Phototransformation of Lignin-related Compounds in Chromophoric Dissolved Organic Matter Solutions.

Lignin is a major terrestrial source of chromophoric dissolved organic matter (CDOM), and studying the phototransformation of lignin monomers and their related compounds can enhance our understanding of CDOM intramolecular interactions. Coniferyl aldehyde (Coni) and sinapaldehyde (Sina) form ground-state complexes with CDOM, with equilibrium constants of 7,800 (± 1,800) and 20,000 (± 2,000) M-1, respectively. In comparison, vanillin (Van) exhibits minimal affinity for CDOM complexation. The bimolecular reaction rate constants between singlet oxygen (1O2) and these phenolic carbonyl compounds ranged from 0.46 (± 0.02) to 1.8 (± 0.1) × 107 M-1s-1, which is approximately one order of magnitude lower than their reaction rate constants (0.51 (± 0.02)-1.25 (± 0.02) × 108 M-1s-1) with the triplet excited state of CDOM (3CDOM*). In acidic CDOM solutions (pH 5.0), 1O2, H2O2, and organic peroxyl radicals had negligible impact on the transformation. Comparing the initial transformation rate in the presence and in the absence of NaN3 or furfuryl alcohol led to an overestimation of the contribution of 1O2 to the transformation of Van, Coni, or Sina. 3CDOM* scavengers could not fully inhibit the transformation of Coni or Sina. The remaining transformation is considered to arise from either the unquenched intra-CDOM phase 3CDOM* or a fraction of Coni⊂CDOM or Sina⊂CDOM complex, which underwent intramolecular photoinduced chemical reactions.

Acceptors and Effectors Alter Substrate Inhibition Kinetics of a Plant Glucosyltransferase NbUGT72AY1 and Its Mutants.

One of the main obstacles in biocatalysis is the substrate inhibition (SI) of enzymes that play important roles in biosynthesis and metabolic regulation in organisms. The promiscuous glycosyltransferase UGT72AY1 from Nicotiana benthamiana is strongly substrate-inhibited by hydroxycoumarins (inhibitory constant Ki < 20 µM), but only weakly inhibited when monolignols are glucosylated (Ki > 1000 µM). Apocarotenoid effectors reduce the inherent UDP-glucose glucohydrolase activity of the enzyme and attenuate the SI by scopoletin derivatives, which could also be achieved by mutations. Here, we studied the kinetic profiles of different phenols and used the substrate analog vanillin, which has shown atypical Michaelis-Menten kinetics in previous studies, to examine the effects of different ligands and mutations on the SI of NbUGT72AY1. Coumarins had no effect on enzymatic activity, whereas apocarotenoids and fatty acids strongly affected SI kinetics by increasing the inhibition constant Ki. Only the F87I mutant and a chimeric version of the enzyme showed weak SI with the substrate vanillin, but all mutants exhibited mild SI when sinapaldehyde was used as an acceptor. In contrast, stearic acid reduced the transferase activity of the mutants to varying degrees. The results not only confirm the multi-substrate functionality of NbUGT72AY1, but also reveal that the enzymatic activity of this protein can be fine-tuned by external metabolites such as apocarotenoids and fatty acids that affect SI. Since these signals are generated during plant cell destruction, NbUGT72AY1 likely plays an important role in plant defense by participating in the production of lignin in the cell wall and providing direct protection through the formation of toxic phytoalexins.

Anti-Inflammatory Activity and ROS Regulation Effect of Sinapaldehyde in LPS-Stimulated RAW 264.7 Macrophages.

