][10][11][12], indicating that this method can signifcantly shorten the test time. Te monomer contents of 8 favonoids in samples from diferent cultivated areas are shown in Table 3. Te favonoids were confrmed according to the comparison of retention time results between the samples and the reference substance.
Te results implied that 8 favonoids were generally found in 38 samples from diferent cultivated areas. Tere were signifcant diferences in the contents of 8 favonoids in Radix Scutellaria from diferent cultivated areas (P < 0.01). , and oroxylin A (2.041 mg·g −1 ) were all at high level, which implied that the quality of the sample from this cultivated area was the best.
Te above results implied that the main active components of favonoids in Radix Scutellaria were baicalin, wogonoside, baicalein, wogonin, and scutellarin, which were consistent with the research results reported in the literature [10,12]. Te contents of these active components could be used to evaluate the quality of medicinal plant S. baicalensis. Tere were signifcant diferences in the content of favonoids in diferent cultivated areas, which revealed that the growth environment had an important impact on the content of favonoids in Radix Scutellaria [11,24,25].
Baicalin, wogonoside, and baicalein had good antibacterial property [41][42][43], which was consistent with the results that Radix Scutellariae had been used to treat antibacterial diseases in clinic [44,45]. Baicalin and baicalein also had potential as therapeutic or supplementary agents for the treatment of breast cancer [46], and the anticancer properties of Radix Scutellariae could be attributed to its high content of wogonin, baicalein, and baicalin [3]. A study conducted by Zhang also revealed that baicalin might be one of the main components of Radix Scutellariae in the treatment of fetal irritability [47]. It was found that baicalin and baicalein were also the main active substances of traditional Chinese medicine Radix Scutellariae with good liver protection and inhibition of liver injury [48]. Baicalein and baicalin were also considered the main material basis of Radix Scutellariae for the treatment of the infection of the upper respiratory tract and to cure hyperactivity cough [49][50][51]. Te above studies had confrmed that baicalin and baicalein were the main active substances of Radix Scutellariae with a variety of bioactive efects.

International Journal of Analytical Chemistry
Te average content of the eight favonoids in diferent planting areas is shown in Table 4. It could be seen from the Table 4 that the contents of favonoids in the samples from seven main genuine producing areas were signifcantly diferent (P < 0.01). Te average contents of baicalin (163.999 mg·g −1 ), wogonoside (10.014 mg·g −1 ), baicalein (15.449 mg·g −1 ), wogonin (4.638 mg·g −1 ), chrysin (2.340 mg·g −1 ), and oroxylin A (1.875 mg·g −1 ) in Gansu cultivated area were all higher than those in other six genuine producing areas, and the content of scutellarin (6.695 mg·g −1 ) and scutellarein (3.072 mg·g −1 ) was at a high level, which resulted in the highest content of TCEF (208.081 mg·g −1 ) and TF (10.778%). Te results implied that the quality of S. baicalensis in Gansu planting cultivated area was the best as the content of main favonoids was significantly higher than that in other planting cultivated areas. Te cultivated areas of Shaanxi were characterized by the highest content of scutellarin (7.066 mg·g −1 ) and the lowest content of wogonoside (6.314 mg·g −1 ). Compared with that in other planting areas, the samples of Henan cultivated area had the highest content of scutellarein (3.662 mg·g −1 ), and the content of baicalin (158.801 mg·g −1 ), wogonoside (9.223 mg·g −1 ), wogonin (2.816 mg·g −1 ), and oroxylin A (1.280 mg·g −1 ) in Henan cultivated area was only lower than that in Gansu cultivated area, while it was higher than that in the other fve cultivated areas, which led to the content of TCEF (190.975 mg·g −1 ) only lower than that in Gansu and higher than that in the samples from other cultivated areas. Te cultivated area in Inner Mongolia was characterized by the lowest content of baicalin (131.090 mg·g −1 ), baicalein (5.747 mg·g −1 ), and wogonin (1.801 mg·g −1 ), and the content of wogonoside (6.410 mg·g −1 ) was also at a low level, which resulted in the lowest content of TCEF (156.590 mg·g −1 ) in the samples of cultivated area in Inner Mongolia. Te contents of chrysin (1.289 mg·g −1 ), scutellarein (2.446 mg·g −1 ), and oroxylin A (0.876 mg·g −1 ) in the samples from Hebei cultivated areas were the lowest among all cultivated areas. At the same time, the contents of scutellarin, wogonoside, and baicalein were also at a low level, which was the main reason that TCEF and TF were at a low level in the samples of Hebei cultivated areas.
It was traditionally believed that the genuine producing areas of S. baicalensis were in Shandong, Henan, Gansu, Shanxi, Hebei, Inner Mongolia, and other places [23]. In this study, the evaluation content of favonoids in Shanxi, Hebei, and Inner Mongolia Autonomous Region was not high, which was consistent with the research results reported in the literature [11,22] but diferent from the research which believed that the content of active components in Radix Scutellariae in Hebei and Inner Mongolia was the highest [21], which might be due to diferent sampling ranges and other reasons. From the experimental results, the quality of Radix Scutellariae in the traditional genuine producing areas was not necessarily the best. Te quality of Radix Scutellariae from diferent cultivated areas could be improved by improving germplasm resources and changing cultivation methods.
Te studies of the efects of diferent elevations and diferent lighting conditions (shade slope and sunny slope) on the contents of favonoids revealed that high altitude and sunny slope were conducive to increasing the accumulation of total favonoids in Radix Scutellariae [24]. Te efects of environmental factors on photosynthetic physiology and favonoid constituent of Radix Scutellariae also suggested that photosynthetic active radiation and soil water content were important environmental factors impacting on photosynthesis of S. baicalensis, and soil water content, relative humidity, and atmospheric CO2 concentration were important environmental factors impacting on baicalin content, and photosynthetic active radiation, atmospheric pressure, and atmospheric temperature were important environmental factors impacting on baicalin content [25]. Te high average altitude, mild and humid climate, and strong light intensity might be the reason for the high content of favonoids in Radix Scutellariae in Tanchang County.
As a bulk medicinal material and a widely used traditional Chinese medicine, S. baicalensis had a large planting scale in China, with the characteristics of large planting area and wide range. Te diference of climate, geographical environment, and other external factors would afect the active components in Radix Scutellariae. Terefore, the systematic determination of the content of main favonoids will provide a guarantee for the quality evaluation of medicinal materials in diferent cultivated areas.

