Comparison of Essential Oils of Houttuynia cordata Thunb. from Different Processing Methods and Harvest Seasons Based on GC-MS and Chemometric Analysis

Table 1

Average relative content of sixty-nine common volatile constituents of DHC and FHC at two harvest seasons.

No.	Name/class	RT (min)	Similarity (%)	Average relative content (%)
				DHC (n = 21)	FHC (n = 23)	DHC1 (n = 11)	DHC2 (n = 10)	FHC1 (n = 12)	FHC2 (n = 11)
Aliphatic compounds
1	Nonane	6.47	99	0.02 (0.02)	0.02 (0.03)	0.02 (0.01)	0.03 (0.03)	0.02 (0.03)	0.02 (0.02)
2	2-Nonanone	10.38	96	0.06 (0.10)	0.02 (0.02)	0.09 (0.13)	0.02 (0.01)	0.01 (0.01)	0.03 (0.03)
3	Undecane	10.59	98	0.04 (0.03)	0.02 (0.01)	0.04 (0.04)	0.04 (0.03)	0.01 (0.01)	0.02 (0.01)
4	Nonanal	10.75	90	0.67 (0.68)	0.07 (0.04)	0.81 (0.85)	0.50 (0.39)	0.05 (0.03)	0.08 (0.05)
5	1-Nonanol	12.75	99	3.10 (1.50)	0.49 (0.55)	2.73 (1.15)	3.51 (1.80)	0.31 (0.21)	0.69 (0.73)
6	Decanal	13.88	99	2.68 (6.35)	2.61 (5.48)	2.55 (7.32)	2.82 (5.47)	1.30 (3.26)	4.04 (7.08)
7	1-Decanol	15.53	99	0.22 (0.55)	0.14 (0.20)	0.29 (0.75)	0.13 (0.13)	0.07 (0.08)	0.22 (0.27)
8	2-Undecanone	16.25	92	44.92 (27.15)	48.49 (15.48)	44.23 (30.29)	45.67 (24.73)	45.94 (13.18)	51.27 (17.87)
9	Undecanal	16.5	99	0.19 (0.40)	0.09 (0.22)	0.25 (0.54)	0.14 (0.16)	0.02 (0.04)	0.17 (0.31)
10	1-Undecanol	18.31	99	0.60 (0.83)	0.17 (0.22)	0.68 (0.97)	0.52 (0.70)	0.17 (0.12)	0.18 (0.30)
11	2-Dodecanone	19.01	91	0.30 (0.31)	0.22 (0.17)	0.28 (0.28)	0.31 (0.36)	0.17 (0.12)	0.28 (0.21)
12	n-Decanoic acid	19.02	98	0.08 (0.05)	0.04 (0.03)	0.06 (0.03)	0.10 (0.07)	0.02 (0.01)	0.05 (0.03)
13	Dodecanal	19.48	99	0.12 (0.17)	0.30 (1.10)	0.07 (0.06)	0.17 (0.23)	0.04 (0.03)	0.58 (1.58)
14	Dodecanol	21.76	99	0.10 (0.19)	0.04 (0.07)	0.12 (0.26)	0.07 (0.04)	0.02 (0.02)	0.06 (0.09)
15	Vinyl decanoate	21.8	89	0.10 (0.05)	0.05 (0.03)	0.08 (0.04)	0.11 (0.05)	0.04 (0.01)	0.06 (0.03)
16	4-Tridecanone	22.66	89	0.55 (0.56)	1.78 (1.11)	0.76 (0.55)	0.32 (0.49)	2.03 (0.79)	1.52 (1.37)
17	2-Tridecanone	22.67	92	2.29 (2.16)	1.18 (1.10)	2.58 (2.20)	1.96 (2.20)	1.41 (1.41)	0.92 (0.58)
18	Ethyl decanoate	27.81	82	0.03 (0.02)	0.80 (0.46)	0.04 (0.02)	0.02 (0.02)	0.81 (0.26)	0.79 (0.63)
19	Tetradecanal	28.4	99	1.48 (1.19)	0.82 (0.38)	1.27 (1.12)	1.72 (1.27)	0.78 (0.39)	0.87 (0.37)
