Citronella oil is an essential oil obtained from the leaves and stems of different species of Cymbopogon (lemongrass). The oil is used extensively as a source of perfumery chemicals such as citronellal, citronellol, and geraniol. These chemicals find extensive use in soap, candles and incense, perfumery, cosmetic, and flavouring industries throughout the world. [1]
Citronella oil is also a plant-based insect repellent and has been registered for this use in the United States since 1948. [2] The United States Environmental Protection Agency considers oil of citronella as a biopesticide with a non-toxic mode of action. [3]
Citronella oil has strong antifungal properties. [4] [5] [6]
Citronella oil is classified in trade into two chemotypes: [7]
The higher proportions of citronellal and geraniol in the Java type oil make it a better source for perfumery derivatives. [1] [8] The standard quality of Java type from Indonesia is regulated by Indonesian authority under SNI 06–3953–1995, which requires citronellal minimum 35% and total geraniol minimum 85%. [9]
Both types probably originated from Mana Grass of Sri Lanka, which according to Finnemore (1962) occurs today in two wild forms – Cymbopogon nardus var. linnae (typicus) and C. nardus var. confertiflorus. Neither wild form is known to be used for distillation to any appreciable extent.
Citronella oil from Cymbopogon species should not be confused with other similar lemony oils from Corymbia citriodora and Pelargonium citrosum .
Citronella oil is used especially as a mosquito repellent, [11] particularly for Aedes aegypti (dengue fever mosquito). [12] Research also indicates that citronella oil is an effective repellent for body lice, head lice, and stable flies. [10] [13] [14] A study conducted by DARPA in 1963 determined that hydroxycitronellal was an effective repellent against both aquatic and terrestrial leeches. [15]
Citronella candles (which burn citronella oil) are not effective at repelling Aedes aegypti, the species of mosquito responsible for spreading dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents. [16]
Although direct application of citronella oil to the skin is non-toxic, its use was not recommended as a topical insect repellent in Canada in 2006. [17] [18] Health Canada banned use of citronella oil as an insect repellent in 2012, but lifted the ban in February 2015. [19]
At present, the world annual production of citronella oil is approximately 4,000 tonnes. The main producers are China and Indonesia - producing 40 percent of the world's supply. The oil is also produced in Taiwan, Guatemala, Honduras, Brazil, Sri Lanka, India, Argentina, Ecuador, Jamaica, Madagascar, Mexico, and South Africa.[ citation needed ]
The market for natural citronella oil has been eroded by chemicals synthesised from turpentine derived from conifers. However, natural citronella oil and its derivatives are preferred by the perfume industry. [20]
Cymbopogon, also known as lemongrass, barbed wire grass, silky heads, oily heads, Cochin grass, Malabar grass, citronella grass or fever grass, is a genus of Asian, African, Australian, and tropical island plants in the grass family. Some species are commonly cultivated as culinary and medicinal herbs because of their scent, resembling that of lemons . The name cymbopogon derives from the Greek words kymbe and pogon "which mean [that] in most species, the hairy spikelets project from boat-shaped spathes." Lemongrass and its oil are believed to possess therapeutic properties.
Citronella may refer to:
Geraniol is a monoterpenoid and an alcohol. It is the primary component of citronella oil and is a primary component of rose oil and palmarosa oil. It is a colorless oil, although commercial samples can appear yellow. It has low solubility in water, but it is soluble in common organic solvents. The functional group derived from geraniol is called geranyl.
Linalool refers to two enantiomers of a naturally occurring terpene alcohol found in many flowers and spice plants. Linalool has multiple commercial applications, the majority of which are based on its pleasant scent. A colorless oil, linalool is classified as an acyclic monoterpenoid. In plants, it is a metabolite, a volatile oil component, an antimicrobial agent, and an aroma compound. Linalool has uses in manufacturing of soaps, fragrances, food additives as flavors, household products, and insecticides. Esters of linalool are referred to as linalyl, e.g. linalyl pyrophosphate, an isomer of geranyl pyrophosphate.
An insect repellent is a substance applied to the skin, clothing, or other surfaces to discourage insects from landing or climbing on that surface. Insect repellents help prevent and control the outbreak of insect-borne diseases such as malaria, Lyme disease, dengue fever, bubonic plague, river blindness, and West Nile fever. Pest animals commonly serving as vectors for disease include insects such as flea, fly, and mosquito; and ticks (arachnids).
