Anxiety is the emotional behaviour and can change the thinking of human. Treatments available for anxiety are much abused and cause adverse effects or dependencies and should be avoided. In order to avoid unwanted effects a natural anxiolytic is worthy to use. Fennel's essential oil is used traditionally to relieve stress and as oil it surely affects CNS but still mechanism of action is not clear. But after searching appropriate dose and chemical molecule, it can be the natural substitute for abused anxiolytics.
Anxiety is an emotional behavior and in severe and/or chronic conditions it really becomes pathological. Even though there are list of drugs in allopathic medicine to treat anxiety disorders, still there is a need for good natural drug because of various systemic side effects of allopathic drugs or they may exhibit tolerance upon chronic use. On other side, ayurvedic medicines have been proved to have no or less side effects (Gopala Krishna, et al., 2006). So it has need to have a natural substituent for allopathic drugs having adverse effects because most commonly prescribed drugs in anxiolytics and sleep disorders are benzodiazepines as they can modulate conductance of GABAA receptor and probability of opening of channel of GABAA receptor. But benzodiazepines are commonly tended to produce dependency and withdrawl symptoms include muscle cramps, insomnia, depression, irritability, phonophobia, photophobia and seizures. The most abused Barbiturates are very rarely prescribed now days (Katzung, et al., 2007, p.___).
Fennel is a fruit from the plant species of Foeniculum genus. Fennel is used as diuretic, antispasmodic, antimicrobial, digestive and anticongestant. It possesses mild estrogenic effect and relieves laxative's gripping action. Essential oil o fennel fruit is anti-oxidant and increases milk flow in breast feeding mothers. Fennel is a tonic for kidneys, liver and spleen (ageless.co.za, Last accessed: 20/02/2010). But fennel exhibits adverse effects like temporary CNS disturbances, restlessness, emesis, poor suckling, lethargy and torpor (Duke, et al., 2002, p.295) and fennel oil is even genotoxic (Sekizava and Shibamoto 1982).
Fennel fruit mostly contains volatile oils or flavanoids like quercetin isoquercetin, kaempferol 3-glucuronide, 3-glucuronide and kaempferol 3-arabinoside (Kunzemann and Hermann 1977) and t-anethol (El-Motaium and El-seoud 2004). Fennel's volatile oil contains anethole which is hypnotic and it is already believed by Sukma et al that hypnotics possess anxiolytic effect (Sukma, et al., 2002). Even one fact is that benzodiazepines and barbiturates also possess hypnotic activity (Treit 1985).
Anethole and estragole present in volatile oil extract of fennel fruit have antiplatelet aggregation characteristic as equivalent as aspirin (Yoshioka, et al., 2005). Fennel also promotes lactation (Mullan and Martin 1992). Serotonin/5-HT has proven its role to promote platelet aggregation (Connor, et al., 2001) and to inhibit lactation (Hernandez, et al., 2008). So volatile oil extract from fennel fruit may inhibit the action of serotonin.
Selective Serotonin Reuptake Inhibitors/SSRIs are used in the treatment of depression as they increase the amount of Serotonin at the synapse (Baldessarini 2006). So serotonin should be anxiogenic (Lucki 1996). In actual, stimulation of 5-HT1A acts as anxiolytic but stimulation of 5-HT2A and 5-HT2C causes anxiety (Sanders-Bush and Mayer 2006). So anyhow it can be believe that Fennel's volatile oil extract may act as a natural anxiolytic which can replace highly addictive allopathic drugs. But still it requires passing through preclinical and clinical trials in order to prove its effect.