Polyphenolic Compounds from Lespedeza Bicolor Root Bark Inhibit Progression of Human Prostate Cancer Cells via Induction of Apoptosis and Cell Cycle Arrest.

From a root bark of Lespedeza bicolor Turch we isolated two new (7 and 8) and six previously known compounds (1-6) belonging to the group of prenylated polyphenols. Their structures were elucidated using mass spectrometry, nuclear magnetic resonance and circular dichroism spectroscopy. These natural compounds selectively inhibited human drug-resistant prostate cancer in vitro. Prenylated pterocarpans 1-3 prevented the cell cycle progression of human cancer cells in S-phase. This was accompanied by a reduced expression of mRNA corresponding to several human cyclin-dependent kinases (CDKs). In contrast, compounds 4-8 induced a G1-phase cell cycle arrest without any pronounced effect on CDKs mRNA expression. Interestingly, a non-substituted hydroxy group at C-8 of ring D of the pterocarpan skeleton of compounds 1-3 seems to be important for the CDKs inhibitory activity.

Cytotoxic polyphenolic compounds from Lespedeza bicolor stem bark.

Four new pterocarpans (6aR,11aR)-6a,11a-dihydrolespedezol A2 (2), (6aR,11aR)-2-isoprenyl-6a,11a-dihydrolespedezol A2 (3), (6aR,11aR,3'R)-6a,11a-dihydrolespedezol A3 (4), (6aR,11aR,3'S)-6a,11a-dihydrolespedezol A3 (5) and one new stilbenoid with 1,2-diketone fragment named bicoloketone (6) along with one previously known pterocarpen lespedezol A2 (1) have been isolated from Lespedeza bicolor stem bark using multistage column chromatography on polyamide and silica gel. The structures of the isolated polyphenolic compounds were determined by spectroscopic methods. The absolute configurations of 4 and 5 were determined by comparison of their electronic circular dichroism (ECD) spectra obtained experimentally and the spectra calculated using time-dependent density functional theory (TDDFT). The isolated compounds exhibited a moderate DPPH scavenging effect and ferric reducing power compared to the reference antioxidant quercetin. The cytotoxicity of compounds against three human cancer cell lines, HTB-19, Kyse-30, and HEPG-2, and two normal cell lines, RPE-1 and HEK-293, was tested using the MTT assay. Compound 3 showed the strongest cytotoxic activity against all cell lines (IC50 6.0-19.1 µM) compared with the positive control cisplatin. The other tested compounds possessed moderate cytotoxic activity against cancer cells.

Polyphenolic compounds from callus cultures of Iris pseudacorus.

A callus culture of Iris pseudacorus L. (Iridaceae) was established from plant leaves using a modified Murashige and Skoog medium. A derivative of cinnamic acid (lavandoside) (1), a neolignan (dehydrodiconiferyl alcohol-4-O-beta-D-glucopyranoside) (2) as well as three isoflavonoids, tectoridin (3), tectorigenin (4), and iristectorigenin A (5) were isolated from the callus culture. Under normal conditions, the calli accumulated 0.4% DW of polyphenols. The addition of phenylalanine to a concentration of 1 mM resulted in a 1.5-fold increase in isoflavonoid production, allowing the accumulation of 0.69% of polyphenols in the callus dry weight. Tectorigenin, a promising chemotherapeutic and chemopreventive agent for the treatment of carcinomas, was produced in I. pseudacorus calli in high quantities (0.3% DW).

Enhanced resveratrol accumulation in rolB transgenic cultures of Vitis amurensis correlates with unusual changes in CDPK gene expression.

It has been established that transformation of Vitis amurensis callus culture with the plant oncogene rolB of Agrobacterium rhizogenes results in a high level of resveratrol production in the transformed culture. In the present report, we investigated two rolB transgenic V. amurensis cell cultures with different levels of rolB expression and resveratrol production. We examined whether the calcium ion flux and later steps of the calcium-mediated signal transduction pathway play a role in resveratrol biosynthesis in the rolB transgenic cultures. It has been shown that the calcium channel blockers, LaCl(3), verapamil, and niflumic acid, significantly reduced the accumulation of resveratrol in the rolB transgenic cultures. The number of the calcium-dependent protein kinase (CDPK) transcript variants and abundance of some of the transcripts were considerably altered in the rolB transgenic cell cultures, as revealed by frequency analysis of RT-PCR products and real-time PCR. Some unusual CDPK transcripts with deletions and insertions in the kinase domain were isolated from cDNA probes of rolB-transformed cells. These results suggest that active resveratrol biosynthesis in rolB transgenic cultures of V. amurensis is Ca2+ dependent. We propose that the rolB gene has an important role in regulation of calcium-dependent transduction pathways in transformed cells.