We evaluated the anti-inflammatory effects of SNAH in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages by performing nitric oxide (NO) assays, cytokine enzyme-linked immunosorbent assays, Western blotting, and real-time reverse transcription-polymerase chain reaction analysis. SNAH inhibited the production of NO (nitric oxide), reactive oxygen species (ROS), tumor necrosis factor (TNF)-α, and interleukin (IL)-6. Additionally, 100 µM SNAH significantly inhibited total NO and ROS inhibitory activity by 93% (p < 0.001) and 34% (p < 0.05), respectively. Protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) stimulated by LPS were also decreased by SNAH. Moreover, SNAH significantly (p < 0.001) downregulated the TNF-α, IL-6, and iNOS mRNA expression upon LPS stimulation. In addition, 3-100 µM SNAH was not cytotoxic. Docking simulations and enzyme inhibitory assays with COX-2 revealed binding scores of -6.4 kcal/mol (IC50 = 47.8 µM) with SNAH compared to -11.1 kcal/mol (IC50 = 0.45 µM) with celecoxib, a known selective COX-2 inhibitor. Our results demonstrate that SNAH exerts anti-inflammatory effects via suppression of ROS and NO by COX-2 inhibition. Thus, SNAH may be useful as a pharmacological agent for treating inflammation-related diseases.

Targeted Metabolomics Analysis and Identification of Biomarkers for Predicting Browning of Fresh-Cut Lettuce.

The metabolism of phenolic compounds is a key factor in the development of wound-induced enzymatic browning of fresh-cut lettuce. In the present study, the lettuce midribs discriminant metabolites, selected in a previous untargeted metabolomics study, were thoroughly identified. Our results showed that their basal contents correlated with browning developed after 5 days of storage. 5- trans-Chlorogenic acid and 5- cis-chlorogenic acid were positively correlated with browning, while sinapaldehyde and its 4-ß-d-glucoside and 4-(6'-malonyl)-ß-d-glucoside conjugates were negatively correlated. Using targeted metabolomics, the metabolites were analyzed in lettuce heads with different degrees of development and different browning susceptibility and these biomarkers were confirmed. Despite the large variability in the browning process of lettuce, the chlorogenic acids/sinapaldehyde derivatives ratio showed a linear correlation ( r2 = 0.79) with the fresh-cut lettuce browning developed in 24 Romaine lettuce cultivars, validating the relevance of these biomarkers. These results show that the analysis of the basal content of these metabolites could be used in lettuce breeding programs to select cultivars that are more appropriate for the fresh-cut industry.

Chemical constituents from stems of Acanthopanax henryi / 中草药

Objective To study the chemical constituents from stems of Acanthopanax henryi based on LPS-induced macrophages RAW264.7 and microglia BV2 as the bioactivity guided model. Methods The compounds were isolated and purified by silica gel and Sephadex LH-20 column chromatography, as well as Prep-TLC and recrystallization methods. Their structures were identified on the basis of their physicochemical properties and spectroscopic data. Results Eighteen compounds were obtained from A. henryi and their chemical structures were identified as p-hydroxybenzoic acid (1), trans-p-hydroxycinnamic acid (2), (E)-caffeic acid methyl ester (3), caffeic acid (4), trans-coniferyl aldehyde (5), syringaldehyde (6), vanillin (7), 6-methoxy-7-hydroxycoumarin (8), trans-sinapaldehyde (9), undecane-1,11-dioic acid monomethyl ester (10), (-)-sesamin (11), 3-O-caffeoyl-quinic acid (12), 5-O-caffeoyl-quinic acid (13), 1,3-di-O-caffeoyl-quinic acid (14), 1,4-di-O-caffeoyl-quinic acid (15), 1,5-di-O-caffeoyl-quinic acid (16), stigmasterol (17), and β-sitosterol (18), respectively. Conclusion To the best of our knowledge, compound 10 was isolated from Araliaceae for the first time. Except compounds 12, 14, 17, and 18, all of other compounds were obtained from this species for the first time.

Sapucaia nut (Lecythis pisonis Cambess) and its by-products: A promising and underutilized source of bioactive compounds. Part II: Phenolic compounds profile.

In this study, the profile of the bioactive compounds of sapucaia nut (Lecythis pisonis Cambess) and its by-products have been investigated. The phenolic profile by LC-ESI-MS/MS, the total phenolic content, the condensed tannins and the antioxidant activity of the sapucaia nut and shell were determined. 14 phenolic compounds were identified in the sapucaia nut extract, primarily phenolic acids and flavonoids. Catechin, epicatechin, myricetin, ellagic acid and ferulic acid presented significant correlation to the antioxidant activity. The sapucaia shell contained 22 phenolic compounds, 13 of which were quantified. The sapucaia shell extract showed a high content of total phenolic compounds, a high condensed tannins content, and high antioxidant activity. The higher antioxidant activity of the shell can be associated with a higher content of phenolics. Overall, it can be concluded that the sapucaia nut is a raw material rich in phenolic compounds that present high antioxidant activity. The nuts and the cake may be used as a promising raw material for the food industry, while the shells could be an alternative source of natural antioxidants. Further use in the cosmetics and pharmaceutical industry may also be envisaged.

