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Tricin [5,7-dihydroxy-2-(4-hydroxy-3,5-dimethoxyphenyl)-4H-chromen-4-one] is a flavone that has been found to be incorporated in grass lignin polymers via 4′–O–β coupling. Herein, we investigated the tricin-lignin structure using nuclear magnetic resonance (NMR) methods by comparing the 1H–13C heteronuclear correlation (HSQC) NMR spectra of the isolated lignin with a series of dimeric and trimeric tricin-4′–O–β-ether model compounds. Results showed that the tricin moiety significantly affects the chemical shift of the Cβ/Hβ of 4′–O–β unit, producing peaks at around δC/δH 82.5–83.5/4.15–4.45, that differ from the Cβ/Hβ correlations from normal 4–O–β units formed solely by monolignols, and that have to date been unassigned., The authors thank the China Scholarship Council, State Education Department, for supporting living expenses for Wu Lan’s Program in the Department of Biological System Engineering, University of Wisconsin, Madison. W.L., F.Y., F.L., and J.R. (John Ralph) were funded by the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science DE-FC02-07ER64494 and DE-SC0018409). J.R. (Jorge Rencoret) and J.C.d.R. were funded by the Spanish Projects CTQ2014-60764-JIN and AGL2017-83036-R (co-financed by FEDER funds).

Termites represent one of the most efficient lignocellulose decomposers on earth. The mechanism by which termites overcome the recalcitrant lignin barrier to gain access to embedded polysaccharides for assimilation and energy remains largely unknown. In the present study, softwood, hardwood, and grass lignocellulose diets were fed to Coptotermes formosanus workers, and structural differences between the original lignocellulose diets and the resulting feces were examined by solution-state multidimensional nuclear magnetic resonance (NMR) techniques as well as by complementary wet-chemical methods. Overall, our data support the view that lignin polymers are partially decomposed during their passage through the termite gut digestive system, although polysaccharide decomposition clearly dominates the overall lignocellulose deconstruction process and the majority of lignin polymers remain intact in the digestive residues. High-resolution NMR structural data suggested preferential removal of syringyl aromatic units in hardwood lignins, but non-acylated guaiacyl units as well as tricin end-units in grass lignins. In addition, our data suggest that termites and/or their gut symbionts may favor degradation of C–C-bonded β–5 and resinol-type β–β lignin inter-monomeric units over degradation of ether-bonded β–O–4 units, which is in contrast to what has been observed in typical lignin biodegradation undertaken by wood-decaying fungi.

New environmentally sound technologies are needed to derive valuable compounds from renewable resources. Lignin, an abundant polymer in terrestrial plants comprised predominantly of guaiacyl and syringyl monoaromatic phenylpropanoid units, is a potential natural source of aromatic compounds. In addition, the plant secondary metabolite tricin is a recently discovered and moderately abundant flavonoid in grasses. The most prevalent interunit linkage between guaiacyl, syringyl, and tricin units is the β-ether linkage. Previous studies have shown that bacterial β-etherase pathway enzymes catalyze glutathione-dependent cleavage of β-ether bonds in dimeric β-ether lignin model compounds. To date, however, it remains unclear whether the known β-etherase enzymes are active on lignin polymers. Here we report on enzymes that catalyze β-ether cleavage from bona fide lignin, under conditions that recycle the cosubstrates NAD + and glutathione. Guaiacyl, syringyl, and tricin derivatives were identified as reaction products when different model compounds or lignin fractions were used as substrates. These results demonstrate an in vitro enzymatic system that can recycle cosubstrates while releasing aromatic monomers from model compounds as well as natural and engineered lignin oligomers. These findings can improve the ability to produce valuable aromatic compounds from a renewable resource like lignin. IMPORTANCE Many bacteria are predicted to contain enzymes that could convert renewable carbon sources into substitutes for compounds that are derived from petroleum. The β-etherase pathway present in sphingomonad bacteria could cleave the abundant β–O–4-aryl ether bonds in plant lignin, releasing a biobased source of aromatic compounds for the chemical industry. However, the activity of these enzymes on the complex aromatic oligomers found in plant lignin is unknown. Here we demonstrate biodegradation of lignin polymers using a minimal set of β-etherase pathway enzymes, the ability to recycle needed cofactors (glutathione and NAD + ) in vitro , and the release of guaiacyl, syringyl, and tricin as depolymerized products from lignin. These observations provide critical evidence for the use and future optimization of these bacterial β-etherase pathway enzymes for industrial-level biotechnological applications designed to derive high-value monomeric aromatic compounds from lignin.

Background The white-rot fungi Ceriporiopsis subvermispora (Cs), Pleurotus eryngii (Pe), and Lentinula edodes (Le) have been shown to be high-potential species for selective delignification of plant biomass. This delignification improves polysaccharide degradability, which currently limits the efficient lignocellulose conversion into biochemicals, biofuels, and animal feed. Since selectivity and time efficiency of fungal delignification still need optimization, detailed understanding of the underlying mechanisms at molecular level is required. The recently developed methodologies for lignin quantification and characterization now allow for the in-depth mapping of fungal modification and degradation of lignin and, thereby, enable resolving underlying mechanisms. Results Wheat straw treated by two strains of Cs (Cs1 and Cs12), Pe (Pe3 and Pe6) and Le (Le8 and Le10) was characterized using semi-quantitative py-GC–MS during fungal growth (1, 3, and 7 weeks). The remaining lignin after 7 weeks was quantified and characterized using 13C lignin internal standard based py-GC–MS and whole cell wall HSQC NMR. Strains of the same species showed similar patterns of lignin removal and degradation. Cs and Le outperformed Pe in terms of extent and selectivity of delignification (Cs ≥ Le >> Pe). The highest lignin removal [66% (w/w); Cs1] was obtained after 7 weeks, without extensive carbohydrate degradation (factor 3 increased carbohydrate-to-lignin ratio). Furthermore, though after treatment with Cs and Le comparable amounts of lignin remained, the structure of the residual lignin vastly differed. For example, Cα-oxidized substructures accumulated in Cs treated lignin up to 24% of the total aromatic lignin, a factor two higher than in Le-treated lignin. Contrarily, ferulic acid substructures were preferentially targeted by Le (and Pe). Interestingly, Pe-spent lignin was specifically depleted of tricin (40% reduction). The overall subunit composition (H:G:S) was not affected by fungal treatment. Conclusions Cs and Le are both able to effectively and selectively delignify wheat straw, though the underlying mechanisms are fundamentally different. We are the first to identify that Cs degrades the major β-O-4 ether linkage in grass lignin mainly via Cβ–O–aryl cleavage, while Cα–Cβ cleavage of inter-unit linkages predominated for Le. Our research provides a new insight on how fungi degrade lignin, which contributes to further optimizing the biological upgrading of lignocellulose.