Principal Component
Analysis. Based on the above content determination results, scutellarin (X1), baicalin (X2), wogonoside (X3), baicalein (X4), and total favonoids (X5) were selected as indicators for PCA. One-way ANOVA was used to compare the data between the treatments, and Bartlett's test of sphericity was used to detect the correlation between variables [32,35]. All statistical analyses were performed at 95% confdence level using SPSS 26.0 software. From the analysis results (Table 5), it could be seen that the value of the Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy (0.587) in this example was greater than 0.5, indicating that PCA could be used to evaluate the results [32,35]. Te signifcance of Bartlett's test of sphericity (0.001) was less than 0.01, which revealed that the correlation between variables was very signifcant, and factor analysis could be carried out in the study [32,35]. Te results of PCA (Table 6) of the above fve components (X1-X5) showed that the characteristic values of the frst two principal components (X1 and X2) were greater than 1, and the contribution rate of cumulative variance was 93.028%, and the characteristic value of the frst principal component was 3.574 and the contribution rate was 71.477%, representing 71.477% of all information, which implied that scutellarin was a main factor closely related to the origin of Radix Scutellariae. Te above results implied that these two factors have a high degree of explanation for the whole result [33]. Te two principal components could be used to replace the above fve specifc contents to evaluate the quality of Radix Scutellariae from diferent planting areas.
Te principal component matrix was employed for the selection of the principal components, the original data were normalized and the variables were saved, and the PCA model according to the principal component matrix was constructed (Table 7). Te principal component model was calculated as follows: According to the principal component model, the principal component scores of seven planting areas were obtained (Table 8). Te results implied that the top three scores in the comprehensive evaluation were 2.963 in Gansu, 0.341 in Shandong, and 0.307 in Henan, indicating that the quality of Radix Scutellariae in Gansu planting area was the best and could be used as genuine medicinal material, followed by Shandong and Henan.

