Chemical composition and antibacterial activity of Dracocephalum kotschyi essential oil obtained by microwave extraction and hydrodistillation

Figures & data

Table 1. Chemical Composition of Dracocephalum kotschyi Boiss. Essential Oils Obtained by Hydrodistillation, Solvent Free Microwave Extraction and Microwave Assisted Extraction.

No.	Compound	RI	LRI	% HD oil	% SFME oil	% MAHD oil
1	α -Pinene^a	938	932	-	0.25	0.41
2	o-Cymene	1026	1022	0.25	-	-
3	Limonene^a	1032	1024	30.59	5.60	9.52
4	Linalool^a	1096	1095	-	0.25	0.33
5	cis-Thujone	1109	1101	-	-	0.15
6	trans-p- Mentha-2,8-dien-1-ol	1122	1119	0.52	0.94	0.88
7	α-Campholenal	1128	1122	1.04	1.02	1.38
8	cis-p-Mentha-2,8-dien-1-ol	1136	1133	0.52	0.97	1.04
9	trans-p-Limonene oxide	1139	1137	0.41	0.17	0.54
10	trans-Pinocarveol	1146	1135	-	0.26	-
11	trans-Verbenol	1148	1140	0.64	1.66	1.92
12	Pinocarvone	1167	1160	-	-	0.15
13	α-Terpineol	1193	1186	0.92	1.47	1.50
14	trans-p-Mentha-1(7),8-dien-2-ol	1190	1187	0.33	-	-
15	cis-Dihydrocarvone	1200	1198	-	-	1.22
16.	Verbenone	1216	1206	0.36	0.40	-
17.	trans-Carveol	1220	1215	3.36	7.20	4.41
18.	cis-Carveol	1232	1226	0.39	1.20	0.30
19.	Nerol	1231	1227	-	1.45	-
20.	cis-p-Mentha-1(7),8-dien-2-ol	1231	1227	-	-	0.22
21.	Neral^a	1242	1235	4.89	6.77	7.14
22.	Carvone	1250	1239	4.55	5.91	6.59
23.	Geraniol^a	1253	1249	-	4.52	2.04
24.	Geranial	1271	1264	6.42	7.20	8.27
25.	Perilla aldehyde^a	1279	1269	26.00	24.80	25.50
26.	Borneyl acetate	1290	1285	0.26	-	0.15
27.	Limonene-10-ol	1297	1288	-	2.59	-
28.	Menthyl acetate	1294	1294	-	-	0.16
29.	Perilla alcohol	1299	1294	-	-	0.34
30.	Methyl geranate	1323	1322	10.80	11.30	11.30
31.	Eugenol	1359	1356	-	0.45	-
32.	α-Copaene	1387	1374	0.21	0.29	-
33.	Geranyl acetate	1378	1379	1.16	3.18	2.90
34.	Germacrene D	1494	1484	0.15	0.68	0.36
35.	β-Bourbonene	1398	1387	-	-	0.21
36.	3Z-3-Hexenyl benzoate	1573	1565	-	0..39	0.16
37.	Globulol	1610	1590	-	-	0.82
38.	Veridiflorol	1610	1592	-	0.62	0.61
	Isolation (min)			240	30	30
	Oxygenated compounds			62.52	84.52	76.47
	Hydrocarbons compounds			31.20	6.82	14.33
	Monoterpene hydrocarbons			30.84	5.85	13.71
	Oxygenated monoterpenes			62.52	83.51	75.04
	Sesquiterpene hydrocarbons			0.36	0.97	0.62
	Oxygenated sesquiterpenes			0	1.01	1.43
	Others compounds			0	0	0
	Total identification (%)			93.72	91.34	90.80

RI: retention index. LRI: retention indices reported from literatures.

a. Identification was confirmed by comparison of the date with those of authentic compound.

Figure 1. Biosynthetic Pathway of Oxygenated Compounds [45], as Well as a Possible Route of Their Conversion into Limonene, due to Prolonged Heating in the Hydrodistillation Method.

Table 2. Comparison of Minimum Inhibitory Concentrations (MIC_S; mg ml⁻¹) of Oils by Microdilution Method.

Test Bacteria	HD	MAHD	SFME
	MIC	MIC	MIC
Staphylococcus aureus (ATCC 25923)	4	2	2
Escherichia coli (ATCC 25922)	4	16	4

Dewick, P.M.;. Medicinal Natural Products: A Biosynthetic Approach; John Wiley & Sons: New Jersey, United States, 2009; 193–198 pp.

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