Milled wood lignins were isolated from green and yellow bamboo (Phyllostachys pubescens), termed MWLg and MWLy, respectively. The structural features of the lignin preparations and the remaining LCC were characterized by quantitative 13C nuclear magnetic resonance (13C NMR) spectroscopy and two-dimensional heteronuclear signal quantum coherence NMR (2D HSQC NMR) spectroscopy. The results indicated that the main substructures in MWLg and MWLy were β-O-4 alkyl-aryl ether, resinol, phenylcoumaran, spirodienone, and α,β-diaryl ether, and their abundances per 100 Ar units were 38.2 and 39.8, 6.9 and 6.3, 3.8 and 2.9, 1.7 and 2.1, 0.4 and 0.3, respectively. The S:G:H ratios of MWLg and MWLy were estimated to be 40:54:6 and 51:44:5, respectively. The γ-acylation of green bamboo lignin was 17.22%, lower than that of yellow bamboo lignin (21.12%). Moreover, a flavonoid compound (tricin) was also detected in the MWLg and MWLy. Some carbohydrates remained in the purified MWL preparations, which were considered as th...

Flavonolignans are plant natural products, composed of a flavonoid moiety and a lignan (phenylpropanoid) part. Current literature focuses on flavonolignans formed from taxifolin and coniferyl alcohol as e.g. silybin and its congeners from fruit extract from the purple variety of the milk thistle (Silybum marianum) denoted as "silymarin". This review describes chemistry and biological activity of so far neglected "non-taxifolin" based flavonolignans, derived from apigenin, luteolin, tricin, chrysoeriol, naringenin and eriodictyol, as the flavonoid part. Up-to-date knowledge on hydnocarpin, hydnocarpin-D, pseudotsuganol, hydnowightin, neohydnocarpin, palstatin, salcolins A and B, anastatins A and B, sinaiticin, silyamandin and silandrin is summarized in the present paper. Most of non-taxifolin derived flavonolignans have been shown to exhibit in vitro and/or in vivo anti-hepatotoxic, anti-oxidant, free radical scavenging, anti-inflammatory, anti-proliferative, anti-cancer, chemotherapy potentiating, anti-melanogenic, anti-bacterial, vasorelaxing, anti-platelet aggregation and/or hypotriglyceridemic activity, often stronger than silybin. Many of these compounds inhibited Staphylococcus aureus multidrug resistance pump NorA and sensitized multidrug resistant cancer cell lines showing a potential as adjuvants. Non-taxifolin derived flavonolignans are a relatively unexplored group of compounds with interesting biological activity and great application potential. Their detailed study could provide a new insight into the biomimetic synthesis in order to obtain new compounds with greater activity and identify new lead structures for the biomedicinal research.

The solubility of tricin in water and ethanol mixtures was measured over the temperature range of (288.15 to 328.15) K. The concentrations of tricin in the aqueous mixtures were assayed by the ultraviolet spectrophotometric method. The experimental solubility data indicated that the solubility of tricin increases with an increase in temperature and an enrichment in ethanol content. The two models, including the modified Apelblat equation and λh equation were used to correlate the experimental solubility data. The calculated solubility of tricin shows good agreement with the experimental results. Additionally, the estimation of thermodynamic properties including the activity coefficients, dissolution enthalpy, and entropy were obtained from the experimental data. Within the studied temperature range the dissolution process of tricin is endothermic, and the driving force is the entropy.

The phenolic allelochemicals from the root exudates of Johnson grass (Sorghum halepense) were collected at different developmental stages and analyzed using high performance liquid chromatography-ultraviolet/photo-diode array. The results revealed that three simple phenolic components, p-hydroxybenzoic acid, p-hydroxybenzaldehyde and ethyl p-hydroxybenzoate, along with two flavonoids, diosmetin (3′,5,7-trihydroxy-4′-methoxyflavone) and tricin (5,7,4′-trihydroxy-3′,5′-dimethoxyflavone), were found in the root exudates of Johnson grass. However, the major phenolic compounds varied and the quality of each compound was dynamic at different developmental stages: the only phenolic compound that was detected in the seedling stage was p-hydroxybenzoic acid; three simple phenolic allelochemicals, p-hydroxybenzoic acid, p-hydroxybenzaldehyde and ethyl p-hydroxybenzoate, were found in the jointing stage; and five compounds, including the two flavonoids, tricin and diosmetin, appeared in the reproductive stage along with the other three simple phenolic allelochemicals. The highest diversity in phenolic constituents was in the reproductive stage, with five allelochemicals. Only p-hydroxybenzoic acid was found in the whole life cycle of Johnson grass, with a range of 2.9 nmol to 6.8 nmol per plant per day. p-Hydroxybenzaldehyde had the highest quality among all the compounds, with the highest releasing rate of 26.8 nmol per plant per day. The lowest-content compounds were the two flavonoids, with the highest quality of 1.8 nmol per plant per day. The results suggest that the temporal dynamic of phenolic allelochemicals in the root exudates of Johnson grass corresponds with the dynamic of development.

Njavara is an indigenous medicinal rice variety traditionally used in Ayurvedic system of medicine practiced in Kerala, India. Tricin is a bioflavonoid present in significantly higher levels in rice bran of Njavara. Present study attempted to identify the molecular target of tricin in TLR mediated signaling pathways by using lipopolysaccharide (LPS) induced human peripheral blood mononuclear cells (hPBMCs) and carrageenan induced paw edema in rats as experimental models. Tricin acted upstream in the activation of inflammation cascade by interfering with TLR4 activation, preferably by blocking the LPS induced activation of TLR4, MYD88 and TRIF proteins in hPBMCs. Subsequently, tricin significantly blocked the activation of downstream kinases like p38MAPK, JNK1/2 and IRF3. Thus the inhibitory effect of tricin on NF-κB and IRF3 together confirms the specific inhibition of both MYD88 dependent and TRIF dependent pathways. Tricin treatment also inhibited the pro-inflammatory effect of LPS by blocking the TLR4 signaling mediated activation of cytosolic phospholipase A2 (cPLA2), which is confirmed by specific inhibition of COX-2. Results demonstrated that in addition to NF-κB, tricin can prevent the activation of STAT proteins by significantly inhibiting the activation of both STAT1 and STAT3 via the down regulation of upstream phosphorylating enzymes like JAK1 and JAK2. The protective anti-inflammatory effect of tricin was also confirmed by in vivo experiments. Thus, this study provides strong evidence that tricin exerts its anti-inflammatory effect via a mechanism involving the TLR4/NF-κB/STAT signaling cascade.