20	Isopentyl decanoate	36.36	78	0.06 (0.04)	0.11 (0.07)	0.06 (0.02)	0.06 (0.06)	0.09 (0.05)	0.13 (0.09)
21	n-Hexadecanoic acid	42.62	94	0.09 (0.06)	0.01 (0.01)	0.07 (0.03)	0.11 (0.07)	0.01 (0.00)	0.02 (0.01)
22	Octadecanol	45.57	99	0.36 (0.39)	0.04(0.03)	0.16 (0.09)	0.58 (0.48)	0.02 (0.01)	0.05 (0.04)
Aromatic compounds
23	Benzeneacetaldehyde	9.35	92	0.06 (0.05)	0.04 (0.04)	0.05 (0.03)	0.08 (0.06)	0.04 (0.05)	0.03 (0.02)
24	4-Isopropyl-1-methylcyclohex-2-enol	11.55	96	0.08 (0.10)	0.06 (0.08)	0.07 (0.06)	0.10 (0.13)	0.08 (0.10)	0.05 (0.05)
25	2-Butanone, 4-(2,6,6-trimethyl-1,3-cyclohexadien-1-yl)-	19.96	85	0.05 (0.05)	0.02 (0.02)	0.03 (0.02)	0.08 (0.06)	0.01 (0.01)	0.03 (0.02)
26	1,4-Di-Tert-Butylbenzene	21.75	80	0.10 (0.12)	0.03 (0.04)	0.11 (0.17)	0.08 (0.05)	0.02 (0.01)	0.05 (0.06)
Monoterpene hydrocarbons
27	Bicyclo[3.1.0]hex-2-ene,2-methyl-5-(1-methylethyl)-	7.04	92	0.04 (0.05)	0.06 (0.06)	0.03 (0.04)	0.05 (0.06)	0.05 (0.06)	0.07 (0.07)
28	α-Pinene	7.23	99	0.63 (0.44)	2.18 (1.15)	0.66 (0.43)	0.59 (0.48)	2.24 (1.14)	2.11 (1.22)
29	Camphene	7.54	99	0.18 (0.14)	0.26 (0.08)	0.20 (0.16)	0.15 (0.13)	0.28 (0.08)	0.25 (0.09)
30	(1S)-(-)-β-Pinene	7.92	91	0.77 (1.05)	1.64 (1.79)	0.62 (0.95)	0.95 (1.17)	1.62 (1.97)	1.67 (1.65)
31	β-Pinene	8.09	99	9.95 (7.16)	8.67 (3.43)	10.59 (7.40)	9.25 (7.21)	9.23 (3.93)	8.07 (2.85)
32	β-Myrcene	8.14	99	17.68 (12.99)	18.36 (7.64)	18.85 (13.44)	16.39 (13.06)	21.33 (8.72)	15.12 (5.58)
33	α-Phellandrene	8.54	98	0.02 (0.02)	0.03 (0.02)	0.02 (0.02)	0.02 (0.01)	0.03 (0.01)	0.04 (0.03)
34	α-Terpinene	8.78	99	0.06 (0.08)	0.16 (0.17)	0.05 (0.07)	0.08 (0.08)	0.13 (0.14)	0.19 (0.20)
35	1-Isopropyl-4-Methylbenzene	8.94	95	0.09 (0.10)	0.08 (0.13)	0.09 (0.11)	0.09 (0.10)	0.06 (0.13)	0.10 (0.14)
36	Limonene	9.06	98	0.37 (0.22)	1.35 (0.55)	0.36 (0.20)	0.38 (0.24)	1.31 (0.52)	1.38 (0.60)
37	β-Phellandrene	9.13	93	0.53 (1.51)	1.82 (2.23)	0.99 (2.02)	0.03 (0.05)	2.82 (2.65)	0.73 (0.83)
38	1,3,6-Octatriene, 3,7-dimethyl-, (Z)-	9.31	96	0.07 (0.06)	0.10 (0.09)	0.06 (0.05)	0.08 (0.07)	0.11 (0.10)	0.09 (0.07)
39	2-Octene, 2-methyl-6-methylene-	9.47	80	0.08 (0.07)	0.01 (0.01)	0.09 (0.09)	0.07 (0.05)	0.01 (0.01)	0.02 (0.01)
40	Gamma-terpinene	9.73	99	0.22 (0.28)	0.44 (0.47)	0.19 (0.27)	0.25 (0.29)	0.32 (0.36)	0.56 (0.56)
41	Terpinolene	10.54	96	0.05 (0.04)	0.11 (0.08)	0.05 (0.04)	0.05 (0.04)	0.09 (0.07)	0.14 (0.10)
