Osladin

Osladin, a steroidal saponin, was isolated as a sweet principle of the fem Polypodium vulgare L. (Polypodiaceae). Later, Nishizawa and Yamada.36 reinvestigated the structure of osladin and revised the stereochemistry at C-22, C-25, and C-26. Although osladin has been reported to be 3000 times sweeter than sucrose, this value was also... 

Three steroidal saponins, polypodosides, were isolated from the rhizomes of Polypodium glycyrrbiza DC. Eaton (Polypodiaceae).37,38 According to the corrected structure of osladin, the structure of polypodoside was also revised.39 Polypodoside A was shown to be highly sweet (600 times sweeter than sucrose). 

Osladin Polypodium vulgare (European fern) Sweet (500X >sucrose)... 

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. 

Osladine aglycone (5) has been synthesized from solasodine via dihydrosolasodine A (6), the triformyl derivative (7), and isoverazine (8)/The pregnane derivative (9) has been prepared from N -acetylsolasodine. Single-crystal X-ray diffraction studies on solasodine monohydrate are in progress. ... 

M. Havel and V. Cerny, Coll. Czech. Chem. Comm., 1975,40,3199. For an earlier synthesis of osladine aglycone from solasodine, see M. Havel and V. Cerny, ibid, 1975, 40, 1579 D. M. Harrison, in The Alkaloids , ed. M. F. Grundon (Specialist Periodical Reports), The Chemical Society, London, 1976, Vol. 6, p. 287. 

Ozonolysis of solasodine (1) and of the derived enone (8), with oxidative work-up, gave the keto-acids (18) and (19), respectively. These products were characterized as their methyl esters and as the acetates of the products of lithium aluminium hydride reduction of the methyl esters. Ozonolyses of (20) and (21) to give analogous products were also described. The aglycone (22) of the steroidal glycoside osladine has been synthesized from solasodine via the azomethine (23) and ketone (24). ... 

Steroidal Saponins The fern genus, Polypodium, has so far yielded three sweet steroidal saponins, namely, osladin (45) and polypodosides A and B (46, 47). The first-named of these compounds was structurally determined without full stereochemistry as an isolate of P. 

SYNTHETIC APPROACH TO INTENSELY SWEET GLYCOSIDES BAIYUNOSIDE OSLADIN... 

Osladin (3) (revised structure) HO Qj j (500 limes swcein- than sucrose)... 

---