Quality evaluation of Eucommiae Folium extracts and discovery of efficacy-associated quality markers based on spectrum-effect relationship

Figures & data

Table 1. The mobile phase system of HPLC fingerprint analysis.

t/min	Organic phase (%)	0.1% Aqueous phase (%)
0.01	7	93
6	14	86
30	30	70
35	70	30
40	70	30
40.01	7	93

Figure 1. HPLC chromatograms of EF extracts at different separation conditions. (a) wavelength, (b) mobile phase, (c) modifying agent, (d) column temperature, and (e) flow rate.

Table 2. Chromatographic analysis results of EF extracts at different separation conditions.

Separation conditions	Peak No.	Retention time	Peak area
Water (A), acetonitrile (B)	94	23.955	2782889
0.1% phosphoric acid -water (A), methanol (B)	76	27.922	26406805
0.1% phosphoric acid -water (A), acetonitrile (B)	105	13.337	26985014
0.1% formic acid -water (A), acetonitrile (B)	93	13.349	13844757
0.1% trifluoroacetic acid -water (A), acetonitrile (B)	95	13.472	27190810
25°C	101	13.977	2860901
30°C	105	13.337	26985014
35°C	97	12.971	27229322
0.8 mL/min	105	13.337	26985014
1.0 mL/min	100	11.827	21260105
1.2 mL/min	101	10.583	17490311

Figure 2. HPLC fingerprints of EF extracts, representative of 12 chromatograms.

Table 3. Total antioxidant capacity of 12 batches of EF extracts.

Samples	Similarity values	Antioxidant capacity（mmol/mg)
1	1.000	0.83±0.02
2	1.000	0.81±0.02
3	0.999	0.79±0.01
4	0.999	0.80±0.02
5	0.999	0.83±0.04
6	0.999	0.83±0.03
7	0.997	0.84±0.01
8	0.997	0.82±0.01
9	0.997	0.79±0.00
10	0.997	0.80±0.02
11	0.996	0.80±0.02
12	0.995	0.78±0.01

Figure 3. Reference atlas from 10 EF extracts chromatograms.

Figure 4. HCA of EF extracts.

Figure 5. Correlations between common characteristic peaks and the antioxidant activity obtained by SIMCA-P.

Figure 6. VIP scores of each characteristic peak.

Figure 7. Correlations between common characteristic peaks and the antioxidant activity obtained by Unscrambler X software.

Figure 8. HPLC of chlorogenic acid reference substance (A) and EF extract (B).