Foeniculum vulgare Mill. with common name fennel, is a very popular spice as well as an important traditional Chinese medicine. The plant is native to Southern Europe and Mediterranean region. It has two important subspecies of Capillaceum and Piperitum. It mainly contains essential oil, fatty acids and phenolic compounds, etc. The most intense odor compounds of fennel are trans-anethole, estragole and fenchone. Fennel has many biological activities due to its volatile and nonvolatile compounds, and it has been used in traditional Chinese medicine for treating various conditions, particularly rheumatism, cold pain and stomach disorder. It is also used as a spice for its aromatic fruit.
Fennel fruits contain carbohydrates, alkaloids, Phytosterols, phenols, tannins and flavonoids. They are also a rich source of dietary fiber, protein, calcium, iron, magnesium and manganese. Pharmacologically, the fruits possess antioxidant, anti-inflammatory, antispasmodic, diuretic, antihypertensive, antimicrobial, Gastro protective, estrogenic, Hepatoprotective and antithrombotic activities.
Fennel is used to treat many bacterial, fungal, viral, and mycobacterial infectious diseases. Fennel has antibacterial activity due to compounds such as, linoleic acid, undecanal, 1, 3-benzenediol, oleic acid and 2,4-undecadienal. Fennel has 5-hydroxy-furanocoumarin which has important role antibacterial activity of this plant. Aqueous extract of fennel shows bactericidal activity against Enterococcus faecalis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Salmonella typhimurium, and Shigella flexneri.
During a study it was found that this plant extract has a significant antibacterial effect against a lot of bacteria except Klebsiella pneumoniae and one strain of Pseudomonas aeruginosa. The essence of plant showed very strong antibacterial activity against pathogens in food such as Escherichia coli, Listeria, monocytogenes, Salmonella typhimurium, Staphylococcus aureus, as well as having enormous activity against Helicobacter pylori and Campylobacter jejuni.
Jazani et al. studied the antibacterial activity of fennel extract on Acinetobacter baumannii strains which cause nosocomial infection. The results showed that fennel extract has antibacterial effect on all bacteria strains so its’ extract can be used to control multiple-antibiotic resistant bacteria.
Fennel extract has antifungal activity against various fungal species such as Candida albicans, species of Aspergillus, and dermatophytes. Also a study on the herb antifungal effect showed significant antifungal activity against fungi in food waste such as Aspergillus niger and Fusarium oxysporum. The MIC of fennel extract for these molds respectively was 750 and 250 micrograms per ml.
Another study showed that dillapional the derivative of fennel stalk phenyl propanoid has antimicrobial properties against Aspergillus niger, Bacillus subtilis and Cladosporium cladosporioides. Also derivates of coumarin named scopoletin had antimicrobial properties against above micro-organisms but was less important than dillapional.
Antifungal activity of fennel essence on Sclerotinia sclerotiorum was investigated. The antifungal effect of this plant against Sclerotinia sclerotiorum observed based on survival of the microorganisms.
A study demonstrated that nitric oxide production in peritoneal macrophages which were treated with fennel extract at a concentration of 10 mg/ml significantly increased. Also the production of reactive oxygen species compared to the control group increased. Lethality study also showed that treated macrophages with concentrations of 10 and 20 mg ml had anti-candidate effects more than control group. Among chemical compositions of the plant extract anethole had the strongest antifungal activity
Oral administration of methanol extract of F. vulgare fruit to rat and mice exhibited inhibitory effects against acute and subacute inflammatory diseases.The anti-inflammatory activity of methanol extract was evaluated by using three screening protocols, namely, carrageenan-induced paw edema, arachidonic acid-induced ear edema, and formaldehyde-induced arthritis. These are widely used for testing nonsteroidal anti-inflammatory drugs. For acute inflammation, methanol extract (200mg/kg) exhibits significant inhibition of paw edema (69%) induced by carrageenan injection as compared to the control group of animals.
Methanol extract of F. vulgare also inhibits ear-edema (70%) induced by arachidonic acid in mice. The level of serum transaminase, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) significantly increases in the presence of methanolic extract of F. vulgare on inflammation induced by formaldehyde as compared to control group. The assessment of the level of AST and ALT provides a good and simple tool to measure the anti-inflammatory activity of the target compounds. These overall results seem to suggest that F. vulgare FME may act on both the cyclooxygenase and lipoxygenase pathways
Methanolic extract of F. vulgare fruit showed significant inhibitory effect on DNFB- (2,4-dinitrofluorobenzene-) induced delayed type hypersensitivityafter oral administration of 200mg/kg once a day for7 days. The inhibitory effect on immunologically inducedswelling suggests the possible immunosuppressive propertiesof F. vulgare
Naim et al., reported the antiviral activity of the essential oil of fruit sample of Foeniculum vulgare against the DNA virus Herpes simplex type-1. Most of the oils and compounds displayed strong antiviral effects against Herpes Simplex Virus-1 (HSV-1), ranging between 0.8 and 0.025μg/ml.