Sesquiterpene hydrocarbons
42	Caryophyllene	20.56	99	0.27 (0.13)	0.16 (0.08)	0.23 (0.10)	0.31 (0.15)	0.13 (0.04)	0.19 (0.11)
43	α-Guaiene	22.37	91	0.07 (0.05)	0.03 (0.01)	0.07 (0.05)	0.08 (0.05)	0.03 (0.01)	0.03 (0.02)
44	Azulene, 1,2,3,5,6,7,8,8a-octahydro-1,4-dimethyl-7-(1-methylethenyl)-, [1S-(1.α.,7.α.,8a.β.)]-	23.5	91	0.14 (0.08)	0.07 (0.04)	0.13 (0.07)	0.16 (0.080	0.07 (0.05)	0.07 (0.03)
Diterpene hydrocarbons
45	3-Methylene-7,11,15-Trimethyl-1,6,10,14-Hexadecatetraene	21.19	90	0.19 (0.12)	0.07 (0.04)	0.17 (0.0)	0.21 (0.13)	0.07 (0.04)	0.07 (0.03)
46	m-Camphorene	42.42	95	0.19 (0.18)	0.11 (0.08)	0.19 (0.15)	0.19 (0.21)	0.12 (0.09)	0.09 (0.06)
47	p-Camphorene	43.3	94	0.09 (0.09)	0.05 (0.04)	0.08 (0.07)	0.10 (0.11)	0.06 (0.05)	0.04 (0.04)
48	(E)-β-Farnesene	46.1	78	0.26 (0.27)	0.03 (0.02)	0.22 (0.20)	0.29 (0.33)	0.02 (0.01)	0.04 (0.02)
Oxygenated monoterpenes
49	(E)-3,7-Dimethyl-2,6-octadien-1-ol	9.06	90	1.55 (1.73)	2.44 (1.99)	1.59 (1.78)	1.51 (1.78)	3.04 (2.44)	1.80 (1.15)
50	(3E,5 E)-2,6-Dimethylocta-3,5,7-trien-2-ol	10.62	85	0.07 (0.04)	0.03 (0.02)	0.06 (0.04)	0.09 (0.05)	0.03 (0.02)	0.04 (0.03)
51	2-Methyl-6-Methylene-2,7-octadien-4-ol	12.06	92	0.07 (0.05)	0.04 (0.03)	0.06 (0.04)	0.08 (0.06)	0.03 (0.02)	0.05 (0.03)
52	Isoborneol	13.03	96	0.09 (0.07)	0.05 (0.02)	0.10 (0.07)	0.07 (0.06)	0.04 (0.01)	0.06 (0.02)
53	4-Terpinenol	13.31	99	0.52 (0.55)	0.93 (1.06)	0.53 (0.61)	0.51 (0.51)	0.65 (0.77)	1.25 (1.26)
54	Neral	13.45	87	0.02 (0.02)	0.02 (0.03)	0.02(0.01)	0.02 (0.030	0.02 (0.03)	0.01 (0.01)
55	α-Terpineol	13.63	99	0.06 (0.03)	0.21 (0.13)	0.07 (0.03)	0.06 (0.02)	0.17 (0.09)	0.26 (0.16)
56	2-Cyclohexen-1-ol, 3-methyl-6-(1-methylethyl)-, trans-	14.06	91	0.06 (0.04)	0.03 (0.02)	0.06 (0.05)	0.05 (0.04)	0.03 (0.02)	0.04 (0.03)
57	β-Cyclocitral	14.36	91	0.12 (0.06)	0.01 (0.01)	0.09 (0.05)	0.15 (0.06)	0.01 (0.00)	0.02 (0.01)
58	3,7-Dimethyl-2,6-octadien-1-ol(trans)	15.1	99	0.18 (0.11)	0.03 (0.01)	0.18 (0.09)	0.17 (0.13)	0.02 (0.01)	0.03 (0.02)
59	4-(1-Methylethenyl)cyclohexene-1-methanol	15.33	86	0.08 (0.06)	0.04 (0.03)	0.05 (0.03)	0.12 (0.07)	0.03 (0.02)	0.05 (0.03)
60	Bornyl acetate	16.18	92	1.89 (0.92)	1.28 (0.26)	1.85 (1.06)	1.93 (0.80)	1.27 (0.22)	1.30 (0.31)
61	α-Terpinyl acetate	17.86	85	0.06 (0.03)	0.07 (0.04)	0.05 (0.03)	0.06 (0.03)	0.06 (0.04)	0.08 (0.04)
