Fallaxosides B 1 and D 3 , triterpene glycosides with novel skeleton types of aglycones from the sea cucumber Cucumaria fallax

Marine natural products

“…The remaining metabolites reported from echinoderms included steroidal glycosides pentacerosides A 1461 and B 1462 (Pentaceraster gracilis), 694 regulusosides S1 1463 and S2 1464 (P. regulus), 695 pentaregulosides A-G 1465-1471 (P. regulus), 696 and granulatoside C 1472 (Choriaster granulatus), 697 all isolated from starsh, as well as sea cucumbersourced triterpene glycosides nobiliside D 1473 (Holothuria nobilis), 698 stichorrenosides A-D 1474-1477 (Stichopus horrens), 699 magnumosides A 1 -A 4 , B 1 -B 4 , C 1 -C 4 1478-1489 (Neothyonidium (¼Massinium) magnum), 700,701 and fallaxosides B 1 and D 3 1490, 1491 (Cucumaria fallax). 702 Nobiliside D 1473 showed strong cytotoxicity towards a panel of six HTCLs, 698 while magnumoside C 4 1489 enhanced the antiproliferative effects of g-radiation on DLD-1 human colorectal adenocarcinoma cells. 700 Biological evaluation of carbohydrate conjugates of the sea urchin quinonoid ethylmompain identied analogues with enhanced cytotoxicity and the ability to inhibit urchin spermatozoids.…”

Progress in the Studies of Triterpene Glycosides From Sea Cucumbers (Holothuroidea, Echinodermata) Between 2017 and 2021

“…Two unprecedented triterpene glycosides, fallaxosides B 1 (1) and D 3 (2) (Figure 1), with two new skeletal types of aglycone, have been found in the sea cucumber Cucumaria fallax (Cucumariidae, Dendrochirotida). 16 It seems to be obvious that the first aglycone is formed as result of intramolecular aldol condensation of a precursor containing a 1,6-diketone fragment (Figure 2). The second aglycone could be formed by pinacol-pinacolone-like rearrangement of another precursor, probably containing a 7,8,9-trihydroxy fragment (or by relative Meinwald rearrangement of its 8,9-epoxy-7-hydroxy analog, an acid-catalyzed conversion of a tetrasubstituted epoxide to a carbonyl compound) (Figure 3).…”

“…Moreover, in the Chinese paper, the HR mass-spectrometric data were absent and the peaks of fragment ions, observed as a result of the molecular ion fragmentation, did not correspond to the disulfated compound. It seems obvious that the structure of philinopside B needs to be reconsidered and actually it may coincide with the structure of coloquadranoside A (16).…”

Structural and Biological Insights into the Hot‐Spot Marine Natural Products Reported from 2012 to 2021

“…It was proposed that the skeleton of fallaxoside B1 was formed by aldol condensation of a 24‐diketone precursor and that the skeleton of fallaxoside D3 was formed by a pinacol‐pinacolone‐like rearrangement of a 7,8‐dihydroxy precursor. [ 216 ]…”