Correlation of antioxidant activity and volatile oil chemical components from Schizonepeta tenuifolia herbs by chemometric methods

Figures & data

Table 1. Chemicals and reagents.

Chemicals and reagents	Supplier
3-octanone (C8H16O, 98.2% purity)	Sigma-Aldrich (Vienna, Austria)
β-myrcene (C10H16, 98.9% purity)	Sigma-Aldrich (Vienna, Austria)
(+)-menthofuran (C10H14O, 98.7% purity)	Sigma-Aldrich (Vienna, Austria)
(-)-limonene (C10H16, 96.0% purity)	National Institutes for Food and Drug Control (Beijing, China)
(-)-menthone (C10H18, 99.8% purity)	National Institutes for Food and Drug Control (Beijing, China)
(+)-pulegone (C10H16O, 99.8% purity)	National Institutes for Food and Drug Control (Beijing, China)
1-octen-3-ol (C8H16O, 99.8% purity)	Nanjing JinYibai Biological Technology Co., Ltd. (Nanjing, China).
β-caryophyllene (C15H24, 95.8% purity)	Nanjing JinYibai Biological Technology Co., Ltd. (Nanjing, China).
Naphthalene (C10H8,AR)	Sinopharm Chemical Reagent (Shanghai, China)
Sodium sulfate anhydrous (AR)	Sinopharm Chemical Reagent (Shanghai, China)
Ultrapure water	Milli-Q system (Millipore, Bedford, MA, USA)
Methanol (HPLC grade)	Merck (Darmsdadt, Germany)
Formic acid (HPLC grade)	Merck (Darmsdadt, Germany)
Ethyl acetate	Xilong Chemical Industry Co., Ltd. (Guangzhou, China)
DPPH	TCI Chemical Industry Co., Ltd. (Shanghai, China)

Table 2. Sample information of different bathes of ST herbs.

NO.	Location (China)	Lot.	NO.	Location (China)	Lot.	NO.	Location (China)	Lot.
1	Nanjing Jiangsu	151024	6	Suzhou Jiangsu	141022	11	Pingnan Guangxi	150819
2	Xuzhou Jiangsu	150712	7	Anguo Hebei	150820	12	Guilin Guangxi	151215
3	Chengdu Sichuan	140304	8	Bozhou Anhui	150912	13	Liuzhou Guangxi	150619
4	Chuxiong Yunnan	150202	9	Baoding Hebei	150724	14	Gaoyao, Guangdong	150725
5	Tongling Anhui	150939	10	Zhaoqing Guangdong	150408	15	Maoming Guangdong	160309

Figure 1. Total ion chromatograms of STVO (sample 2, A1) and reference substances (B1); extract ion chromatograms of STVO (sample 2, A1) and reference substances (B2).

1-octen-3-ol (S1), 3-octanone (S2), β-myrcene (S3), (-)-limonene (S4), (-)-menthone (S5).(+)-menthofuran (S6), (+)-pulegone (S7), β-caryophyllene (S8), and naphthalene (IS).

Figure 2. EI mass spectra and chemical structures of eight compounds in STVO.

1-octen-3-ol (S1), 3-octanone (S2), β-myrcene (S3), (-)-limonene (S4), (-)-menthone (S5), (+)-menthofuran (S6), (+)-pulegone (S7), β-caryophyllene (S8).

Table 3. Contents of eight components from 15 batches of STVO (means±SD‚n = 3).

