Names | |||
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Preferred IUPAC name Butan-2-yl 2-(2-hydroxyethyl)piperidine-1-carboxylate | |||
Other names
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Identifiers | |||
3D model (JSmol) | |||
ChEMBL | |||
ChemSpider | |||
ECHA InfoCard | 100.102.177 | ||
PubChem CID | |||
UNII | |||
CompTox Dashboard (EPA) | |||
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Properties | |||
C12H23NO3 | |||
Molar mass | 229.320 g·mol−1 | ||
Appearance | colorless liquid | ||
Odor | odorless | ||
Density | 1.07 g/cm3 | ||
Melting point | −170 °C (−274 °F; 103 K) | ||
Boiling point | 296 °C (565 °F; 569 K) | ||
0.82 g/100 mL | |||
Solubility | 752 g/100mL (acetone) | ||
Refractive index (nD) | 1.4717 | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Icaridin, also known as picaridin, is an insect repellent which can be used directly on skin or clothing. [1] It has broad efficacy against various arthropods such as mosquitos, ticks, gnats, flies and fleas, and is almost colorless and odorless. A study performed in 2010 showed that picaridin spray and cream at the 20% concentration provided 12 hours of protection against ticks. [2] Unlike DEET, icaridin does not dissolve plastics, synthetics or sealants, [3] is odorless and non-greasy [4] and presents a lower risk of toxicity when used with sunscreen, as it may reduce skin absorption of both compounds. [5]
The name picaridin was proposed as an International Nonproprietary Name (INN) to the World Health Organization (WHO), but the official name that has been approved by the WHO is icaridin. The chemical is part of the piperidine family, [1] along with many pharmaceuticals and alkaloids such as piperine, which gives black pepper its spicy taste.
Trade names include Bayrepel and Saltidin among others. The compound was developed by the German chemical company Bayer in the 1980s [6] and was given the name Bayrepel. In 2005, Lanxess AG and its subsidiary Saltigo GmbH were spun off from Bayer [7] and the product was renamed Saltidin in 2008. [8]
Having been sold in Europe since 1998, [9] on 23 July 2020, icaridin was approved again by the EU Commission for use in repellent products. The approval entered into force on 1 February 2022 and is valid for ten years. [10]
Icaridin and DEET are the most effective insect repellents available. A 2018 systematic review found no consistent performance difference between icaridin and DEET in field studies and concluded that they are equally preferred mosquito repellents, noting that 50% DEET offers longer protection but is not available in some countries. [11]
Icaridin has been reported to be as effective as DEET at a 20% concentration without the irritation associated with DEET. [12] [13] According to the WHO, icaridin “demonstrates excellent repellent properties comparable to, and often superior to, those of the standard DEET.”
Icaridin-based products have been evaluated by Consumer Reports in 2016 as among the most effective insect repellents when used at a 20% concentration. [14] Icaridin was earlier reported to be effective by Consumer Reports (7% solution) [15] and the Australian Army (20% solution). [16] Consumer Reports retests in 2006 gave as result that a 7% solution of icaridin offered little or no protection against Aedes mosquitoes (vector of dengue fever) and a protection time of about 2.5 hours against Culex (vector of West Nile virus), while a 15% solution was good for about one hour against Aedes and 4.8 hours against Culex. [17]
The United States Centers for Disease Control and Prevention recommends using repellents based on icaridin, DEET, ethyl butylacetylaminopropionate (IR3535), or oil of lemon eucalyptus (containing p-menthane-3,8-diol, PMD) for effective protection against mosquitoes that carry the West Nile virus, eastern equine encephalitis and other illnesses. [18]
Icaridin can cause mild to moderate eye irritation on contact and is slightly toxic if ingested. [19]
A 2018 study found that a commercial repellent product containing 20% icaridin, in what the authors described as "conservative exposure doses", is highly toxic to larval salamanders, a major predator of mosquito larvae. [20] The study observed high larval salamander mortality occurring delayed after the four days of exposure. Because the widely used LC50 test for assessing a chemical's environmental toxicity is based on mortality within four days, the authors suggested that icaridin would be incorrectly deemed as "safe" under the test protocol. [21] However, icaridin was also non-toxic in a 21-day reproduction test on the water flea Daphnia magna [22] and a 32-day early life-stage test in zebrafish. [23]
Since only the icaridin content of the tested repellent product is known, the observed effects cannot be readily attributed to icaridin. Furthermore, the effects of the repellent product showed no dose-response relationship, i.e., there was neither an increase of the magnitude or severity of the observed effects (mortality, tail deformation), nor did the effects occur at earlier time points. The study has been regarded as invalid by the Danish Environmental Protection Agency, [24] [25] which has evaluated icaridin prior to its approval under the EU Biocidal Product Regulation. The reasons for rejection were the testing of a mixture of undisclosed composition, the use of a non-standard test organism, the lack of analytical verification of actual test concentrations, and the fact that the test solution was never renewed with the 25 days of study duration.
