Free radical scavenging activity of different extracts and some constituents from the leaves of Ligustrum vulgare and L. delavayanum

The free radical scavenging activity of the water infusions, different organic solvent extracts and some constituents from Ligustrum vulgare and Ligustrum delavayanum leaves was assessed with the aid of DPPH radical. Among the samples screened, water infusions had the strongest free radical scavenging capacity. From the tested compounds scavenging active flavonoid aglycones are present in the most active chloroform fractions from both leaves samples.     

Neuroprotective activity of galloylated cyanogenic glucosides and hydrolysable tannins isolated from leaves of Phyllagathis rotundifolia

The galloylated cyanogenic glucosides based on prunasin (1-7), gallotannins (8-14), ellagitannins (15-17), ellagic acid derivatives (18, 19) and gallic acid (20) isolated from the leaves of Phyllagathis rotundifolia (Melastomataceae) were investigated for their neuroprotective activity against hydrogen peroxide (H₂O₂)-induced oxidative damage in NG108-15 hybridoma cell line. Among these compounds, the gallotannins and ellagitannins exhibited remarkable neuroprotective activities against oxidative damage in vitro as compared to galloylated cyanogenic glucosides and ellagic acid derivatives in a dose-dependent manner. They could be explored further as potential natural neuroprotectors in various remedies of neurodegenerative diseases.     

Triterpenes and steroids from the leaves of Aglaia exima (Meliaceae)

A study on the leaves of Aglaia exima led to the isolation of one new and seven known compounds: six triterpenoids and two steroids. Their structures were elucidated and analyzed mainly by using spectroscopic methods; 1D and 2D NMR, mass spectrometry, UV spectrometry and X-ray. All the triterpenoids and steroids were measured in vitro for their cytotoxic activities against eight cancer cell lines; lung (A549), prostate (DU-145), skin (SK-MEL-5), pancreatic (BxPC-3), liver (Hep G2), colon (HT-29), breast (MCF-7) and (MDA-MB-231). The new cycloartane triterpenoid, 24(E)-cycloart-24-ene-26-ol-3-one 1, showed potent cytotoxic activity against colon (HT-29) cancer cell line (IC₅₀ 11.5 μM).     

Triterpenes and steroids from the roots of Scorzonera austriaca

A new D:B-friedoolean-type triterpene, 3β-acetoxyglutin-5(10)-en-6-oxo (1), together with seventeen known compounds (2-18) was isolated from the roots of Scorzonera austriaca. Their structures were elucidated mainly by NMR and HR-ESI-MS, as well as on comparison with the reported data. Cytotoxicities of compounds 2, 4, 6, 10-14 and 16 against selected cancer cells of human promyelocytic leukemia (HL-60) and human hepatoma (BEL-7404) were measured in vitro.     

ent-Isopimarane diterpenoids of the leaves from Rabdosia forrestii

Two new diterpenes, forrestin H, ent-isopimaran-8 beta, 15R, 16-triol (1), forrestin I, ent-isopimaran-16-acetoxy-8 beta, 15R-diol (2) and the acetonide derivative of forrestin H were isolated from the leaves of Rabdosia forrestii. The structures were established on the basis of NMR spectroscopic analysis and of the modified Mosher's (1H) method.     

A new aromatic alkine from the tuber of Sparganium stoloniferum

A new aromatic alkine was isolated from the tuber of Sparganium stoloniferum . Its structure was assigned to be methyl 3,6-dihydroxy-2-[2-(2-hydroxyphenyl)-ethynyl]benzoate (1) by spectroscopic methods.     

Two new cerebrosides from the pollen of Typha angustifolia

Two new cerebrosides, 1-O-(β-d-glucopyranosyloxy)-(2S,3S,4R,8Z)-2-[(2′R)-2′-hydroxytricosanoylamino]-8-nonadecene-3,4-diol (1) and 1-O-(β-d-glucopyranosyloxy)-(2S,3R,4E,8Z)-2-[(2′R)-2′-hydroxynonadecanoylamino]-4,13-nonadecene-3-diol (2), were isolated from the pollen of Typha angustifolia. Their structures were elucidated by chemical and spectral means. This is the first report on the occurrence of cerebroside in Typha (Typhaceae). Compounds 1 and 2 exhibited effect on the proliferation of cultured vascular smooth muscle cell (VSMCs) induced by fatal bovine serum (FBS).     