Selective Oxidation of Lignin Model Compounds.

Lignin, the planet's most abundant renewable source of aromatic compounds, is difficult to degrade efficiently to welldefined aromatics. We developed a microwave-assisted catalytic Swern oxidation system using an easily prepared catalyst, MoO2 Cl2 (DMSO)2 , and DMSO as the solvent and oxidant. It demonstrated high efficiency in transforming lignin model compounds containing the units and functional groups found in native lignins. The aromatic ring substituents strongly influenced the selectivity of ß-ether phenolic dimer cleavage to generate sinapaldehyde and coniferaldehyde, monomers not usually produced by oxidative methods. Time-course studies on two key intermediates provided insight into the reaction pathway. Owing to the broad scope of this oxidation system and the insight gleaned with regard to its mechanism, this strategy could be adapted and applied in a general sense to the production of useful aromatic chemicals from phenolics and lignin.

Ultrasonic-assisted extraction combined with sample preparation and analysis using LC-ESI-MS/MS allowed the identification of 24 new phenolic compounds in pecan nut shell [Carya illinoinensis (Wangenh) C. Koch] extracts.

Ultrasonic-assisted extraction combined with statistical tools (factorial design, response surface methodology and kinetics) were used to evaluate the effects of the experimental conditions of temperature, solid-to-solvent ratio, ethanol concentration and time for the extraction of the total phenolic content from pecan nut shells. The optimal conditions for the aqueous and hydroalcoholic extract (with 20% v/v of ethanol) were 60 and 80 °C; solid to solvent ratio of 30 mL·g-1 (for both) and extraction time of 35 and 25 min, respectively. Using these optimize extraction conditions, 426 and 582 mg GAE·g-1 of phenolic compounds, from the aqueous and hydroalcoholic phases respectively, were obtained. In addition, the analysis of the phenolic compounds using the LC-ESI-MS/MS system allowed the identification of 29 phenolic compounds, 24 of which had not been reported in literature for this raw material yet.

Phenolic constituents from fruit of Gardenia jasminosides var. radicans / 中草药

Objective To investigate the phenolic constituents in the fruit of Gardenia jasminosides var. radicans. Methods The phenolic constituents were isolated and identified by chromatography on silica gel, Toyopearl HW-40, Sephadex LH-20, MCI gel CHP-20, ODS, and RP-HPLC. Their structures were elucidated on the basis of physicochemical properties and spectral analyses. Results Seventeen compounds were isolated from 50% aqueous acetone extract from the fruit of Gardenia jasminosides var. radicans and identified as 3,3',5-trimethoxy-9,9'-epoxylignane-4,4'-diol (1), 3,4-divanillyltetrahydrofuran (2), marphenol C (3), sinapaldehyde (4), hydroxycinnamic acid (5), isoferulic acid (6), caffeic acid (7), isofraxidin (8), isoscopoletin (9), 6-methoxy-7-hydroxycoumarin (10), 6,7-dihydroxycoumarin (11), syringic acid (12), 3-hydroxy-4-methoxybenzoic acid (13), 3,4-dihydroxybenzoic acid (14), p-hydroxybenzoate (15), 4,5-dihydroxy-3-methoxy-benzoic acid (16), and gallic acid (17). Conclusion All 17 compounds are isolated from this plant for the first time.

