Induction of cell cycle arrest and apoptosis by the ethyl acetate fraction of Kalopanax pictus leaves in human colon cancer cells.

Kalopanax pictus is a deciduous tree used in traditional medicine; its leaves are also consumed as a vegetable. In this study, the ethyl acetate fraction of K. pictus leaves (EFK) was tested in vitro for anticancer activity against four cell lines: human colon cancer (HT-29) cells, human stomach cancer (NCI-N87) cells, human breast cancer (MDA-MB231) cells, and mouse melanoma (B16F1) cells. Results indicated that EFK showed the most potent tumor selective growth inhibitory activity against HT-29 cells with less cytotoxic effect on normal cell lines. Cytotoxicity of EFK on HT-29 cells was associated mainly with cell chromatin condensation, DNA fragmentation, and loss of membrane phospholipid asymmetry with appearance of G2/M phase arrest. Cell death induced by EFK displayed features characteristic of apoptosis, and was associated with generation of reactive oxygen species (ROS) and increase of Bax/Bcl-2 ratio. These findings suggest that K. pictus leaves have anticancer properties and may be valuable for application in pharmaceutical industry.

Kaempferol glycosides with antioxidant activity from Brassica juncea.

From the leaves of Brassica juncea, three kaempferol glycosides, kaempferol-3-O-(2-O-sinapoyl)-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside-7-O-beta-D-glucopyranoside (1), kaempferol-3-O-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside-7-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (2), and kaempferol-3-O-(2-O-sinapoyl)-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside-7-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (3) were isolated and the structures elucidated on the basis of spectral and chemical evidences. Antioxidant activities were determined by measuring the scavenging activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and peroxynitrite (ONOO(-)). Compounds 1 and 3 showed good antioxidant activities with respective IC(50) values of 28.61 and 36.93 microM toward DPPH; respective IC(50) values of 9.79 and 11.40 microM toward ONOO(-). However, compound 2 showed no DPPH scavenging activity and weak ONOO(-) scavenging activity with an IC(50) value of 32.00 microM.

A new abietic acid-type diterpene glucoside from the needles of Pinus densiflora.

From the ethyl acetate fraction of the methanol extract of the needles of Pinus densiflora (Pinaceae), a new diterpenoid glucoside [9alpha,13alpha-epoxy-8beta,14beta-dihydroxy-abietic acid-18-O-beta-D: -glucopyranoside] (1), two flavonoid glucosides [kaempferol 3-O-beta-D: -glucoside (2) and 6-C-methyl kaempferol 3-O-beta-D: -glucoside (3)], and two monoterpenoid glucosides [bornyl 6-O-alpha-Larabinofuranosyl (1-->6)-beta-D: -glucopyranoside (4) and bornyl 6-O-beta-D: -apiofuranosyl (1-->6)-beta-D: -glucopyranoside (5)] were isolated and characterized on the basis of spectral analysis. Of all the compounds, 2 and 3 showed peroxynitrite scavenging activity.

Free radical scavenging and total phenolic contents from methanolic extracts of Ulmus davidiana.

A methanolic (MeOH) extract of Ulmus davidiana was analyzed for antioxidant activity using model systems, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, hydroxyl radical (OH) scavenging, reducing power, and total phenolic content. The MeOH extract exhibited strong antioxidant activity in the tested model systems. Among fractions using several solvents, the ethyl acetate (EtOAc)-soluble fraction, which exhibited strong antioxidant activity, was further purified by silica-gel and Sephadex LH-20 column chromatography. The (-)-Catechin (1) and (-)-catechin-7-O-ß-d-apiofuranoside (2) were isolated as the active principles. Compounds 1 and 2 exhibited strong antioxidant activity on DPPH radicals, with IC50 values of 6.37±0.02µM and 6.41±0.03µM, respectively, and strong activity on OH radicals at 10µg/ml, with 53.65±0.01% and 52.56±0.01% inhibition. U. davidiana extracts may be exploited as biopreservatives in food applications as well as for health supplements of functional food, to alleviate oxidative stress.

Antidiabetic properties of 2,5-dihydroxy-4,3'-di(beta-D-glucopyranosyloxy)-trans-stilbene from mulberry (Morus bombycis koidzumi) root in streptozotocin-induced diabetic rats.