Coumarate 3-hydroxylase (C3H) catalyzes a key step of the synthesis of the two main lignin subunits, guaiacyl (G) and syringyl (S) in dicotyledonous species. As no functional data are available in regards to this enzyme in monocotyledonous species, we generated C3H1 knock-down maize plants. The results obtained indicate that C3H1 participates in lignin biosynthesis as its down-regulation redirects the phenylpropanoid flux: as a result, increased amounts of p-hydroxyphenyl (H) units, lignin-associated ferulates and the flavone tricin were detected in transgenic stems cell walls. Altogether, these changes make stem cell walls more degradable in the most C3H1-repressed plants, despite their unaltered polysaccharide content. The increase in H monomers is moderate compared to C3H deficient Arabidopsis and alfalfa plants. This could be due to the existence of a second maize C3H protein (C3H2) that can compensate the reduced levels of C3H1 in these C3H1-RNAi maize plants. The reduced expression of C3H1 alters the macroscopic phenotype of the plants, whose growth is inhibited proportionally to the extent of C3H1 repression. Finally, the down-regulation of C3H1 also increases the synthesis of flavonoids, leading to the accumulation of anthocyanins in transgenic leaves., Funding: This work was supported by the Spanish “Ministerio de Economía y Competitividad” [AGL2011-30545-C02-01 to D.C.-R., AGL2011-30545-C02-02 to A.E., and AGL2011-25379 (co-financed by FEDER funds) to J.C.R.] and received financial support from the CONSOLIDER-INGENIO program [CSD2007-00036] from the Spanish Ministerio de Ciencia e Innovación. This work was carried out within the framework of the “Xarxa de Referència de Biotecnologia” (XarBa) from the Autonomous Government of Catalonia. R.S. was financed by the postdoctoral contracts “Isidro Parga Pondal” supported by the Autonomous Government of Galicia and the European Social Fund and “Ramón y Cajal”, supported by the Spanish Ministry of Economy and Competitiveness and the University of Vigo. J.R. thanks CSIC for a JAE-DOC contract of the program “Junta para la Ampliación de Estudios” co-financed by the European Social Fund.

Flavones are ubiquitously accumulated in land plants, but their biosynthesis in monocots remained largely elusive until recent years. Recently, we demonstrated that the rice (Oryza sativa) cytochrome P450 enzymes CYP93G1 and CYP93G2 channel flavanones en route to flavone O-linked conjugates and C-glycosides, respectively. In tricin, the 3′,5′-dimethoxyflavone nucleus is formed before O-linked conjugations. Previously, flavonoid 3′,5′-hydroxylases belonging to the CYP75A subfamily were believed to generate tricetin from apigenin for 3′,5′-O-methylation to form tricin. However, we report here that CYP75B4 a unique flavonoid B-ring hydroxylase indispensable for tricin formation in rice. A CYP75B4 knockout mutant is tricin deficient, with unusual accumulation of chrysoeriol (a 3′-methoxylated flavone). CYP75B4 functions as a bona fide flavonoid 3′-hydroxylase by restoring the accumulation of 3′-hydroxylated flavonoids in Arabidopsis (Arabidopsis thaliana) transparent testa7 mutants and catalyzing in vitro 3′-hydroxylation of different flavonoids. In addition, overexpression of both CYP75B4 and CYP93G1 (a flavone synthase II) in Arabidopsis resulted in tricin accumulation. Specific 5′-hydroxylation of chrysoeriol to selgin by CYP75B4 was further demonstrated in vitro. The reaction steps leading to tricin biosynthesis are then reconstructed as naringenin → apigenin → luteolin → chrysoeriol → selgin → tricin. Hence, chrysoeriol, instead of tricetin, is an intermediate in tricin biosynthesis. CYP75B4 homologous sequences are highly conserved in Poaceae, and they are phylogenetically distinct from the canonical CYP75B flavonoid 3′-hydroxylase sequences. Recruitment of chrysoeriol-specific 5′-hydroxylase activity by an ancestral CYP75B sequence may represent a key event leading to the prevalence of tricin-derived metabolites in grasses and other monocots today.

Summary Flavonoids not only play crucial roles in plant development and resistance, but also provide one of the major natural sources in human nutrition. To investigate the distribution of flavonoids in the shoot system of Medicago truncatula, a high-performance liquid chromatography coupled with electrospray ionisation tandem mass spectrometer (HPLC-ESI-MS/MS) method was established and then applied to determine the quantitation of flavonoids in different parts of the plant. There were twenty-two, fifteen and eleven different kinds of flavonoids identified from the flower, leaf and stem of M. truncatula, respectively. The identified constituents were either aglycone or glycosides of the typical flavonoid backbones, such as myricetin, quercetin, luteolin, kaempferol, tricin, apigenin and laricitrin. It was found that the shoot system of M. truncatula can be differentiated by flavonoids in terms of structures and contents. Our results provide instruction to utilise the shoot system of legume crops as fodder and herb medicine in the future.

Tricin (5,7,4′-trihydroxy-3′,5′-dimethoxyflavone) is a valuable secondary metabolite which is widely present in gramineous plants, including cultivated rice (Oryza sativa L.) (Poaceae). It can defend the rice plant against damage by the brown planthopper (BPH), Nilaparvata lugens (Stal) (Hemiptera: Delphacidae), one of the most important pests of rice. This study was conducted to elucidate the mechanisms of action of tricin on BPH feeding behavior. BPH feeding behavior in resistant (Rathu Heenati, RHT) and susceptible (Taichuang native 1, TN1) rice varieties and artificial diets was monitored using the electrical penetration graph (EPG) technique. Tricin concentrations in leaves of varieties RHT and TN1 were quantitatively analyzed by liquid chromatography, coupled to tandem mass spectrometric techniques. Six (NP and N1-5) and four (NP, N1, N2, and N4) types of waveforms occurred during feeding on rice plants and artificial diets, respectively. The tricin concentration of rice varieties was correlated with total and average durations of N4. Moreover, EPG data indicated that tricin significantly increased the duration of non-probing and pathway periods and strongly inhibited phloem ingestion (N4). The inhibition was strongly dose dependent, resulting in complete suppression of activity in the phloem region when the tricin concentration was increased to 1 g l−1. This study revealed that tricin disturbed the feeding behavior of BPH mainly by increasing the non-probe period and inhibiting phloem ingestion. We confirmed the hypothesis that tricin is a ‘stylet probing stimulant’ of rice planthoppers as proposed in previous studies. The information on the ecological effect of tricin from this study may be useful to clarify the resistance mechanism against BPH of RHT and other tricin-containing rice varieties.

In the course to find compounds that inhibit melanin biosynthesis (i.e., whitening agents), we evaluated the effects of the methanol-soluble fraction (i.e., the water-soluble portion of methanol extracts-CHP20P-MeOH eluted fraction) from young green barley leaves on melanin production in B16 melanoma cells. Activity-guided fractionation led to an isolate called tricin (compound 1) as an inhibitory compound of melanin production in B16 melanoma cells. Furthermore, tricin analogs such as tricetin, tricetin trimethyl ether, luteolin, and apigenin were used for analyzing the structure-activity relationships (SAR) of 5,7-dihydroxyflavones studies. Tricin demonstrated stronger inhibitory activity compared to three other compounds. The results suggest that a hydroxyl group at the C-4' position and methoxy groups at the C-3',5' positions of the tricin skeleton may have important roles in this inhibitory activity in B16 melanoma cells. Our results suggest that tricin inhibits melanin biosynthesis with higher efficacy than arbutin, and it could be used as a whitening agent.

