Ocimum basilicum, O. americanum, and O. micranthum
Ocimum basilicum (common basil), O. americanum, and O. micranthum are members of the family Lamiaceae. These plants, as well as oils from them, have received lots of attention for their potential medicinal properties. Of these plants, O. basilicum is the most widely used. It is used in cosmetics, liqueurs, medicines, and perfumes.
Most Ocimum spp. can be grown and found throughout the world. However, they are not native to all areas. For example, O. micranthum originated in Central America. It grows to a height of approximately 50cm. The leaves are oval and slightly toothed, and the flowers are white or purple. O. basilicum looks very similar, but grows a bit taller (50-80cm).
There are many compounds in Ocimum spp. The dried leaves of O. basilicum contain 0.20-1% essential oil. The major compounds in the oil are linalool and methylchaviol. The exact amounts, however, vary considerably. For example, in some studies camphene has been found in O. americanum and not in O. basilicum. Conversely, cineole has been found in O. basilicum and not in O. americanum. Also, differences in the potassium to calcium ratio in the culture media can change the quantity of the major constituents in the essential oil.
Some of the Compounds in Ocimum basilicum(for a more complete list see USDA Phytochemical and Ethnobotanical Databases.):
There is little available literature on the toxicity of Ocimum spp. However, O. basilicum, the species that appears to be used the most medicinally and the one for which the most analysis has been done, contains several potentially dangerous compounds. Some of these compounds are: safrole, rutin, caffeic acid, tryptophan, and quercetin.
Acute bovine pulmonary emphysema (ABPE), a respiratory disease in cattle, is caused by absorbed metabolites of tryptophan. Usually, ABPE occurs in cattle over 2-3yrs of age that are suddenly moved onto lush pasture. Tryptophan is toxic at a dose of 0.25-0.35g/kg body weight (BW). Whether or not a dose of Ocimum spp. could cause ABPE is not known.
P-coumaric acid and caffeic acid (phenolic acids) can inhibit digestion of plant cell walls in ruminants, because of their antimicrobial activity. When these phenolic acids are metabolized by rumen microbes, benzoic acid, 3-phenyl-propionic acid (PPA), and cinnamic acid may be formed. When these compounds are detoxified, hippuric acid is formed. PPA can decrease metabolic efficiency. Detoxifying the compounds costs the animal nitrogen, which also can decrease productivity.
Quercetin (a flavanoid) may be a cocarcinogen in bracken fern (Pteridium aquilinum). It has been suggested that it may interact with Bovine papilloma virus type 4, leading to malignant epithelial papillomas in the upper alimentary tract. Adverse effects from quercetin in Ocimum spp., when used to treat animals, is not known.
Safrole, which was used to flavor sodas, was banned as a food additive in the U.S. It has been shown to cause cancer in rats. Oil of Ocimum also contains d-limonene, which has anticarcinogenic properties.
Both the essential oil, leaves, seeds, flowers, and roots of Ocimum spp. are used as medicines. The essential oil has been shown in vitro to have antibacterial activity against Staphylococcus aureus, Salmonella enteritidis and Escherichia coli, antiseptic activity against Proteus vulgaris, Bacillus subtilis, and Salmonella paratyph, and antifungal activity against Candida albicans, Penicillium notatum, and Microsporeum gyseum.
Oils from some Ocimum spp. have been shown to repel insects and have larvicidal activity against houseflies, blue bottle flies, and mosquitoes. The effective concentration of the oil to kill 90% of the larva ranged from 113-283 ppm. Camphor, d-limonene, myrcene, and thymol are some of the compounds in the oil that may provide the repellent properties. Eugenol and methylchavicol may be responsible for the larvicidal activity.
Little published information can be found about the use of oil from Ocimum and fresh plant materials in the treatment of animals. Therefore, efficacious doses are not known. However, O. basilicum has been used as an expectorant in animals. Also, O. micranthum has been combined with Chenopodium ambrosioides to treat stomach pain and colic in animals. It also has been used as a paste to massage the udder of livestock.
Some Uses in Humans:
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