Coumaroyl Esters Research Articles

Biocatalytic system for comparatively assessing the functional association of monolignol cytochrome P450 monooxygenases with their redox partners.

Lignin is a complex heterogenous polymer derived from oxidative radical polymerization of three monolignols, i.e., p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol. These lignin monomeric precursors structurally differ in their methoxy groups of the benzene rings. In phenylpropanoid-monolignol biosynthetic pathway, the endoplasmic reticulum (ER)-resident cytochrome P450 monooxygenases, cinnamate 4-hydroxylase, coumaroyl ester 3'-hydroxylase and ferulate 5-hydroxylase, establish the key structural characteristics of monolignols. The catalysis of cytochrome P450 monooxygenase requires reducing power, which is supplied by the ER electron transfer chains, composed of cytochrome P450 oxidoreductase (CPR), cytochrome b5 reductase (CBR) and/or cytochrome b5 protein (CB5), from cofactor NADPH or NADH. While NADPH-dependent CPR serves as the typical electron donor for most P450 enzymes, in some cases, the CBR-CB5 or CPR-CB5 electron transfer system also transfers electrons to the terminal P450 enzymes. There are tremendous studies focusing on the discovery and characterization of cytochrome P450 monooxygenases. However, very limited attention has been paid to the versatility and the roles of electron transfer components in the P450 catalytic system. Due to the membrane-residence property of both P450 enzymes and electron transfer components, it is challenging to establish an effective experimental system to evaluate the functional association of P450s with their redox partners. This chapter describes a yeast cell biocatalytic system and the related experimental procedures for comparatively assessing the functional relationship of monolignol biosynthetic P450 enzymes and different redox partners in their catalysis.

Profiling beneficial phytochemicals in a potato somatic hybrid for tuber peels processing: phenolic acids and anthocyanins composition.

The purpose of this study was to characterize the peels of a CN1 somatic hybrid obtained from two dihaploid potato lines (Cardinal H14 and Nicola H1) in terms of the health‐promoting phenolic compounds (phenolic acids and anthocyanins). The CN1 hybrid is defined by a pink tuber skin color making it different from the light‐yellow‐skinned “Spunta,” which is the most commonly grown potato cultivar in Tunisia. Oven‐dried peel samples derived from CN1 hybrid and cv. Spunta were ground, and phenolic compounds were extracted with water or methanol for quantification. Lyophilized peels were used for the phenolic acid and anthocyanin analyses. Higher total quantities of phenolic compounds were recovered in methanol extracts compared with water extracts. A slightly higher concentration of phenolic acids (100 mg/100 g DW) was obtained in the lyophilized peels extract of CN1 hybrid than in the cv. Spunta corresponding sample (83 mg/100 g DW). The profiles of the chlorogenic acid isomers were almost identical in both of CN1 hybrid and cv. Spunta. Caffeic acid (CA) and three caffeoylquinic acids (CQAs): 3‐CQA, 4‐CQA, and 5‐CQA, were identified from both genotypes, 5‐CQA being the dominant form in both potatoes. Since the CN1 hybrid has a pink skin color, its anthocyanin profile was also determined. The anthocyanin quantity in the CN1 peels was 5.07 mg/100 g DW, involving six different anthocyanins that were identified within the extract, namely, Pelargonidin‐3‐rutinoside‐5‐glucoside, peonidin‐3‐rutinoside‐5‐glucoside, coumaroyl ester of pelargonidin‐3‐rutinoside‐5‐glucoside, coumaroyl ester of peonidin‐3‐rutinoside‐5‐glucoside, feruloyl ester of pelargonidin‐3‐rutinoside‐5‐glucoside, and feruloyl ester of peonidin‐3‐rutinoside‐5‐glucoside. These results suggest that the peel waste of CN1 somatic hybrid can be considered as a promising source of high‐value compounds for food industry.

