saponin

sapon- +‎ -in

• IPA^(key): /ˈsæpənɪn/

saponin (plural saponins)

1. (organic chemistry, biochemistry) Any of various steroid glycosides found in plant tissues that dissolve in water to give a soapy froth.
   • 1985, Wade Davis, The Serpent and the Rainbow, Simon & Schuster, page 111:

     “Saponins aren't absorbed by the intestines. You've got to get the stuff into the blood.”

   • 2015, Beth Terry, Plastic-Free: How I Kicked the Plastic Habit and How You Can Too‎, Simon and Schuster, →ISBN:

     Soapnuts are the dried fruit of a tree called Sapindus mukorossi (Chinese Soapberry) and contain saponin, a natural surfactant that foams just like soap.