22 páginas.-- 5 figuras.-- 2 tablas.-- 58 referencias.-- Supplemental Data inhttp://www.plantphysiol.org/content/167/4/1284/suppl/DC1, Open access.-- Artículo en acceso abierto, © 2014 American Society of Plant Biologists. All Rights Reserved. Tricinwas recentlydiscoveredinligninpreparations fromwheat (Triticum aestivum) strawandsubsequentlyinallmonocotsamplesexamined. To provide proof that tricin is involved in lignification and establish the mechanism bywhich it incorporates into the lignin polymer, the 4¢-O-b coupling products of tricinwith themonolignols (p-coumaryl, coniferyl, and sinapyl alcohols) were synthesized alongwith the trimer that would result fromits 4¢-O-b-couplingwith sinapyl alcohol and then coniferyl alcohol. Tricinwas also found to cross couplewithmonolignols to form tricin-(4¢-O-b)-linked dimers in biomimetic oxidations using peroxidase/hydrogen peroxide or silver (I) oxide. Nuclear magnetic resonance characterization of gel permeation chromatography-fractionated acetylated maize (Zeamays) lignin revealed that the tricinmoieties are found in even the highestmolecularweight fractions, ether linked to lignin units, demonstrating that tricin is indeed incorporated into the lignin polymer.Thesefindingssuggest that tricin is fullycompatiblewithlignification reactions, isanauthentic ligninmonomer, and,because it can only start a lignin chain, functions as a nucleation site for lignification in monocots. This initiation role helps resolve a long-standing dilemma that monocot lignin chains do not appear to be initiated by monolignol homodehydrodimerization as they are in dicots that have similar syringyl-guaiacyl compositions. The term flavonolignin is recommended for the racemic oligomers and polymers ofmonolignols that start from tricin (or incorporate other flavonoids) in the cell wall, in analogy with the existing term flavonolignan that is used for the lowmolecular mass compounds composed of flavonoid and lignan moieties., This work was supported by the Department of Energy Great Lakes Bioenergy Research Center (grant no. DE–FC02–07ER64494) and the Multidisciplinary Research Partnership Biotechnology for a Sustainable Economy (grant no. 01MRB510W) of Ghent University.

The structure of the lignin from brewer’s spent grain (BSG) has been studied in detail. Three different lignin preparations, the so-called “milled-wood” lignin (MWL), dioxane lignin (DL), and cellulolytic lignin (CEL), were isolated from BSG and then thoroughly characterized by pyrolysis GC/MS, 2D-NMR, and derivatization followed by reductive cleavage (DFRC). The data indicated that BSG lignin presents a predominance of guaiacyl units (syringyl/guaiacyl ratio of 0.4−0.5) with significant amounts of associated p-coumarates and ferulates. The flavone tricin was also present in the lignin from BSG, as also occurred in other grasses. 2D-NMR (HSQC) revealed that the main substructures present are β-O-4′ alkyl-aryl ethers (77−79%) followed by β-5′ phenylcoumarans (11−13%) and lower amounts of β-β′ resinols (5−6%) and 5-5′ dibenzodioxocins (3−5%). The results from 2D-NMR (HMBC) and DFRC indicated that p-coumarates are acylating the γ-carbon of lignin side chains and are mostly involved in condensed structures. DFRC analyses also indicated a minor degree of γ-acylation with acetate groups, which takes place preferentially on S lignin (6% of S units are acetylated) over G lignin (only 1% of G units are acetylated)., This study has been funded by the Spanish Project AGL2011-25379 (cofinanced by FEDER funds) and the EU Project LIGNODECO (KBBE-244362). J.R. thanks the CSIC for a JAE-DOC contract of the program “Junta para la Ampliación de Estudios” cofinanced by Fondo Social Europeo (FSE). P.P. thanks the Spanish Ministry of Science and Innovation for an FPI fellowship.

This study was performed to evaluate the enhancement of functional components of germinated rough rice. Rough rice was germinated at 37 °C for 6 days, and subjected to a high hydrostatic pressure treatment (HPT) at 30 MPa for 24 h (HP24) and 48 h (HP48). Germinated rough rice without HPT (HP0), HP24, and HP48 were analysed for their functional components. The highest γ-aminobutyric acid, total arabinoxylan, and tricin 4'-O-(threo-β-guaiacylglyceryl) ether contents were 121.21 mg/100g, 10.6%, and 85.82 μg/g, respectively, after HP48 for 2 days. γ-Oryzanol contents increased from 23.19-36.20 mg/100g (at HP0) to 31.80-40.32 mg/100g (at HP48). The highest vitamin B (60.99 mg/100g) and E (4.07 mg/100g) contents were observed after HP24 for 5 and 2 days, respectively. These results suggest that a combination of HPT and germination efficiently enhances the functional characteristics of rough rice.

Lippia alba is a popular Brazilian herb known as 'cidreira' that presents several chemotypes which exhibit different chemical profile and they are widely used as seasonings and traditional medicine. This work describes the seasonal variation of metabolites of polar extracts of carvone and linalool chemotypes, identified by GC-MS analyses of the essential oils. A methodology was elaborated in order to obtain a seasonal variation in the chemical composition of leaf employing HPLC-DAD. Acteoside, isoacteoside, geneposidic acid, 8-epi-loganin, mussaenoside, luteolin 7-O-glucoside, apigenin 7-O-glucuronide and tricin 7-O-diglucuronide have been isolated and identified for validation procedures and chromatographic analysis. Geneposidic acid was presented in all samples, in contrast to the 8-epi-loganin and, mussaenoside which were presented only in the carvone-chemotype. Acteoside was the major metabolite detected from July to November while tricin-7-O-diglucuronide was the major compound in all other months. Besides, phenylpropanoids are predominant in winter and flavonoids in summer season.

V zadnjem času se razvija vse več okolju ter ljudem prijaznih oblik zaščite lesa. Ena od okolju prijaznih alternativ je tudi termična modifikacija lesa. Ena največjih pomanjkljivosti termične modifikacije je poslabšanje mehanskih lastnosti. Zato smo pred termično modifikacijo les impregnirali še s spojinama bicin ali tricin, da bi videli, če lahko s tem ohranimo odpornost termično modificiranega lesa na vodo in obenem izboljšamo mehanske lastnosti tega lesa. Smrekove in bukove vzorce smo tako zaščitili, nato pa testirali njihove lastnosti. Testirali smo sorpcijske lastnosti, navzem kapilarne vode, stični kot kapljic. Modificiranemu lesu smo določili tudi mehanske lastnosti, in sicer upogibno trdnost, tlačno trdnost in trdoto. Rezultati so pokazali, da impregnacija lesa s tema spojinama pred termično modifikacijo poveča ravnovesno vlažnost in vpijanje kapilarne vode. Mehanske lastnosti se v večini primerov izboljšajo. Lately, more and more environmentally and people friendly types of wood protection are being developed. One of those friendly alternatives is thermal modification of wood. One of the biggest disadvantages of thermal modification is deterioration of mechanical properties. Therefore, prior to thermal modification we impregnated wood with compounds bicine and tricine to see if this can preserve resistance of thermally modified wood to water and at the same time improve its mechanical properties. We impregnated and thermally modificated spruce and beech samples, and then tested their properties. We tested sorption properties, capillary water absorption and contact angle of water. We also determined mechanical properties, namely bending strength, compressive strength and hardness. The results showed that the impregnation of wood with these compounds prior to thermal modification increases moisture content of modified wood and absorption of capillary water. Mechanical properties are improved in most cases.

