Glycosylation of Stilbene Compounds by Cultured Plant Cells.

Oxyresveratrol and gnetol are naturally occurring stilbene compounds, which have diverse pharmacological activities. The water-insolubility of these compounds limits their further pharmacological exploitation. The glycosylation of bioactive compounds can enhance their water-solubility, physicochemical stability, intestinal absorption, and biological half-life, and improve their bio- and pharmacological properties. Plant cell cultures are ideal systems for propagating rare plants and for studying the biosynthesis of secondary metabolites. Furthermore, the biotransformation of various organic compounds has been investigated as a target in the biotechnological application of plant cell culture systems. Cultured plant cells can glycosylate not only endogenous metabolic intermediates but also xenobiotics. In plants, glycosylation reaction acts for decreasing the toxicity of xenobiotics. There have been a few studies of glycosylation of exogenously administrated stilbene compounds at their 3- and 4'-positions by cultured plant cells of Ipomoea batatas and Strophanthus gratus so far. However, little attention has been paid to the glycosylation of 2'-hydroxy group of stilbene compounds by cultured plant cells. In this work, it is described that oxyresveratrol (3,5,2',4'-tetrahydroxystilbene) was transformed to 3-, 2'-, and 4'-ß-glucosides of oxyresveratrol by biotransformation with cultured Phytolacca americana cells. On the other hand, gnetol (3,5,2',6'-tetrahydroxystilbene) was converted into 2'-ß-glucoside of gnetol by cultured P. americana cells. Oxyresveratrol 2'-ß-glucoside and gnetol 2'-ß-glucoside are two new compounds. This paper reports, for the first time, the glycosylation of stilbene compounds at their 2'-position by cultured plant cells.

Synthesis of Ester-linked Docetaxel-glycoside Conjugate and Its Application to Drug Delivery System using Immunoliposome Targeted with Trastuzumab.

Chemo-enzymatic synthesis of the ester-linked monosaccharide conjugate of docetaxel, 7-glycolyldocetaxel 2"-O-ß-D-galactopyranoside, was achieved by using lactase as a biocatalyst. The water-solubility and, EE and LE values for the liposome of 7-glycolyldocetaxel 2"-O-ß-D-galactopyranoside were much higher than those of docetaxel. The immunoliposome containing 7-glycolyldocetaxel 2"-O-ß-D-galactopyranoside showed effective suppression of tumor growth.

Optical Resolution of (RS)-Denopamine to (R)-Denopamine P-D- Glucoside by Glucosyltransferase from Phytolacca americana Expressed in Recombinant Escherichia coli.

The optical resolution of racemic compounds by stereoselective glucosylation was investigated using plant glucosyltransferase from Phytolacca americana expressed in recombinant Escherichia coli. The glucosyltransferase glucosylated chemoselectively the phenolic hydroxyl group of phenol compounds. The (R)-stereoselective glucosylation of (RS)-denopamine by glucosyltransferase occurred to give (R)-denopamine ß-D-glucoside.

Synthesis and pharmacological evaluation of glycosides of resveratrol, pterostilbene, and piceatannol.

To enhance their water solubility and pharmacological activities, the stilbenes resveratrol, pterostilbene, and piceatannol were glycosylated to their monoglucosides (ß-glucosides) and diglycosides (ß-maltosides) by cultured cells and cyclodextrin glucanotransferase (CGTase). Cultured cells of Phytolacca americana and glucosyltransferase (PaGT) were capable of glucosylation of resveratrol to its 3- and 4'-ß-glucosides. Pterostilbene was slightly transformed into its 4'-ß-glucoside by P. americana cells. Piceatannol was readily converted into piceatannol 4'-ß-glucoside, with the highest yield among the three substrates. The 3- and 4'-ß-glucosides of resveratrol were subjected to further glycosylation by CGTase to give 3- and 4'-ß-maltoside derivatives. The inhibitory action of resveratrol and pterostilbene toward histamine release induced with compound 48/80 from rat peritoneal mast cells was improved by ß-glucosylation and/or ß-maltosylation (i.e., the inhibitory activity for histamine release of the 3- and 4'-ß-glucosides of resveratrol, the 3- and 4'-ß-maltosides of resveratrol, and the 4'-ß-glucoside of pterostilbene was higher than that of the corresponding aglycones, resveratrol and pterostilbene, respectively). In addition, the phosphodiesterase (PDE) inhibitory activity of resveratrol and pterostilbene was enhanced by ß-glucosylation and/or ß-maltosylation (i.e., the PDE inhibitory activities of the 3- and 4'-ß-glucosides of resveratrol, the 4'-ß-maltoside of resveratrol, and the 4'-ß-glucoside of pterostilbene were higher than those of the corresponding aglycones, resveratrol and pterostilbene, respectively).

