I’ve been intrigued by the observation that some of them (polygama that is) are spicy, somewhat suggesting hot pepper/chili. I seen that One Green World sells a cultivar with that trait. I’ve not tried em, but would like to. A friend ordered one this year, so I hope to try from his and perhaps grow some out myself. The orange fruit are intriguing too.
I’ve noticed that my ‘Ken’s Red’ (arguta x melanandra) tastes spicy sometimes. It’s a bit more subtle than hot pepper, but I would describe it as somewhat similar. Apart from their effect on cats, apparently kiwis are used to tenderize meat. I’ve wondered if it might be the enzymes tenderizing the meat in my mouth!
Also, I’m not sure if other Actinidia besides polygama have psychoactive effects on felines, but I had a good size bobcat jump up in my kiwi trellis a couple of years ago,
and spend several minutes in the ‘Ken’s Red’ section.