Antiprotozoal activities of Triterpenic Acids and Ester Derivatives Isolated from the Leaves of Vitellaria paradoxa

AbstractLeaves of Vitellaria paradoxa, also called “Shea butter tree”, are used in traditional medicine to treat various symptoms including malaria fever, dysentery, or skin infections. Composition of the dichloromethane extract of V. paradoxa leaves possessing antiparasitic activities was investigated. Five pentacyclic triterpenic acids together with 6 ester derivatives were isolated and identified by standards comparison, MS and 1H-NMR analysis. Corosolic, maslinic, and tormentic coumaroyl esters and their corresponding triterpenic acids were isolated from this plant for the first time. The antiparasitic activities of the 11 isolated compounds were evaluated in vitro on Plasmodium falciparum, Trypanosoma brucei brucei, and Leishmania mexicana mexicana and their selectivity determined by cytotoxicity evaluation on WI38 cells. None of the isolated compounds showed good antiplasmodial activity. The antitrypanosomal activity of individual compounds was in general higher than their antileishmanial one. One isolated triterpenic ester mixture in equilibrium, 3-O-p-E/Z-coumaroyltormentic acids, showed an attractive promising antitrypanosomal activity (IC50 = 0.7 µM) with low cytotoxicity (IC50= 44.5 µM) compared to the corresponding acid. Acute toxicity test on this ester did not show any toxicity at the maximal cumulative dose of 100 mg/kg intraperitoneally on mice. In vivo efficacy evaluation of this compound, at 50 mg/kg by intraperitoneal route on a T. b. brucei-infected mice model, showed a significant parasitemia reduction on day 4 post-infection together with 33.3% survival improvement. Further bioavailability and PK studies are needed along with mode of action investigations to further assess the potential of this molecule.

Cytotoxic and Anti-inflammatory Terpenoids from the Whole Plant of Vaccinium emarginatum

Two new Δ12 ursene-type triterpenoid coumaroyl esters (1: and 2: ), one new Δ7,15 isopimarane-type diterpenoid glycoside (20: ), and two new irido-δ-lactone-type iridoids (21: and 22: ), together with 17 known pentacyclic triterpenoids (3: - 19: ), were isolated during the phytochemical investigation of a methanol extract of the whole plant of Vaccinium emarginatum. Their structures were determined by detailed analysis of standard spectroscopic data (MS, IR, 1D, and 2D NMR) and comparison with data of known analogs. The isolates were evaluated for their cytotoxicity against the PC-3 and Du145 prostate cancer cell lines (as assessed by an MTT cell proliferation assay), as well as for their anti-inflammatory activity via the inhibition of nitric oxide production in lipopolysaccharide-induced murine macrophage RAW 264.7 cells. Among the isolates, the triterpenoid coumaroyl and feruloyl esters (1, 3: , and 4: ) exhibited strong cytotoxicity against PC-3 prostate cancer cells, with 85.6 - 90.2% inhibition at 10.0 µg/mL. The pomolic acid coumaroyl and feruloyl esters (1: and 3: ) also showed moderate anti-inflammatory activity against nitric oxide production in lipopolysaccharide-induced RAW 264.7 cells, with 59.2 (± 1.0) and 47.1% (± 0.2) inhibition at 12.5 µg/mL, respectively.

Downregulation of p-COUMAROYL ESTER 3-HYDROXYLASE in rice leads to altered cell wall structures and improves biomass saccharification.

p-Coumaroyl ester 3-hydroxylase (C3'H) is a key enzyme involved in the biosynthesis of lignin, a phenylpropanoid polymer that is the major constituent of secondary cell walls in vascular plants. Although the crucial role of C3'H in lignification and its manipulation to upgrade lignocellulose have been investigated in eudicots, limited information is available in monocotyledonous grass species, despite their potential as biomass feedstocks. Here we address the pronounced impacts of C3'H deficiency on the structure and properties of grass cell walls. C3'H-knockdown lines generated via RNA interference (RNAi)-mediated gene silencing, with about 0.5% of the residual expression levels, reached maturity and set seeds. In contrast, C3'H-knockout rice mutants generated via CRISPR/Cas9-mediated mutagenesis were severely dwarfed and sterile. Cell wall analysis of the mature C3'H-knockdown RNAi lines revealed that their lignins were largely enriched in p-hydroxyphenyl (H) units while being substantially reduced in the normally dominant guaiacyl (G) and syringyl (S) units. Interestingly, however, the enrichment of H units was limited to within the non-acylated lignin units, with grass-specific γ-p-coumaroylated lignin units remaining apparently unchanged. Suppression of C3'H also resulted in relative augmentation in tricin residues in lignin as well as a substantial reduction in wall cross-linking ferulates. Collectively, our data demonstrate that C3'H expression is an important determinant not only of lignin content and composition but also of the degree of cell wall cross-linking. We also demonstrated that C3'H-suppressed rice displays enhanced biomass saccharification.

