Antioxidant activities of new flavonoids from <Emphasis Type="Italic">Cudrania tricuspidata</Emphasis> root bark

Two new flavonoids, hydroxybenzyl flavonoid glycosides (6-p-hydroxybenzyl kaempferol-7-O-β-D-glucopyranoside named cudranian 1 and 6-p-hydroxybenzyl quercetin-7-O-β-D-glucopyranoside named cudranian 2), and 3 known flavonoids (kaempferol-7-O-β-D-glucopyranoside, quercetin-7-O-β-D-glucopyranoside and aromadendrin) were isolated from root bark of Cudrania tricuspidata and their structures were elucidated by spectroscopic methods. These compounds showed remarkable radical scavenging effects against 1, 1-diphenyl-2-picrylhydrazyl (DPPH) and anti-lipid peroxidation efficacy on human low-density lipoprotein by TBARS assay.     

Antioxidant flavone glycosides from the leaves of<Emphasis Type="Italic">Sasa borealis</Emphasis>

Sasa borealis (Poaceae) is a perennial medicinal plant which is a major source of bamboo leaves in Korea. Then-BuOH extract ofS. borealis leaves exhibited significant antioxidant activity against the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and a cytoprotective effect against oxidative damage in HepG2 cells. Bioactivity-guided fractionation by column chromatography led to the isolation of two antioxidative flavonoid C-glycoside derivatives, isoorientin (2) and isoorientin 2”-O-α-i_-rhamnoside (4) along with tricin 7-0-β-D-glucopyranoside (1) and apigenin 6-C-β-D-xylopyranosyl-8-C-β-D-glucopyranoside (3). Their structures were identified on the basis of chemical and spectroscopic methods. The radical scavenging activity and cytoprotective effect against oxidative damage of all the isolated compounds were also evaluated. Isoorientin (2) and isoorientin 2-O-α-L-rhamnoside (4) showed potent free radical scavenging activity with 1C₅₀ values of 9.5 and 34.5 μM, respectively, and strong cytoprotective effects againstt-BOOH-induced oxidative damage in HepG2 cells, at very low concentrations of 1.1 μM isoorientin and 0.8 μM isoorientin 2-O-α-L-rhamnoside. This is the first report of the isolation and antioxidant activity of compounds 2 and 4 from S.borealis.     

Antioxidant activity from the stem bark of<Emphasis Type="Italic">Albizzia julibrissin</Emphasis>

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.     

Antioxidant principles of<Emphasis Type="Italic">Nelumbo nucifera</Emphasis> stamens

In our ongoing study to identity antioxidants from natural sources, the antioxidant activity of Nelumbo nucifera stamens was evaluated for their potential to scavenge stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, inhibit total reactive oxygen species (ROS) generation, in kidney homogenatas using 2',7'-dichlorodihydrofluorescein diacetate (DCHF-DA), and scavenge authentic peroxynitrites (ONOO-). A methanol (MeOH) extract of the stamens of N. nucifera showed strong antioxidant activity in the ONOO- system, and marginal activity in the DPPH and total ROS systems, so were therefore fractionated with several organic solvents, such as dichloromethane (CH2Cl2), ethyl acetate (EtOAc) and n-butanol (n-BuOH). The EtOAc soluble fraction, which exhibited strong antioxidant activity in all the model systems tested, was further purified by repeated silica gel and Sephadex LH-20 column chromatographies. Seven known flavonoids [kaempferol (1), kaempferol 3-O-beta-D-glucuronopyranosyl methylester (2), kaempferol 3-O-beta-D-glucopyranoside (3), kaempferol 3-O-beta-D-galactopyranoside (4), myricetin 3',5'-dimethylether 3-O-beta-D-glucopyranoside (5), kaempferol 3-O-alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (6) and kaempferol 3-O-beta-D-glucuronopyranoside (7)], along with beta-sitosterol glucopyranoside (8), were isolated. Compound 1 possessed good activities in all the model systems tested. Compounds 2 and 7 showed scavenging activities in the DPPH and ONOO- tests, while compounds 3 and 4 were only active in the ONOO- test. Conversely, compound 8 showed no activities in any of the model systems tested.     

Inhibitory effect of<Emphasis Type="Italic">Trans-N-p</Emphasis>-coumaroyl tryamine from the twigs of<Emphasis Type="Italic">Celtis chinensis</Emphasis> on the acetylcholinesterase

The methanolic extract of the twigs of Celtis chinensis was found to show inhibitory activity on acetylcholinesterase (AChE), an enzyme that plays a role in the metabolic hydrolysis of ACh. Bioassay-guided fractionation of the methanolic extract resulted in the isolation of N-p-coumaroyl tyramine, as an inhibitor on AChE. This compound inhibited AChE activity in a dose-dependent manner, and the IC50 value of trans-N-p-coumaroyl tyramine was 34.5 microg/mL (122 microM).     

