Inhibitory effects of Zingiber officinale Roscoe derived components on aldose reductase activity in vitro and in vivo.

Ginger (Zingiber officinale Roscoe) continues to be used as an important cooking spice and herbal medicine around the world. Scientific research has gradually verified the antidiabetic effects of ginger. Especially gingerols, which are the major components of ginger, are known to improve diabetes including the effect of enhancement against insulin-sensitivity.

Studies on the constituents of Scutellaria species (XXII). Constituents of the roots of Scutellaria amabilis HARA.

From the roots of Scutellaria amabilis HARA, eleven new flavonoids, 5,7,2'-trihydroxy-8-methoxyflavone 7-O-beta-D-glucopyranoside, 5,7,2'-trihydroxy-8-methoxyflavone 2'-O-beta-D-glucopyranoside, 5,7-dihydroxy-8,2'-dimethoxyflavone 7-O-beta-D-glucopyranoside, 5,7,2'-trihydroxyflavone 2'-O-beta-D-glucopyranoside, 5,7,2',5'-tetrahydroxyflavone 7-O-beta-D-glucuronopyranoside, (2S)-5,7,2',5'-tetrahydroxyflavanone, (2S)-5,7,2',5'-tetrahydroxyflavanone 7-O-beta-D-glucopyranoside, (2S)-5,7,2',5'-tetrahydroxyflavanone 7-O-beta-D-glucuronopyranoside, (2S)-7,2'-dihydroxy-5-methoxyflavanone 7-O-beta-D-glucuronopyranoside, (I-2S)-I-5,II-5,I-7,II-7,I-2',II-2',II-5'-heptahydroxy-[I-6,II-6']-flavanonylflavone and (I-2S)-I-5,II-5,I-7,II-7,I-2',II-2',I-5',II-5'-octahydroxy-[I-6,II-6']-flavanonylflavone, were isolated, together with ten known flavonoids, wogonin (5,7-dihydroxy-8-methoxyflavone), 5,7-dihydroxy-8,2'-dimethoxyflavone, (2S)-5,7,2'-trihydroxyflavanone, scutevulin (5,7,2'-trihydroxy-8-methoxyflavone), 5,7,4'-trihydroxy-8-methoxyflavone, alpinetin ((2S)-7-hydroxy-5-methoxyflavanone), 5,7,2'-trihydroxyflavone, 5,7,2',5'-tetrahydroxyflavone, (2S)-7,2'-dihydroxy-5-methoxyflavanone and 5,7-dihydroxy-8,2'-dimethoxyflavone 7-O-beta-D-glucuronopyranoside. The structures were determined on the basis of chemical and spectral data.

Studies on nepalese crude drugs. XXVIII. Chemical constituents of Bhote Khair, the underground parts of Eskemukerjea megacarpum HARA.

From the underground parts of Eskemukerjea megacarpum HARA, two new stilbenes (14, 15) were isolated, together with a known coumarin, 5,7-dihydroxycoumarin (1), a tyramine derivative, trans-feruloyltyramine (2), two pyrogallol derivatives, gallic acid (3) and beta-glucogallin (4), four flavonoids, trifolin (5), hyperin (6), myricetin 3-O-beta-D-galactopyranoside (7), and myricitrin (8), five stilbenes, resveratorol (9), astringenin (10), piceid (11) astringin (12), and resveratorol 3-O-beta-D-(6-O-galloyl)glucopyranoside (13), a flavan-3-ol, (-)-epigallocatechin 3-O-gallate (16), two proanthocyanidins, catechin-(4alpha-->8)-epigallocatechin 3-O-gallate (17) and epicatechin 3-O-gallate-(4beta-->8)-epigallocatechin 3-O-gallate (18), and an anthocyanin, idaein (19). Compounds 14 and 15 were identified as (E)-3,5,3',4'-tetrahydroxystilbene 3-O-beta-D-(6-O-galloyl)glucopyranoside and (E)-3,5,4'-trihydroxystilbene 3-O-beta-D-(6-O-galloyl)glucopyranoside, respectively, based on spectral and chemical data.

Iminosugar-producing Thai medicinal plants.

Alpha-1-C-hydroxymethylfagomine (7), 3-O-beta-D-glucopyranosyl-DMDP (12), and 2,5-dideoxy-2,5-imino-D-glucitol (13) were isolated from the Thai traditional crude drug "Non tai yak" (Stemona tuberosa), which also contains a high concentration level of alpha-homonojirimycin (0.1% dry weight). "Thopthaep" (Connarus ferrugineus) and "Cha em thai" (Albizia myriophylla) contained 1-deoxymannojirimycin (DMJ) (10) at levels of 0.

Glycosidase-inhibiting pyrrolidines and pyrrolizidines with a long side chain in Scilla peruviana.

2,5-Dideoxy-2,5-imino-d-glycero-d-manno-heptitol (homoDMDP) is widely distributed in Hyacinthaceae plants and can also be regarded as the alpha-1-C-(1,2-dihydroxyethyl) derivative of 1,4-dideoxy-1,4-imino-d-arabinitol (d-AB1). In a search for glycosidase inhibitors in this family of plants, we isolated three new d-AB1 derivatives bearing the 2-hydroxypropyl (1), 1,2-dihydroxypropyl (2), and 1,5,7,12,13-pentahydroxytridecyl (3) side chains at the C-1alpha position, respectively, from the bulbs of Scilla peruviana. Alkaloid 3 was a powerful inhibitor of bacterial beta-glucosidase (IC(50) = 80 nM) and bovine liver beta-galactosidase (IC(50) = 90 nM).

New polyhydroxylated pyrrolidine, piperidine, and pyrrolizidine alkaloids from Scilla sibirica.

Chromatographic separation of an extract of the bulbs of Scilla sibirica resulted in the isolation of five pyrrolidines, two pyrrolidine glycosides, six piperidines, one piperidine glycoside, and eight pyrrolizidines. 2,5-Dideoxy-2,5-imino-glycero-d-manno-heptitol (homoDMDP, 1) is a common alkaloid in all plants of the Hyacinthaceae examined to date and was also found in S. sibirica.

Effects of catechins on vascular tone in rat thoracic aorta with endothelium.

The effects of eight catechin derivatives on vascular tone in rat thoracic aorta were examined. Catechin derivatives (10 microM) potentiated the contractile response to phenylephrine in endothelium-intact arteries. The potentiations produced by EGCg and EGC were almost absent in endothelium-denuded arteries and abolished by N(G)-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthesis.

New sugar-mimic alkaloids from the pods of Angylocalyx pynaertii.

Chromatographic separation of the pod extract of Angylocalyx pynaertii resulted in the isolation of 13 sugar-mimic alkaloids (1-13). The structures of the new alkaloids were elucidated by spectroscopic methods as the 6-O-beta-D-glucoside (10) and N-hydroxyethyl derivative (11) of 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) (1), 1,6-dideoxynojirimycin (12), and 1,3,4-trideoxynojirimycin (13). 2,5-Imino-1,2,5-trideoxy-L-glucitol (7), 2,5-dideoxy-2,5-imino-D-fucitol (8), and beta-homofuconojirimycin (9), isolated from the pods as well as the bark, were very specific inhibitors of alpha-L-fucosidase with no significant inhibitory activity toward other glycosidases.