Chemical composition and antimicrobial activity of essential oils from Centaurea appendicigera and Centaurea helenioides

Figures & data

Table 1.  Identified components in the essential oils of C. appendicigera and C. helenioides ^a.

No.	Compounds	A		B		Exp. RI	Ident. LRI
		% Area	Q (%)	% Area	Q (%)
1	2-Heptanone	0.4	91	-	-	892	892
2	Benzaldehyde	0.1	83	-	-	965	963
3	2-Pentylfuran	0.4	94	0.1	91	994	991
4	n-Octanal	0.2	91	0.1	91	1003	1001
5	Limonene	0.7	86	tr	93	1024	1027
6	Benzeneacetaldehyde	0.4	91	0.2	91	1046	1045
7	Linalool	0.4	81	0.2	91	1094	1091
8	n-Nonanal	0.4	90	0.6	91	1101	1102
9	1-Nonanol	0.2	86	-	-	1166	1169
10	Safranal	0.2	83	-	-	1198	1197
11	n-Decanal	0.6	91	0.1	91	1205	1204
12	Pulegone	-	-	0.2	83	1235	1237
13	Dihydroedulan I	-	-	2.6	92	1288	1289
14	Thymol	-	-	0.1	93	1296	1294
15	n-Undecanal	0.2	96	-	-	1306	1306
16	(E,E)-2,4-Decadienal	0.3	81	0.2	93	1317	1317
17	α-Copaene	1.6	99	0.6	98	1377	1377
18	(E)-β-Damascenone	1.8	87	0.6	96	1385	1385
19	Tetradecane	-	-	0.3	91	1400	1400
20	Dodecanal	1.0	91	-	-	1410	1409
21	β-Caryophyllene	17.5	99	3.5	99	1421	1420
22	β-Copaene	-	-	0.4	96	1431	1432
23	α-trans-Bergamotene	1.7	96	-	-	1438	1436
24	Aromadendrene	1.9	96	-	-	1442	1441
25	α-Humulene	2.1	99	1.0	98	1456	1455
26	(E)-β-Farnesene	-	-	0.7	97	1459	1458
27	δ-Gurjunene	7.6	85	-	-	1474	1473
28	γ-Muurolene	-	-	0.6	82	1478	1478
29	Germacrene-D	-	-	7.3	99	1483	1482
30	β-Ionone	-	-	1.5	98	1486	1485
31	Bicyclogermacrene	1.5	98	1.2	94	1497	1496
32	1-Pentadecene	0.4	99	-	-	1492	1491
33	(E,E)-α-Farnesene	-	-	0.9	98	1509	1508
34	β-Bisabolene	1.9	99	-	-	1510	1510
35	γ-Cadinene	4.5	93	-	-	1511	1513
36	α-Amorphene	1.4	95	0.6	88	1516	1516
37	δ-Cadinene	1.3	92	1.4	81	1526	1524
38	α-Cadinene	-	-	0.4	96	1540	1538
39	Nerolidol	-	-	0.6	95	1567	1564
40	1,5-Epoxysalvial-4(14)-ene			2.1	99	1569	1569
41	Spathulenol	2.7	98	5.1	98	1581	1578
42	Caryophyllene oxide	17.1	90	18.2	86	1586	1584
43	Salvial-4(14)-en-1-one	1.1	99	2.8	99	1596	1598
44	Humulene epoxide II	1.5	91	3.6	83	1611	1614
45	epi-Cedrol	-	-	0.7	93	1620	1619
46	3-iso-Thujopsanone	-	-	3.7	83	1639	1643
47	β-Eudesmol	1.3	93	1.0	87	1653	1653
48	ar-Turmerone	2.2	90	1.3	80	1669	1669
49	Caryophyllenol-II	1.8	95	3.1	91	1675	1676
50	epi- α-Bisabolol	-	-	2.1	80	1688	1685
51	2-Pentadecanone	0.4	87	-	-	1699	1694
52	(E)-2-Tetradecen-1-ol	0.6	91	-	-	1714	1713
53	Pentadecanal	0.6	91	1.7	91	1715	1715
54	Benzyl benzoate	1.4	97	-	-	1767	1763
55	Hexahydrofarnesylacetone	0.4	91	1.0	99	1847	1846
56	Ethyl linoleolate	0.2	91	0.4	90	1894	1891
57	n-Nonacosane	-	-	0.3	89	1901	1900
58	Farnesyl acetone	-	-	0.3	91	1920	1919
59	n-Heneicosane	0.2	96	0.4	98	2101	2100
60	cis-Phytol	0.5	86	6.2	86	2115	2213
61	n-Docosane	-	-	0.1	91	2200	2200
62	Neophytadiene	-	-	0.1	96	2222	2218
63	n-Tricosane	0.6	99	1.0	99	2300	2300
64	n-Tetracosane	-	-	0.2	98	2400	2400
65	n-Pentacosane	0.6	96	0.8	99	2500	2500
66	n-Heptacosane	1.6	96	1.5	99	2700	2700