A new kaempferol 7-<Emphasis Type="Italic">O</Emphasis>-triglucoside from the leaves of<Emphasis Type="Italic">Brassica juncea</Emphasis> 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.     

A new <Emphasis Type="Italic">Erythrina</Emphasis> alkaloid from <Emphasis Type="Italic">Erythrina herbacea</Emphasis>

A new Erythrina alkaloid, 10-hydroxy-11-oxoerysotrine (1), has been isolated from the flowers of Erythrina herbacea together with five known compounds: erytharbine (2), 10,11-dioxoerysotrine (3), erythrartine (4), erysotramidine (5) and erysotrine-N-oxide (6). The structure of the new compound was elucidated on the basis of its spectral data, including 2-D NMR and mass (MS) spectra. The new compound is a rare C-10 oxygenated Erythrina alkaloid. The antioxidant activities of the isolated compounds 1–6 were evaluated by scavenging with peroxynitrite.     

Hypocholesterolemic property of<Emphasis Type="Italic">Yucca schidigera</Emphasis> and<Emphasis Type="Italic">Quillaja saponaria</Emphasis> extracts in human body

This study was undertaken to observe the effects of the blend of partially purified Yucca schidigera and Quillaja saponaria extracts on cholesterol levels in the human's blood and gastrointestinal functions, and to determine if a new cholesterol-lowering drug can be developed by the further purification of the extracts. Ultrafiltration and sequential diafiltration increased the amounts of steroidal saponin in aqueous yucca extract and terpenoid saponin in aqueous quillaja extract from 9.3% and 21.4% to 17.2% and 61.8%, respectively. Taking 0.9 mg of the blend (6:4, v:v) of the resulting filtrates a day for 4 weeks resulted in the decreases in total and LDL cholesterol levels in blood plasma of hyper-cholesterolemic patients with enhancement in gastrointestinal symptoms of patients.     

<Emphasis Type="Italic">In Vitro</Emphasis> antioxidant and anti-inflammatory activities of Jaceosidin from <Emphasis Type="Italic">Artemisia princeps</Emphasis> Pampanini <Emphasis Type="Italic">cv.</Emphasis> Sajabal

Oxidized low-density lipoprotein (oxLDL) plays a key role in the inflammatory processes of atherosclerosis. Jaceosidin isolated from the methanolic extracts of the aerial parts of Artemisia princeps Pampanini cv. Sajabal was tested for antioxidant and anti-inflammatory activities. Jaceosidin inhibited the Cu²⁺-mediated LDL oxidation with IC₅₀ values of 10.2 μM in the thiobarbituric acid-reactive substances (TBARS) assay as well as the macrophage-mediated LDL oxidation. The antioxidant activities of jaceosidin were exhibited in the conjugated diene production, relative electrophoretic mobility, and apoB-100 fragmentation on copper-mediated LDL oxidation. Jaceosidin also inhibited the generation of reactive oxygen species (ROS) concerning in regulation of NF-κB signaling. And jaceosidin inhibited nuclear factor-kappa B (NF-κB) activity, nitric oxide (NO) production, and suppressed expression of inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-induced RAW264.7 macrophages.     

Antioxidant phenolic compounds from rhizomes of<Emphasis Type="Italic">Curculigo crassifolia</Emphasis>

A pair of new phenolic glycosides, crassifoside G (5) and isocrassifoside G (6), along with five known phenolic compounds (1-4 and 7), were isolated from the ethanolic extract of the rhizomes of Curculigo crassifolia. Their structures were established by spectroscopic techniques and chemical methods. Most of the isolated compounds exhibited strong antioxidant activity in the 1, 1-diphenyl-2-picryldydrazyl (DPPH) radical scavenging assay.     

Hypocholesterolemic activity of<Emphasis Type="Italic">Bifidobacteria</Emphasis> isolated from a healthy korean

This study was undertaken to investigate the hypocholesterolemic activity of Bifidobacteria (B. breve K-110, B. breve K-111, and B. infantis K-525) isolated from a healthy Korean. The administration of B. breve K-110 and K-111 with a high cholesterol diet significantly protected the increase of serum total cholesterol and LDL cholesterol relative to that of a high cholesterol diet alone. Such a diet supplemented with 0.5% B. breve K-111 decreased serum total cholesterol and LDL cholesterol to 57 and 55%, respectively. The administration of Bifidobacteria also significantly inhibited the lipid-deposited surface in the aorta. The normalizing activity of serum cholesterol level in cholesterolemic rats was accelerated by Bifidobacteria. The normalizing activity of B. breve K-111 on serum cholesterol level was superior to that of B. breve K-110. These results suggest that Bifidobacteria in the human intestine play a role in the prophylactics of arteriosclerosis.     