62	4-Hexen-1-ol, 5-methyl-2-(1-methylethenyl)-, acetate	18.02	90	0.11 (0.08)	0.06 (0.03)	0.09 (0.07)	0.12 (0.08)	0.04 (0.01)	0.07 (0.04)
63	Geranyl acetate	18.62	98	2.65 (1.80)	0.75 (0.46)	2.23 (0.94)	3.12 (2.41)	0.59 (0.30)	0.91 (0.56)
64	2,6-Octadien-1-ol, 3,7-dimethyl-, acetate, (Z)-	18.63	94	0.28 (0.21)	0.15 (0.10)	0.22 (0.12)	0.34 (0.27)	0.08 (0.03)	0.23 (0.09)
Oxygenated sesquiterpenes
65	trans-Nerolidyl formate	26.01	97	0.34 (0.35)	0.07 (0.06)	0.32 (0.27)	0.36 (0.450	0.07 (0.05)	0.07 (0.06)
66	Caryophyllene oxide	27.95	96	0.37 (0.25)	0.04 (0.02)	0.34 (0.25)	0.39 (0.27)	0.03 (0.01)	0.05 (0.03)
	Oxygenated diterpenes
67	5,9,13,17-Tetramethyl 4,8,12,16-Octadecatetraenoic acid	34.51	88	0.08 (0.11)	0.03 (0.04)	0.06 (0.05)	0.11 (0.15).	0.02 (0.01)	0.04 (0.06)
68	Phytol	46.42	96	1.06 (0.94)	0.19 (0.21)	0.54 (0.20)	1.63 (1.11)	0.07 (0.03)	0.33 (0.24)
69	1,6,10,14-Hexadecatetraen-3-ol,3,7,11,15-tetramethyl-, (E,E)-	56.29	81	0.07 (0.05)	0.06 (0.03)	0.05 (0.03)	0.08 (0.07)	0.04 (0.01)	0.08 (0.03)
	Total identified (%)			95.62 (4.63)	98.41 (2.01)	94.88 (5.12)	96.43 (4.13)	99.09 (0.61)	97.67 (2.70)
Class composition
Nonterpene compounds				58.34 (23.28)	57.66 (12.39)	57.51 (25.68)	59.25(21.67)	53.51 (12.04)	62.19 (11.62)
Aliphatic compounds				58.04 (23.34)	57.50 (12.47)	57.25 (25.74)	58.91 (21.75)	53.36 (12.15)	62.03 (11.67)
Aromatic compounds				0.30 (0.18)	0.15 (0.11)	0.25 (0.18)	0.34 (0.17)	0.15 (0.13)	0.16 (0.09)
Terpenoids				41.66 (23.28)	42.34 (12.39)	42.49 (25.68)	40.75 (21.67)	46.49 (12.04)	37.81 (11.62)
Terpene hydrocarbons				31.95 (21.79)	35.79 (10.95)	33.93 (23.15)	29.77 (21.20)	40.13 (10.06)	31.05 (10.25)
Monoterpene hydrocarbons				30.74 (21.40)	35.27 (10.85)	32.84 (22.53)	28.42 (21.04)	39.62 (9.88)	30.52 (10.21)
Sesquiterpene hydrocarbons				0.48 (0.22)	0.26 (0.11)	0.42 (0.19)	0.55 (0.24)	0.23 (0.08)	0.29 (0.13)
Diterpene hydrocarbons				0.73 (0.62)	0.26 (0.17)	0.66 (0.51)	0.80 (0.75)	0.28 (0.19)	0.24 (0.14)
Oxygenated terpenes				9.72 (4.07)	6.55 (2.09)	8.56 (3.21)	10.99 (4.69)	6.36 (2.33)	6.76 (1.88)
Oil yield (%, v/w)				0.04 (0.03)	0.08 (0.03)	0.04 (0.03)	0.03 (0.03)	0.08 (0.03)	0.07 (0.03)
Total identified (%)				95.62 (4.63)	98.41 (2.01)	94.88 (5.12)	96.43 (4.13)	99.09 (0.61)	97.67 (2.70)

Note: RT represents retention time. Data were presented as mean (SD).