Citronellal or rhodinal (C10H18O) is a monoterpenoid aldehyde, the main component in the mixture of terpenoid chemical compounds that give citronella oil its distinctive lemon scent.
Citral is an acyclic monoterpene aldehyde. Being a monoterpene, it is made of two isoprene units. Citral is a collective term which covers two geometric isomers that have their own separate names; the E-isomer is named geranial or citral A. The Z-isomer is named neral or citral B. These stereoisomers occur as a mixture, often not in equal proportions; e.g. in essential oil of Australian ginger, the neral to geranial ratio is 0.61.
Rose oil is the essential oil extracted from the petals of various types of rose. Rose ottos are extracted through steam distillation, while rose absolutes are obtained through solvent extraction, the absolute being used more commonly in perfumery. The production technique originated in Greater Iran. Even with their high price and the advent of organic synthesis, rose oils are still perhaps the most widely used essential oil in perfumery.
Myrcene, or β-myrcene, is a monoterpene. A colorless oil, it occurs widely in essential oils. It is produced mainly semi-synthetically from Myrcia, from which it gets its name. It is an intermediate in the production of several fragrances. α-Myrcene is the name for the isomer 2-methyl-6-methylene-1,7-octadiene, which has not been found in nature.
Citronellol, or dihydrogeraniol, is a natural acyclic monoterpenoid. Both enantiomers occur in nature. (+)-Citronellol, which is found in citronella oils, including Cymbopogon nardus (50%), is the more common isomer. (−)-Citronellol is widespread, but particularly abundant in the oils of rose (18–55%) and Pelargonium geraniums.
Nerol is a monoterpenoid alcohol found in many essential oils such as lemongrass and hops. It was originally isolated from neroli oil, hence its name. This colourless liquid is used in perfumery. Like geraniol, nerol has a sweet rose odor but it is considered to be fresher. Esters and related derivatives of nerol are referred to as neryl, e.g., neryl acetate.
Eucalyptus oil is the generic name for distilled oil from the leaf of Eucalyptus, a genus of the plant family Myrtaceae native to Australia and cultivated worldwide. Eucalyptus oil has a history of wide application, as a pharmaceutical, antiseptic, repellent, flavouring, fragrance and industrial uses. The leaves of selected Eucalyptus species are steam distilled to extract eucalyptus oil.
Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen functionality or missing a methyl group, are called monoterpenoids. Monoterpenes and monoterpenoids are diverse. They have relevance to the pharmaceutical, cosmetic, agricultural, and food industries.
Corymbia citriodora, commonly known as lemon-scented gum and other common names, is a species of tall tree that is endemic to north-eastern Australia. It has smooth white to pink bark, narrow lance-shaped to curved adult leaves, flower buds in groups of three, white flowers and urn-shaped or barrel-shaped fruit.
Cymbopogon nardus, common name citronella grass, is a species of perennial aromatic plant from the family Poaceae, originating in tropical Asia. C. nardus cannot be eaten because of its unpalatable nature and is an invasive species that renders pastureland useless, since cattle will starve even in its abundance.
Nootkatone is an organic compound, a sesquiterpenoid, which means that it is a C15 derivative that also contains an oxygen-containing functional group. It is the most valuable aroma compound of grapefruit. Nootkatone was originally isolated from the wood of the Alaskan yellow cedar, Cupressus nootkatensis. The species name, nootkatensis, is derived from the language of the Nuu-Chah-Nulth people of Canada.
Cymbopogon citratus, commonly known as West Indian lemon grass or simply lemon grass, is a tropical plant native to Maritime Southeast Asia and introduced to many tropical regions.
Cymbopogon martinii is a species of grass in the genus Cymbopogon (lemongrasses) native to India and Indochina but widely cultivated in many places for its aromatic oil. It is best known by the common name palmarosa as it smells sweet and rose-like. Other common names include Indian geranium, gingergrass, rosha, and rosha grass.
The micro-atmosphere method is an antimicrobial sensitivity testing method involving the use of potentially bacteriostatic or fungicidal compounds which are obtained from the volatile oils of plants, such as citronella grass. This method involves the use of essential oils, a growth medium, a selection of bacterial or fungal cultures, and an incubator.
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