New Bioactive Lupane Triterpene Coumaroyl Esters Isolated from Buxus cochinchinensis.

Five new lupane triterpene coumaroyl esters (1-5), together with betulin (6) and a known Buxus alkaloid, N-3-benzoyldihydrocyclomicrophylline F (7), were isolated from a CHCl3-soluble partition of a methanol extract of Buxus cochinchinensis Pierre ex Gagnep. (Buxaceae) collected in Vietnam. Isolation work was monitored using human colon cancer cells (HT-29). The structures of the new compounds (1-5) were determined on the basis of spectroscopic data interpretation. In addition to their cytotoxicity against HT-29 cells and nuclear factor-kappa B (p65) inhibitory activity in an enzyme-linked immunosorbent assay, all isolates as well as two semisynthetic compounds derived from betulin and 5, respectively, were also evaluated for their in vitro antiplasmodial activities against the drug-resistant Dd2 strain of Plasmodium falciparum and antifungal effects on the growth of the pathogenic yeast Candida albicans. The new lupane triterpene coumaroyl esters (1-5), along with a betulin derivative and the known Buxus alkaloid, were found to show significant in vitro antimalarial activities, with IC50 values ranging from 0.26 to 2.07 µM.

Chemical constituents and antioxidant activity of leaves and branches ofEugenia copacabanensisKiaersk (Myrtaceae)

Phytochemical investigation of Eugenia copacabanensis allowed for the isolation and identification of following compounds: β-sitosterol, β-sitosterol-glucoside, eight triterpenes, (mixture of α- and β-amyrins, ursolic acid, 30-hydroxy-ursolic acid, betulin, friedelin, friedelan-3,4-lactone, and taraxerol), a mixture of three sesquiterpenes, (clovandiol, globulol, and viridiflorol), three flavonoids (kaempferol-3-O-β-D-rhamnoside, quercetin-3-O-α-L-arabinoside, and quercetin), and a mixture of four coumaroyl esters (octacosanyl, heptacosanyl, hexacosanyl, and tetracosanyl coumarates). The structures of these compounds were assigned based on comparison with literature data and spectroscopic analysis, including analysis by two-dimensional NMR techniques. Total phenolic content and total flavonoids were evaluated. Antioxidant activities of methanol extracts and fractions were measured by the 1,2-diphenyl-2-picryl-hidrazyl free radical scavenging assay.

Cycloartanes from Krameria pauciflora and Their In Vitro PLA2, COX-1, and COX-2 Enzyme Inhibitory Activities

