Norlignan derivatives from <Emphasis Type="Italic">Curculigo crassifolia</Emphasis> and their DPPH radical scavenging activity

A novel norlignan derivative, crassifogenin C (1), and a known compound, curcapital (2), were isolated from the ethanolic extract of the rhizomes of Curculigo crassifolia. Their structures were elucidated on the basis of spectroscopic evidence and comparisons with literature data. Curcapital (2) was isolated from this plant for the first time. The free radical scavenging activity of the isolated compounds along with crassifoside E (3) and crassifoside F (4), which were reported previously, was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. All compounds showed strong radical scavenging activity. The primary structure-activity relationship is also discussed.     

Antioxidative iridoid glycosides and phenolic compounds from <Emphasis Type="Italic">Veronica peregrina</Emphasis>

Eight iridoid glycosides and four phenolic compounds were isolated from the EtOAc soluble fraction of Veronica peregrina MeOH extract as the radical scavengers for antioxidant activity. The compounds were identified as protocatechuic acid (1), luteolin (2), veronicoside (3), minecoside (4), specioside (5), amphicoside (6), catalposide (7), 6-O-cis-p-coumaroyl catalpol (8), p-hydroxy benzoic acid methyl ester (9), verproside (10), verminoside (11), and chrysoeriol 7-glucuronide (12) by spectroscopic analysis. All compounds except for 1 and 2 were isolated for the first time from this plant. The antioxidant activity was evaluated by the ORAC(Oxygen Radical Absorbance Capacity) assay, which measures scavenging activity against peroxy radicals induced by 2,2′-azobis (2-methoxypropion-amidine) dihydrochloride, and the ORAC value is expressed as relative trolox equivalent. Compounds 2, 4, 5, 6, 8, and 12 exhibited potent antioxidant activity, and compounds 1, 11 had similar activity with trolox, whereas the other compounds showed weaker activity than trolox.     

Changes in antioxidant activity,total phenolic and abscisic acid constituents in the aquatic plants <Emphasis Type="Italic">Myriophyllum spicatum</Emphasis> L. and <Emphasis Type="Italic">Myriophyllum triphyllum</Emphasis> Orchard exposed to cadmium

Changes in antioxidant activity, total phenolic and abscisic acid (ABA) constituents of Myriophyllum spicatum L. and Myriophyllum triphyllum Orchard, cadmium (Cd) aqueous macrophytes, were investigated exposed to 0, 2, 4, 6, 8, 16 mg l^-1 Cd concentrations. M. triphyllum exhibited strong antioxidant activity but not M. spicatum before and after exposure. Free radical scavenging activity of M. triphyllum was significantly affected from the Cd concentrations and a significant increase was observed at 6 mgl^-1 Cd concentration. Total phenolic constituent and ABA concentration of M. triphyllum is higher than that of M. spicatum with or without heavy metal exposure (P < 0.05). While total phenolic constituents of both species were not significantly affected from Cd concentrations except for 6 mgl^-1 Cd concentration ABA contents did. ABA content of M. triphyllum increased from 1.81 ± 0.10 μg g^-1 (control) to 5.13 ± 0.15 μg g^-1 at 16 mg l^-1 Cd concentration and increase was from 0.59 ± 0.08 μg g^-1 (control) to 2.05 ± 0.10 μg g^-1 for M. spicatum at the same Cd concentration. Both species accumulated ABA indicating submerge plants can also accumulate ABA and its concentration increase with increasing Cd concentration. Such studies as this one may be important for evaluation of the metabolic variations of toxic metal tolerant macrophytes that grown in polluted aqueous ecosystem.     

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.     

Antioxidant activities of isoflavones from the rhizomes of<Emphasis Type="Italic">belamcanda chinensis</Emphasis> on carbon tetrachloride-lnduced hepatic injury in rats

The present study was carried out to clarify whether tectorigenin and tectoridin isolated from the rhizomes of Belamcanda chinensis (Iridaceae) inhibit hepatic damage induced by carbon tetrachloride (CCl4)-intoxication in rats by the experimental methods in vitro and in vivo. Tectorigenin and tectoridin exhibited a significant decrease in serum transaminase activities elevated by hepatic damage induced by CCl4-intoxication in rats, as well as in a lipid peroxidation causing a significant decrease in malondialdehyde (MDA) production by thiobarbituric acid (TBA)-reactant assay. Both compounds also showed strong increase in the antioxidant enzymes such as hepatic cytosolic superoxide dismutase (SOD), catalase and glutathione peroxidase (GSH-px) activities in CCl4-intoxicated rats. These results suggested that tectorigenin and tectoridin isolated from the rhizomes of B. chinensis possess not only the antioxidative, but also the hepatoprotective activities in CCl4-intoxicated rats.     

