Isolation and Structural Characterization of Lignin Polymer from Dendrocalamus sinicus

Dendrocalamus sinicus, which is the largest bamboo species in the world, has broad prospects in the fields of bioenergy and biorefinery application. In this study, dewaxed D. sinicus samples were sequentially treated with 80 % ethanol containing 0.025 M HCl, 80 % ethanol containing 0.5 % NaOH, and aqueous alkaline solutions (containing 2.0, 5.0, and 8.0 % NaOH, respectively) at 75 °C for 4 h, in which 9.63, 8.71, 21.83, 21.09, and 13.09 % of the original lignin were isolated, respectively. The lignin fractions obtained were comparatively characterized by chemical composition, molecular weights, and structural features by wet chemical and instrumental analysis methods. It was found that the bamboo lignin fractions isolated by ethanol had lower weight-average molecular weights (1,360–1,380 g?mol^?1) and contained much higher amounts of associated hemicelluloses, while the lignin fractions isolated by aqueous alkaline solutions had higher weight-average molecular weights (5,300–6,040 g?mol^?1) and contained lower amounts of associated hemicelluloses. Spectroscopy analyses indicated that the bamboo lignin was a typical grass lignin, consisting of p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) units. A small percentage of the lignin side-chain was found to be acetylated at the γ-carbon, predominantly at syringyl units. The major interunit linkages present in the bamboo lignin obtained were β-O-4′ aryl ether linkages, together with lower amounts of β-β′, β-5′, and β-1′ linkages.     

Structural and physico-chemical characterization of hemicelluloses from ultrasound-assisted extractions of partially delignified fast-growing poplar wood through organic solvent and alkaline solutions

One organic and three alkaline hemicellulosic fractions were isolated by an ultrasound-assisted extraction which partially delignified the fast-growing poplar wood. Successive treatments were conducted with dimethyl sulfoxide under ultrasonic irradiation at 570 W, 25 °C for 30 min, 70% ethanol containing 1% NaOH, 3% NaOH and 6% NaOH at 75 °C for 3 h, respectively. The four hemicellulosic fractions obtained were comparatively studied by sugar analysis, alkaline nitrobenzene oxidation of bound lignin, GPC, FT-IR, 1D and 2D NMR spectroscopy as well as TGA and DTA. The results showed that the ultrasonic treatment and sequential extractions with three different concentrations of NaOH led to a release of 75.5% of the original hemicelluloses and 96.2% of the lignin. All four purified hemicellulose fractions contained relatively low amounts of associated lignin, ranging between 0.96 and 3.10%. In addition, the hemicellulosic fraction H₄ isolated with 6% NaOH is formed by a linear backbone of four (β-1 → 4)-xylopyranosyl residues and at least one of the xylose residues is monosubstituted at C-2 by a 4-O-methylglucuronic acid, giving a typical ratio of 4-O-methyl glucuronic acid to Xyl of 1 to 4.     

Physicochemical characterization of cellulose from perennial ryegrass leaves (Lolium perenne)

In this study, we investigated the physicochemical properties of the cellulosic preparations obtained from both untreated perennial ryegrass leaves and de-juiced leaves. It was found that treatment at 22 degrees C with 18% NaOH and 18% KOH for 2h, and 10% NaOH and 10% KOH for 16 h yielded 28.2%, 28.8%, 22.7%, 23.4%, respectively, of 'cellulose' residue from untreated ryegrass leaves and 35.7%, 36.8%, 32.8% and 34.6%, respectively, from the de-juiced leaves. For each cellulosic fraction, the glucose content was 71.6%, 69.6%, 67.8%, 66.7%, 69.7%, 68.6%, 63.9% and 61.7%, respectively. The structure of the cellulose samples was examined using FTIR and CP/MAS (13)C NMR spectroscopy and X-ray diffraction. The cellulosic preparations were free of bound lignin except for noticeable amounts of residual hemicelluloses (28.4-38.3%), and had intrinsic viscosities between 275.1 and 361.0 mL/g, along with molecular weights from 144,130 to 194,930 g/mol. This study found that the cellulose samples isolated from both de-juiced ryegrass leaves and the untreated leaves had a much lower percent crystallinity (33.0-38.6%) than that from wood-based fibres (60-70%) and had much shorter fibres (0.35-0.49 mm) than those of either cereal straws, bagasse or wood. In addition, a partial disruption of the hydrogen bonds and microfibrils may occur during the de-juicing process by mechanical activity, which results in a decreased cellulose crystallinity and fibre length. These findings are significant in relation to hydrolysing ryegrass cellulose for bio-ethanol production.     