We investigated the antidiabetic properties of 2,5-dihydroxy-4,3-di(beta-D-glucopyranosyloxy)-trans-stilbene (DGTS) isolated from Morus bombycis Koidzumi in streptozotocin (STZ)-induced diabetic rats. The DGTS prevented the increase in aspartate aminotransferase, alanine aminotransferase, and blood urea nitrogen levels in serum of diabetic rats. At doses of 200-800 mg/kg, DGTS improved hyperglycemia in the rats, and the hypoglycemic effect of DGTS was comparable to that of tolbutamide. The histological observations showed that DGTS prevented atrophy of pancreatic beta-cells and vascular degenerative changes in the islets. DGTS reversed STZ-induced diabetes and had antioxidant activity in assays of FeCl(2)/ascorbic acid-induced lipid peroxidation in the rats. Levels of cytochrome P450 2E1 mRNA, as measured by reverse transcription-polymerase chain reaction, were lower in the livers of the DGTS-treated rats than those of the control group. These results suggest that DGTS might be beneficial in the treatment of type 1 diabetes.

Phenolic glycosides from the stem bark of Albizzia julibrissin.

From the stem bark of Albizzia julibrissin DURAZZ (Leguminosae), two new phenolic glycosides (albibrissinosides A and B) were isolated. Their structures were determined by spectroscopic analysis. The albibrissinoside B was found to be a radical scavenger on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical.

Isolation of flavonoids and a cerebroside from the stem bark of Albizzia julibrissin.

From the EtOAc fraction of the MeOH extract of Albizzia julibrissin (Leguminosae), a rare 5-deoxyflavone (geraldone, 1), isookanin (2), luteolin (3), an isoflavone (daidzein, 4), five prenylated flavonoids [sophoflavescenol (5), kurarinone (6), kurarinol (7), kuraridin (8) and kuraridinol (9)], a cerebroside (soya-cerebroside I, 10), and (-)-syringaresinol-4-O-beta-D-glucopyranoside (11) were isolated and characterized on the basis of spectral data. Compounds 2, 3, and 11, showed 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity.

Inhibitory activity of flavonoids from Prunus davidiana and other flavonoids on total ROS and hydroxyl radical generation.

Since reactive oxygen species (ROS) and hydroxyl radicals (*OH) play an important role in the pathogenesis of many human degenerative diseases, much attention has focused on the development of safe and effective antioxidants. Preliminary experiments have revealed that the methanol (MeOH) extract of the stem of Prunus davidiana exerts inhibitory/scavenging activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, total ROS and peroxynitrites (ONOO-). In the present study, the antioxidant activities of this MeOH extract and the organic solvent-soluble fractions, dichloromethane (CH2Cl2), ethyl acetate (EtOAc), and n-butanol (n-BuOH), and the water layer of P. davidiana stem were evaluated for the potential to inhibit *OH and total ROS generation in kidney homogenates using 2',7'-dichlorodihydrofluorescein diacetate (DCHF-DA), and for the potential to scavenge authentic ONOO-. We also evaluated the inhibitory activity of seven flavonoids isolated from P. davidiana stem, kaempferol, kaempferol 7-O-beta-D-glucoside, (+)-catechin, dihydrokaempferol, hesperetin 5-O-beta-D-glucoside, naringenin and its 7-O-beta-D-glucoside, on the total ROS, *OH and ONOO- systems. For the further elucidation of the structure-inhibitory activity relationship of flavonoids on total ROS and *OH generation, we measured the antioxidant activity of sixteen flavonoids available, including three active flavonoids isolated from P. davidiana, on the total ROS and *OH systems. We found that the inhibitory activity on total ROS generation increases in strength with more numerous hydroxyl groups on their structures. Also, the presence of an ortho-hydroxyl group, whether on the A-ring or B-ring, and a 3-hydroxyl group on the C-ring increased the inhibitory activity on both total ROS and *OH generation.

Antioxidant principles from the needles of red pine, Pinus densi fl ora.

