3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||166.220 g·mol−1|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Nepetalactone is a name for multiple iridoid analog stereoisomers. Nepetalactones are produced by Nepeta cataria (catnip) and a many other plants belonging to the genus Nepeta, in which they protect these plants from herbivorous insects by functioning as insect repellents. They are also produced by many aphids, in which they are sex pheromones. Nepetalactones are cat attractants, and cause the behavioral effects that catnip induces in domestic cats. However, they affect visibly only about 2/3 of adult cats. They produce similar behavioral effects in many other Felidae, especially in lions and jaguars. McElvain and colleagues were the first to extract and name nepetalactones, which they did in 1941.
Structure and properties
Plants belonging to the Nepeta genus produce 4 different nepetalactone stereoisomers: (Z,Z)-, (Z,E)-, (E,Z)- and (E,E)-nepetalactone. Their relative occurrence varies between plant species. Small amounts of (Z,E)- and (E,Z)-nepetalactone also occur in the wood of Lonicera tatarica, but its cat attractant effects are assumed to be caused by actinidine, which occurs in it in higher concentrations.
Nepetalactones are also produced by many aphids, in which they function as sex pheromones. The most common isomer in aphids is (Z,E)-nepetalactone. Aphids also commonly produce a structurally related (1R,4αS,7S,7αR)-nepetalactol, which is also an aphid sex pheromone. Relative concentrations of these two compounds varies between aphid species.
Effects in felines
Duration and efficacy between species
Nepetalactones affect domestic cats via nasal mucosa. Oral ingestion has no effects. They induce noticeable behavioral effects in about 2/3 of adult cats. However, all cats are probably affected by them, but the effects in 1/3 of adult cats are less visible. Nepetalactones do not noticeably affect kittens that are less than 3 months old. Their effects also tend to be less pronounced in neutered cats in comparison to non-neutered cats, but not significantly.
Lions (Panthera leo) and jaguars (Panthera onca) are sensitive to nepetalactones. Their effects can last in them for up to 60 minutes. They also affect leopards (Panthera pardus). They do not affect tigers (Panthera tigris), bobcats (Lynx rufus), cougars (Puma concolor) or oncillas (Leopardus tigrinus).
2/3 of adult domestic cats begin to lick, sniff, eat, scratch or roll over the nepetalactone source after being exposed to it. They may also begin pawing, shaking their heads, rubbing their cheeks, licking themselves or vocalizing. About 1/3 of adult cats react more passively to nepetalactones, and may assume a sphinx-like posture, decrease vocalization or decrease movement. The effects of nepetalactones are similar in other Felidae.
Mechanism of action
Felidae olfactory receptor exposure to nepetalactones or nepetalactols induces β-endorphin secretion to blood. This endorphin activates µ-opioid receptors as an agonist, thus working in a similar manner as morphine or other opioids. Naloxone, a µ-opioid receptor antagonist, is known to block the effects of nepetalactones and nepetalactols in domestic cats, which supports this endorphin related mechanism of action. Repeated exposure to nepetalactones or nepetalactols does not induce opioid withdrawals in Felidae probably because endogenous β-endorphin secretion is controlled. (Z,E)- and (E,Z)-nepetalactones have both been shown to function as cat attractants in domestic cats in studies of poor quality. Both isomers occur in catnip for example, but (Z,E)-isomer is the major one.
Evolutionary reasons for the effects
Felidae react to plants that contain nepetalactones by licking them and rubbing them in their fur. Nepetalactones and nepetalactols repel some disease causing insects. For example, nepetalactols are able to repel Aedes albopictus. Felidae typically hunt other animals by stalking them. This requires being still or slow movements, which allow insects to bite Felidae more easily. This would make evolutionary pressure select for the behavior of rubbing of natural insect repellent. This was proposed to be the reason for this widely preserved behavioral trait in Felidae in a paper published in 2021.
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