Four acylated flavonol glycosides from leaves of Strychnos variabilis

Four new acylated flavonol glycosides have been isolated and identified from the leaves of Strychnos variabilis: quercetin 3-(4″-trans-p-coumaroyl)robinobioside-7-glucoside (variabiloside A) and its cis derivative (variabiloside B), kaempferol 3-(4″-trans-p-coumaroyl)robinobioside-7-glucoside (variabiloside C) and its cis derivative (variabiloside D).     

Flavonol and secoiridoid glycosides from Coutoubea spicata

Two flavonol glycosides, unusual for the Gentianaceae, clovin and the new quercetin 3-O-rhamnosyl-(1 → 6)-(4″-trans-p-coumaroyl)galactoside 7-O-rhamnoside (4″-trans-p-coumaroylclovin) have been isolated from the aerial parts ofCoutoubea spicata. The bitter principles of C.spicata were identified as gentiopicrin and swertiamarin. Minor polyphenolic glycosides were characterized by high pressure liquid chromatography with photodiode array detection (HPLC-UV/Vis).     

Linkage of p-coumaroyl and feruloyl groups to cell-wall polysaccharides of barley straw

Treatment of cell walls of barley straw with Oxyporus “cellulase” (a mixture of polysaccharide hydrolases) released compounds containing p-coumaroyl and feruloyl groups bound to carbohydrates, two of which were identified as O-[5-O-(trans-p-coumaroyl)-α-l-arabinofuranosyl]-(1→3)-O-β-d-xylopyranosyl-(1→4)-d-xylopyranose (PAXX) and O-[5-O-(trans-feruloyl)-α-l-arabinofuranosyl]-(1→3)-O-β-d-xylopyranosyl-(1→4)-d-xylopyranose (FAXX).     

Four new iridoid glucoside p-coumaroyl esters from Ajuga decumbens

From the methanolic extract of the dried whole plant ofAjuga decumbens, four new iridoid glucosidecis- andtrans-p-coumaroyl esters, decumbeside A (1), B (2), C (7) and D (8) were isolated together with the known reptoside (6) and 8-acetylharpagide (9). The structures of the new compounds have been elucidated on the basis of spectroscopic and chemical evidence.     

Jacoumaric acid,a new triterpene ester from Jacaranda caucana

Jacoumaric acid isolated from Jacaranda caucana is shown to be 2α-hydroxy-3β-trans-p-coumaryloxy-urs-12-en-28-oic acid.     

Methylation of anthocyanins by cell-free extracts of flower buds of Petunia hybrida

An O-methyltransferase activity which catalyses the methylation of anthocyanins was extracted from flowerbuds of Petunia hybrida. The methyltransferase uses S-adenosyl-l-methionine as methyl donor. Only anthocyanidin 3(p-coumaroyl)rutinosido-5-glucoside was methylated. No methylating activity towards anthocyanidins, anthocyanidin 3-glucosides, anthocyanidin 3-rutinosides, caffeic acid or p-coumaric acid could be detected.     

Three New Phenolic Amides from the Roots of Eggplant (Solanum melongena L.)

The isolation of four phenolic amides, four phenolic compounds and an aromatic amine from the roots of eggplant is described. The phenolic amides were identified as N-trans-feruloyl tyramine (V), N-trans-p-coumaroyl tyramine (VII), N-trans-feruloyl octopamine (VIII) and N-trans-p-coymaroyl octopamine (IX). The three amides V, VIII and IX are new compounds. Furthermore, four phenolic compounds were identified as vanillin (I), isoscopoletin (II), ethyl caffeate (IV) and ferulic acid (VI). The aromatic amine was identified as p-aminobenzal-dehyde (III).     