27 páginas.-- 4 figuras.-- 56 referencias.-- Supplemental Data in version online https://doi.org/10.1104/pp.17.00362, [OPEN] Articles can be viewed without a subscription. www.plantphysiol.org/cgi/doi/10.1104/pp.17.00362, Lignin, the plant cell wall polymer that binds fibers together but makes processing difficult, is traditionally formed from three monomers, the so-called monolignols (p-coumaryl, coniferyl, and sinapyl alcohols). Recently we discovered, in grass lignins, a phenolic monomer that falls outside the canonical lignin biosynthetic pathway, the flavone tricin. As we show here, palm fruit (macaúba, carnauba, and coconut) endocarps contain lignin polymers derived in part from a previously unconsidered class of lignin monomers, the hydroxystilbenes, including the valuable compounds piceatannol and resveratrol. Piceatannol could be released from these lignins upon DFRC, a degradative method that cleaves β-ether bonds, indicating that at least a fraction is incorporated through labile ether bonds. NMR spectroscopy of products from the copolymerization of piceatannol and monolignols confirms the structures in the natural polymer, and demonstrates that piceatannol acts as an authentic monomer participating in coupling and cross-coupling reactions during lignification. Palm fruit endocarps therefore contain a new class of 'stilbenolignin' polymers, further expanding the definition of lignin and implying that compounds such as piceatannol and resveratrol are potentially available in what is now essentially a waste product, J.C.d.R, J.Re., and A.G. were funded by the Spanish projects AGL2014-53730-R and CTQ2014-60764-JIN (co-financed by FEDER funds), and the CSIC project 2014-40E-097; J.Ra. and H.K. were funded by the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science DE-FC02-07ER64494).

Despite increasing knowledge of allelochemicals as leads for new herbicides, relatively little is known about the mode of action of allelochemical-based herbicides on herbicide-resistant weeds. In this study, herbicidal activities of a series of allelochemical tricin-derived compounds were evaluated. Subsequently, a benzothiazine derivative 3-(2-chloro-4-methanesulfonyl)-benzoyl-hydroxy-2-methyl-2H-1,2-benzothiazine-1,1-dioxide with 4-hydroxyphenyl-pyruvate dioxygenase (HPPD) inhibiting activity was identified as a target compound on photosynthetic performance of penoxsulam-resistant versus -susceptible barnyardgrass (Echinochloa crus-galli). Regardless of barnyardgrass biotype, the benzothiazine derivative greatly affected chlorophyll fluorescence parameters (Fv/Fm, ETR1min and NPQ1min), reduced the chloroplast fluorescence levels and expression of HPPD gene. In particular, the benzothiazine derivative interfered with photosynthetic performance of resistant barnyardgrass more effectively than the allelochemical tricin itself. These results showed that the benzothiazine derivative effectively inhibited the growth of resistant barnyardgrass and its mode of action on photosynthesis system was similar to HPPD-inhibiting sulcotrione, making it an ideal lead compound for further development of allelochemical-based herbicide discovery.

The effect of tricin, a methylated flavone widely distributed in cereals, on glucose uptake and the underlying molecular mechanism was investigated using C2C12 myotubes. Tricin significantly increased glucose uptake in C2C12 myotubes, regardless of the absence (1.4-fold at 20 μM) or presence (1.6-fold at 20 μM) of insulin. The GLUT4 expression on the plasma membrane was increased 1.6-fold after tricin treatment (20 μM) in the absence of insulin. Tricin treatment significantly activated the insulin-dependent cell signaling pathway, including the activation of insulin receptor substrate-1 (IRS1), phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), and AKT substrate of 160 kDa (AS160). The oral administration of tricin (64 and 160 mg kg–1 of body weight day–1) also significantly lowered blood glucose levels in glucose-loaded C57BL/6 mice (p < 0.05). These results suggest that tricin has great potential to be used as a functional agent for glycemic control.

Background In previous investigation, we have identified antioxidative effects of water-soluble ethanolic extracts (named as AKE) from Arenaria kansuensis and inferred that these extracts or their constituents may also have antihypoxic activity. A. kansuensis has been widely used in traditional Tibetan medicine for altitude sickness (AS) and has been known as the herb of anti-inflammatory and hypoxia resistance for a long time. Purpose The purpose of this study is to evaluate protective effects of AKE and its major constituents against hypoxia-induced lethality in mice and RSC96 cells. Study design and methods Hypoxia-induced lethality in mice was investigated by 3 experimental animal models of hypoxia. Meanwhile, we established a RSC96 cell model of hypoxia which applied to screen and assess the anti-hypoxic activity of compounds isolated from A. kansuensis. Results Results indicated that AKE dose-dependently prolonged survival time of hypoxia induced lethality in mice compared to vehicle group and exhibited significantly anti-hypoxic effect. AKE also enhanced the number of red blood cells (RBC) and the concentration of hemoglobin (HB). 8 compounds were bio-guided separated and purified from AKE based on the animal model and cell model of hypoxia. Among which pyrocatechol (C16) and tricin 7-O-β- d -glucopyranoside (C13) were confirmed to express better protective effects on cell damage induced by hypoxia, suggesting that these two compounds are major active constituents of AKE for anti-hypoxia. Conclusion This study demonstrated that pyrocatechol and tricin 7-O-β- d -glucopyranoside could be therapeutic candidates for treatment of AS. It is the first time to find the major active constituents of AKE for anti-hypoxia. Meanwhile, a RSC96 cell model of hypoxia was established to screen anti-hypoxic activity of compounds for the first time.

Elymus natans, a perennial gramineous grass, plays an important role in animal husbandry and environmental sustenance in the Qinghai–Tibet plateau as a result of its high forage quality and good adaptability to the local environment. A bioassay showed that the extracts of green grasses of E. natans (GG) exhibited stronger phytotoxic activities than withered grasses (WG) against crops and grasses. In view of the secondary metabolites, which may be responsible for the resistance of the plant, the chemical components of GG were investigated. The flavone tricin, E1, and 10 flavonolignans, E2–E11, including three new flavonolignans, E2, E10, and E11, were isolated and identified. As far as we know, this is the first report on the chemical constitutions of the plant until now. The contents of compounds E1 and E4–E7 in GG were significantly higher than those in WG in high-performance liquid chromatography analysis, and they also showed observably phytotoxic activities against lettuce and Festuca arundinacea.