Synthesis of Resveratrol Glycosides by Plant Glucosyltransferase and Cyclodextrin Glucanotransferase and Their Neuroprotective Activity.

Resveratrol was converted by glucosyltransferase from Phytolacca americana into its 3- and 4'-O-ß-D-glucosides. On the other hand, further glycosylation of resveratrol 4'-O-ß-D-glucoside by cyclodextrin glucanotransferase gave the 4'-O-ß-maltoside, 4'-O-ß-maltotrioside, 4'-O-ß-maltotetraoside, and 4'-O-ß- maltopentaoside of resveratrol. The six resveratrol glycosides synthesized here showed higher phosphodiesterase inhibitory activity than resveratrol.

Synthesis of ε-Viniferin Glycosides by Glucosyltransferase from Phytolacca americana and their Inhibitory Activity on Histamine Release from Rat Peritoneal Mast Cells.

Glycosylation of (+)-ε-viniferin was investigated using glucosyltransferase from Phytolacca americana (PaGT3) as a biocatalyst. (+)-ε-Viniferin was converted by PaGT3 into its 4b- and 13b-ß-D-glucosides, the inhibitory activities on histamine release from rat peritoneal mast cells of which were higher than that of (+)-ε-viniferin.

Glycosylation of quercetin with cultured plant cells and cyclodextrin glucanotransferase.

Quercetin was glucosylated by cultured plant cells of lpomoea batatas to its 3- and 7-O-beta-D-glucosides, and 3,7-O-beta-D-diglucoside. On the other hand, further glycosylation of quercetin 3-O-beta-D-glucoside by cyclodextrin glucanotransferase gave the 3-O-beta-maltoside, 3-O-beta-maltotrioside, and 3-O-[beta-maltotetraosides of quercetin.

Regioselective hydroxylation and glucosylation of alpha- and beta-pinenes with cultured cells of Eucalyptus perriniana.

Cultured plant cells of Eucalyptus perriniana regioselectively hydroxylated (+)- and (-)-alpha-pinenes to the corresponding (+)- and (-)-verbenols. In addition, (+)- and (-)-verbenols were converted into mono-beta-D-glucosides. On the other hand, (+)- and (-)-beta-pinenes were transformed into (+)- and (-)-pinocarveol 3-O-beta-D-glucosides via (+)- and (-)-pinocarveols.

Glucosylation of taxifolin with cultured plant cells.

Cultured plant cells of Eucalyptus perriniana glucosylated taxifolin to its 3'- and 7-O-beta-D-glucosides and 3',7-O-beta-D-diglucoside. On the other hand, taxifolin was converted into 3'- and 7-O-beta-D-glucosides by cultured cells of Nicotiana tabacum and Catharanthus roseus.

Regioselective hydroxylation and glucosylation of flavanones with cultured plant cells of Eucalyptus perriniana.

Cultured plant cells of Eucalyptus perriniana catalyzed reduction, regioselective hydroxylation, and regioselective glycosylation of flavanones. (2S)-Flavanone was converted into (2S)-flavan-4-ol, (2S)-flavan-4,7-diol, (2S)-flavan-7-ol, (2S)-flavan-7-yl glucoside, and (2S)-flavan-7-yl gentiobioside. The cells glucosylated (2S)-flavan-6-ol to (2S)-flavan-6-yl glucoside. (2S)-Flavan-2'-ol was transformed to (2S)-flavan-2',4-diol, (2S)-flavan-2',7-diol, (2S)-flavan-2'-yl glucoside. In addition, (2S)-flavan-4'-ol was transformed to (2S)-flavan-4,4'-diol, (2S)-flavan-4',7-diol, (2S)-flavan-4'-yl glucoside.

Synthesis of resveratrol glycosides by cultured plant cells.

Incubation of cultured cells of Glycine max with trans-resveratrol gave its 3-O-beta-D- and 4'-O-beta-D-glucosides. Cultured Gossypium hirsutum cells glycosylated trans-resveratrol to its 3-O-beta-D-, 4'-O-beta-D-, and 3,4'-O-beta-D-diglucosides. On the other hand, trans-resveratrol was converted into cis-resveratrol 4'-O-beta-D-glucoside, together with trans-resveratrol 3-O-beta-D-glucoside and trans-resveratrol 4'-O-beta-D-glucoside, by Eucalyptus perriniana.

Formation of tetrahydrocurcumin by reduction of curcumin with cultured plant cells of Marchantia polymorpha.

Cultured plant cells of Marchantia polymorpha, Nicotiana tabacum, Phytolacca americana, Catharanthus roseus, and Gossypium hirsutum were examined for their ability to reduce curcumin. Only M. polymorpha cells converted curcumin into tetrahydrocurcumin in 90% yield in one day. Time-course experiment revealed a two-step formation of tetrahydrocurcumin via dihydrocurcumin.