Evolution of rosmarinic acid biosynthesis

Rosmarinic acid and chlorogenic acid are caffeic acid esters widely found in the plant kingdom and presumably accumulated as defense compounds. In a survey, more than 240 plant species have been screened for the presence of rosmarinic and chlorogenic acids. Several rosmarinic acid-containing species have been detected. The rosmarinic acid accumulation in species of the Marantaceae has not been known before. Rosmarinic acid is found in hornworts, in the fern family Blechnaceae and in species of several orders of mono- and dicotyledonous angiosperms. The biosyntheses of caffeoylshikimate, chlorogenic acid and rosmarinic acid use 4-coumaroyl-CoA from the general phenylpropanoid pathway as hydroxycinnamoyl donor. The hydroxycinnamoyl acceptor substrate comes from the shikimate pathway: shikimic acid, quinic acid and hydroxyphenyllactic acid derived from l-tyrosine. Similar steps are involved in the biosyntheses of rosmarinic, chlorogenic and caffeoylshikimic acids: the transfer of the 4-coumaroyl moiety to an acceptor molecule by a hydroxycinnamoyltransferase from the BAHD acyltransferase family and the meta-hydroxylation of the 4-coumaroyl moiety in the ester by a cytochrome P450 monooxygenase from the CYP98A family. The hydroxycinnamoyltransferases as well as the meta-hydroxylases show high sequence similarities and thus seem to be closely related. The hydroxycinnamoyltransferase and CYP98A14 from Coleus blumei (Lamiaceae) are nevertheless specific for substrates involved in RA biosynthesis showing an evolutionary diversification in phenolic ester metabolism. Our current view is that only a few enzymes had to be “invented” for rosmarinic acid biosynthesis probably on the basis of genes needed for the formation of chlorogenic and caffeoylshikimic acid while further biosynthetic steps might have been recruited from phenylpropanoid metabolism, tocopherol/plastoquinone biosynthesis and photorespiration.     

Evaluation of human neutrophil elastase inhibitory effect of iridoid glycosides from Hedyotis diffusa

Five iridoid glycosides were isolated from the MeOH extract of Hedyotis diffusa, and their structures were elucidated as E-6-O-p-methoxycinnamoyl scandoside methyl ester (1), Z-6-O-p-methoxycinnamoyl scandoside methyl ester (2), E-6-O-p-feruloyl scandoside methyl ester (3), E-6-O-p-coumaroyl scandoside methyl ester (4), and Z-6-O-p-coumaroyl scandoside methyl ester (5) by interpretation of their spectroscopic data. All the isolated compounds were evaluated for human neutrophil elastase inhibitory effect, and compound 1 showed potent activity with an IC₅₀ value of 18.0 μM. The molecular docking simulation suggested a structural model for the inhibition of human neutrophil elastase by compound 1.     

Accumulation and enzymatic synthesis of 2-O-acetyl-3-O-(p-coumaroyl)-meso-tartaric acid in spinach cotyledons

2-O-Acetyl-3-O-[(E)-p-coumaroyl]-meso-tartaric acid was isolated from cotyledons of Spinacia oleracea and its structure elucidated and characterized with the aid of TLC, HPLC, FAB MS and ¹H NMR. Accumulation and enzymatic synthesis of the diester are described, proceeding first via 1-O-(p-coumaroyl)-β-glucose in the formation of p-coumaroyltartaric acid and second via acetyl-CoA in the formation of 2-O-acetyl-3-O-[(E)-p-coumaroyl]-meso-tartaric acid. Some properties of the CoA-thioester-dependent acyltransferase activity were studied.     

Copigments in the blueing of sepal colour of Hydrangea macrophylla

From blue sepals of Hydrangea macrophylla, copigments which show a blueing effect on the hydrangea anthocyanin were isolated and identified as 3-p-coumaroylquinic acid and 3-caffeoylquinic acid. 5-Caffeoylquinic acid (chlorogenic acid) which was also found in the blue sepals, however, did not show such a blueing effect though it acted as a copigment. Likewise, the 4-esters of p-coumaroyl- and caffeoylquinic acids (not found in sepals) produced purple rather than blue colours. The facts suggest that the stereostructures of 3-p-coumaroyl- and 3-caffeoylquinic acids are effective for molecular interaction between the p-coumaroyl or caffeoyl residue in the compounds and the anthocyanin. The anthocyanin in red and blue sepals of hydrangea was confirmed to be delphinidin 3-monoglucoside.     