Antioxidant activity of Pinus densiflora Sieb. et Zucc. (Pinaceae) was evaluated for potential to inhibit hydroxyl radicals, inhibit total reactive oxygen species generation in kidney homogenates using 2',7'-dichlorodihydro fluorescein diacetate (DCHF-DA) and scavenge authentic peroxynitrites. The methanolic extract of P. densiflora showed strong antioxidant activity in the tested model systems and thus fractionated with several solvents. The antioxidant activity potential of the individual fraction was in the order of ethyl acetate > n-butanol > water > dichloromethane fraction. The ethyl acetate soluble fraction exhibiting strong antioxidant activity was further puri fi ed by repeated silica gel and Sephadex LH-20 column chromatographies. An active lignan (+)-isolarisiresinol xylopyranoside, as well as two active flavonoids [kaempferol 3-O-beta-galactopyranoside and its 6"-acetyl derivative], were isolated.

Antioxidant activity from the stem bark of Albizzia julibrissin.

The antioxidant activity of the stem bark from Albizzia julibrissin was evaluated for its potential to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, to inhibit the generation of the hydroxyl radical (*OH), total reactive oxygen species (ROS) and to scavenge authentic peroxynitrites (ONOO-). The methanol extract of A. julibrissin exhibited strong antioxidant activity in the tested model systems. Therefore, it was further fractionated using several solvents. The antioxidant activity of the individual fractions were in the order of ethyl acetate (EtOAc) > n-butanol (n-BuOH) > dichloromethane (CH2Cl2) > and water (H2O). The ethyl acetate soluble fraction, which exhibited strong antioxidant activity, was further purified by repeated silicagel, Sephadex LH-20 and RP-18 gel column chromatography. Sulfuretin (1) and 3',4',7-trihydroxyflavone (2) were isolated as the active principles. Compounds 1 and 2 exhibited good activity in all tested model systems. Compound 1 exhibited five times more inhibitory activity on the total ROS than Trolox. Compound 2 showed six times stronger DPPH radical scavenging activity than L-ascorbic acid. These results show the possible antioxidant activity of the A. julibrissin crude extract and its major constituents.

A new (E)4-hydroxy-dodec-2-enedioic acid from the stem bark of Albizzia julibrissin.

A new unsaturated hydroxy acid was isolated from the stem bark extract of Albizzia julibrissin through repeated silica gel and Sephadex LH-20 column chromatography. The chemical structure of the new acid was determined as (E)-4-hydroxy-dodec-2-enedioic acid on the basis of several spectral data including 2D-NMR. The stereochemical feature of the double bond was determined to be E on the basis of the coupling pattern of related proton signals in the 1H-NMR and COSY experiments.

A new kaempferol 7-O-triglucoside from the leaves of Brassica juncea L.

From the leaves of Brassica juncea, a new rare kaempferol 7-O-triglucoside isolated and characterized as kaempferol 7-O-beta-D-glucopyranosyl-(1-->3)-[beta-D-glucopyranosyl-(1-->6)]-glucopyranoside (1) based on the spectroscopic evidences. This compound was found to be a scavenger of 1,1-diphenyl-2-picrylhydrazyl radical.

Further isolation of peroxynitrite and 1,1-diphenyl-2-picrylhydrazyl radical scavenging isorhamnetin 7-O-glucoside from the leaves of Brassica juncea L.

From the leaves of Brassica juncea, an radical scavenging isorhamnetin 7-O-glucoside on peroxynitrite and 1,1-diphenyl-2-picrylhydrazyl (DPPH) was isolated and characterized based on the spectroscopic evidence. The compound showed the peroxynitrite and DPPH scavenging activities with IC50 values of 2.07 +/- 0.17 and 13.3 microM, respectively. Penicillamine and L-ascorbic acid as positive control exhibited radical scavenging activities with IC50 values of 3.17 +/- 0.39 and 12.78 microM, respectively.

The structure-activity relationship of flavonoids as scavengers of peroxynitrite.

Peroxynitrite is a cytotoxic intermediate produced by the reaction between a superoxide anion radical and nitric oxide. The scavenging activities of flavonoids on peroxynitrite were investigated to illustrate the structure-activity relationship. Peroxynitrite was scavenged by the presence of various flavonoids, whose structures seem to be closely related to the degree of scavenging. Of 31 compounds tested, the most active was quercetin, with an IC50 value of 0.93 microM. Others had IC50 values ranging from 0.96 to more than 10 microM. The scavenging activity was postulated to be governed by the position of the hydroxyl group. Ortho-hydroxyl structures increased the scavenging activity on peroxynitrite.