Development of sequential-co-culture system (Pichia stipitis and Zymomonas mobilis) for bioethanol production from Kans grass biomass

Sequential-co-culture technique was investigated in this study for the production of bioethanol from relatively cheaper lignocellulosic biomass of Kans grass (Saccharum spontaneum). The consortium of Pichia stipitis and Zymomonas mobilis was used to develop a suitable sequential-co-culture system. The Kans grass biomass was hydrolyzed in such a manner that the two sugar fractions, xylose rich and glucose rich were generated (a separate study). The P. stipitis cells and respective fermentation media (xylose rich) were fed to the fermentation vessel, after the set fermentation time Z. mobilis cells and respective media were fed to the same vessel. Different strategies have been followed and experiments were conducted initially at flask level. The selected strategy was then applied at bioreactor level using both synthetic fermentation media and Kans grass hydrolysate media to compare the kinetic parameters. The sequential addition of cultures with their respective media and imposed process conditions, showed better utilization of total sugars added (>95%). Microaerobic condition for P. stipitis and strictly anaerobic condition for Z. mobilis fermentation were found significant. The average ethanol yield (Y_p/s) and overall volumetric productivity (r_po) were found as 0.453 g_p/g_s and 1.580 g/l/h respectively for Kans grass hydrolysate media and 0.474 g_p/g_s and 2.901 g/l/h respectively for synthetic fermentation media.     

Polysaccharides from the pulp of cupuassu (Theobroma grandiflorum): Structural characterization of a pectic fraction

Cupuassu (Theobroma grandiflorum, Schumann) is a Brazilian Amazonian fruit whose pulp contains volatile compounds that have been extensively studied. In this work, the pulp from fruits of cupuassu was ground, treated with MeOH–H₂O, and defatted with p-Tol–EtOH. The residue (4% in relation to the fresh pulp) was submitted to sequential extractions with water, aqueous citric acid and aqueous NaOH, resulting in polysaccharide fractions with 0.3–15% yield. The main pectic fraction (7% yield) was obtained with water at 25 °C (W-1 fraction) and was chosen to be better characterized. Chemical and spectroscopic analyses showed that W-1 is composed mainly of a homogalacturonan highly esterified (DE 53%; DA 1.7%) with some rhamnogalacturonan insertions, carrying side chains containing galactose and arabinose.     

Pancreatic lipase inhibitory and antioxidative constituents from the aerial parts of Paeonia lactiflora Pall. (Ranunculaceae)

To date, there have been reports mostly about research results of the peony root in comparison to the aerial parts. According to our study, the aerial parts of P.lactiflora showed superior anti-oxidative and pancreatic lipase inhibitory activities than its root. Especially, the water extract and the ethyl acetate fraction of the ethanol extract exhibited potent pancreatic lipase inhibitory activity by 53.11 ± 1.22% and 46.16 ± 1.55% at the same dose of orlistat (62.5 ± 1.27%). The ethanol extract exhibited the best anti-oxidative activity with IC₅₀ of 17.08 ± 0.9 μg/mL, and the ethyl acetate fraction 19.75 ± 0.02 μg/mL, respectively, comparing to the positive control rutin (IC₅₀, 22.66 ± 0.29 μg/mL). From the anti-oxidative and pancreatic lipase inhibitory active fractions three new compounds, monplacphloroside (1), monplachydroxyquinoside (2) and herbacetin-7-O-β-d-sophoroside (3) were isolated along with 19 (4-22) known ones.Compounds, PGG (14), 1-O-methyl-2,3,4,6-tetra-O-galloyl-β-d-glucopyranose (17) and ethylgallate (9) were found to be the strongest antioxidants and pancreatic lipase inhibitors. Monoterpenes, albiflorin R₂ (19) and albiflorin (20) were determined for the first time as strong pancreatic lipase inhibitors. The presence of the esterified galloyl moiety, with its increasing numbers or the β-lactone cycle within the molecular structure plays an essential role for the enhancement of the pancreatic lipase enzyme inhibitory activity.     

