The structure of osladin - the sweet principle of the rhizomes of polypodium vulgare L.

Sweet and Umami Taste: Natural Products, Their Chemosensory Targets, and Beyond

“…thaumatin (31) 1600 brazzein (32) 2000 pentadin (33) 500 monellin (34) 3000 mabinlin (35) 375 [d] curculin (neoculin) (36) 550…”

“…[33] More than 40 years ago a sweet steroidal saponin was isolated from the European fern Polypodium vulgare L. (Poliypodiaceae) by Jizba and Herout, and named osladin (24) after the Czech name of the fern ("osladic"). [34] After the compound, assigned as osladin, was synthesized by means of independent organic synthesis and found not to induce any sweetness sensation, the stereochemistry of osladin had to be reassigned. [35] Single-crystal X-ray diffraction studies of natural osladin revealed that the correct structure is the 22R,25S,26R isomer and not the 22S,25R,26S isomer suggested earlier.…”

“…The sweet-tasting protein monellin (34), named after the Monell Chemical Senses Center in the USA where it was discovered in 1969, [49] was isolated from the fruit of the West African shrub Dioscoreophyllum cumminsii (Stapf) Diels., also know as "serendipity berry". Bohak and Li showed that monellin consists of two subunits, A and B, which contain 42 and 50 amino acids, respectively.…”

Moleküle und biologische Mechanismen des Süß‐ und Umamigeschmacks

“…[33] Vor mehr als 40 Jahren isolierten Jizba und Herout aus dem europäischen Farn Polypodium vulgare L. (Polypodiaceae) ein süßes Steroid-Saponin, das nach dem tschechischen Namen für Farn ("osladic") Osladin (24) genannt wurde. [34] Als die Verbindung, die als Osladin angesehen wurde, durch unabhängige organische Synthese hergestellt wurde, fand man, dass sie keine süße Empfindung hervorruft, weshalb die Konfiguration von Osladin neu zugeordnet werden musste. [35] Einkristallröntgenstrukturanalysen an natürlichem Osladin ergaben, dass das 22R,25S,26R-Isomer die richtige Struktur aufweist und nicht, wie früher angenommen,…”

Occurrence, Structure and Taxonomic Implications of Fern Constituents

“…Osladin (818) is a potent sweetener isolated from Polypodium vulgare (444). Though its content is low (0.03% on a dried rhizome weight basis), it is about 3000 times as sweet as saccharose.…”