Antioxidant caffeic acid derivatives from leaves of<Emphasis Type="Italic">parthenocissus tricuspidata</Emphasis>

Five caffeic acid derivatives; methyl ester of caffeoylglycolic acid (1), dimethyl ester of caffeoyltartaric acid (2), dimethyl ester of caffeoyltartronic acid (3), monomethyl ester of caffeoyltartronic acid (4), methyl ester of caffeic acid (5), and some other secondary metabolites including; quercetin, quercetin 3-O-beta-D-glucuronide methyl ester, kaempferol, 3,5,7,4'-O-tetramethylkaempferol, beta-sitosterol glucoside, 2alpha-hydroxyursolic acid and 2,24-dihydroxyursolic acid, have been isolated and characterized. All the isolated compounds were characterized with the help of NMR spectroscopy and mass spectrometry. Structure of compound 3 was also confirmed by a single X-ray crystallographic technique. Isolates were evaluated for antioxidant activities and most of the tested compounds were found to be potent in DPPH free radical scavenging (IC50 = 4.56-14.17 microg/mL) and superoxide anion scavenging (IC50 = 0.58-7.39 microg/mL) assays.     

Main phenolic compounds from the flower of <Emphasis Type="Italic">Trachelospermum asiaticum</Emphasis> var. <Emphasis Type="Italic">intermedium</Emphasis> (Apocynaceae)

Six phenolic compounds were isolated from the flowers of Trachelospermum asiaticum var. intermedium (Apocynaceae). These structures were determined on the basis of spectral data.     

Flavonoids and aromatic compounds from the rhizomes of<Emphasis Type="Italic">Zingiber zerumbet</Emphasis>

Repeated column chromatography of the CHCl3-soluble fraction of Zingiber zerumbet led to the isolation and identification of two aromatic compounds, p-hydroxybenzaldehyde (1) and vanillin (2), and six kaempferol derivatives, kaempferol-3,4',7-O-trimethylether (3), kaempferol-3-O-methylether (4), kaempferol-3,4'-O-dimethylether (5), 4'-O-acetylafzelin (6), kaempferol-3-O-(4-O-acetyl-alpha-L-rhamnopyranoside)], 2',4'-O-diacetylafzelin (7), kaempferol-3-O-(2,4-O-diacetyl-alpha-L-rhamnopyranoside)], and 3',4'-O-diacetylafzelin (8), kaempferol-3-O-(3,4-O-diacetyl-alpha-L-rhamnopyranoside)]. The structures of 1-8 were identified by analysis of spectroscopic data as well as by comparison with published values. This is the first report on the isolation of compounds 1-3 from this plant.     

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.     

Phenolic compounds obtained from stems of<Emphasis Type="Italic">couepia ulei</Emphasis> with the potential to induce quinone reductase

Activity-guided fractionation of the EtOAc-soluble extract of the stems of Couepia ulei, using a bioassay based on the induction of quinone reductase (QR) in cultured Hepa 1c1c7 mouse hepatoma cells led to the isolation of two active compounds, a new natural product, erythro-2,3-bis(4-hydroxy-3-methoxyphenyl)-3-ethoxypropan-1-ol (1), and a known compound, evofolin-B (2), along with five inactive compounds all of known structure, viz., betulinic acid, oleanolic acid, pomolic acid, (+/-)-syringaresinol, and ursolic acid. These isolates were identified by analysis of physical and spectral data. Compounds 1 and 2 exhibited QR inducing activity, with observed CD (concentration required to double induction) values of 16.7 and 16.4 microM, respectively.     

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.     

Biological Activities of the Chemical Constituents of<Emphasis Type="Italic">Erythrina stricta</Emphasis> and<Emphasis Type="Italic">Erythrina subumbrans</Emphasis>

Phytochemical investigation of the hexane and CH2Cl2 extracts of Erythrina stricta roots and E. subumbrans stems led to the isolation of six pterocarpans, one flavanone, one isoflavone, two alkaloids, five triterpenes, six steroids and alkyl trans-ferulates. The structures of all known compounds were determined on the basis of spectroscopic evidence. Sophoradiol (15), a mixture of stigmast-4-en-3-one (19) and stigmasta-4,22-dien-3-one (20), lupeol (21), cycloeucalenol (22), a mixture of 3beta-hydroxystigmast-5-en-7-one (23) and 3beta-hydroxystigmast-5,22-dien-7-one (24) and melilotigenin C (25) were first isolated from the genus Erythrina. The isolated compounds were evaluated for antiplasmodial activity, antimycobacterial activity and cytotoxicity. Among the tested compounds, 5-hydroxysophoranone (8) exhibited the highest antiplasmodial activity against Plasmodium falciparum (IC50 2.5 microg/mL). Compound 8, erystagallin A (5), erycristagallin (7) and erysubin F (10) showed the same level of antimycobacterial activity against Mycobacterium tuberculosis (MIC 12.5 microg/mL). For cytotoxicity, erybraedin A (2) showed the highest activity against the NCI-H187 and BC cells (IC50 2.1 and 2.9 microg/mL, respectively), whereas 10 exhibited the highest activity against the KB cells (IC50 4.5 microg/mL).     