This study aimed to evaluate the in vitro activity of D. insularis extracts and fractions against gastrointestinal nematodes of goats and its cytotoxicity on Vero cells. The egg hatch (EHT) and larval motility (LMT) tests were conducted to investigate the anthelmintic effects of the crude hydroethanolic (CH), ethyl acetate (EA), butanolic (BT) and residual hydroethanolic (RH) extracts. The elution of the active extract (EA) on column chromatography (SiO2) using organic solvents furnished six fractions (FR1 to FR6), which were also tested. Cytotoxicity was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Trypan Blue exclusion assays. All extracts, FR2 and FR3, inhibited egg hatching in a concentration-dependent manner. The EHT led to EC50 values (effective concentration 50%) of 0.64; 0.69; 0.77; 0.96; 0.27 and 0.65 mg/mL for CH, EA, BT, RH, FR2 and FR3, respectively. However, the extracts exhibited low effect on the motility of L3. In the cytotoxicity evaluation (MTT assay), the IC50 (inhibitory concentration 50%) was 1.18 (EA), 1.65 (FR2) and 1.59 mg/mL (FR3), which was relatively high (low toxicity) in comparison to the EC50 values in EHT, mainly for FR2. The chemical analyses of most active fractions (FR2) by Liquid Chromatography coupled to Mass Spectrometry (LC–MS) led the characterization of the flavones tricin and diosmetin. These results showed the high anthelmintic effect and low cytotoxicity of D. insularis and also that the flavones can be probably responsible for the nematocidal activity of this plant.

© 2017, Public Library of Science, All rights reserved. This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication. Lignin in plant biomass represents a target for engineering strategies towards the development of a sustainable bioeconomy. In addition to the conventional lignin monomers, namely p-coumaryl, coniferyl and sinapyl alcohols, tricin has been shown to be part of the native lignin polymer in certain monocot species. Because tricin is considered to initiate the polymerization of lignin chains, elucidating its biosynthesis and mechanism of export to the cell wall constitute novel challenges for the engineering of bioenergy crops. Late steps of tricin biosynthesis require two methylation reactions involving the pathway intermediate selgin. It has recently been demonstrated in rice and maize that caffeate O-methyltransferase (COMT) involved in the synthesis syringyl (S) lignin units derived from sinapyl alcohol also participates in the synthesis of tricin in planta. In this work, we validate in sorghum (Sorghum bicolor L.) that the O-methyltransferase responsible for the production of S lignin units (SbCOMT / Bmr12) is also involved in the synthesis of lignin-linked tricin. In particular, we show that biomass from the sorghum bmr12 mutant contains lower level of tricin incorporated into lignin, and that SbCOMT can methylate the tricin precursors luteolin and selgin. Our genetic and biochemical data point toward a general mechanism whereby COMT is involved in the synthesis of both tricin and S lignin units.

5 páginas.-- 5 figuras.-- 18 referencias.-- Comunicación oral presentada en el 19th International Symposium on Wood, Fibre and Pulping Chemistry, Aug. 28-Sept. 01, 2017. Porto Seguro, BA, Brazil., Lignin is a phenylpropanoid polymer derived from the oxidative radical coupling of three phydroxycinnamyl alcohols, the so-called monolignols: p-coumaryl, coniferyl, and sinapyl alcohols. Several other phenolic compounds, all deriving from the shikimate-derived monolignol biosynthetic pathway, have been found to behave as lignin monomers in many plants, including the monolignol ester conjugates (with acetate, p-coumarate, ferulate and p-hydroxybenzoate) or the incompletely methylated monomers caffeyl and 5-hydroxyconiferyl alcohols, among others. However, recent studies have demonstrated the occurrence of polyphenolic compounds derived from other biosynthetic pathways in the lignins of several plants. This is the case for the flavone tricin recently established as a monomer in the lignins from grasses and other monocots or the newly discovered hydroxystilbenes (resveratrol, isorhapontigenin and piceatannol) that are implicated as monomers in the lignification of palm fruit endocarps. The discovery of ‘non-conventional’ phenolic precursors arising from other biosynthetic pathways expands the traditional definition of lignin and reveals that any phenolic compound that are delivered to the cell wall may be oxidized and incorporated into the lignin polymer during lignification., This study has been funded by the Spanish projects AGL2014-53730-R and CTQ2014-60764-JIN (cofinanced by FEDER funds) and the CSIC project 2014-40E-097. John Ralph and Hoon Kim were funded by the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science DE-FC02-07ER64494).

A unique process for the fractionation of lignin from wheat straw is proposed: Ball milling for 8 h, followed by a direct and an acidolysis-assisted dioxane–water extraction. Four distinctly different lignin structures were thus obtained: (1) one free non-core lignin, which is a cellulose–lignin with lowest molar mass and highest contents of p -hydroxycinnamic acids, condensed phenolic hydroxyl groups and tricin moieties, and with a detectable amount of cinnamyl alcohols; (2) two core xylan–lignins differing in their degree of branching as indicated by their xylose/arabinose ratios of >4 and ∼2, respectively; (3) one core cellulose–lignin which is the residual fraction resistant to all extractions. Based on the mass balance of Klason lignin the yields of these four fractions are 13.8%, 18.1%, 37.5% and 12.5%, respectively, thus accounting for 82% of the total KL in wheat straw. Therefore, the isolated lignin fractions could be considered as highly representative allowing a good insight into the different features of wheat straw lignin.

Polar and non-polar extracts of Njavara yellow rice (NYr) and bran (NYb) were investigated for antioxidant activity, chemical indices, anti-inflammatory effects, and bioactive compounds, of which the results were compared between the 2 staple varieties Uma and Jaya. Methanol extracts of NYb showed significantly (p

PaulowniatomentosaSteud flowers have been used for many therapeutic purposes in traditional pharmacopeia. The components of the extract ofPaulowniatomentosaSteud flowers were separated using ethanol elution. The antioxidant properties of different components (20% component, 40% component, 60% component, and 80% component) and synthetic antioxidants (BHA and BHT) were evaluated by scavenging DPPH, superoxide anions, and hydroxyl radical methods. All components showed strong antioxidant properties, especially the 60% component, which exhibited excellent antioxidant activity. These components may be developed for use as natural antioxidants. The main compounds in these components were identified using UPLC-TOF-MS/MS and UV spectra analysis. Two compounds, abscisic acid and t-abscisic acid, were found in the 20% component. Five compounds, t-abscisic acid, luteolin, apigenin, tricin, and 4′,5,7-trihydroxy-3′-methoxyflavone, were found in the 40% component. Three compounds, t-abscisic acid, apigenin and 4′,5,7-trihydroxy-3′-methoxyflavone, were found in the 60% component. Six compounds, luteolin, apigenin, 4′,5,7-trihydroxy-3′-methoxyflavone, paulownin, 3'-methyldiplacol, and diplacone, were found in the 80% component. The antioxidant activity of these components can be attributed to the main chemical composition of the components of the extract ofPaulowniatomentosaSteud flowers.

