Chemical analysis and in vitro antiviral and antifungal activities of essential oils from Glechon spathulata and Glechon marifolia

Figures & data

Table 1. Antiviral activity of Glechon spathulata and Glechon marifolia essential oils on Vero cells expressed as reduction of virus titer (log₁₀) by yield reduction assay.

		HSV-1 yield reduction (log10)^a
Sample	Dose MTD	Strain KOS	Strain VR733	Strain 29-R
Glechon  spathulata oil	0.0095% v/v	2.25 ± 0.25	2.33 ± 0.30	1.83 ± 0.25
Glechon  marifolia oil	0.039% v/v	2.33 ± 0.31	2.25 ± 0.25	NA
Acyclovir	0.010 mg/mL	3.16 ± 0.28	3.00 ± 0.25	NA

MTD, maximum tolerated concentration (%v/v). The data represent the mean ± standard deviation for four replicate samples of three separate experiments. NA, no activity; acyclovir, positive control.

^aWhen compared with controls. HSV-1 titers: 10⁶ TCID₅₀/µL for strain KOS, 10⁴ TCID₅₀/µL for strain VR733 (ATCC), and 10^5.5 TCID₅₀/µL for strain 29-R (ACV^res).

Table 2. Effect of Glechon spathulata and Glechon marifolia essential oils addition after virus inoculation expressed as reduction of virus titer (log₁₀).

		HSV-1 yield reduction (log10)^a
Sample	Dose	Strain KOS	Strain VR733	Strain 29-R
Glechon  spathulata oil	0.0095% v/v	2.00 ± 0.25	2.17 ± 0.51	2.25 ± 0.14
Glechon  marifolia oil	0.039% v/v	3.08 ± 0.25	3.16 ± 0.38	NA
Acyclovir	0.01 mg/mL	3.83 ± 0.28	4.08 ± 0.29	NA

The data represent the mean ± standard deviation for four replicate samples of three separate experiments. NA, no activity; acyclovir, positive control.

^aWhen compared with controls. HSV-1 titers: 10⁶ TCID₅₀/µL for strain KOS, 10⁴ TCID₅₀/µL for strain VR733 (ATCC), and 10^5.5 TCID₅₀/µL for strain 29-R (ACV^res).

Figure 1. Chromatograms obtained by GC/MS for analysis of the chemical composition of essential oils of Glechon spathulata, before and after sunlight exposition. Note: Essential oil of G. spathulata before (A) and after (B) sunlight exposition. Peak 1 – α- pinene; 2 – β-pinene; 3 – β-caryophyllene; 4 – Bicyclogermacrene; 5 – Spathulenol.

Figure 2. Chromatograms obtained by GC/MS for analysis of the chemical composition of essential oils of Glechon marifolia, before and after sunlight exposition. Note: Essential oil of G. marifolia before (A) and after (B) sunlight exposition. Peak 1 - β-caryophyllene; 2 – α-humuleme; 3 - Germacrene D; 4 – Bicyclogermacrene; 5 – Spathulenol.

Table 3. Percentual composition of the essential oils from aerial parts of Glechon species, before and after sunlight exposition.

IR^a	Compounds	Glechon spathulata	Glechon spathulata sunlight exposure	Glechon marifolia	Glechon marifolia sunlight exposure
	Monoterpene hydrocarbons	24.0	7.9	4.1	–
915	Tricyclene	0.3
922	α-Pinene	6.9	2.4	0.7
935	Camphene	0.1
960	Sabinene	4.4	1.4	0.2
963	β-Pinene	8.5	3.2	0.8
979	Myrcene	0.2		0.5
1006	α-Terpinene	0.1
1013	o-Cimene	0.1	0.1	0.1
1017	Limonene	3.2	0.8	1.8
1047	γ-Terpinene	0.2
	Oxygenated monoterpenes	4.9	6.2	0.8	–
1013	1,8-Cineole	2.2	1.4	0.5
1090	Linalool	1.4	2.1	0.3
1164	Terpinen-4-ol	0.7	1.0
1178	α-Terpineol	0.4	0.9
1243	Linalool acetate	0.2	0.3
1269	Bornyl acetate		0.2
1276	trans-Sabinyl acetate		0.3
	Sesquiterpene hydrocarbons	40.1	23.3	84.5	63.0
1332	α-Cubebene			0.1
1360	α-Copaene	1.5	1.4	2.7	3.3
1369	β-Bourbonene		0.3	1.0	1.1
1374	β-Cubebene	0.6	0.6	0.6
1377	β-Elemene	0.2	0.3	0.8
1390	α-Gurjunene			0.3
1405	β-Caryophyllene	14.2	11.6	32.2	31.7
1408	β-Gurjunene			0.2
1436	α-Humulene	0.9	0.9	23.3	22.0
1442	allo-Aromadendrene	0.8	1.2	0.8
1463	Germacrene D	4.0	0.7	4.3	1.9
1481	Bicyclogermacrene	17.1	5.9	16.5	3.0
1485	Germacrene A	0.3		0.8
1505	δ-Cadinene	0.5	0.4	0.9
	Oxygenated sesquiterpenes	15.1	47.1	7.9	28.4
1574	Spathulenol	3.0	19.0	3.5	15.3
1576	Caryophyllene oxide		2.8	1.3	6.4
1578	Globulol	1.3		1.9
1583	epi-Globulol	0.8			4.6
1586	Eudesmol^c			0.5
1587	Guaiol		1.2
1597	Humulene epoxide II		0.4	0.6	2.1
1607	γ-Eudesmol		6.1
1629	iso-Spathulenol	0.2		0.1
1658	Not identified ^b	9.8	17.6
Total compounds identified		74.3	66.9	97.3	91.4

^aRI: retention index on DB-5 column relative to C₈–C₂₂ n-alkanes.

^bm/z (rel. int.): 41(55), 54(23), 82(100), 93(28), 105(13), 121(30), 145(11), and 218(6).

^cCorrect isomeric form not identified.

Table 4. Antifungal activity of Glechon spathulata essential oil against clinical isolates of dermatophytes.

		Terfinafine	Amphotericin B	Essential oil
Microorganisms	Strains	MIC	MIC	MIC	MIC90
Trichophyton rubrum	TRU 09	0.5	1	20.8	41.6
	TRU 31	0.25	0.5	10.4
	TRU 04	0.25	0.5	20.8
	TRU 23	1	2	41.6
	TRU 13	0.25	1	83.12
Epidermophyton floccosum	EPF 01	0.25	0.5	166.25	166.25
	EPF 31	0.5	1	83.12
	EPF 18	32	4	166.25
	EPF 07	0.25	0.25	166.25
	EPF W4	0.25	0.5	>500

MIC, minimum inhibitory concentration (μg/mL).