Krameria pauciflora is a species belonging to the Krameriaceae family. It has been used to treat inflammatory disorders in folkloric Mexican medicine; however, chemistry and pharmacological studies have not been carried out on this species. In this work, from the dichloromethane root extract of K. pauciflora, five cycloartane-type triterpenoids were isolated: cyclomargenyl-3-O-β-caffeoyl ester (1), cyclomargenyl-3-O-β-feruloyl ester (2), cyclomargenyl-3-O-β-coumaroyl ester (3), cyclomargenol (4, polysthicol), and cyclomargenone (5). Additionally, the lignane 6'-methoxyrataniaphenol was isolated. To the best of our knowledge, compounds 1-3 are new natural products, whereas compounds 4 and 5 are isolated for the first time in the Krameria genus and the Krameriaceae family. The structures of all of these compounds were established by 1D and 2D NMR spectroscopy including ¹H, ¹³C, DEPT, COSY, HSQC, and HMBC experiments, as well as by EI mass spectrometry. There is an incomplete previous report about the spectroscopic data of compounds 4 and 5. However, in this work, a complete and unambiguous assignation has been realized. Due to the traditional use of this plant and other species from this genus, such as K. lappacea, cycloartanes isolated herein were evaluated by their inhibition of phospholipase A₂, cyclooxygenase-1, and cyclooxygenase-2 enzymes. Cyclomargenyl-3-O-β-caffeoyl ester (1) showed inhibition of phospholipase A₂, cyclooxygenase-1, and cyclooxygenase-2 target enzymes for nonsteroidal anti-inflammatory drugs. Both cyclooxygenases were inhibited by cyclomargenol (4); however, cyclomargenyl-3-O-β-feruloyl ester (2) showed inhibition only on cyclooxygenase-1.

Flavonoid Glycosides and their p-Coumaroyl Esters from Campylospermum calanthum Leaves

Six new compounds, comprising three flavonoid glycosides and their respective coumaroyl esters, have been isolated and characterized from the methanol extract of the leaves of Campylospermum calanthum, along with three known flavonoid aglycones, 7-O-methyl apigenin (1), 7-O-methyl luteolin (2), and 7-O-methyl quercetin (3). Their structures were elucidated based on chemical evidence as well as spectroscopic analysis including 1D and 2D NMR (1H-1H COSY, HSQC, HMBC, and NOESY) spectroscopy and by comparing their spectral data with those reported for related compounds.

New Cytotoxic Lupane Triterpenes fromPerrottetia arisanensis

Eight new lupane triterpenes, including 7beta-cis-coumaroylbetulinic acid (1), 7beta-trans-coumaroylbetulinic acid (2), 7beta-cis-coumaroyl-3-epi-betulinic acid (3), 7beta-trans-coumaroyl-3-epi-betulinic acid (4), 7beta-cis-coumaroylbetulonic acid (5), 7beta-trans-coumaroylbetulonic acid (6), 7beta-hydroxybetulinaldehyde (7) and 28-norlup-20(29)-ene-3alpha,17beta-diol (8), together with fifteen known compounds were isolated from the bioactive methanol extract of the stems of Perrottetia arisanensis. The structures of the new compounds were elucidated by spectroscopic and HR-ESI-MS analysis. All new compounds were evaluated for their cytotoxicity against six human cancer cell lines. Among them, lupane triterpene coumaroyl esters 1-6 showed moderate cytotoxicity with IC (50) values ranging from 3.75 to 21.29 microM. This is the first report for lupane triterpenes with a phenylpropane moiety substituted at C-7.

Dynamics of anthocyanin and flavonol profiles in the ‘Crimson Seedless’ grape berry skin during development and ripening

‘Crimson Seedless’ grapes ( Vitis vinifera L.) do not develop adequate berry colour in different parts of the world including Australia and USA leading to serious economic losses to the growers. In the present study, various anthocyanins and flavonols were identified in the skin of the ‘Crimson Seedless’ grape berries using LC/PDA/ESI-MS and their changes in the berry skin during development and ripening of ‘Crimson Seedless’ grape berries were investigated during 2005–2006 and 2006–2007. Eleven anthocyanins and two flavonols were identified in the berry skin using LC/PDA/ESI-MS. Of the anthocyanins identified, four anthocyanins including cyanidin 3- O-(6″- O-acetyl)-glucoside, peonidin 3- O-(6″- O-acetyl)-glucoside, malvidin 3- O-(6″- O-acetyl)-glucoside and malvidin 3- O-(6″- O-coumaroyl)-glucoside were not reported earlier. During both the years, the concentration of the 3- O-glucosides of delphinidin, petunidin, peonidin, and malvidin as well as the acetyl and coumaroyl esters of the 3- O-glucosides of cyanidin, peonidin, and malvidin in the berry skin increased during berry development and ripening. During 2006–2007, the concentration of cyanidin 3- O-glucoside in the berry skin increased during the early stages of berry ripening and subsequently declined till harvest while in 2005–2006, the concentration increased during the initial phase of berry ripening and remained relatively stable thereafter till harvest. The concentration of total anthocyanins in the berry skin was higher during 2006–2007 as compared to 2005–2006. During both years, the concentration of quercetin 3- O-glucoside in the berry skin increased during berry development and ripening while the concentration of quercetin 3- O-glucuronide in the berry skin decreased during the same period. To the best of our knowledge, this is the first report on the evolution of different anthocyanins and flavonols in the ‘Crimson Seedless’ berry skin during berry development and ripening.