Acetylcholinesterase inhibitory effects of the bulb of Ammocharis coranica (Amaryllidaceae) and its active constituent lycorine

Ammocharis coranica (Ker-Gawl.) Herb. (Amaryllidaceae) is used in southern Africa for the treatment of mental illnesses. The ethanol extracts of the bulb of A. coranica and its total alkaloids rich fractions were screened for inhibition of acetylcholinesterase enzyme (AChE), which is implicated in the pathophysiology of Alzheimer's disease. The ethanolic extracts significantly inhibited AChE with IC₅₀ value of 14.3 ± 0.50 μg/ml. The basic ethyl acetate and butanol fractions of the crude extracts were the most active against AChE with IC₅₀ values of 43.1 ± 1.22 and 0.05 ± 0.02 μg/ml respectively. Bioassay-guided fractionation of the basic fractions led to the isolation of lycorine and 24-methylenecycloartan-3β-ol. Lycorine which was isolated from both butanol and ethyl acetate fractions had IC₅₀ of 29.3 ± 3.15 μg/ml, while 24-methylenecycloartan-3β-ol was not active.     

Allelopathic activity of luteolin 7-O-β-glucuronide isolated from Chrysanthemum morifolium L.

Two flavones, luteolin 7-O-β-glucuronide and diosmetin 7-O-β-glucuronide, were isolated and identified from Chrysanthemum morifolium L. v. Ramat leaves. Identification techniques included HPLC DAD, MS, ¹H and ¹³C NMR spectroscopy. At concentrations of 0.2 and 2.0 mM, luteolin 7-O-β-glucuronide significantly reduced the frond number and chlorophyll content of Lemna gibba plants, but did not significantly affect dry weight. At a concentration of 0.2 mM diosmetin 7-O-β-glucuronide had no significant effect on frond number, dry weight or chlorophyll concentration of L. gibba. These results indicate that an ortho-3′,4′-dihydroxy arrangement of the B-flavonoid ring in the luteolin compound is probably responsible for allelopathic activity.     

New oleanane-type saponins: Leptocarposide B-D,from Ludwigia leptocarpa (Onagraceae)

Three new oleanane-type saponins, leptocarposide B-D (1–3), were isolated from the whole plant of Ludwigia leptocarpa (Nutt.) Hara, together with ten known compounds 4–13.The structures of these compounds were determined by interpretation of their spectral data, mainly HR-TOFESIMS, 1D-NMR (¹H, ¹³C) and 2D-NMR (¹H–¹H COSY, HSQC, HMBC, and NOESY), and by comparison with the literature data. The structures of the new compounds were established as 28-O-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-[α-l-arabinopyranosyl-(1 → 3)]-4-O-(3′-hydroxybutanoyloxy-3-hydroxybutanoyloxy)-β-d-fucopyranosyl zanhic acid (1); 3-O-β-d-glucopyranosyl-28-O-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-4-O-(3′-hydroxybutanoyloxy-3-hydroxybutanoyloxy)-β-d-fucopyranosyl medicagenic acid (2); 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-28-O-β-d-xylopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 2)-[α-l- arabinopyranosyl-(1 → 3)]-4-O-(3′-hydroxybutanoyloxy-3-hydroxybutanoyloxy)-β-d-fucopyranosyl zanhic acid (3).     

Synthesis and in vitro activities of a new antiviral duplex drug linking Zidovudine (AZT) and Foscarnet (PFA) via an octadecylglycerol residue

