Table 2.

Antiviral activity of essential oil-derived components.

No	Components	Viruses	IC50	SI	Intercellular or Intracellular Mechanisms	References
1	β-Caryophyllene	HSV-1	0.25 μg/mL	140	Intercellular	[39]
2	Farnesol	HSV-1	3.5 μg/mL	11.4	Intercellular	[39]
3	β-Eudesmol	HSV-1	6 μg/mL	5.8	Intercellular	[39]
4	Trans-anethole	HSV-1	20 μg/mL	5	Intercellular	[39]
5	Eugenol	HSV-1	35 μg/mL	2.4	Intercellular	[39]
6	Thymol	HSV-1	0.002%	7	Intercellular	[14]
7	Carvacrol	HSV-1	0.037%	1.4	Intercellular	[14]
8	p-Cymene	HSV-1	>0.1%	ND	Intercellular	[14]
9	Carvacrol	HSV-1	48.6 μg/mL	5.1	Intracellular	[33]
10	Thymol	HSV-1	7 µM	43	Intercellular	[49]
11	Carvacrol	HSV-1	7 µM	43	Intercellular	[49]
12	β-Pinene	HSV-1	3.5 μg/mL	24.3	Intercellular	[50]
13	Limonene	HSV-1	5.9 μg/mL	10.2	Intercellular	[50]
14	Carvacrol	Acyclovir-resistant HSV-1	28.6 μg/mL	8.7	Intracellular	[33]
15	Carvacrol	IFV-A (H1N1)	2.6 μg/mL	<0.15	ND	[51]
16	Eugenol	IFV-A (H1N1)	<3.1 μL/mL	ND	ND	[23]
17	β-Santalol	IFV-A (H3N2)	10–100 μg/mL		Intracellular a	[52]
18	Germacrone	IFV-A (H1N1)	6.03 μM	>41	Intercellular and intracellular b	[53]
19	1, 8-Cineole	BVDV	331.17 μg/mL	9.1	Intercellular	[45]
20	Camphor	BVDV	318.51 μg/mL	13.9	Intercellular	[45]
21	Thymol	BVDV	248.56 μg/mL	5.6	Intercellular	[45]
22	Carvacrol	BVDV	50.7 μg/mL	4.2	Intracellular	[33]
23	Carvacrol	Bovine herpes virus 2	663 μg/mL	0.3	Intracellular	[33]
24	Carvacrol	Respiratory syncytial virus	62 μg/mL	4.1	Intracellular	[33]
25	Carvacrol	Human rotavirus	27.9 μg/mL	33	Intracellular	[33]
26	Citral	Yellow fever virus	17.6–25 μg/mL	1.1–1.5	ND	[46]
27	β-Caryophyllene	Dengue virus	22.5 μM	71.1	Intercellular and intracellular b	[13]
28	Thymohydroquinone dimethyl ether	Zika virus	45 μg/mL	9.1	Intercellular	[47]

Note: SI, selectivity index; HSV, human herpes viruses; HIV, human immunodeficiency virus; BVDV (Bovine viral diarrhoea virus); ND, not determined. “Intercellular” signifies mechanisms of action targeting virus surface during or before adsorption, while “intracellular” indicates action on intracellular events in viral lifecycle. ^a The late stage of viral lifecycle. ^b The early stage of viral lifecycle.