Polypodium vulgare osladin from

The steroidal saponin osladin (58) was isolated as a sweet principle from the fern Polypodium vulgare L. (Polypodiaceae) nearly 40 years ago [20,28]. However, the original structure proposed was later revised because the synthetic compound produced was not sweet at all [87]. The correct structure of osladin (58) was characterized by single crystal X-ray... 

Osladin (62) is a steroidal glycoside that is about 500-times sweeter than sucrose. It was isolated by the Czech chemists Jizba and Herout in 1967 [112] from the rhizomes of European fern Polypodium vulgare known for its very sweet taste. Its structure has been recently revised [113] by total synthesis. During the synthesis it was shown that minute changes in the structure result in total loss of the sweet taste. Thus, this is a t5 ical glycoside whose overall structure - including the glycosidic part - is crucial for the respective activity. 

Another sweet-tasting saponin, osladin (17), occurs at rather low concentrations (about 0.03%) in the roots of the fern Polypodium vulgare (Hodge and Inglett, 1974). Similar steroidal glycosides have been isolated from the rhizomes of Polypodium glycyrrhiza (Kim et al., 1988 Kim and Kinghom, 1989). The major intensely sweet compound of that plant is polypodoside A, a 26-0-a-L-rhamnopyranosyl-pol-... 

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