Kiani Sadegh, et al., investigated that the essential oil of Foeniculum vulgare has antischistosomal activity and cytotoxic effects against V79 cell. The plant of displayed moderate in vitro schistosomicidal activity against adult S. mansoni worms, exerted remarkable inhibitory effects on the egg development, and was of low toxicity.
Gastro protective effect
Pretreatment with fennel water extract significantly reduced ethanol-induced gastric damage in rats, which was suggested to be due to reduction in lipid peroxidation and augmentation in the antioxidant activity. The water extract is reported to increase gastric acid secretion by more than three times of basal secretion in rats that was not blocked by atropine; but significantly reduced basal acid secretion in aspirin-induced gastric mucosal damage. Oral administration of essential oil and anethole is also significantly protective against ethanol-induced gastric lesions in rats. The antioxidant activity of phenol contents is partly credited for the anti-ulcer effects
A number of experimental studies point to the estrogenic effects of fennel. Water extract shows renoprotective effects in experimental polycystic ovary syndrome in rats and prevents ovariectomy-induced bone loss, reducing both osteoclast differentiation and function. Administration of acetone fruit extract also exhibited oestrogenic activity increasing weight of mammary glands oviducts of ovariectomized rats vaginal cornification and oestrus cycle in female rats, and significantly reducing protein contents of testes and vas deferens in male rats
Naturally-occurring antioxidants can be used to protect human beings from oxidative stress damage (Scalbert et He and Huang 3597 al., 2005). Fennel was known as excellent sources of nature antioxidants and contributed to the daily antioxidant diet (Shahat et al., 2011). Wild fennel was found to exhibit a radical scavenging activity with higher content phenolic and flavonoid than medicinal and edible fennel, and the aerial parts of the Italian populations showed the highest DPPH scavenging activity (Faudale et al., 2008).
Phenolic compounds of fennel, including caffeoylquinicad, Rosmarinicacid, eriodictyol-7-Orutinoside, quercetin-3-O-galactoside and kaempferol-3-O-glucoside, showed antioxidant activities (Parejo et al.,2004). The volatile oil showed strong antioxidant activity in comparison with butyrated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) (Singh, 2006). Ethanol and water extracts of fennel showed less antioxidant activity compared with essential oil (Diaz-Maroto et al., 2005).
Fennel essential oil could inhibit the CCl4 induced acute hepatotoxicity by decreasing levels of serum aspirate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and bilirubin. D-limonene and β-myrcene of the oil might be the potential candidates (Ozbek et al., 2003).
Anxiety is the unpleasant feeling of fear and concern. When anxiety becomes excessive, it may be considered as an anxiety disorder. Anxiolytic fennel is a drug used for the treatment of anxiety and its related psychological and physical symptoms. Naga Kishore et al. investigated the anxiolytic activity of ethanolic extract of F. vulgare fruit with the help of elevated plus maze, rota rod, open field test, and whole board models. The 100 to 200mg dose of extract per kg of body weight of animal revealed significant activity when compared to reference anxiolytic drug called diazepam (1mg/kg). Thus, fennel extract may possess anxiolytic activity supporting its traditional claim about anxiolytic activity reported in 19th edition of Pharmacology and Pharmacotherapeutics by Sathodkar, Bhandarkar and Rege.
Alzheimer’s disease is a neurodegenerative disorder associated with a decline in cognitive abilities. Dementia is one of the age-related mental problems and a characteristic symptom of Alzheimer’s disease. There is some evidence in favor of use of F. vulgare for the treatment of cognitive disorders like dementia and Alzheimer’s disease. Methanol extract of the whole plant of F. vulgare administered for eight successive days ameliorated the amnesic effect of scopolamine and aging-induced memory deficits in mice.This extract increased step-down latency and acetylcholinesterase inhibition in mice significantly.Thus, F. vulgaremay be employed in treatment of cognitive disorders such as dementia and Alzheimer’s disease as a nootropic and anticholinesterase agent
Cardiovascular and lipid activity
The study of the anti- cholesterol and anti-atherogenic effect of fennel methanol extract showed that treatment with the extract significantly reduced plasma lipid levels. Also the plant had important anti-atherogenic effects. It reduced triglycerides in fatty liver and facilitated blood flow in the coronary arteries by preventing the buildup of fatty deposit in arteries through reduction of plasma and liver fats. As a result because of hypolipidemic and anti-atherogenic activities, this herb could be used for controlling cardiovascular disorders. Also intravenous injection of the extract significantly reduced blood pressure, without affecting the heart rate and respiration. It seems that fennel extract effect on blood pressure was not mediated by adrenergic, muscarinic, ganglion, serotonergic receptors. In other study, oral administration of the extract reduced systolic blood pressure. The fennel extract acts as a diuretic and natriuretic, too
Other medical uses
Galatogenic, Antihirsutism, Expectorant, Anticolitic, Antinociceptive, Oculohypotensive, Antimutagenic, Cytotoxicity, Diuretic, Antithrombotic, chemomodulatory, antipyretic, hypolipidemic, cytoprotection and antitumor, hypoglycemic, antispasmodic, bronchiodilatory, apoptotic, antioxidant, antiaging, cytochrome P4530 3A4 inhibitory activity