A new prenylated dihydrochalcone from the leaves of <Emphasis Type="Italic">Artocarpus lowii</Emphasis>

A new prenylated dihydrochalcone, 2′,4′-dihydroxy-4-methoxy-3′-prenyldihydrochalcone (1), along with two known compounds, 2′,4′,4-trihydroxy-3′-prenylchalcone (2) and 2′,4-dihydroxy-3′,4′-(2,2-dimethylchromene)chalcone (3) were isolated from the leaves of Artocarpus lowii. The structures of 1–3 were elucidated by spectroscopic methods and by comparison with data reported in the literature. Compounds 1–3 showed strong free radical scavenging activity towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) measured by electron spin resonance (ESR) spectrometry.     

Antioxidant constituents and a new triterpenoid glycoside from<Emphasis Type="Italic">Flos Lonicerae</Emphasis>

As a component of our continuing investigations into herb-derived antioxidant agents, we have evaluated the antioxidant effects of Flos Lonicerae (Lonicera japonica flowers), via 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, total reactive oxygen species (ROS), hydroxyl radical (*OH), and peroxynitrite (ONOO-) assays. Among the methanolic extract and the dichloromethane, ethyl acetate, n-butanol, and water fractions, the EtOAc fraction of Flos Lonicerae exhibited marked scavenging/inhibitory activities, as follows: IC50 values of 4.37, 27.58 +/- 0.71, 0.47 +/- 0.05, and 12.13 +/- 0.79 microg/mL in the DPPH, total ROS, ONOO-, and *OH assays, respectively. Via a bioactivity-guided fractionation approach, a new triterpenoid glycoside, oleanolic acid 28-O-alpha-L-rhamnopyranosyl-(1-->2)-[beta-D-xylopyranosyl(1-->6)]-beta-D-glucopyranosyl ester (12), along with eleven known compounds, including chrysoeriol (1), luteolin (2), 5-hydroxymethyl-2-furfural (3), caffeic acid (4), protocatechuic acid (5), chrysoeriol 7-O-beta-D-glucopyranoside (6), isorhamnetin 3-O-beta-D-glucopyranoside (7), kaempferol 3-O-beta-D-glucopyranoside (8), quercetin 3-O-beta-D-glucopyranoside (9), hederagenin 3-O-alpha-L-arabinopyranoside (10), and luteolin 7-O-beta-D-glucopyranoside (11), were isolated from the EtOAc fraction. The structures of isolated compounds 1-12 were elucidated via spectroscopic analyses. Compound 12 was isolated from a natural source for the first time. Compounds 2, 4, 5, 7, 9, and 11 evidenced marked scavenging activities, with IC50 values of 2.08-11.76 microM for DPPH radicals, and 1.47-6.98 microM for ONOO-.     

Anti-Inflammation activity of<Emphasis Type="Italic">Actinidia polygama</Emphasis>

The fruit of Actinidia polygama (AP) has long been used as a folk medicine in Korea for treating pain, rheumatic arthritis and inflammation. The present investigation was carried out to determine the in vivo and in vitro anti-inflammatory activity of AP using several animal models of inflammation. The 70% ethanol extract of the fruit of AP significantly inhibited acetic acid-induced, vascular permeability in a dose dependent manner (23%, 38%, and 41% inhibition at doses of 200 mg/kg, 500 mg/kg and 1000 mg/kg, respectively). This effect was maintained in AP water-soluble fraction (APW). The APW fraction also showed significant inhibitory activity against the rat paw edema induced by a single treatment of carrageenan. In vitro experiments were performed to demonstrate the inhibitory activities of APW (100 microg/ml) on lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production. The results showed that APW dose-dependently suppressed LPS-induced NO production in RAW 264.7 macrophages without a notable cytotoxic effect and also decreased inducible NO synthase (iNOS) protein expression. APW also showed a significant inhibitory effect in LPS-induced PGE2 production and cyclooxygenase-2 (COX-2) expression.     