Pentacyclic triterpenoids from the mangrove plant Rhizophora stylosa

Seven pentacyclic triterpenoids including 3β-O-(E)-coumaroyl-15α-hydroxy-β-amyrin (1), 15α-hydroxy-β-amyrin (2), 3β-taraxerol (3), 3β-taraxerol formate (4), 3β-taraxerol acetate (5), 3β-O-(E)-coumaroyl-taraxerol (6), and 3β-O-(Z)-coumaroyl-taraxerol (7) were isolated and identified from the stems and twigs of the mangrove plant Rhizophora stylosa. The structures of the isolated compounds were determined by extensive analysis of their spectroscopic data. Among these metabolites, compound 1 is a new oleanane-type triterpenoid coumaroyl ester, while compound 4 is a new natural product obtained here as an isolated substance for the first time. The full spectroscopic detail of compound 4 is also reported here for the first time.

Coumaroyl triterpenes from Casuarina equisetifolia

Seven new β-amyrin derived oleanane-type triterpene coumaroyl esters were isolated from the twigs and leaves of Casuarina equisetifolia, together with two known triterpenoids, erythrodiol and oleanolic acid, and a number of benzoic acid derivatives. The structures of the seven new compounds have been elucidated as 3-O-(E)-coumaroyl β-amyrin, 3-O-(Z)-coumaroyl β-amyrin, 3-O-dihydrocoumaroyl β-amyrin, 3-O-(E)-coumaroyl erythrodiol, 3-O-(Z)-coumaroyl erythrodiol, 3-O-(E)-coumaroyl oleanolic acid and 3-O-(Z)-coumaroyl oleanolic acid by spectroscopic analyses and chemical degradation. Evaluation of the antioxidant activities of the isolated compounds indicates that gallic acid is one of the antioxidant substances present in C. equisetifolia.

Phenolic profiles of untransformed and hairy root cultures of Plantago lanceolata

Untransformed root cultures and Agrobacterium rhizogenes induced root cultures (hairy roots) of Plantago lanceolata were investigated for caffeic acid glycoside esters, i.e. verbascoside (V) and plantamoside (P), by HPLC. Levels of V (6–12 mg.g –1 DW) and P (30–80 mg.g –1 DW) from untransformed and hairy root cultures were not modified by 0.1 mM ( E)-cinnamic acid addition in Murashige and Skoog's culture medium. A part of the cinnamic acid was converted into ( E)- p-coumaroyl-1-O- β-D-glucopyranoside, a phenolic derivative absent from control cultures without cinnamic acid. Maximum levels of this coumaroyl ester (6–8 mg.g –1 DW) were detected during 10 d and then slightly decreased from both root chemical profiles.

Chemotaxonomic value of anthocyanins in Podalyria and Virgilia (tribe Podalyrieae: Fabaceae)

Anthocyanin pigments responsible for purple and pink flower colours in the tribe Podalyrieae have been identified. The considerable variation in flower colour is not reflected in the chemical variation and the flower pigments are surprisingly conservative. Virgilia flowers always have the acetic acid esters of cyanidin-3-glucoside and peonidin-3-glucoside as major compounds, together with trace amounts of the coumaroyl ester of cyanidin-3-glucoside. Podalyria flowers invariably have the rather more stable coumaroyl ester of cyanidin. The data support a close affinity between the two genera but also show that flower colour is only partially homologous.