Valerian root, many cat owners have found, makes their cats turn hyper. Cats aren’t the only creatures that have their behavior affected by valerian root. Slime molds literally go out of their way to seek it out, and that provided researchers a clue to why cats love it so much.
Physarum polycephalum is a slime mold, and as such can take many different forms. It can form into a fruiting body and give off spores. It can go dormant by become a sort of crusty tissue. Most of the time, however, it is a plasmodium, and streams around old rotting logs and leaves. Recently, researchers have become interested in using these slime molds as living computers by manipulating the plasmodium using chemical signals. It’s attracted to sugars like glucose and maltose, but one research team found that it’s also attracted to herbal calming tablets like Kalms Sleep and Nytol. After testing the ingredients, they learned that it was the valerian root in the tablets that proved to be the strongest chemoattractant for the plasmodium.
What was it about valerian root that made it irresistible to slime molds? It could be any number of things, but the researchers believe that it’s actinidine. Actinidine is “structurally close” to the compound nepetalactone, the component in catnip that drives cats crazy. When the group tested nepetalactone on the plasmodium, they found that it was attracted to the catnip component, if much less attracted to nepetalactone than it was to actinidine.
Rats and, to some extent, insects, also react to both actinidine and nepetalactone. So this approximate chemical structure works across a wide variety of species, including humans. It doesn’t have the same effect across species—most pet owners say valerian root makes their cats hyper, humans put both valerian root and catnip in tea because they find it calming, and slime molds just want to be around it—but it does have an effect.
[Source: Physarum Attraction]