To prepare a new antiviral duplex drug linking Zidovudine (AZT) and Foscarnet (PFA) via a lipophilic octadecylglycerol residue we condensed 1-O-4-monomethoxytrityl-3-O-octadecyl-sn-glycerol-2-hydrogenphosphonate obtained from 3-O-octadecyl-sn-glycerol with AZT by the phosphonate method. The purified condensation product was de-tritylated resulting in 3′-azido-3′-deoxythymidylyl-(5′ → 2-O)-3-O-octadecyl-sn-glycerol, followed by treatment with (ethoxycarbonyl)phosphoric dichloride. The resulting 3′-azido-3′-deoxy-thymidylyl-(5′ → 2)-3-O-octadecyl-sn-glycerol-1-O-(ethoxycarbonyl)phosphonate was purified by preparative RP-18 column chromatography. The antiviral duplex drug 3′-azido-3′-deoxythymidylyl-(5′ → 2-O)-3-O-octadecyl-sn-glycerol-1-O-phosphonoformate trisodium salt (AZT–lipid–PFA) was obtained after alkaline cleavage of the phosphonoformate ethylester residue. The overall yield of the five step synthesis performed at gram scale was about 30%. According to a supposed pathway AZT–lipid–PFA could be cleaved to yield a mixture of different antiviral compounds such as AZT, AZT-5′-monophosphate, octadecylglycerol–AZT, PFA and octadecylglycerol–PFA, possibly producing additive and/or synergistic antiviral effects. In vitro studies showed that the duplex drug exhibits antiviral activities against HIV and especially against drug-resistant strains and clinical isolates of HSV and HCMV. The E₅₀ values of AZT–lipid–PFA against HIV ranged between 170 and 200 nM. The half-maximal inhibitory doses (IC₅₀) against highly acyclovir (ACV)-resistant HSV isolates determined by a plaque reduction assay ranged between 1.87 and 4.59 μM. Using ganciclovir (GCV)-sensitive, GCV resistant and drug cross-resistant HCMV strains the IC₅₀-values of AZT–lipid–PFA were between 2.78 and 1.18 μM. With regard to PFA, the IC₅₀-value of AZT–lipid–PFA determined on a multi-drug-resistant HCMV strain was about 90-fold lower than that of PFA, demonstrating the superior antiviral effect of the duplex-drug.     

Highly glycosylated flavonols with an O-linked branched pentasaccharide from Iberis saxatilis (Brassicaceae)

Four flavonol glycosides isolated from non-flowering leafy shoots of Iberis saxatilis (Brassicaceae) were characterised by spectroscopic and chemical methods as saxatilisins A–D, the 3-O-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 2)[β-d-glucopyranosyl-(1 → 2)-α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside, 3-O-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 2)[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside, 3-O-(6-O-E-sinapoyl)-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 2)[β-d-glucopyranosyl-(1 → 2)-α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside, and 3-O-(6-O-E-feruloyl)-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 2)[β-d-glucopyranosyl-(1 → 2)-α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside of isorhamnetin (3,5,7,4′-tetrahydroxy-3′-methoxyflavone), respectively. Analysis of ²J_HC correlations detected with the H2BC (heteronuclear two-bond correlation) pulse sequence aided the unambiguous assignment of glycosidic resonances in the ¹H and ¹³C NMR spectra of these compounds. Saxatilisins A, C, and D, are the first flavonol glycosides to be described with a pentasaccharide chain at a single glycosylation site. Several pentaglycosides of kaempferol and quercetin, tentatively assigned as saxatilisin analogues from LC–MS/MS analyses, were present as minor constituents of the extracts.     

Isolation of diverse bioactive compounds from Euphorbia balsamifera: Cytotoxicity and antibacterial activity studies

Antibacterial and cytotoxic activities of Euphorbia balsamifera, fractions and pure compounds were evaluated. The cytotoxic assays for HCT116, HePG2 and MCF7 showed a significant IC₅₀: 54.7 and 76.2 µg/mL of non-polar fraction “n-hexane” against HCT116 and HePG2, respectively. Antibacterial results revealed that plant fractions exhibited significant potential against the tested pathogens than the total extract where n-butanol and ethyl acetate fractions showed significant antibacterial activity (P < 0.05) against tested bacterial strains. Isolation and structure determination of compounds from n-hexane and n-butanol fractions were performed. From n-hexane fraction, 29-nor-cycloartanol (1), lanost-8-en-3-ol (2a), cycloartanol (2b) and kampferol-3,4'-dimethyl ether (3) were isolated and structurally identified, along with 24 compounds were tentatively identified by GC–MS. From the polar n-butanol fraction, 4-O-β-D-glucopyranosyl-2-hydroxy-6-methoxyacetophenone (4), 4-O-α-L-rhamnosyl-(1 → 6)-β-D-glucopyranosyl-2-hydroxy-6methoxy-acetophenone (5), quercetin-3-O-glucopyranoside (6) and isoorientin (7) were assigned. Structures of the obtained compounds were determined by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. Except compounds 1 and 5, all reported compounds announced antibacterial efficiency. Compound 2 showed selectively the highest activity against Enterococcus faecalis (22 ± 0.13 mm), meanwhile 4-O-β-D-glucopyranosyl-2-hydroxy-6-methoxyacetophenone (4) showed broadly the highest antibacterial activity with MIC of 1.15–1.88 mg/mL against the test Gram-positive and Gram-negative bacteria. Cytotoxic assays indicated that kampferol-3,4'-dimethyl ether (3) exhibited the highest activity with matching IC₅₀ values to doxorubicin; 111.46, 42.67 and 44.90 µM against HCT116, HePG2 and MCF7, respectively, however, it is toxic on retina normal cell line RPE1.     

