Bulbus Allii Cepae is the fresh or dried bulbs of Allium cepa L. (Liliaceae) or its varieties and cultivars
Allium esculentum Salisb., Allium porrum cepa Rehb
Selected vernacular names
It is most commonly known as “onion”. Basal, basl, cebolla, cebolla morada, cepa bulb, cepolla, cipolla, common onion, cu hanh, hom hua yai, hom khaao, hom yai, hu-t’sung, hu t’sung t’song, hua phak bhu, i-i-bsel, kesounni, khtim, Küchenzwiebel, l’oignon, loyon, Madras oignon, oignon, palandu, piyaj, piyaz, pyaz, pyaaz, ralu lunu, red globe onion, sibuyas, Spanish onion, tamanegi, umbi bawang merah, vengayan, yellow Bermuda onion, white globe onion, Zwiebel
A perennial herb, strong smelling when crushed; bulbs vary in size and shape from cultivar to cultivar, often depressed-globose and up to 20cm in diameter; outer tunics membranous. Stem up to 100cm tall and 30mm in diameter, tapering from inﬂated lower part. Leaves up to 40cm in height and 20mm in diameter, usually almost semicircular in section and slightly ﬂattened on upper side; basal in ﬁrst year, in second year their bases sheathing the lower sixth of the stem. Spathe often 3-valved, persistent, shorter than the umbel. Umbel 4– 9cm in diameter, subglobose or hemispherical, dense, many-ﬂowered; pedicels up to 40mm, almost equal. Perianth stellate; segments 3–4.5 2–2.5mm, white, with green stripe, slightly unequal, the outer ovate, the inner oblong, obtuse or acute. Stamens exserted; ﬁlaments 4–5mm, the outer subulate, the inner with an expanded base up to 2mm wide and bearing short teeth on each side. Ovary whitish. Capsule about 5mm, 2n 16
Bulbus Allii Cepae varies in size and shape from cultivar to cultivar, 2–20cm in diameter; ﬂattened, spherical or pear-shaped; white or coloured.
Odour strong, characteristic alliaceous; taste strong; crushing or cutting the bulb stimulates lachrymation.
The external dried leaf scales of the bulbs show a large-celled epidermis with lightly spotted cell walls; the cells are elongated longitudinally. The underlying hypodermis runs perpendicular to the epidermis and contains large calcium oxalate crystals bordering the cell walls. The epidermis of the ﬂeshy leaf scales resembles that of the dried leaf scales, and the epidermal cells on the dorsal side are distinctly longer and more elongated than the epidermal cells on the ventral side. Large calcium oxalate crystals are found in the hypodermis; stomata rare; large cell nuclei conspicuous; and spiral vessel elements occur in the leaf mesophyll
Powdered plant material
Contains mainly thin-walled cells of the mesophyll with broken pieces of spiral vessel elements; cells containing calcium oxalate crystals are scarce
Uses supported by clinical data
The principal use of Bulbus Allii Cepae today is to prevent age-dependent changes in the blood vessels, and loss of appetite.
Uses described in pharmacopoeias and in traditional systems of medicine
Treatment of bacterial infections such as dysentery, and as a diuretic. The drug has also been used to treat ulcers, wounds, scars, keloids (3), and asthma. Bulbus Allii Cepae has also been used as an adjuvant therapy for diabetes.
Uses described in folk medicine, not supported by experimental or clinical data
As an anthelminthic, aphrodisiac, carminative, emmenagogue, expectorant, and tonic, and for the treatment of bruises, bronchitis, cholera, colic, earache, fevers, high blood pressure, jaundice, pimples, and sores .
An aqueous extract or the juice of Bulbus Allii Cepae inhibited the in vitro growth of Escherichia coli, Serratia marcescens, Streptococcus species, Lactobacillus odontolyticus, Pseudomonas aeruginosa, and Salmonella typhosa .
A petroleum ether extract of Bulbus Allii Cepae inhibited the in vitro growth of Clostridium paraputriﬁcum and Staphylococcus aureus (24). The essential oil has activity against a variety of fungi including Aspergillus niger, Cladosporium werneckii, Candida albicans, Fusarium oxysporium, Saccharomyces cerevisiae, Geotrichum candidum, Brettanomyces anomalus, and Candida lipolytica .
The hypoglycaemic effects of Bulbus Allii Cepae have been demonstrated in vivo. Intragastric administration of the juice, a chloroform, ethanol, petroleum ether (0.25g/kg) or water extract (0.5ml), suppressed alloxan-, glucose- and epinephrine-induced hyperglycaemia in rabbits and mice.
Inhibition of platelet aggregation by Bulbus Allii Cepae has been demonstrated both in vitro and in vivo. An aqueous extract inhibited adenosine diphosphate-, collagen-, epinephrine- and arachidonic acid-induced platelet aggregation in vitro.