Studies on constituents from rhizome of Arundo donax / 中草药

Objective: To study chemical components of rhizome of Arundo donax, a folk medicine. Methods: Using different methods such as chromatography and recrystallization purification to get chemical components, and the structures were identified by physical and chemical properties and spectral data. Results: Twenty-three compounds were isolated and identified as following: hexadecanoic acid (1), n-docosane (2), myristic acid glycerides (3), 5,6-epoxy-22,24-ergosta-8(14),22-diene-3,7-diol (4), 5,6-epoxy-22,24-ergosta-8(9),22-diene-3,7-diol (5), 5,8-epidioxy-22,24-ergosta-6,22-dien-3-ol (6), stigmast-4-ene-3,6-dione (7), 6,9-epoxy-ergosta-7,22-dien-3-ol (8), stigmast-22-en-3,6, 9-triol (9), 3,4,5-trimethoxyphenol (10), 2,6-dimethoxy-1,4-quinone (11), sinapaldehyde (12), hydroxycinnamic acid (13), β-sitostenone (14), α-asarone (15), 4-dodecylbenzaldehyde (16), β-sitosterol (17), α-spinasterol (18), p-hydroxybenzaldehyde (19), ursolic acid (20), N-acetyltryptamine (21), daucosterol (22), and (-)-syringaresinol (23). Conclusion: Compouds 1-16 and 18-23 are isolated from the plant in genus Arundo L. for the first time.

Study on chemical constituents from green husk of Juglans sigillata / 中草药

Objective: To investigate the chemical constituents in the green husk of Juglans sigillate. Methods: The chemical constituents were isolated by silica gel, RP-18, MCI column chromatographies and so on. The structures were identified on the basis of spectroscopic analysis (MS, 13C-NMR, 1H-NMR). Results: Eleven compounds were isolated from the extract of green husk of J. sigillate. And their structures were characterized as: sinapaldehyde (1), (Z)-10-eicosenoic acid (2), 5α, 8α-epidioxyergosta-6, 22E-diene-3β-ol (3), 5, 8-dihydroxy-4-methoxy-α-tetralone (4), regiolone (5), 4, 5-dihydroxy-α-tetralone (6), 4, 5, 8-trihydroxy-α-tetralone (7), 5-hydroxy-4-methoxy-α-tetralone (8), 5-hydroxy-2-methoxy-1, 4-naphthoquinone (9), naringenin (10), and β-sitosterol (11). Conclusion: Compounds 1-2 are isolated from the plants of Juglans Linn. for the first time.

Antimicrobial activities of some Thai traditional medical longevity formulations from plants and antibacterial compounds from Ficus foveolata.

CONTEXT: Medicinal plants involved in traditional Thai longevity formulations are potential sources of antimicrobial compounds. OBJECTIVE: To evaluate the antimicrobial activities of some extracts from medicinal plants used in traditional Thai longevity formulations against some oral pathogens, including Streptococcus pyogenes, Streptococcus mitis, Streptococcus mutans, and Candida albicans. An extract that possessed the strongest antimicrobial activity was fractionated to isolate and identify the active compounds. MATERIALS AND METHODS: Methanol and ethyl acetate extracts of 25 medicinal plants used as Thai longevity formulations were evaluated for their antimicrobial activity using disc diffusion (5 mg/disc) and broth microdilution (1.2-2500 µg/mL) methods. The ethyl acetate extract of Ficus foveolata Wall. (Moraceae) stems that exhibited the strongest antibacterial activity was fractionated to isolate the active compounds by an antibacterial assay-guided isolation process. RESULTS AND DISCUSSION: The ethyl acetate extract of F. foveolata showed the strongest antibacterial activity with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 19.5-39.0 and 39.0-156.2 µg/mL, respectively. On the basis of an antibacterial assay-guided isolation, seven antibacterial compounds, including 2,6-dimethoxy-1,4-benzoquinone (1), syringaldehyde (2), sinapaldehyde (3), coniferaldehyde (4), 3ß-hydroxystigmast-5-en-7-one (5), umbelliferone (6), and scopoletin (7), were purified. Among these isolated compounds, 2,6-dimethoxy-1,4-benzoquinone (1) exhibited the strongest antibacterial activities against S. pyogenes, S. mitis, and S. mutans with MIC values of 7.8, 7.8, and 15.6 µg/mL, and MBC values of 7.8, 7.8, and 31.2 µg/mL, respectively. In addition, this is the first report of these antibacterial compounds in the stems of F. foveolata.