Glucósidos esteroidales de la esponja marina Pandaros acanthifolium

Abstract

La investigación de la composición química de la esponja Pandaros acanthifolium, llevó al aislamiento de siete nuevos glicósidos esteroideos: pandarosides A – D (1, 3, 4 y 6) junto con los tres ésteres de metilo de pandarosides A, C y D (2, 5 y 7). Sus estructuras fueron caracterizadas como 3β-[β - ácido de glucopyranosyl-(1→2)-β - glucopyranosyloxyuronic] -16-hidroxi-5α, 14β - poriferast-16-ene-15,23-dione (1) y su éster metílico (2), 3 β-[β - glucopyranosyloxyuronic el ácido] -16-hidroxi - 5α, 14 β - poriferast-16-ene-15,23-diona (3), 3 β-[β - glucopyranosyl-(1→2) - β - glucopyranosyloxyuronic el ácido] -16-hidroxi-5α, 14 β - cholest-16-ene-15,23-diona (4) y su metil éster (5), 3 β-(β - glucopyranosyloxyuronic el ácido) -16-hidroxi-5α, 14 β - cholest-16-ene-15 , 23-dione (6) y itsmethyl éster (7) sobre la base de análisis espectroscópico detallado, incluyendo estudios de RMN y HRESIMS 2D. Pandarosides A – D y sus ésteres metílicos (1-7) se caracterizan por una rara hidroxiciclopentenona 2 D-anillo con una configuración de 14β. La configuración absoluta de la parte aglicona de pandaroside A (1) fue asignada por comparación entre experimental y TDDFT calcularon espectros de dicroísmo circular en la norma más estable. The chemical composition of the Caribbean sponge Pandaros acanthifolium was investigated and led to the isolation of seven new steroidal glycosides namely pandarosides A–D (1, 3, 4 and 6) along with the three methyl esters of pandarosides A, C, and D (2, 5 and 7). Their structures were characterized as 3β-[ β - glucopyranosyl-(1→2)- β -glucopyranosyloxyuronic acid]-16-hydroxy-5α,14β -poriferast-16-ene-15,23-dione (1) and its methyl ester (2), 3 β -[ β -glucopyranosyloxyuronic acid]-16-hydroxy-5α,14 β -poriferast-16-ene-15,23-dione (3), 3 β -[ β -glucopyranosyl-(1→2)- β -glucopyranosyloxyuronic acid]-16-hydroxy-5α,14 β -cholest-16-ene-15,23-dione (4) and its methyl ester (5), 3 β -( β -glucopyranosyloxyuronic acid)-16-hydroxy-5α,14 β -cholest-16-ene-15,23-dione (6) and itsmethyl ester (7) on the basis of detailed spectroscopic analyses, including 2D NMR and HRESIMS studies. Pandarosides A–D and their methyl esters (1–7) are all characterized by a rare 2 hydroxycyclopentenone D-ring with a 14β configuration. The absolute configuration of the aglycon part of pandaroside A (1) was assigned by comparison between experimental and TDDFT calculated circular dichroism spectra on the more stable conformer.