Table 1.

Summary of studies on aromas associated with the GABAergic system.

Aroma	Major Components	Inhalation Duration	Subject	Test/Experiment/ Intervention	Observed Effect	Motor Activity	Mechanism of Action	Reference
Acorus gramineus	β-asarone euasarone α-uasarone	3 h twice daily for 7, 14 & 30 days respectively	Mice	Assays	Inhibitory CNS effects Anxiolytic-like ↑ PB induced sleep duration	Reduced	Inhibiting GABA transaminase, ↑ GABA levels, ↓ glutamate levels	[46]
Alpinia zerumbet	α-pinene p-cymene 1,8-cineole limonene	90 min	Mice	EPM LDB OFT	Anxiolytic-like	Increased		[49,50]
Anthriscus nemorosa	Caryophyllene trans-pinocarveol germacrene D β-elemene α-terpineol	15 min for 21 Continual days	Rats	EPM	Anxiolytic-like	Increased		[51]
Aquilaria spp.	Benzylacetone α-gurjunene (+)-calarene	60 min	Mice	OFT	Sedative	Reduced		[52]
Cananga odorata	Benzyl benzoate linalool benzyl salicylate benzyl alcohol	10 min for 7 consecutive days	Mice	EPM, LDB, OFT	Anxiolytic-like	No effect	5-HTnergic & DAnergic pathways (↑ 5-HT, ↓ DA)	[53]
Chamaecyparis obtusa	δ-cadinene α-pinene	90 min	Mice	EPM Stress biomarkers within the brain	Anxiolytic-like, Stress reducing	Not evaluated	↑ NGFR ↑ Arc gene expression	[54]
Citrus aurantium	Limonene linalyl acetate linalool	7 min	Rats	EPM, OFT, Social interaction test	Anxiolytic	No change		[55,56]
		30–35 min	Dental patients (n = 56)	BP, PR, RR	Anxiolytic	N/A		[57]
		30 min	CML patients (n = 42)	STAI BP, CF, RF	Anxiolytic	N/A		[58]
		30 min	Pregnant women (n = 126)	STAI Vital signs	Anxiolytic	N/A		[59]
		5 min	5 min Crack users (n = 51)	STAI HAS TEMP, ESC, BP, HR	Anxiolytic	N/A		[38]
		20 min 2 days after hospitilisation	ACS Patients (n = 140)	STAI	Anxiolytic	N/A		[60]
Citrus bergamia	Limonene linalool linalyl acetate	7 min	Rats	EPM, HBT	Anxiolytic Stress reducing	Increased	↓ corticosterone	[61]
Citrus limon	Limonene sabinene citronellal	90 min	Rats	EPM, FST, OFT	Anxiolytic-like, Sedative Stress reducing	Reduced	5-HTnergic & DAnergic pathways	[62,63]
		Continual for 2 weeks	Rats	EPM	Anxiogenic	Reduced		[64]
		25 min	Nursing students (n = 39)	CTAS	Anxiolytic	N/A		[65]
		Ad libitum	Nursing students (n = 31)	CTAS	None	N/A		[66]
Citrus sinensis	Limonene	5 min	Rats	EPM, LDB	Anxiolytic-like	Not evaluated		[67]
		30 min	Mice	LDB	Anxiolytic-like Sedative	Reduced		[55]
		Not specified	Dental patients (n = 72)	STAI	Sedative Relaxant	N/A		[68]
		30 min 2 min activation every 10 min	Child (n = 30) mins	Salivary cortisol PR	Anxiolytic	N/A	↓ cortisol	[69]
		5 min	Healthy males (n = 40)	STAI HR, EMG	Anxiolytic	N/A		[70]
Coffee		Not specified	Healthy women (n = 9)	EEG–alpha waves	Relaxant	N/A		[71]
Compound Anshen	D-limonene linalool linalyl acetate α-Pinene α-Santalol	60 min for 7 consecutive days	Mice	OFT Assays	Anxiolytic Sedative Hypnotic Prolonged sleep time	Reduced	↑ 5-HT ↑ GABA	[72]
Coriander sativium	Linalool	60 min for 21 consecutive days	Rats	EPM, FST	Anxiolytic	Increased		[20]
Cryptomeria japonica VOC	δ-cadinene α-murolene	30 min	Healthy male students (n = 16)	Salivary stress markers (α-amylase, cortisol, IgA, CgA) ECG	Relaxant Stress reducing	N/A	↓ α-amylase Inhibiting ↑ CgA	[73]
Cryptomeria japonica	δ-cadinene 4-epi-cubebol cubebol	30 min	Female participants (n = 29)	Salivary stress markers (cortisol, DHEA-s, α-amylase, CgA), POMS	Relaxant Stress reducing	N/A	↓ cortisol ↓ DHEA-s ↓ α-amylase	[74]
Cymbopogon citratus	Geranial neral geranyl acetate	Not specified	Healthy male graduate students (n = 40)	STAI SPIN Self-evaluation of tension level EMG, HR	↓ basal levels of anxiety ↓ Subjective tension	N/A		[75]
Eucalyptus globulus	1,8-cineole, limonene α-pinene	3 min	Cancer patients (n = 130)	STAI	No reduction in anxiety	N/A		[76]
		5 min	SNRB Patients (n = 62)	STAI POMS A-VAS BP, PR	Anxiolytic	N/A		[32]
Forest Abies sachalinensis	α-pinene camphene	90 min	Mice	EPM	Anxiolytic- Like	Not Evaluated		[77]
Fragrant compounds from Oolong tea	Cis-jasmone, jasmine lactone, linalool oxide methyl jasmonate		Xenopus laevis oocytes	Voltage clamp technique	↑ PB-induced sleep time	N/A	Potentiation of GABAA receptor response	[78]
Heracleum afghanicum	Hexyl butyrate octyl acetate	60 min	Mice	OFT	Sedative	Reduced		[79]