In 2014, a potential odorant receptor for icaridin (and DEET), CquiOR136•CquiOrco, was suggested for Culex quinquefasciatus mosquito. [26]
Recent crystal and solution studies showed that icaridin binds to Anopheles gambiae odorant binding protein 1 (AgamOBP1). The crystal structure of AgamOBP1•icaridin complex (PDB: 5EL2) revealed that icaridin binds to the DEET-binding site in two distinct orientations and also to a second binding site (sIC-binding site) located at the C-terminal region of the AgamOBP1. [27]
Recent evidence with Anopheles gambiae mosquitoes suggests icaridin does not strongly activate olfactory receptor neurons, but instead functions to reduce the volatility of the odorants to which it is mixed. [28] By reducing odor volatility, icaridin functions to "mask" the ability of volatile odorants on the skin to activate olfactory neurons and attract mosquitoes. [28]
Icaridin contains two stereocenters: one where the hydroxyethyl chain attaches to the ring, and one where the sec-butyl attaches to the oxygen of the carbamate. The commercial material contains a mixture of all four stereoisomers.
Commercial products containing icaridin include Cutter Advanced, Muskol, Repeltec, [29] Skin So Soft Bug Guard Plus, Sawyer Picaridin Insect Repellent, Off! FamilyCare, Autan, Smidge, PiActive and MOK.O. [30]
Mosquitoes, the Culicidae, are a family of small flies consisting of 3,600 species. The word mosquito is Spanish and Portuguese for little fly. Mosquitoes have a slender segmented body, one pair of wings, three pairs of long hair-like legs, and specialized, highly elongated, piercing-sucking mouthparts. All mosquitoes drink nectar from flowers; females of some species have in addition adapted to drink blood. Evolutionary biologists view mosquitoes as micropredators, small animals that parasitise larger ones by drinking their blood without immediately killing them. Medical parasitologists view mosquitoes instead as vectors of disease, carrying protozoan parasites or bacterial or viral pathogens from one host to another.
A biocide is defined in the European legislation as a chemical substance or microorganism intended to destroy, deter, render harmless, or exert a controlling effect on any harmful organism. The US Environmental Protection Agency (EPA) uses a slightly different definition for biocides as "a diverse group of poisonous substances including preservatives, insecticides, disinfectants, and pesticides used for the control of organisms that are harmful to human or animal health or that cause damage to natural or manufactured products". When compared, the two definitions roughly imply the same, although the US EPA definition includes plant protection products and some veterinary medicines.
N,N-Diethyl-meta-toluamide, also called diethyltoluamide or DEET, is the oldest, one of the most effective and most common active ingredient in commercial insect repellents. It is a slightly yellow oil intended to be applied to the skin or to clothing and provides protection against mosquitoes, flies, ticks, fleas, chiggers, leeches, and many other biting insects.
Bifenthrin is a pyrethroid insecticide. It is widely used against ant infestations.
