Nepetalactone is an organic compound, first isolated from the plant catnip (Nepeta cataria), which acts as a cat attractant. Nepetalactone is bicyclic monoterpenoid, i.e., it is a ten-carbon compound derived from isoprene with two fused rings: a cyclopentane and a lactone. It belongs to the class of iridoids. The structure and the effects of the compound are similar to those of valepotriates. A number of isomers of nepetalactone are known.
Nepetalactone was first reported in 1941 after it was isolated by steam distillation of catnip.
The compound is also present in the wood of tartarian honeysuckle (Lonicera tatarica), shavings of which are often used in cat toys.
4aα,7α,7aα-Nepetalactone is the active isomer in Nepeta cataria and has a characteristic effect on cats. Around 67–80% of cats are affected. Susceptibility is gene-linked. The chemical interacts as a vapor at the olfactory epithelium.
Nepetalactone has effects on some insects: it repels cockroaches and mosquitos.