Phenylethanoid and flavone glycosides from Ruellia tuberosa L.

A new phenylethanoid glycoside, isocassifolioside (8), and two new flavone glycosides, hispidulin 7-O-α-L-rhamnopyranosyl-(1'″ → 2″)-O-ß-D-glucuronopyranoside (11) and pectolinaringenin 7-O-α-L-rhamnopyranosyl-(1'″ → 2″)-O-ß-D-glucuronopyranoside (12) were isolated from the aerial portions of Ruellia tuberosa L., together with verbascoside (1), isoverbascoside (2), nuomioside (3), isonuomioside (4), forsythoside B (5), paucifloside (6), cassifolioside (7), hispidulin 7-O-ß-D-glucuronopyranoside (9) and comanthoside B (10). The structure elucidations were based on analyses of chemical and spectroscopic data including 1D- and 2D-NMR. The isolated compounds 1-12 exhibited radical scavenging activity using ORAC assay.

Unprecedented furan-2-carbonyl C-glycosides and phenolic diglycosides from Scleropyrum pentandrum.

Five unprecedented furan-2-carbonyl C-glycosides, scleropentasides A-E, and two phenolic diglycosides, 4-hydroxy-3-methoxybenzyl 4-O-ß-D-xylopyranosyl-(1→6)-ß-D-glucopyranoside and 2,6-dimethoxy-p-hydroquinone 1-O-ß-D-xylopyranosyl-(1→6)-ß-d-glucopyranoside, were isolated from leaves and twigs of Scleropyrum pentandrum together with potalioside B, luteolin 6-C-ß-D-glucopyranoside (isoorientin), apigenin 8-C-ß-D-glucopyranoside (vitexin), apigenin 6,8-di-C-ß-D-glucopyranoside (vicenin-2), apigenin 6-C-α-L-arabinopyranosyl-8-C-ß-D-glucopyranoside (isoschaftoside), apigenin 6-C-ß-D-glucopyranosyl-8-C-ß-D-xylopyranoside, adenosine and l-tryptophan. Structure elucidations of these compounds were based on analyses of chemical and spectroscopic data, including 1D and 2D NMR. In addition, the isolated compounds were evaluated for their radical scavenging activities using both DPPH and ORAC assays.

3-Hydroxydihydrobenzofuran glucosides from Gnaphalium polycaulon.

A new 3-hydroxydihydrobenzofuran glucoside, gnaphaliol 9-O-ß-D-glucopyranoside (2), was isolated from the aerial parts of Gnaphalium polycaulon together with 1-{(2R*,3S*-3-(ß-D-glucopyranosyloxy)-2,3-dihydro-2-[1-(hydroxyl methyl)vinyl]-1-benzofuran-5-yl}-ethanone or gnaphaliol 3-O-ß-D-glucopyranoside (1), (Z)-3-hexenyl O-ß-D-glucopyranoside (3) and adenosine (4). The absolute configurations at C-2 and C-3 positions of compound 1 were determined to be 2R and 3R. The structures of these compounds were elucidated on the basis of their physical and spectroscopic data.

Unusual glycosides of pyrrole alkaloid and 4'-hydroxyphenylethanamide from leaves of Moringa oleifera.

Glycosides of pyrrole alkaloid (pyrrolemarumine 4″-O-α-L-rhamnopyranoside) and 4'-hydroxyphenylethanamide (marumosides A and B) were isolated from leaves of Moringa oleifera along with eight known compounds; niazirin, methyl 4-(α-L-rhamnopyranosyloxy)benzylcarbamate, benzyl ß-D-glucopyranoside, benzyl ß-D-xylopyranosyl-(1→6)-ß-D-glucopyranoside, kaempferol 3-O-ß-D-glucopyranoside, quercetin 3-O-ß-D-glucopyranoside, adenosine and L-tryptophan. Structure elucidations were based on analyses of chemical and spectroscopic data including 1D- and 2D-NMR.

An efficient method for the selective synthesis of 2-deoxy-2-iodo-glycosides by O-glycosidation of D-glucal using I2-Cu(OAc)2.

An efficient and convenient method for the synthesis of 2-deoxy-2-iodo-O-glycosides from tri-O-acetyl-D-glucal with various alcohols by using I2-Cu(OAc)2 is described. The 21 examples of corresponding glycosides were obtained in high yields, with good anomeric selectivity.

L-(-)-(N-trans-cinnamoyl)-arginine, an acylamino acid from Glinus oppositifolius (L.) Aug. DC.

An amino acid derivative, L-(-)-(N-trans-cinnamoyl)-arginine, was isolated from the whole plant of Glinus oppositifolius (L.) Aug. DC. along with kaempferol 3-O-galactopyranoside, isorhamnetin 3-O-beta-D-xylopyranosyl-(1-->2)-beta-D-galactopyranoside, vitexin, vicenin-2, adenosine and L-phenylalanine. The structure determinations were based on analyses of chemical and spectroscopic methods.

Total synthesis of natural and unnatural lamellarins with saturated and unsaturated D-rings.

Twenty-eight natural and unnatural lamellarins with either a saturated or an unsaturated D-ring were synthesized according to our developed synthetic route. The key step involved the Michael addition/ring closure (Mi-RC) of the benzyldihydroisoquinoline and alpha-nitrocinnamate derivatives, which provided the 2-carboethoxypyrrole intermediates in moderate to good yields (up to 78% yield). Subsequent hydrogenolysis/lactonization furnished lamellarins with a saturated D-ring in excellent yields (up to 93% yield). DDQ oxidation of the saturated lamellarin acetates led directly to the corresponding unsaturated analogues in 54-95% yield. In addition, only two steps in our developed strategy require column chromatography.