Hierarchical Cluster Analysis of the Samples.
Taking the content of 8 favonoids and total favonoids in Radix Scutellariae as indicators, the clustering analysis of Radix Scutellariae from diferent cultivated areas was carried out by the clustering method of square Euclidean distance coefcient and centroid clustering (Figure 3). Te results revealed that the seven cultivated areas could be divided into three groups: group I was Shandong and Henan; group II was Inner Mongolia, Hebei, Shaanxi, and Shanxi; and group III was Gansu. Tere were similarities and diferences in the content of favonoids in Radix Scutellariae from diferent cultivated areas. Te contents of baicalin, wogonoside, and baicalein in group III were signifcantly higher than those in group I and group II. Te contents of scutellarin, scutellarein, and chrysin in group I were higher than those in group II. Due to the high content of baicalin, wogonoside, and baicalein, the quality of Radix Scutellariae in Gansu Province was the best. Shandong and Henan were clustered together earlier, which might be related to the diference of their growth environment and the small diferentiation of population diversity, and results were consistent with the research results reported in the literature [11].
Te cluster analysis method refected the diversity differentiation of S. baicalensis in diferent cultivated areas, and the diferent cultivated areas would make the chemical composition and content of active components of Radix Scutellariae diferent. It also revealed that the quality of Radix Scutellariae was afected by geographical location and environmental factors, which might be related to the superposition of precipitation, atmospheric temperature, sunshine duration, and soil properties [11,24,25].
Te results suggested that the favonoid extracts of Radix Scutellariae from diferent cultivated areas had certain efects of scavenging free radicals and inhibitory activity on cancer cells, but the activity varied greatly in diferent cultivated areas. Te sample from Gansu Province had the strongest scavenging efect on DPPH and ABTS free radicals, as well as the inhibitory efect on cancer cell HepG2, which was closely related to the high content of favonoids in the samples. From the inhibitory activity of favonoids on cancer cells, although the compounds scutellarin (65.913 ± 4.22 μg·mL −1 ) and oroxylin A (67.389 ± 3.14 μg·mL −1 ) had greater inhibitory efect on cancer cell HepG2 than that of other compounds, the efects of the two compounds on the anticancer activity of the samples from corresponding places were weak because of the relatively low contents in the samples. Baicalein and baicalin were the main favonoids in Radix Scutellariae, and the high antitumor activities of baicalein (69.608 ± 4.01 μg·mL −1 ) and baicalin However, based on the results of activity determination, the activities of favonoids extract did not have a good positive correlation with the total content of favonoids in Radix Scutellariae, and higher total favonoid content did not mean a higher bioactivity. It implied that the bioactivities of Radix Scutellariae were related to the content of active favonoids and the bioactivity of the favonoids.

Conclusions
In this study, a method for the simultaneous determination of 8 main favonoids in Radix Scutellariae from diferent genuine producing areas was established for the frst time, and the chromatographic conditions were optimized. Te chromatographic conditions with good resolution and appropriate retention time were obtained. Te results suggested that favonoids in Radix Scutellariae from diferent cultivated areas varied greatly, and baicalin, wogonoside, baicalein, wogonin, and scutellarin were the main favonoids in Radix Scutellariae, and the content of baicalin was the highest, accounting for more than 77% of the total favonoids. Te content of favonoids in Radix Scutellariae planted in Gansu cultivated areas was the highest with the content of baicalein, baicalin, wogonin, chrysin, wogonoside, and oroxylin A, and TCEF and TF were much higher than those in other cultivated areas. It implied that the content of favonoids in Radix Scutellariae of Gansu was high in the cultivated areas, which implied that the quality of     Radix Scutellariae might be good. In addition, the content of favonoids in Radix Scutellariae in Henan and Shandong cultivated areas was also at high level. Te results of PCA revealed that Gansu, Shandong, and Henan were the three producing areas with the highest content of favonoids and the best quality. Te results of HCA also confrmed that S. baicalensis planted in Gansu cultivated areas had higher content of favonoids than those of other cultivated areas. Te antioxidant and anticancer activities of the extract of Radix Scutellaria were closely related to the content of favonoids, and high contents of baicalin, wogonoside, and baicalein were helpful to improve biological activities. Te results implied that there were great diferences in the content of favonoids in samples from diferent genuine producing areas of S. baicalensis. Tis study had good guiding signifcance for the quality evaluation of Radix Scutellariae.

Data Availability
Te data used to support the fndings of this study are available from the corresponding author upon request.

Conflicts of Interest
Te authors declare that they have no conficts of interest.