Iridoids ofVerbascum georgicum

Gmelinosides A−L, Twelve Acylated Iridoid Glycosides from Gmelina arborea

“…A combination of polyamide and Si gel column chromatography followed by further purification using reversed-phase chromatography and Sephadex LH 20 column chromatography led to the isolation of several new acylated gmelinosides glycosides A-L (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) in addition to several known iridoid and phenylpropanoid glycosides. These known compounds were identified by direct comparison with authentic samples and by spectroscopic analysis (UV, IR, 1 H and 13 C NMR, and FABMS) as 6-O-R-L-rhamnopyranosylcatalpol (1), 12 6-O-(3′′-O-trans-feruloyl)-R-L-rhamnopyranosylcatalpol (14), 15 6-O-(2′′-O-acetyl-3′′, 4′′-O-di-trans-cinnamoyl)-R-L-rhamnopyranosylcatalpol (15), 8 verbascoside, 35 and martynoside, 36 respectively.…”

“…These known compounds were identified by direct comparison with authentic samples and by spectroscopic analysis (UV, IR, 1 H and 13 C NMR, and FABMS) as 6-O-R-L-rhamnopyranosylcatalpol (1), 12 6-O-(3′′-O-trans-feruloyl)-R-L-rhamnopyranosylcatalpol (14), 15 6-O-(2′′-O-acetyl-3′′, 4′′-O-di-trans-cinnamoyl)-R-L-rhamnopyranosylcatalpol (15), 8 verbascoside, 35 and martynoside, 36 respectively. All 13 C NMR multiplicities of gmelinosides A-L (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) were confirmed by DEPT measurements, and signal connectivities were determined by HMBC and HMQC. The new iridoid constituents (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) of G. arborea contained the same iridoid enol-ether system of 6-O-R-L-rhamnopyranosylcatalpol, and were esterified with cinnamoyl or benzoyl derivatives attached to different hydroxyl groups on the sugars or the aglycon moieties.…”

“…In general, carbons bearing esterifed hydroxyl groups were readily identified by HMBC-connectivity analysis and by the usual downfield shift of the carbon bearing the ester groups relative to the nonesterified equivalent. The 12 new iridoids (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) were identified as follows.…”

“…4′),3.18 (1H, m, H-5′),3.54 (1H, dd, J ) 12.0, 5 8. Hz, H-6′A), 3.95 (1H, dd, J ) 12.0, 1.8 Hz,; rhamnosyl moiety δ 5.11 (1H, d, J ) 1.8 Hz,,3.94 (1H, brd, J ) 3 8.…”

“…Our present research on the leaves of G.arborea has resulted in the isolation of several new monoacylated, diacylated, and triacylated iridoid glycosides. We wish to report herein the isolation and structure elucidation of 12 new acylated iridoid glycosides (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) isolated from the leaves of G. arborea, in addition to three known iridoid glycosides (1,14,15) and two known phenylpropanoid glycosides.…”