Flavones are a major class of flavonoids with a wide range of physiological functions in plants. They are constitutively accumulated as C-glycosides and O-linked conjugates in vegetative tissues of grasses. It has long been presumed that the two structural modifications of flavones occur through independent metabolic routes. Previously, we reported that cytochrome P450 93G2 (CYP93G2) functions as a flavanone 2-hydroxylase (F2H) that provides 2-hydroxyflavanones for C-glycosylation in rice (Oryza sativa). Flavone C-glycosides are subsequently formed by dehydratase activity on 2-hydroxyflavanone C-glycosides. On the other hand, O-linked modifications were proposed to proceed after the flavone nucleus is generated. In this study, we demonstrate that CYP93G1, the closest homolog of CYP93G2 in rice, is a bona fide flavone synthase II (FNSII) that catalyzes the direct conversion of flavanones to flavones. In recombinant enzyme assays, CYP93G1 desaturated naringenin and eriodictyol to apigenin and luteolin, respectively. Consistently, transgenic expression of CYP93G1 in Arabidopsis (Arabidopsis thaliana) resulted in the accumulation of different flavone O-glycosides, which are not naturally present in cruciferous plants. Metabolite analysis of a rice CYP93G1 insertion mutant further demonstrated the preferential depletion of tricin O-linked flavanolignans and glycosides. By contrast, redirection of metabolic flow to the biosynthesis of flavone C-glycosides was observed. Our findings established that CYP93G1 is a key branch point enzyme channeling flavanones to the biosynthesis of tricin O-linked conjugates in rice. Functional diversification of F2H and FNSII in the cytochrome P450 CYP93G subfamily may represent a lineage-specific event leading to the prevalent cooccurrence of flavone C- and O-linked derivatives in grasses today.

The stems of Zea mays L., otherwise known as cornstalks, were extracted with 80 % aqueous MeOH, and the concentrated extract was successively partitioned with ethyl acetate (EtOAc), normal butanol, and water. From the EtOAc fraction, a new lignan along with three known flavonoids, tricin (1), salcolin A (2), and salcolin B (3), were isolated. The chemical structure of the lignan was determined to be tetrahydro-4,6-bis(4-hydroxy-3-methoxyphenyl)-1H,3H-furo[3,4-c]furan-1-one (4) through spectroscopic data analyses including NMR, MS, and IR. All compounds were isolated for the first time from this plant. The isolated compounds were evaluated for their inhibitory activity against NO production in Lipopolysaccharide-induced RAW 264.7 cells and their protective activity in glutamate-induced cell death in HT22 cells. The compounds 1, 2 and 4 showed anti-inflammatory effects with IC50 values of 2.63, 14.65, and 18.91 μM, respectively, as well as neuroprotective effects with EC50 values of 25.14, 47.44, and >80 μM, respectively.

Alfalfa (Medicago sativa) has been used to cure a wide variety of ailments. However, only a few studies have reported its anticancer effects. In this study, extracts were obtained from alfalfa leaves and their cytotoxic effects were assessed on several sensitive and multidrug-resistant tumor cells lines. Using the mouse leukaemia P388 cell line and its doxorubicin-resistant counterpart (P388/DOX), we showed that the inhibition of cell growth induced by alfalfa leaf extracts was mediated through the induction of apoptosis, as evidenced by DNA fragmentation analysis. The execution of programmed cell death was achieved via the activation of caspase-3, leading to PARP cleavage. Fractionation of toluene extract (To-1), the most active extract obtained from crude extract, led to the identification of 3 terpene derivatives and 5 flavonoids. Among them, (-)-medicarpin, (-)-melilotocarpan E, millepurpan, tricin, and chrysoeriol showed cytotoxic effects in P388 as well as P388/DOX cells. These results demonstrate that alfalfa leaf extract may have interesting potential in cancer chemoprevention and therapy.

Previous studies have shown that elevated levels of carbon dioxide [CO2] may increase, decrease, or have no effect on the concentrations of phenolic compounds in plants. The underlying causes of these variations in responses remain poorly understood. In the present study, it was hypothesized that different plant responses come mainly from the duration of exposure to the gas, growing conditions, and sampling procedures. A two-year field study was conducted in open-top chambers (375 vs. 550 μmol CO2 mol−1 air) using a japonica rice variety (Oryza sativa L. cv. Ariete) as the test crop, with plants grown under elevated [CO2] during their entire life cycle. Leaf, stem and root samples were collected at five different growth stages, and submitted to a series of physiological and biochemical measurements. The carbon:nitrogen ratio and total non-structural carbohydrates were increased by elevated [CO2] in all plant tissues. Data showed that under elevated [CO2], there was a reduction in the total phenolic and total flavonoid contents measured during the seedling, tillering, elongation, and flowering stages in all plant organs, probably resulting from a relaxation of the antioxidative system during seed germination. By contrast, the total phenolic and flavonoid contents increased under elevated [CO2] at maturity, a change in response which coincided with acclimation of photosynthesis. The same trends were observed for sixteen individual phenolic compounds, including the allelopathic tricin, the phytoalexin sakuranetin and several O-glycosylated flavonoids of ecological importance. Overall, the results indicated that during the early stages of plant development, photosynthates were mainly used to synthesize proteins and meet the growth demand of the plant. Growth reduction at maturity made more resources available for the synthesis of phenolic compounds.

Chemical changes of lignin induced by the steam explosion (SE) process were elucidated. Wheat straw was studied as the raw material, and lignins were isolated by the enzymatic mild acidolysis lignin (EMAL) procedure before and after the SE treatment for analyses mainly by two-dimensional (2D) [heteronuclear single-quantum coherence (HSQC) and heteronuclear multiple-bond correlation (HMBC)] and 31P nuclear magnetic resonance (NMR). The β-O-4 structures were found to be homolytically cleaved, followed by recoupling to β-5 linkages. The homolytic cleavage/recoupling reactions were also studied by computational methods, which verified their thermodynamic feasibility. The presence of the tricin bound to wheat straw lignin was confirmed, and it was shown to participate in lignin reactions during the SE treatment. The preferred homolytic β-O-4 cleavage reaction was calculated to follow bond dissociation energies: G–O–G (guaiacyl) (69.7 kcal/mol) > G–O–S (syringyl) (68.4 kcal/mol) > G–O–T (tricin) (67.0 kcal/mol).

There have been no studies conducted with the objective of investigating the effect of elevated CO 2 concentrations ([CO 2 ]) on antioxidants in grains. Therefore, a two-year field experiment was conducted using open-top chambers with two levels of atmospheric CO 2 (375 and 550 μmol/mol) to evaluate their effects on rice grain antioxidants. Following exposure to high [CO 2 ], the total phenolic content of all rice milling fractions decreased (3%–18%), with the highest reduction in the brown rice for sinapic acid (167%), and in the white rice for p -hydroxybenzoic acid (100%). The total flavonoid content also decreased under elevated [CO 2 ] in all rice milling fractions (8%–14%), with apigenin (25%) being highly affected in the white rice, and tricin (12%) in the bran. The same trend was found for γ -oryzanol, with decreases of 35%, 32%, 25%, and 2% in the white rice, brown rice, husk, and bran, respectively. In the white and brown rices, tocopherols and tocotrienols were all lower under elevated [CO 2 ], with reductions larger for α -tocotrienol (69%), γ -tocotrienol (46%), and α -tocopherol (38%). Good correlations between antioxidant contents and DPPH radical scavenging capacities indicated that these decreases may be meaningful in the preventive ability of rice against free radical-mediated degenerative diseases.