Platelet aggregation was inhibited in rabbits after administration of the essential oil, or a butanol or chloroform extract of the drug.
An ethanol, butanol or chloroform extract or the essential oil (10–60µg/ml) of the drug inhibited aggregation of human platelets in vitro by decreasing thromboxane synthesis.
Both raw onions and the essential oil increased ﬁbrinolysis in ex vivo studies on rabbits and humans. An increase in coagulation time was also observed in rabbits.
Intragastric administration of the juice or an ether extract (100mg/kg) of the drug inhibited allergen- and platelet activating factor-induced allergic reactions, but not histamine- or acetylcholine-induced allergenic responses in guinea-pigs.
A water extract of the drug was not active. A chloroform extract of Bulbus Allii Cepae (20–80mg/kg) inhibited allergen- and platelet aggregation factor-induced bronchial obstruction in guinea-pigs.
The thiosulphinates and cepaenes appear to be the active constituents of Bulbus Allii Cepae. Both ethanol and methanol extracts of Bulbus Allii Cepae demonstrated diuretic activity in dogs and rats after intragastric administration.
Antihyperlipidaemic and anticholesterolaemic activities of the drug were observed after oral administration of minced bulbs, a water extract, the essential oil (100mg/kg), or the ﬁxed oil to rabbits or rats. However, one study reported no signiﬁcant changes in cholesterol or lipid levels of the eye in rabbits, after treatment of the animals for 6 months with an aqueous extract (20% of diet).
Oral administration of an ethanol extract of the drug to guinea-pigs inhibited smooth muscle contractions in the trachea induced by carbachol and inhibited histamine-, barium chloride-, serotonin-, and acetylcholine-induced contractions in the ileum.
Topical application of an aqueous extract of Bulbus Allii Cepae (10% in a gel preparation) inhibited mouse ear oedema induced by arachidonic acid (54). The active antiallergic and anti-inﬂammatory constituents of onion are the ﬂavonoids (quercetin and kaempferol).
The ﬂavonoids act as antiinﬂammatory agents because they inhibit the action of protein kinase, phospholipase A2, cyclooxygenase, and lipoxygenase (56), as well as the release of mediators of inﬂammation (e.g. histamine) from leukocytes.
In vitro, an aqueous extract of Bulbus Allii Cepae inhibited ﬁbroblast proliferation. A 0.5% aqueous extract of onion inhibited the growth of human ﬁbroblasts and of keloidal ﬁbroblasts (enzymically isolated from keloidal tissue).
In a comparative study, an aqueous extract of Bulbus Allii Cepae (1– 3%) inhibited the proliferation of ﬁbroblasts of varying origin (scar, keloid, embryonic tissue).
The strongest inhibition was observed with keloid ﬁbroblasts (65–73%) as compared with the inhibition of scar and embryonic ﬁbroblasts (up to 50%).
In human skin ﬁbroblasts, both aqueous and chloroform onion extracts, as well as thiosulﬁnates, inhibited the plateletderived growth factor-stimulated chemotaxis and proliferation of these cells. In addition, a protein fraction isolated from an onion extract exhibited antimitotic activity.
Bulbus Allii Cepae
Oral administration of a butanol extract of Bulbus Allii Cepae (200mg) to subjects given a high-fat meal prior to testing suppressed platelet aggregation associated with a high-fat diet.
Administration of a butanol extract to patients with alimentary lipaemia prevented an increase in the total serum cholesterol, -lipoprotein cholesterol, and -lipoprotein and serum triglycerides.
A saponin fraction (50mg) or the bulb (100mg) also decreased serum cholesterol and plasma ﬁbrinogen levels. However, fresh onion extract (50g) did not produce any signiﬁcant effects on serum cholesterol, ﬁbrinogen, or ﬁbrinolytic activity in normal subjects.
Antihyperglycaemic activity of Bulbus Allii Cepae has been demonstrated in clinical studies. Administration of an aqueous extract (100mg) decreased glucose-induced hyperglycaemia in human adults.
The juice of the drug (50mg) administered orally to diabetic patients reduced blood glucose levels.
Addition of raw onion to the diet of non-insulin-dependent diabetic subjects decreased the dose of antidiabetic medication required to control the disease. However, an aqueous extract of Bulbus Allii Cepae (200mg) was not active.
The immediate and late cutaneous reactions induced by injection of rabbit anti-human IgE-antibodies into the volar side of the forearms of 12 healthy volunteers were reduced after pretreatment of the skin with a 50% ethanol onion extract.
Immediate and late bronchial obstruction owing to allergen inhalation was markedly reduced after oral administration of a 5% ethanol onion extract 1 hour before exposure to the allergen .
In one clinical trial in 12 adult subjects, topical application of a 45% ethanolic onion extract inhibited the allergic skin reactions induced by anti-IgE.