A benzenoid from the stem of<Emphasis Type="Italic">Acanthopanax senticosus</Emphasis>

Seven compounds were isolated from the stem of Acanthopanax senticosus by repeated column chromatography. Their structures were elucidated as isovanillin (1), (-)-sesamin (2), isofraxidin (3), (+)-syringaresinol (4), 5-hydroxymethylfurfural (5), eleutheroside B (6), and eleutheroside E (7) by spectral analysis. Among them, isovanillin (1) was isolated for the first time from the family Araliaceae.     

Platelet anti-aggregatory effects of coumarins from the roots of<Emphasis Type="Italic">Angelica genuflexa</Emphasis> and<Emphasis Type="Italic">A. gigas</Emphasis>

Five coumarins, isoimperatorin (1), pabulenol (2), isooxypeucedanin (3), oxypeucedanin hydrate (4) and osthol (5) were isolated from the MeOH extract of Angelica genuflexa in the course of searching for anti-platelet and anti-coagulant components from plants. Pabulenol (2) was isolated from A. genuflexa for the first time. The five compounds isolated from A. genuflexa, together with decursinol angelate (6), decursin (7) and nodakenin (8) from A. gigas were evaluated for their effects on platelet aggregation and blood coagulation. Compounds 2, 5, 6 and 7 were observed to be either equally effective or 2-4 times more inhibitory than ASA in both arachidonic acid and U46619 (TXA2 mimetic) induced platelet aggregations.     

<Emphasis Type="Italic">In Vitro</Emphasis> hepatoprotective compounds from <Emphasis Type="Italic">Suaeda glauca</Emphasis>

Bioassay-guided fractionation of the MeOH extract of Suaeda glauca yielded four phenolic compounds, methyl 3,5-di-O-caffeoyl quinate (1) and 3,5-di-O-caffeoyl quinic acid (2), isorhamnetin 3-O-beta-D-galactoside (3), and quercetin 3-O-beta-D-galactoside (4). Compounds 1 and 2 were hepatoprotective against tacrine-induced cytotoxicity in human liver-derived Hep G2 cells with the EC(50) values of 72.7+/-6.2 and 117.2+/-10.5 microM, respectively. Silybin as a positive control showed an EC(50) value of 82.4+/-4.1 microM.     

Antioxidant and antiatherogenic activity of<Emphasis Type="Italic">cis</Emphasis>-hinokiresinol from<Emphasis Type="Italic">Trapa pseudoincisa</Emphasis>

cis-Hinokiresinol, also known as (+)-nyasol, was isolated for the first time from an aquatic herbaceous plant, Trapa pseudoincisa NAKAI, via silica gel and octadecyl silica gel column chromatographies. The chemical structure was determined via analyses of the spectroscopic data, including NMR, MS and IR. cis-Hinokiresinol was also found to exhibit antioxidant and antiatherogenic activities. The ICso values for the scavenging activities of cis-hinokiresinol on ABTS cation and superoxide anion radicals were 45.6 and 40.5 microM, respectively. The IC50 values for the inhibitory effects on Lp-PLA2, hACAT1, hACAT2 and LDL-oxidation were 284.7, 280.6, 398.9 and 5.6 microM, respectively.     

Two new phenolic constituents of<Emphasis Type="Italic">Humulus japonicus</Emphasis> and their cytotoxicity test<Emphasis Type="Italic">In Vitro</Emphasis>

Two new phenolic constituents (4 and 6), together with four known constituents, methyl ferulate (1), eugenyl-beta-D-glucopyranoside (2), apigenin-7-O-beta-D-glucopyranoside (3), and (E)-resveratrol-3-O-beta-D-glucopyranoside (5) were isolated from the MeOH extract of the aerial part sof Humulus japonicus. The structures of the new compounds were determined by spectroscopic methods to be divarin-3-O-beta-glucopyranoside (4), and lariciresinol-9-O-beta-xylopyranoside (6). Compounds 1 and 3 exhibited moderate cytotoxicity against two human cancer cell lines (SK-OV-3 and HCT15) with ED50 values ranging from 8.84 to 8.79 microM.     

Acetylcholinesterase inhibitors from the aerial parts of<Emphasis Type="Italic">Corydalis speciosa</Emphasis>

In a bioassay-guided search for acetylcholinesterase inhibitors from Korean natural resources, four isoquinoline alkaloids, corynoxidine (1), protopine (2), palmatine (3), and berberine (4) have been isolated from the methanolic extract of the aerial parts of Corydalis speciosa. Structures of these compounds were elucidated on the basis of spectroscopic techniques. These compounds inhibited acetylcholinesterase activity in a dose-dependent manner, and the IC50 values of compounds 1-4 were 89.0, 16.1, 5.8, and 3.3 microM, respectively.