Unknown	RI	m/z (%)				A	B
Un-1	1395	204(5), 189(17), 137(100), 121(40), 95(24)				1.7	-
Un-2	1555	220(4), 205(20), 123(58), 106(78), 91(80), 79(100).				1.5	-
Un-3	1646	220(20), 204(41), 135(64), 105(83), 91(100), 79(76)				-	0.6
Un-4	1661	246(2), 206(10), 133(100), 119(30), 91(54), 79(38)				-	4.3
Un-5	1663	220(5), 205(15), 133(60), 119(75), 91(100), 79(77)				1.3	-
Un-6	1684	220(32), 177(90), 123(100), 107(48), 91(62), 81(55)				-	0.9
Un-7	1744	220(10), 218(52), 175(94), 105(80), 91(100), 79(82)				-	1.7
Un-8	1760	220(31), 177(80), 105(70), 91(100), 79(68), 67(46)				-	1.2
Un-9	1769	236(12), 218(22), 147(49), 105(57), 95(60), 81(100)				-	1.9
Un-10	1775	220(5), 218(53), 173(75), 105(77), 91(100), 79(64)				-	0.9
Un-11	1798	220(41), 189(100), 133(36), 105(40), 91(53), 79(32)				-	0.6
Un-12	1870	243(6), 223(18), 167(10), 149(100), 57(20)				-	1.0
Un-13	1881	302(2), 287(2), 97(80), 83(100), 69(80), 55(92)				1.4	-
Un-14	2146	287(7), 278(39), 121(60), 93(64), 79(84), 67(100)				-	0.9
Un-15	2150	302(15), 287(10), 178(27), 134(100), 119(60), 81(57)				1.5	-
Un-16	2619	429(7), 302(38), 207(30), 135(38), 71(77), 57(100)				1.4	-
Total						8.8	14.0
Total isolate		85.5	83.7
Total unknown		8.8	14.0
Total		94.3	97.7

RI, retention index; LRI, literature retention index; tr, trace, less than 0.05%; Q, quality; A, Centaurea appendicigera; B, Centaurea helenioides.

^a Compounds are listed in order of elution. RI (retention index) values are calculated from retention times relative to that of n-alkanes (C₆-C₃₂) on the nonpolar HP-5 column.

Table 2.  The chemical class distribution of the essential oil components of C. appendicigera and C. helenioides.

Compound class	C. appendicigera		C. helenioides
	% Area	Number of compounds	% Area	Number of compounds
Monoterpene	0.7	1	tr	1
Monoterpenoids	2.4	3	1.1	4
Sesquiterpenes	43.0	11	20.7	14
Sesquiterpenoids	28.1	8	47.6	14
Diterpene	-	-	0.1	1
Diterpenoid	0.5	1	6.2	1
Others	10.8	21	8.0	16
The common compounds	63.0	30	58.5	30

Table 3.  Major compounds of the chemical class distribution in the essential oil components of C. appendicigera and C. helenioides.

Compound class	C. appendicigera			C. helenioides
	Major component	% Area	RI	Major component	% Area	RI
Monoterpene	Limonene	0.7	1624	Limonene	tr	1624
Monoterpenoid	(E)-β-Damascenone	1.8	1385	Dihydroedulan I	2.6	1288
Sesquiterpene	β-Caryophyllene	17.5	1421	Germacrene-D	7.3	1483
Sesquiterpenoid	Caryophyllene oxide	17.1	1586	Caryophyllene oxide	18.2	1586
Diterpene	-	-	-	Neophytadiene	0.1	2222
Diterpenoid	cis-Phytol	0.5	2115	cis-Phytol	6.2	2115
Others	n-Heptacosane	1.6	2700	Pentadecanal	1.7	1715

Table 4.  Screening results for antimicrobial activity of the essential oils from C. appendicigera and C. helenioides.

Sample	Stock solution μg/mL	Microorganisms and MIC value (μg/mL)
		Ec	Kp	Pa	Ef	Sa	Bc	Ca
C. appendicigera	1900	-	-	-	80	80	-	190
C. helenioides	3300	-	-	-	165	165	-	330
Ampicillin		8	32	>128	2	2	2
Fluconazole								8

MIC, the lowest concentration causing total inhibition of microbial growth in μg/mL; Ec, Escherichia coli ATCC 25922; Kp, Klebsiella pneumoniae ATCC 13883; Pa, Pseudomonas aeruginosa ATCC 10145; Ef, Enterococcus faecalis ATCC 29212; Sa, Staphylococcus aureus ATCC 25923; Bc, Bacillus cereus 702 Roma, Candida albicans ATCC 10231; Amp., Ampicillin; Flu., Fluconazole; -, no activity at stock solution concentration.