Thirteen phenolic compounds were isolated from pear (Pyrus ussuriensis Maxim.) peels and leaves extracts by using various column chromatography techniques with a guided DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging assay, the result of antioxidant activity of phenolic compounds is then verified by measurement of ROS (reactive oxygen species). The isolated compounds were identified as rutin (1), (-)-catechin (2), orobol (3), daidzein (4), tricin 4'-O-[threo-β-guaiacyl-(7″-O-methyl)-glyceryl] ether (5), tricin 4'-O-[threo-β-guaiacyl-(7″-O-methyl-9″-O-acetyl)-glyceryl] ether (6), 5,7,3',5'-tetrahydroxyflavanone (7), artselaeroside A (8), trilobatin (9), 3-(2,4,6-trihydroxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one (10), quercetin-3-O-(3″-O-galloyl)-α-l-rhamnopyranoside (11), apigenin (12) and quercetin (13) on the basis of nuclear magnetic resonance spectroscopy along with comparison with literature data. Among these compounds, quercetin and quercetin-3-O-(3″-O-galloyl)-α-l-rhamnopyranoside exhibited potent DPPH radical-scavenging activity with IC50 (Half Maximal Inhibitory Concentration) value of 6.06 and 9.60μg/mL, respectively. The results revealed that P. ussuriensis could be used in the fields of food and medicine to prevent human aging diseases.

Potentilla parvifolia Fisch. (Rosaceae) is a traditional medicinal plant in P. R. China. In this study, seven flavonoids, ayanin (1), tricin (2), quercetin (3), tiliroside (4), miquelianin (5), isoquercitrin (6), and astragalin (7), were separated and purified from ethyl acetate extractive fractions from ethanol extracts of P. parvifolia using a combination of sevaral chromatographic methods. The human neuroblastoma SH-SY5Y cells were differentiated with all trans-retinoic acid and treated with okadaic acid to induce tau protein phosphorylation and synaptic atrophy, which could establish an Alzheimer's disease cell model. The neuroprotective effects of these flavonoids in cellular were evaluated in vitro by this cell model. Results from the Western blot and morphology analysis suggested that compounds 3 and 4 had the better neuroprotective effects.

Phenolic compounds (PCs) affect the bread quality and can also affect the other types of end-use food products such as chapatti (unleavened flat bread), now globally recognised wheat-based food product. The detailed analysis of PCs and their biosynthesis genes in diverse bread wheat (Triticum aestivum) varieties differing for chapatti quality have not been studied. In this study, the identification and quantification of PCs using UPLC-QTOF-MS and/or MS/MS and functional genomics techniques such as microarrays and qRT-PCR of their biosynthesis genes have been studied in a good chapatti variety, ‘C 306’ and a poor chapatti variety, ‘Sonalika’. About 80% (69/87) of plant phenolic compounds were tentatively identified in these varieties. Nine PCs (hinokinin, coutaric acid, fertaric acid, p-coumaroylqunic acid, kaempferide, isorhamnetin, epigallocatechin gallate, methyl isoorientin-2’-O-rhamnoside, and cyanidin-3-rutinoside) were identified only in the good chapatti variety and four PCs (tricin, apigenindin, quercetin-3-O-glucuronide, and myricetin-3-glucoside) in the poor chapatti variety. Therefore, about 20% of the identified PCs are unique to each other and may be ‘variety or genotype’ specific PCs. Fourteen PCs used for quantification showed high variation between the varieties. The microarray data of forty-four phenolic compound biosynthesis genes and seventeen of them on qRT-PCR showed variation in expression level during seed development and majority of them showed low expression in the good chapatti variety. The expression pattern in the good chapatti variety was largely in agreement with that of phenolic compounds. The level of variation of twelve genes was high between the good and poor chapatti quality varieties and has potential in development of markers. The information generated in this study can be extended onto a larger germplasm set for development of molecular markers using QTL and/or association mapping approaches for their application in wheat breeding.

Phytochemical examination of corncob extracts led to the isolation of a new lignan identified as 7,7'-dihydroxy-3'-O-demethyl-4-methoxymatairesinol, together with seven known compounds, identified as β-sitosterol, β-sitosteryl-β-D-glucoside, 6β-hydroxy-campest-4-en-3-one, 5α,8α-epidioxyergosta-6,22-dien-3β-ol, tricin, kaempferol and p-coumaric acid. The isolated compounds were identified by one and two-dimensional NMR spectroscopies and mass spectrometry.

Nine flavonoids were isolated from the dry leaves of Neosinocalamus affinis (Rendle) Keng f. The flavonoid structures were determined by spectroscopy using UV, 1D and 2D NMR, and MS. Two new C-glycosyl flavones, tricin-6-C-β-boivinopyranosyl-8-C-β-glucopyranoside (1) and 5,7,4′-trihydroxy-3′-methoxy-6-C[β-D-xylopyranosyl-(1 → 2)]-β-D-glucopyranosyl flavonoside (4), were found in addition to seven known flavonoids, apigenin-6-C-β-boivinopyranosyl-7-O-β-glucopyranoside (2), luteolin-6-C-β-boivinopyranosyl-7-O-β-glucopyranoside (3), isovitexin-2″-xyloside (5), isoorientin-2″-xyloside (6), tricin-7-O-β-glucopyranoside (7), isoorientin (8), and tricin (9). This is the first reported isolation of these flavonoids from N. affinis.

In the present work, a new expansion pretreatment was used to fractionate agricultural wastes (rice straw and rice husk) into lignin and carbohydrates. The expansion pretreatment takes the advantages of extrusion and milder steam explosion. The lignin fractions obtained from expanded rice straw and rice husk by mild alkaline extraction were characterized by gel permeation chromatography (GPC), sugar analysis, 2D NMR and derivatization followed by reductive cleavage (DFRC). Results showed that the expansion pretreatment resulted in higher extraction yields of lignin from pretreated rice straw than that from untreated control. The results from molecular weight measurement and DFRC analysis suggested that the condensation reaction could take place between lignin units during the expansion processing. 2D NMR spectra showed that guaiacyl (G) and syringyl (S) units were predominant in the lignin fractions, and a small amount of p-hydroxyphenyl (H) unit was also detected. It was also found that the flavones-type structure tricin was apparently present in lignin fractions from rice straw but not in rice husk. Considering the high extraction yields and purity of lignins from pretreated biomass, the expansion pretreatment could be an attractive method for fractionation of agricultural wastes.