	Content (%)± SD (%)
No.	1-octen-3-ol	3-octanone	β-myrcene	(-)-limonene	(-)-menthone	(+)-menthofuran	(+)-pulegone	β-caryophyllene
1	0.67 ± 0.0091	0.14 ± 0.0012	0.64 ± 0.0062	4.44 ± 0.028	18.74 ± 0.093	0.32 ± 0.0089	67.36 ± 0.136	0.74 ± 0.0053
2	0.53 ± 0.0062	0.17 ± 0.0013	0.68 ± 0.0056	5.06 ± 0.048	19.35 ± 0.085	0.29 ± 0.0022	71.20 ± 0.134	0.80 ± 0.0064
3	0.46 ± 0.0054	0.13 ± 0.0019	0.62 ± 0.0052	3.59 ± 0.036	20.79 ± 0.102	0.40 ± 0.0011	71.97 ± 0.165	0.66 ± 0.0052
4	0.62 ± 0.0082	0.13 ± 0.0016	0.63 ± 0.0064	5.39 ± 0.054	19.80 ± 0.142	0.28 ± 0.0045	70.08 ± 0.243	0.86 ± 0.0062
5	0.63 ± 0.0063	0.15 ± 0.0017	0.59 ± 0.0056	4.28 ± 0.043	20.35 ± 0.149	0.21 ± 0.0021	65.05 ± 0.306	0.83 ± 0.0060
6	0.64 ± 0.0052	0.17 ± 0.0012	0.68 ± 0.0063	3.85 ± 0.040	15.68 ± 0.102	0.43 ± 0.0056	74.27 ± 0.218	0.73 ± 0.0070
7	0.69 ± 0.0074	0.25 ± 0.0020	0.68 ± 0.0076	6.05 ± 0.068	19.56 ± 0.084	0.21 ± 0.0038	63.60 ± 0.148	0.85 ± 0.0073
8	0.67 ± 0.0082	0.14 ± 0.0015	0.70 ± 0.0074	6.00 ± 0.060	19.04 ± 0.093	0.53 ± 0.0035	60.52 ± 0.241	0.94 ± 0.0084
9	0.63 ± 0.0073	0.12 ± 0.0013	0.68 ± 0.0067	6.70 ± 0.058	18.58 ± 0.106	0.22 ± 0.0036	65.28 ± 0.142	0.81 ± 0.0083
10	0.61 ± 0.0064	0.15 ± 0.0018	0.59 ± 0.0061	4.45 ± 0.047	16.37 ± 0.121	0.51 ± 0.0039	63.52 ± 0.284	0.87 ± 0.0074
11	0.59 ± 0.0051	0.17 ± 0.0019	0.58 ± 0.0062	6.95 ± 0.055	18.95 ± 0.162	0.29 ± 0.0013	62.71 ± 0.352	0.65 ± 0.0057
12	0.62 ± 0.0078	0.11 ± 0.0023	0.63 ± 0.0068	4.25 ± 0.048	20.56 ± 0.125	0.21 ± 0.0013	68.34 ± 0,265	0.69 ± 0.0072
13	0.58 ± 0.0064	0.32 ± 0.0016	0.72 ± 0.0073	4.09 ± 0.052	19.60 ± 0.116	0.38 ± 0.0027	63.64 ± 0,232	0.73 ± 0.0062
14	0.62 ± 0.0073	0.31 ± 0,0018	0.76 ± 0.0086	3.99 ± 0.038	19.96 ± 0.133	0.38 ± 0.0021	63.12 ± 0.148	0.81 ± 0.0070
15	0.59 ± 0.0065	0.12 ± 0.0013	0.61 ± 0.0070	4.21 ± 0.057	20.44 ± 0.164	0.32 ± 0.0042	66.19 ± 0.157	0.93 ± 0.0083

Table 4. Interpretation equation of scavenging DPPH free radical of STVOs (means ± SD).

No.	Probit	R^2	IC50 (mg/ml)	NO.	Probit	R^2	IC50 (mg/ml)
1	p = 0.160x-0.048	0.988	0.297 ± 0.022	9	p = 0.140x-0.088	1.000	0.630 ± 0.028
2	p = 0.175x-0.032	0.996	0.185 ± 0.013	10	p = 0.127x-0.193	0.974	1.518 ± 0.094
3	p = 0.209x-0.003	0.951	0.016 ± 0.001	11	p = 0.124x-0.145	0.978	1.178 ± 0.091
4	p = 0.176x-0.052	0.993	0.293 ± 0.021	12	p = 0.133x-0.030	0.999	1.172 ± 0.087
5	p = 0.165x-0.125	0.997	0.756 ± 0.031	13	p = 0.139x-0.097	0.996	0.695 ± 0.021
6	p = 0.169x-0.008	0.939	0.046 ± 0.004	14	p = 0.148x-0.113	0.996	0.762 ± 0.033
7	p = 0.226x-0.169	0.999	0.573 ± 0.021	15	p = 0.168x-0.129	0.998	0.765 ± 0.041
8	p = 0.143x-0.187	0.980	1.310 ± 0.014

Figure 3. Change curves of DPPH radical scavenging with reaction time (A) and DPPH concentration (B).

Table 5. Partical correlations of content and antioxidant activity.

Compounds	Correlation	t	p-Value	Compounds	Correlation	t	p-Value
1-octen-3-ol	0.038	0.482	0.104	(-)-menthone	−0.536	3.132	0.006
3-octanone	0.072	0.578	0.092	(+)-menthofuran	−0.116	1.543	0.072
β-myrcene	0.177	1.412	0.086	(+)-pulegone	−0.737	3.243	0.005
(-)-limonene	−0.274	2.003	0.053	β-caryophyllene	0.092	0.623	0.082

t > 2.145(df = 14), p < 0.05; t > 2.977, p < 0.01(df = 14).

Table 6. Coefficients of eight components and their antioxidant activity in PLEA.

Compounds	Coefficient	VIP	Compounds	Coefficient	VIP
1-octen-3-ol	0.0427	0.4038	(-)-menthone	−0.2169	1.0496
3-octanone	0.0536	0.2054	(+)-menthofuran	0.1878	0.8802
β-myrcene	0.1219	0.6963	(+)-pulegone	−0.2985	1.0814
(-)-limonene	−0.0696	0.3602	β-caryophyllene	0.0569	0.2543

VIP (Variable Importance Plot).

Figure 4. PLSA scores plot of the 15 STVOs.