Anthraquinone,anthrone and phenylpyrone components of Aloe nyeriensis var. kedongensis leaf exudate

The leaf exudate of Aloe nyeriensis var. kedongensis yielded six compounds which were identified on the basis of spectral data and inter-conversions as two groups of three allied compounds. These were (a) 4-methoxy-6(2′,4′-dihydroxy-6′- methylphenyl)-pyran-2-one, its 2′-O-β-D-glucopyranoside (aloenin) and the 2″-O-p-coumaroyl ester of aloenin, (b) the anthracene derivatives l,2,8-trihydroxy- 6-methylanthraquinone (nataloe-emodin), its 2-O-β-D-glucopyranosyl ester and the corresponding 10-C -β-D-glucopyranoside nataloin.     

Distribution of some triterpenes and phenolic compounds in the extractives of endemic dipterocarpaceae species of Sri Lanka

Extractives of bark and/or timber of 11 species belonging to the genera Cotylelobium, Hopea, Shorea, Vateria and Vatica yielded a fatty-acid ester, a sitosteryl ester, β-amyrin acetate, β-amyrin, dipterocarpol, ursolic acetate, lupeol, sitosterol, ursolic acid, betulinic acid, hexamethyl-coruleoellagic acid, tetramethylellagic acid, chrysophanol and scopoletin. The distribution of these compounds in 18 other species was examined by TLC screening.     

Tetra-acylated cyanidin 3-sophoroside-5-glucosides from the flowers of Iberis umbellata L. (Cruciferae)

The structures of 11 acylated cyanidin 3-sophoroside-5-glucosides (pigments 1-11), isolated from the flowers of Iberis umbellata cultivars (Cruciferae), were elucidated by chemical and spectroscopic methods. Pigments 1-11 were acylated with malonic acid, p-coumaric acid, ferulic acid, sinapic acid and/or glucosylhydroxycinnamic acids.Pigments 1-11 were classified into four groups by the substitution patterns of the linear acylated residues at the 3-position of the cyanidin. In the first group, pigments 1-3 were determined to be cyanidin 3-O-[2-O-(2-O-(acyl)-β-glucopyranosyl)-6-O-(trans-p-coumaroyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside], in which the acyl moiety varied with none for pigment 1, ferulic acid for pigment 2 and sinapic acid for pigment 3. In the second one, pigments 4-6 were cyanidin 3-O-[2-O-(2-O-(acyl)-β-glucopyranosyl)-6-O-(4-O-(β-glucopyranosyl)-trans-p-coumaroyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside], in which the acyl moiety varied with none for pigment 4, ferulic acid for pigment 5 and sinapic acid for pigment 6. In the third one, pigments 7-9 were cyanidin 3-O-[2-O-(2-O-(acyl)-β-glucopyranosyl)-6-O-(4-O-(6-O-(trans-feruloyl)-β-glucopyranosyl)-trans-p-coumaroyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside], in which the acyl moiety varied with none for pigment 7, ferulic acid for pigment 8, and sinapic acid for pigment 9. In the last one, pigments 10 and 11 were cyanidin 3-O-[2-O-(2-O-(acyl)-β-glucopyranosyl)-6-O-(4-O-(6-O-(4-O-(β-glucopyranosyl)-trans-feruloyl)-β-glucopyranosyl)-trans-p-coumaroyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside], in which acyl moieties were none for pigment 10 and ferulic acid for pigment 11.The distribution of these pigments was examined in the flowers of four cultivars of I. umbellata by HPLC analysis. Pigment 1 acylated with one molecule of p-coumaric acid was dominantly observed in purple-violet cultivars. On the other hand, pigments (9 and 11) acylated with three molecules of hydroxycinnamic acids were observed in lilac (purple-violet) cultivars as major anthocyanins. The bluing effect and stability on these anthocyanin colors were discussed in relation to the molecular number of hydroxycinnamic acids in these anthocyanin molecules.     