Bioactive phenolics from the fruits of Livistona chinensis

This study investigated the antioxidant and cytotoxic activity of the phenolics isolated from the fruits of Livistona chinensis. Four new compounds, 1-{ω-isoferul[6- (4-hydroxybutyl)pentadecanoic acid]}-glycerol (1), E-[6′-(5″-hydroxypentyl)tricosyl]-4-hydroxy-3-methoxycinnamate (2), 2-(3′-hydroxy-5′-methoxyphenyl)-3-hydroxylmethyl-7-methoxy-2,3-dihydrobenzofuran-5- carboxylic acid (3), 7-hydroxy-5,4′-dimethoxy-2-arylbenzofuran (4), together with eleven known phenolics (5-15), were isolated and identified. Among these compounds, 1-4, 5-O-caffeoylshikimic acid (5), caffeic acid (7), and 3-O-caffeoylshikimic acid (8) showed potent antioxidant activity. 1-5, and 8 showed potent antiproliferative activities with IC₅₀ values among 5-150 μM against HepG2 human liver cancer, HL-60 human myeloid leukemia, K562 human myeloid leukemia, and CNE-1 human nasopharyngeal carcinoma cell lines. On the basis of these findings, it could be proposed that the fruits of L. chinensis may serve as attractive mines of powerful anticancer and antioxidant agents for various purposes.     

A new phenolic glucoside from the leaves of Heliciopsis lobata

A new phenolic glucoside ester, 6'-E-(2'-methyl-2'-butenoyl) arbutin (1), was isolated from the leaves of Heliciopsis lobata. Its structure was elucidated by spectral analysis.     

Protection of spruce from colonization by the bark beetle, Ips perturbatus, in Alaska

Field bioassays were conducted in south-central Alaska in a stand of Lutz spruce, Picea × lutzii, to determine whether a semiochemical interruptant (verbenone and trans-conophthorin) and/or a defense-inducing plant hormone (methyl jasmonate, MJ) could be used to protect individual standing trees from bark beetle attack. During two experiments (initiated in May 2004 and 2005, respectively), attacks by Ips perturbatus on standing trees were induced by using a three-component aggregation pheromone (ipsenol, cis-verbenol, and ipsdienol) and prevented by using the interruptant. In 2005, treatments from 2004 were repeated and additional treatments were evaluated by using MJ spray or injection with and without the interruptant. Aggregation began before 3 or 7 June, and attack density was monitored through 3 or 16 August. During both years, tree mortality caused by I. perturbatus was recorded twice (in August, and in May of the following year). In both experiments, attack density was greatest on trees baited with the three-component attractive pheromone, but was significantly reduced by addition of the semiochemical interruptant to trees baited with the attractant. There were no significant differences in attack density between attractant + interruptant-treated trees and unbaited trees. In 2004, mortality was highest among attractant-baited trees, whereas addition of the interruptant significantly reduced the level of initial (10 week post-treatment) and final (54 week post-treatment) mortality. In 2005, no significant reduction in attack density occurred on trees baited with the attractant when MJ was sprayed or injected. The highest initial (10.6 week post-treatment) and final (49.4 week post-treatment) mortality was observed among trees that had been injected with MJ and baited with the attractant. Mortality at the final assessment was significantly lower in all other treatment groups. As in 2004, addition of the interruptant to attractant-baited trees significantly reduced the level of final mortality compared to attractant-baited trees. MJ was not attractive or interruptive to I. perturbatus or associated bark beetles in a flight trapping study. However, MJ-treated trees (sprayed or injected) exuded copious amounts of resin on the bark surface. Anatomical analyses of felled trees from four treatment groups [Tween (solvent)-sprayed, MJ-sprayed, Tween-injected, and MJ-injected + attractant baited] showed that treatment with MJ increased the number and size of resin ducts produced following treatment. These analyses also revealed a reduction in radial growth in MJ-treated trees. Our results show that during both years, treatment with a simple, two-component interruptant system of verbenone and trans-conophthorin significantly reduced I. perturbatus attack density and tree mortality on attractant-baited trees and provided a full year of protection from bark beetle attack.     

A new flavonoid glycoside from the leaf of Cephalotaxus koreana

A new flavone glycoside, apigenin 5-O-alpha-L-rhamnopyranosyl-(1-->3)-beta-D-glucopyranoside (1), along with four known flavonol glycosides (2-5), were isolated from the leaf of Cephalotaxus koreana. The new glycoside 1 showed inhibitory activity in superoxide radical scavenging assay with IC(50) value of 13.0 microM, while it showed weak activity in 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. Compounds 2-5 exhibited antioxidant activity in scavenging DPPH and superoxide radicals with IC(50) values ranging from 5.7 to 22.3 microM.     

Reactive oxygen species scavenging activities and inhibition on DNA oxidative damage of dimeric compounds from the oxidation of (−)-epigallocatechin-3-O-gallate

The dimeric catechins dehydrotheasinensin A (2) and theacitrin C (3) were prepared from the oxidation of (−)-epigallocatechin-3-O-gallate (EGCG, 1), and their antioxidant activity was investigated using a chemiluminescence (CL) method in vitro. Both compounds showed significant inhibitory effects on reactive oxygen species (O₂⁻, H₂O₂ and •OH) and DNA oxidative damage, with 2 being more potent than 3 and EGCG itself.     

A new flavone glycoside from the seeds of Shorea robusta

A new flavonoid, 3,7-dihydroxy-8-methoxyflavone 7-O-α- -rhamnopyranosyl-(1→4)-α- -rhamnopyranosyl-(1→6)-β- -glucopyranoside (1), was isolated from the seeds of Shorea robusta.