Osladin

Osladine is a high-intensity sweetener isolated from the rhizome of "Polypodium vulgare". It is a saponin, sapogenin steroid glycoside, 500 times sweeter than sucrose.
A related compound, polypodoside A, has been identified from "Polypodium glycyrrhiza" and is 600 times sweeter than a sucrose solution at 6%.