Phenanthrene derivatives from Aristolochia argentina

Aristolochic acid Ia, aristolochic acid I methyl ester and aristolochic acid II methyl ester were identified in the roots of Aristolochia argentina.     

Measurement of feruloyl/p-coumaroyl esterase by capillary zone electrophoresis

Ferulic andp-coumaric acid can be separated from their corresponding aliphatic methyl esters by capillary zone electrophoresis, which allows the convenient determination of feruloyl andp-coumaroyl esterase activities using synthetic esters as substrates. A feruloyl-containing sugar ester from wheat bran was also efficiently separated and used as substrate for the enzyme assays.Penicillium expansum was shown to produce feruloyl/p-coumaroyl esterase activity when grown on wheat bran in solid-state culture.The authors are with the Food Microbiology Research Division, Department of Agriculture for Northern Ireland, Newforge Lane, Belfast BT9 5PX, UK; A.M. McKay is also affiliated with the Department of Food Science (Microbiology), The Queen's University of Belfast, Newforge Lane, Belfast BT9 5PX, UK.     

Cestric acid,a caffeic acid ester from Cestrum euanthes

Cestric acid, a new phenolic ester was isolated from leaves of Cestrum euanthes. By means of GC, HPLC, mass spectroscopy, GC/MS, and ¹³C NMR, it was shown to be an ester of caffeic acid with glucaric acid. The ester occurs as an equilibrium mixture of four isomers.     

Structure of acacigenin-B,a novel triterpene ester isolated from Acacia concinna

The structure of acacigenin-B, a novel ester genin from the pods of Acacia concinna was established from its PMR and ¹³ C NMR spectra. It was identified as the 21-hydroxy ester of acacic acid; the esterifying acid was a hitherto unknown monoterpene acid of tetrahydrofuranoid structure. This appears to be the first report of a higher terpenoid forming an ester with a monoterpene acid     

New trans- and cis-p-coumaroyl flavonol tetraglycosides from the leaves of Mitragyna rotundifolia

Two new flavonol tetraglycosides, quercetin 3-O-(4-O-trans-p-coumaroyl)-α-l-rhamnopyranosyl (1→2) [α-l-rhamnopyranosyl (1→6)]-β-d-glucopyranoside-7-O-α-l-rhamnopyranoside (krathummuoside A) and quercetin 3-O-(4-O-cis-p-coumaroyl)-α-l-rhamnopyranosyl (1→2) [α-l-rhamnopyranosyl (1→6)]-β-d-glucopyranoside-7-O-α-l-rhamnopyranoside (krathummuoside B) were isolated from the leaves of Mitragyna rotundifolia in addition to eight known compounds, quercetin 3-O-α-l-rhamnopuranosyl (1→2) [α-l-rhamnopyranosyl (1→6)]-β-d-glucopyranoside-7-O-α-l-rhamnopyranoside, rutin, (−)-epi-catechin, 3,4,5-trimethoxyphenyl β-d-glucopyranoside, (6S, 9R)-roseoside, 3-O-β-d-glucopyranosyl quinovic acid 28-O-β-d-glucopyranosyl ester, (+)-lyoniresinol 3α-O-β-d-glucopyranoside, and (+)-syringaresinol-4-O-β-d-glucopyranoside. The structure elucidation of these compounds was based on analyses of spectroscopic data including 1D- and 2D-NMR.     

A new diterpenic acid and other constituents of Haplopappus foliosus and H. Angustifolius

Hentriacontane, friedelan-3-one, epi-friedelinol, hexacosanol, stigmasterol, a new diterpenic acid and its monomethyl ester are amongst the constituents of Haplopappus foliosus and H. angustifoliosus. The new acid has been called haplopappic acid.