Isoflavonoid composition of a callus culture of the relict tree Maackia amurensis Rupr. et Maxim.

Isoflavonoids, an interesting and restricted group of secondary metabolites of legumes, exhibit estrogenic, antiangiogenic, and anticancer activities and are now popular as dietary supplements. Plant cell cultures that possess an increased ability to synthesize these metabolites were examined. During the investigation, cell cultures of the Far Eastern relict tree Maackia amurensis (Leguminosae) were established. A selection of seed-derived cell aggregates yielded the callus line designated A-18. This culture produces 20 isoflavonoids, namely, the isoflavones genistein, daidzein, formononetin, calycosin, derrone, and pseudobaptigenin and their glycosylated conjugates genistin, 6''-O-malonylgenistin, ononin, 6''-O-malonylononin, daidzin, 3'-methoxydaidzin, 4'-O-beta-D-glucopyranosyldaidzin, 4'-O-beta-D-glucopyranosylgenistin, and 7-O-beta-D-glucopyranosylcalycosin; the pterocarpans maackiain and medicarpin and their glycosylated conjugates 6'-O-malonyl-3-O-beta-D-glucopyranosylmaackiain and 6'-O-malonyl-3-O-beta-D-glucopyranosylmedicarpin; and the new pterocarpan glucoside 6'-O-malonyl-3-O-beta-D-glucopyranosyl-6,6a-dehydromaackiain. These isoflavonoids, possessing a hepatoprotective activity, were stably produced by the A-18 calli for prolonged periods of observation.

High rabdosiin and rosmarinic acid production in Eritrichium sericeum callus cultures and the effect of the calli on masugi-nephritis in rats.

During an investigation of plant cell cultures that might be useful in the treatment of renal disorders, we established a vigorously-growing E-4 callus culture of Eritrichium sericeum that produced large amounts of caffeic acid metabolites, (-)-rabdosiin (1.8% dry wt) and rosmarinic acid (4.6% dry wt). Elicitation of the calli by methyl jasmonate induced a 38% increase in total polyphenol production. The most efficient method of eliciting (-)-rabdosiin biosynthesis was through the treatment of E-4 calli with cuprum glycerate, which induced an increase in (-)-rabdosiin production of as much as 4.1% dry wt. Oral administration of E-4 callus biomass (100 mg/kg/d for 30 d) to rats with induced Masugi-nephritis caused an increase in diuresis and lowered creatinine excretion and proteinuria levels as compared with Masugi-nephritis untreated rats. While all of the Masugi-nephritis untreated rats began to suffer, near a quarter of the E-4 treated rats remained in good health. This result indicates that the E-4 culture has the potential to alleviate the symptoms associated with nephritis.

Caffeic acid metabolites from Eritrichium sericeum cell cultures.

Eritrichium sericeum (Boraginaceae) callus and root cultures were established and analyzed for caffeic acid metabolite (CAM) production. Two substances, (-)-rabdosiin and rosmarinic acid, were identified as main CAMs produced by these cultures. The E. sericeum Er-1 root culture accumulated up to 1.5 % and 4.5 % DW of (-)-rabdosiin and rosmarinic acid, respectively. Rabdosiin in the Lithospermum erythrorhizon callus cultures was produced exclusively as the (+)-enantiomer while in both Eritrichium cultures it occurred as the (-)-enantiomer. The E. sericeum Er-1 culture accumulated 3-fold higher levels of CAMs than the L. erythrorhizon culture. A new compound, named eritrichin, was isolated from the cultured E. sericeum cells. The structure of this compound was established as (2R)-3-(3,4-dihydroxyphenyl)-2-[4-(3,4-dihydroxyphenyl)-6,7-dihydroxy-2-naphthoyloxy]propanoic acid on the basis of spectral data.