Permethrin is a medication and an insecticide. As a medication, it is used to treat scabies and lice. It is applied to the skin as a cream or lotion. As an insecticide, it can be sprayed onto outer clothing or mosquito nets to kill the insects that touch them.
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).
Transfluthrin is a fast-acting pyrethroid insecticide with low persistency. It has the molecular formula C15H12Cl2F4O2.
Dimethyl phthalate (DMP) is an organic compound and phthalate ester. it is a colourless and oily liquid that is soluble in organic solvents, but which is only poorly soluble in water.
Aerogard is an Australian brand of outdoor insect repellent . It comes in aerosol sprays, bottled creams and roll-ons, the manufacturer is owned by the Anglo-Dutch company Reckitt Benckiser.
A larvicide is an insecticide that is specifically targeted against the larval life stage of an insect. Their most common use is against mosquitoes. Larvicides may be contact poisons, stomach poisons, growth regulators, or (increasingly) biological control agents.
Baygon is a pesticide brand produced by S. C. Johnson & Son. It is an insecticide used for extermination and control of household pests such as crickets, roaches, ants, carpenter ants, spiders, silverfish and mosquitoes. In 1975, Baygon introduced Australia’s first surface spray for killing cockroaches, ticks and other crawling insects.
Odorant-binding proteins (OBPs) are small soluble proteins secreted by auxiliary cells surrounding olfactory receptor neurons, including the nasal mucus of many vertebrate species and in the sensillar lymph of chemosensory sensilla of insects. OBPs are characterized by a specific protein domain that comprises six α-helices joined by three disulfide bonds. Although the function of the OBPs as a whole is not well established, it is believed that they act as odorant transporters, delivering the odorant molecules to olfactory receptors in the cell membrane of sensory neurons.
p-Menthane-3,8-diol, also known as para-menthane-3,8-diol, PMD, or menthoglycol, is an organic compound classified as a diol and a terpenoid. It is colorless. Its name reflects the hydrocarbon backbone, which is that of p-menthane. A total of eight stereoisomers are possible, based on the three stereocenters of the ring. Depending on the source, one or more may predominate.
Ethyl butylacetylaminopropionate is an insect repellent whose trade name is IR3535 and was developed and commercialized by Merck KGaA (Germany). It is a colorless and odorless oil with a good skin feel in final products, and it is biodegradable.
VUAA1 is a chemical compound that works by over activating an insect's olfactory senses causing a repellent effect. It is considered to be an Orco allosteric agonist. It was discovered at Vanderbilt University with research being partially funded by the Bill and Melinda Gates Foundation.
Metofluthrin is a pyrethroid used as an insect repellent. The vapors of metofluthrin are highly effective and capable of repelling up to 97% of mosquitoes in field tests. Metofluthrin is used in a variety of consumer products, called emanators, for indoor and outdoor use. These products produce a vapor that protects an individual or area. Effectiveness is reduced by air movement. Metofluthrin is neurotoxic, and is not meant to be applied directly to human skin.
SS220 is an insect repellent with a broad range of efficacy.
Callicarpenal is a terpenoid that has been isolated from plants of the genus Callicarpa (beautyberry). It acts as an insect repellent against mosquitoes and fire ants. It also has activity against ticks.
Attractive toxic sugar baits (ATSBs) are oral insecticides designed to reduce malaria infections by killing the host vector – the mosquito – rather than the parasite itself.
Howard Carter is a British inventor and businessman. He foundered Incognito in 2007. He is an expert in the field of insects and specifically as a mosquito bite prevention expert. After contracting two life-threatening diseases from mosquito bites, despite using a high-percentage DEET-based repellent, he was motivated to invent a totally natural, equally effective mosquito repellent, incognito anti-mosquito. This was, in part, because statistics were suggesting more mosquitoes were becoming resistant to synthetic repellents that contained controversial pesticides such as DDT and DEET.
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