Two new phenolic glycosides from <Emphasis Type="Italic">Syringa reticulata</Emphasis>

Two new phenolic glycosides—3′-O-β-d-glucopyranosysalidroside (1) and cis-echinacoside (2)—together with four known ones—forsythoside B (3), decaffeoylacteoside (4), osmanthuside F (5) and (−)-olivil-4′-O-β-d-glucopyranoside (6)—were isolated from the leaves of Syringa reticulata. Their structures were established on the basis of spectral and chemical data.     

Anti-oxidant activities of<Emphasis Type="Italic">acanthopanax senticosus</Emphasis> stems and their lignan components

The antioxidant activities of Acanthopanax senticosus stems were evaluated in CCl4-intoxicated rats. The n-butanol fraction from the water extract of the stems, when pretreated orally at 200 mg/kg/day for 7 consecutive days in rats, was demonstrated to exhibit significant increases in antioxidant enzyme activities such as hepatic cytosolic superoxide dismutase, catalase and glutathione peroxidase by 30.31, 19.82 and 155%, respectively. The n-butanol fraction whereas showed a significant inhibition of serum GPT activity (65.79% inhibition) elevated with hepatic damage induced by CCl4-intoxication. Eleutheroside B, a lignan component, isolated from the n-butanol fraction was found to cause a moderate free radical scavenging effect on DPPH, its scavenging potency as indicated in IC50 value, being 58.5 microM. These results suggested that the stems of A. senticosus possess not only antioxidant but also hepatoprotective activities.     

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.     

Cytotoxic phenolic compounds from <Emphasis Type="Italic">Chionanthus retusus</Emphasis>

Cytotoxicity-guided fractionation and purification of MeOH extract from Chionanthus retusus Lindl. et Paxton resulted in the isolation of compounds. Fourteen phenolic compounds were isolated from the EtOAc soluble fraction, and their structures were determined by spectroscopic analysis. Isolated compounds were identified as phillygenin (1), scopoletin (2), pinoresinol (3), kaempferol (4), aromadendrin (5), 2-(4-hydroxyphenyl)ethanol (6), 3,3′,5,5′,7-pentahydroxyflavanone (7), luteolin (8), quercetin (9), apigenin (10), chrysoeriol (11), phillyrin (12), oleuropein (13), (7R,8R)-guaiacylglycerol (14). All compounds except for 12 and 13 were isolated for the first time from this plant and genus Chionanthus. Anti-proliferative effect of isolated compounds were evaluated by the sulforhodamin B assay against four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT15). Compounds 4 and 8–10 were significantly active with ED50 values of 1.84–6.35 μg/mL. Also, compounds 1, 3, 5 and 7 revealed cytotoxic effects at concentrations below 30 μg/mL.     

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.     

Antibacterial compounds from the leaves of<Emphasis Type="Italic">Acanthopanax senticosus</Emphasis>

Chiisanogenin (1), hyperin (2) and chiisanoside (3) were isolated from the leaves of Acanthopanax senticosus, and were tested for their inhibitory activities against 6 strains of bacteria. Among them, chiisanogenin (1) revealed broad but moderate antibacterial activities against G (+) and G (-) bacteria, the minimum inhibitory concentration (MIC) being in the range of 50-100 microg/ml.     

A new phenolic glycoside syringate from the bark of <Emphasis Type="Italic">Juglans mandshurica</Emphasis> MAXIM. var. <Emphasis Type="Italic">sieboldiana</Emphasis> MAKINO

A new phenolic glycoside syringate, 4′-hydroxy-2′,6′-dimethoxyphenol 1-O-β-d-(6-O-syringoyl) glucopyranoside (1), together with two known ones, 2′-hydroxy-4′-methoxyphenol 1-O-β-d-(6-O-syringoyl) glucopyranoside (2) and 4′-hydroxy-2′-methoxyphenol 1-O-β-d-(6-O-syringoyl) glucopyranoside (3), were isolated from the bark of Juglans mandshurica MAXIM. var. sieboldiana MAKINO. Their structures were established on the basis of spectral and chemical data.     

Diterpenoids from the stem barks of<Emphasis Type="Italic">Croton robustus</Emphasis>

Three compounds were isolated from the stem barks of Croton robustus. Their structures were elucidated as trachyloban-19-oic acid, trachyloban-19-ol and poilaneic acid by spectroscopic analysis. Among them, trachyloban-19-ol and methyl trachyloban-19-oate exhibited weak cytotoxic activity against gastric carcinoma and colon carcinoma with ED50 of 9.2, 9.6 and 8.3, 9.1 microg/mL, respectively.