Ethanol and furfural production from corn stover using a hybrid fractionation process with zinc chloride and simultaneous saccharification and fermentation (SSF)

A two-stage hybrid fractionation process was investigated to produce cellulosic ethanol and furfural from corn stover. In the first stage, zinc chloride (ZnCl₂) was used to selectively solubilize hemicellulose. During the second stage, the remaining treated solids were converted into ethanol using commercial cellulase and Saccharomyces cerevisiae or recombinant Escherichia coli, KO11. This hybrid fractionation process recovered 93.8% of glucan, 89.7% of xylan, 71.1% of arabinan, and 74.9% of lignin under optimal reaction conditions (1st stage: 5% acidified ZnCl₂, 7.5 ml/min, 150 °C (10 min) and 170 °C (10 min); 2nd stage: simultaneous saccharification and fermentation (SSF) using S. cerevisiae). The furfural yield from the hemicellulose hydrolysates was 58%. The SSF of the treated solids resulted in 69–98% of the theoretical maximum ethanol yields based on the glucan content in the treated solids. After fermentation, the solid residues contained primarily lignin. Based on the total lignin in untreated corn stover, the lignin recovery yield was 74.9%.     

A study of lipid- and water-soluble arsenic species in liver of Northeast Arctic cod (Gadus morhua) containing high levels of total arsenic

In the present study liver samples (n = 26) of Northeast Arctic cod (Gadus morhua), ranging in total arsenic concentrations from 2.1 to 240 mg/kg liver wet weight (ww), were analysed for their content of total arsenic and arsenic species in the lipid-soluble and water-soluble fractions. The arsenic concentrations in the lipid fractions ranged from 1.8 to 16.4 mg As/kg oil of liver, and a linear correlation (r² = 0.80, p < 0.001) was observed between the total arsenic concentrations in liver and the total arsenic concentrations in the respective lipid fractions of the same livers. The relative proportion of arsenolipids was considerably lower in liver samples with high total arsenic levels (33–240 mg/kg ww), which contained from 3 to 7% of the total arsenic in the lipid-soluble fraction. In contrast liver samples with low arsenic concentrations (2.1–33 mg/kg ww) contained up to 50% of the total arsenic as lipid-soluble species. Arsenic speciation analysis of the lipid-soluble fractions of the livers, using reversed-phase high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC–ICP-MS), revealed the presence of several arsenolipids. Three major arsenic-containing hydrocarbons (C₁₇H₃₉AsO, C₁₉H₄₁AsO and C₂₃H₃₇AsO) and five arsenic-containing fatty acids (C₁₇H₃₅AsO₃, C₁₉H₃₉AO₃, C₁₉H₃₇AsO₃, C₂₃H₃₇AsO₃ and C₂₄H₃₇AsO₃) were identified using HPLC coupled to quadrupole time-of-flight mass spectrometry (qTOF-MS). Arsenobetaine was the major arsenic species in the water-soluble fraction of the livers, while dimethylarsinate, arsenocholine and inorganic arsenic were minor constituents. Inorganic arsenic accounted for less than 0.1% of the total arsenic in the liver samples.     