Hypericum scabrum	α-pinene β-pinene myrcene	15 min for 21 continuous days	Rats	EPM, FST	Anxiolytic	Reduced		[80]
Illicium verum	Trans-anethole	90 min	Mice	EPM	No effect on anxiety	Not evaluated		[81]
Jasminum grandiflorum	Benzyl acetate benzyl benzoate phytol linalool	5 min	Male & female participants (n = 31)	EEG (α–waves) BP, PR, HR, RR, muscle potential, skin conductance, TEMP	Relaxant	N/A		[82,83]
Lantana camara	Sabinene 1,8-cineole	60 min	Mice	OFT	Sedative	Reduced		[84]
Lavandula spp.	Linalyl acetate Linalool 1,8-cineole β-ocimene terpinen-4-ol camphor	15 min	Mice	EPM, MBT	Anxiolytic-like	No effect	5-HTnergic neurotransmission–possibly via 5-HT1A receptors	[85,86]
		3 min	Child dental patients (n = 126)	FIS BP, PR	Anxiolytic	N/A		[87]
		3 min	Xenopus laevis oocytes Cancer Pateints (n = 123)	Two-electrode voltage clamp technique STAI-I	No effect on anxiety	N/A N/A	Potentiated GABAA receptor response	[88] [76]
Matricaria chamomilla	α-bisabolol oxides A & B α-bisabolol chamazulene β-farnesene	60 min twice daily for 3 days	Rats	Restriction stress Plasma ACTH	Anxiolytic effects Sedative	Not evaluated	↓ ACTH GABAergic neurotransmission	[89,90]
Microtoena patchouli	1-octen-3-ol, terpinolene, patchouli alcohol methyl salicylate.	20 min, 35 min	Mice	OFT	Sedative	Reduced		[91]
Nardostachys chinensis	Calarene aristolene	60 min	Mice	OFT	Sedative	Reduced		[92]
Ocimum basilicum & Living plant	Eugenol linalool methyl eugenol	60 min	Mice	OFT	Sedative	Reduced		[93]
Ocimum basilicum	Linalool camphor β-elemene α-bergamo-tene bornyl-acetate estragole eugenol 1,8-cineole	60 min for 21 continual days	Rats	EPM, FST	Anxiolytic	Increased		[94]
Ocimum gratissimum	Thymol p-cymene terpinene-4-ol	60 min	Mice	OFT, LDB	Anxiolytic-like Sedative	Reduced		[95]
Ocimum sanctum	Linalool camphor β-elemene α-bergamo-tene bornyl-acetate estragole eugenol 1,8-cineole	60 min for 21 continual days	Rats	EPM, FST	Anxiolytic	Increased		[94]
Pelargonium graveolens	Citronellol trans-geraniol	20 min for 2 consecutive Patients	Acute MI Patients (n = 80)	STAI	Anxiolytic	N/A		[96]
		Not Specified	Pregnant women (n = 100)	STAI BP, RR, PR	Anxiolytic	N/A		[97]
Phytoncides	α-pinene cis-3-hexenol β-thujaplicin		Xenopus laevis oocytes	Two-electrode voltage clamp technique		N/A	Potentiated GABAA receptor response	[88]
Pimpinella peregrine	Trans-pinocarveol pregeijerene α-cubebene	15 min Rats for 21 continuous days	Rats	EPM	Anxiolytic	Increased		[98]
Piper guineense	Linalool 3,5-dimethoxytoluene	60 min	Mice	LDB, OFT	Anxiolytic Sedative	Decreased		[99]
Rosa damascena	β citronellol nonadecane, geraniol henicosane	7 min	Rats	EPM	Anxiolytic-like	Increased		[100,101]
Santalum album	α-santalol β-santalol	90 min	Mice	EPM	Anxiolytic	Not evaluated		[102]
Santalum spicatum	α-santalol β-santalol	Not specified	Female & male participants (n = 32)	BP Salivary Cortisol	Stress reducing	N/A	↓ Cortisol	[103]
Thymus vulgaris	Linalool β-myrcene terpinen-4-ol	90 min	Mice	EPM	Anxiolytic-like	No change		[104]
Valeriana officinalis	Isovaleric acid valerenic acid bornyl acetate	60 min	Rats	GABA transaminase assay	↑ PB-induced sleep time	Not evaluated	↓ GABA transaminase ↑ GABA	[105,106]
Whisky fragrance and components	Ethoxy lactone derivatives ethyl-phenylpropanoate		Xenopus laevis oocytes	Voltage clamp technique	↑ PB-induced sleep time	N/A	Potentiation of GABAA receptor response	[107,108]

Note: 5-HT: serotonin; Arc: activity regulated cytoskeletal-associated protein; A-VAS: anxiety visual analogue scale; BP: blood pressure; CF: cardiac frequency; CGA: chromogranin A; CTAS: cognitive test anxiety scale; DA: dopamine; DHEA-s: dehydroepiandrosterone sulfate; ECG: electrocardiogram; ECS: electrical conductance of the skin; EEG: electroencephalograph; EMG: electromyography; EPM: elevated plus maze; FIS: face image scale; FST: forced swim test; HAS: humor analog scale; HR: heart rate; IgA: secretory immunoglobulin A; LDB: light dark box; MBT: marble burying test; NGFR: nerve growth factor; OFT: open field test; PB: pentobarbital; POMS: profile of mood states; PR: pulse rate; RF: respiratory frequency; RR: respiratory rate; SPIN: social phobia inventory; STAI: state-trait anxiety inventory. ↑: up regulated; ↓: down regulated.