Fractional and structural characterization of hemicelluloses from perennial ryegrass (Lolium perenne) and cocksfoot grass (Dactylis glomerata)

Sequential three-stage treatments with 80% EtOH containing 0.2% NaOH, 2.5% H2O2-0.2% EDTA containing 1.5% NaOH and 2.5% H2O2-0.2% TAED containing 1.0% NaOH at 75 degrees C for 3h released 8.0% and 10.4%, 79.1% and 77.0% and 12.9% and 12.5% of the original hemicelluloses from perennial grass and cocksfoot grass, respectively. It was found that the four alkaline peroxide-soluble hemicellulosic fractions contained higher amounts of xylose (33.4-38.2%), uronic acids (9.3-15.3%) and rhamnose (3.0-3.9%), but were lower in glucose (25.1-28.3%), galactose (13.3-15.3%) and mannose (0.4-1.5%) than those of the two alkaline EtOH-soluble hemicellulosic fractions in which glucose (32.9-36.0%), xylose (20.1-22.6%), arabinose (14.1-21.4%), galactose (16.6-19.9%), mannose (4.1-9.9%) and uronic acids (3.4-7.4%) were the major sugar components. 13C NMR spectroscopy confirmed that all the six hemicellulosic fractions were composed of galactoarabinoxylans, 4-O-methylglucuronoarabinoxylans and beta-glucan. In addition, the studies showed that the four alkaline peroxide-soluble hemicellulosic fractions were more linear and acidic and had larger molecular weights (Mw, 28,400-38,650 g mol(-1)) than those of the two alkaline EtOH-soluble hemicellulosic fractions (Mw, 16,460-17,420 g mol(-1)).     

Lentinula edodes (shiitake mushroom): An assessment of in vitro anti-atherosclerotic bio-functionality

Mushrooms have been highly regarded as possessing enormous nutritive and medicinal values. In the present study, we evaluated the anti-oxidative and anti-atherosclerotic potential of shiitake mushroom (Lentinula edodes) using its solvent–solvent partitioned fractions that consisted of methanol:dichloromethane (M:DCM), hexane (HEX), dichloromethane (DCM), ethyl acetate (EA) and aqueous residue (AQ). The hexane fraction (1 mg/mL) mostly scavenged (67.38%, IC₅₀ 0.55 mg/mL) the 2,2-diphenyl-1-picryl hydrazyl (DPPH) free radical, contained the highest reducing capacity (60.16 mg gallic acid equivalents/g fraction), and most potently inhibited lipid peroxidation (67.07%), low density lipo-protein oxidation and the activity of 3-hydroxy 3-methyl glutaryl co-enzyme A reductase (HMGR). GC–MS analyses of the hexane fraction identified α-tocopherol (vitamin E), oleic acid, linoleic acid, ergosterol and butyric acid as the bio-functional components present in L. edodes. Our findings suggest that L. edodes possesses anti-atherosclerotic bio-functionality that can be applied as functional food-based therapeutics against cardiovascular diseases.     

Phytochemical screening of flavonoids with their antioxidant activities from rapeseed (Brassica napus L.)

Ten flavone compounds, including three new flavonoid glycosides, were isolated from defatted rapeseed, and their protective antioxidant effect on H₂O₂-induced oxidative damage in human umbilical vein endothelial cells (ECV-304) was investigated. Three new flavonoid glycosides were identified as kaempferol-3-O-[(6-O-sinapoyl)-β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranoside]-7-O-β-d-glucopyranoside (8), kaempferol-3,7-di-O-β-d-glucopyranoside-4'-O-(6-O-sinapoyl)-β-d-glucopyranoside (9), and kaempferol-3-O-[(3-O-sinapoyl)-β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranoside]-7-O-β-d-glucopyranoside (10). The protective effects of all of the isolated compounds on H₂O₂-induced oxidative damage were assessed, and the activities of superoxide dismutase (SOD) and lactate dehydrogenase (LDH) were measured. All of compounds had a protective effect on H₂O₂-induced oxidative damage in ECV-304 cells and the presence of a substituted sinapoyl group and its position in the structures were used to elucidate the activity differences.     

Novel dammarane saponins from Gynostemma pentaphyllum and their cytotoxic activities against HepG2 cells

Two new dammarane saponins, 2α,3β,12β-trihydroxydammar-20(22),24-diene-3-O-[β-d-glucopyranoxyl(1→2)-β-d-6″-O-acetylglucopyranoside (1, namely damulin C) and 2α,3β,12β-trihydroxydammar-20(21),24-diene-3-O-[β-d-glucopyranoxyl(1→2)-β-d-6″-O-acetylglucopyranoside (2, namely damulin D), were isolated from the ethanol extract of Gynostemma pentaphyllum, which had been heat processed by steaming at 125 °C. The NMR spectroscopic data of the novel saponins were completely assigned by using a combination of 2D NMR experiments including ¹H–¹H COSY, HSQC, and HMBC. Their cytotoxic activities of human liver adenocarcinoma HepG2 cells were evaluated in vitro. They showed cytotoxicities against HepG2 cell line with IC₅₀ of 40 ± 0.7 and 38 ± 0.5 μg/ml, respectively.     

Three new flavonoid glycosides from the aerial parts of Graptophyllum grandulosum Turril (Acanthaceae)

Grandulosides A-C, three new flavonoid glycosides, were isolated from the aerial parts of Graptophyllum grandulosum Turill and identified as chrysoeriol-7-O-β-d-apiofuranosyl-(1 → 2)-β-d-xylopyranoside (1), chrysoeriol-7-O-[4′′′-O-acetyl-β-d-apiofuranosyl-(1 → 2)]-β-d-xylopyranoside (2) and 7-O-α-l-rhamnopyranosyl-(1 → 6)-β-d-(4′′-Sodium hydrogeno sulfate) glucopyranoside (3). Four known compounds, chrysoeriol-7-O-β-d-xyloside (4), isorhamnetin-3-O-α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside (5), luteolin-7-O-β-d-apiofuranosyl-(1 → 2)-β-d-xylopyranoside (6) and sucrose (7) were also obtained. The structures of these compounds were established by interpretation of their spectral data, mainly HR-TOFESIMS, 1D-NMR (¹H, ¹³C) and 2D-NMR (COSY, NOESY, HSQC and HMBC) and by comparison with the literature data.     

An ozone response relationship for four Phleum pratense genotypes based on modelling of the phytotoxic ozone dose (POD)

In the last decade extensive research has focused on the development of dose–response relationships based on stomatal plant ozone uptake (phytotoxic ozone dose, POD). So far most work has concentrated on crops and forest trees. This study provides a flux-based dose–response function for timothy (Phleum pratense), a widespread grassland species, which can be used in risk assessment for ground-level ozone. In 1996 and 2001 timothy was exposed in open-top chambers to ozone concentrations ranging from around 10 nmol mol⁻¹ in the charcoal filtered treatments up to 60 nmol mol⁻¹ in the fumigated treatments (08:00–20:00) in. In 1996 there was a negative effect of ozone on biomass production in the non-filtered treatment while in 2001 no such ozone effect in the non-filtered treatment could be seen. Measurements of stomatal conductance on four timothy genotypes in 2001 were used to calibrate a Jarvis-type multiplicative stomatal conductance model. The maximum conductance varied between the genotypes, from 477 to 589 mmol O₃ m⁻² s⁻¹ (projected leaf area). The model includes functions describing the reduction of stomatal conductance of senescing leaves and the direct effects on stomatal conductance by light, temperature and water vapour pressure deficit. A function describing ozone induced senescence of the leaves was included since exposure to ozone is known to cause premature senescence. The function for ozone was applied when it suggested ozone to be more limiting to stomatal conductance than phenology. To avoid overestimation of stomatal conductance in days with high VPD, a function reflecting the effect on leaf water potential on stomatal conductance was included. Comparison between modelled and measured conductance for the four timothy genotypes resulted in an r² value at 0.57 and a very small average deviation of observed from modelled values. The calibrated stomatal conductance model was used to estimate the accumulated POD, i.e. the accumulated stomatal flux of ozone, of the plants in the 1996 and 2001 experiments. The strongest relationship between ozone relative effects on biomass was obtained when POD was accumulated from 105 degree days after emergence to 1000 degree days after emergence, and integrated using an uptake rate threshold of 7 nmol m⁻² s⁻¹ (POD₇). The response relationship between biomass and POD₇ resulted in an r² value of 0.71 over all four genotypes. This r² value was somewhat higher than for the corresponding relationship based on the accumulated ozone exposure over 40 nmol mol⁻¹ (AOT40; r² = 0.66). With an uptake rate threshold at 7 nmol m⁻² s⁻¹, ozone concentrations above ∼20 nmol mol⁻¹, contribute to reduce the biomass production of timothy if meteorological conditions promote maximum stomatal conductance.