Kinetic study of possible intermediates in the biosynthesis of chlorogenic acid in Cestrum poeppigii

p-Coumaric and 3-O-p-coumarylquinic acid seem to be important precursors of chlorogenic acid in the leaves of Cestrum poeppigii. 3-O-Cinnamylquinic acid, which has a very small metabolic activity, is of little importance in this respect. The kinetics of incorporation of radioactivity from t-cinnamic acid-3-[¹⁴C] into p-coumaric, 3-O-p-coumarylquinic, chlorogenic and 3-O-cinnamylquinic acid showed that the biosynthetic rates for these products decrease in the order shown. For p-coumaric acid, which has a markedly high metabolic activity, a turnover rate of 28 μg/hr and per gram fresh plant leaf, was calculated. Some trapping experiments with caffeic acid, and the acids mentioned above and using either t-cinnamic acid-3-[¹⁴C] or p-coumaric acid-2-[¹⁴C] as precursor, are discussed. A HPLC method for the rapid determination of phenolic acids in plant extracts, is described.     

Triterpene glycosides related to quadranguloside from Passiflora quadrangularis

Two new cyclopropane triterpene glycosides were isolated from the methanol extracts of leaves of Passiflora quadrangularis. On the basis of hydrolysis, spectral evidence and comparison with quadranguloside, these compounds were assigned the structures 9,19-cyclolanosta-22,25-epoxy-3β-21,22(R)-triol-3β-O-gentiobioside and 9,19-cyclolanosta-21,24-epoxy-3β-25,26-triol-3β-O-gentiobioside,respectively. Oleanolic acid-3-sophoroside was also isolated for the first time from a natural source.     

Time-course tracer studies on the metabolism of cinnamic acid in Cestrum poeppigii

Time-course tracer studies were performed on the metabolism of trans-cinnamic acid-[3-¹⁴C] and trans-p-coumaric acid-[2-¹⁴C] in the     

Biosynthesis of p-hydroxybenzoic acid in poplar lignin

Biosynthetic pathways to p-hydroxybenzoic acid in polar lignin were examined by tracer experiments. High incorporation of radioactivity to the acid was observed when shikimic acid-[1-¹⁴C], phenylalanine-[3-¹⁴C], trans-cinnamic acid-[3-¹⁴C], p-coumaric acid-[3-¹⁴C] and p-hydroxybenzoic acid-[COOH-¹⁴C] were administered, while incorporation was low from shikimic acid-[COOH-¹⁴C], phenylalanine-[1-¹⁴C], phenylalanine-[2-¹⁴C], tyrosine-[3-¹⁴C], benzoic acid-[COOH-¹⁴C], sodium acetate-[1-¹⁴C] and d-glucose-[U-¹⁴C]. Thus p-hydroxybenzoic acid in poplar lignin is formed mainly via the pathway: shikimic acid → phenylalanine → trans-cinnamic acid → p-coumaric acid → p-hydroxybenzoic acid.     

Perennial peanut (Arachis glabrata Benth.) leaves contain hydroxycinnamoyl-CoA:tartaric acid hydroxycinnamoyl transferase activity and accumulate hydroxycinnamoyl-tartaric acid esters

Many plants accumulate hydroxycinnamoyl esters to protect against abiotic and biotic stresses. Caffeoyl esters in particular can be substrates for endogenous polyphenol oxidases (PPOs). Recently, we showed that perennial peanut (Arachis glabrata Benth.) leaves contain PPO and identified one PPO substrate, caftaric acid (trans-caffeoyl-tartaric acid). Additional compounds were believed to be cis- and trans-p-coumaroyl tartaric acid and cis- and trans-feruloyl-tartaric acid, but lack of standards prevented definitive identifications. Here we characterize enzymatic activities in peanut leaves to understand how caftaric acid and related hydroxycinnamoyl esters are made in this species. We show that peanut leaves contain a hydroxycinnamoyl-CoA:tartaric acid hydroxycinnamoyl transferase (HTT) activity capable of transferring p-coumaroyl, caffeoyl, and feruloyl moieties from CoA to tartaric acid (specific activities of 11 ± 2.8, 8 ± 1.8, 4 ± 0.8 pkat mg^?1 crude protein, respectively). The HTT activity was used to make cis- and trans-p-coumaroyl- and -feruloyl-tartaric acid in vitro. These products allowed definitive identification of the corresponding cis- and trans-hydroxycinnamoyl esters extracted from leaves. We tentatively identified sinapoyl-tartaric acid as another major phenolic compound in peanut leaves that likely participates in secondary reactions with PPO-generated quinones. These results suggest hydroxycinnamoyl-tartaric acid esters are made by an acyltransferase, possibly a BAHD family member, in perennial peanut. Identification of a gene encoding HTT and further characterization of the enzyme will aid in identifying determinants of donor and acceptor substrate specificity for this important class of biosynthetic enzymes. An HTT gene could also provide a means by genetic engineering for producing caffeoyl- and other hydroxycinnamoyl-tartaric acid esters in forage crops that lack them.     

Chemical constituents from Potentilla fragarioides L

Phytochemical investigation on Potentilla fragarioides L. has led to the identification of twelve compounds including β-sitosterol (1), β-daucosterol (2), ursolic acid (3), pomolic acid (4), swinhoeic acid (5), (1-p-hydroxy-cis-cinnamoyl)cinnamic acid (6), trans-caffeoylisocitric acid (7), trans-caffeic acid (8), quercetin (9), quercetin-3-O-β-D-glucuronide (10), (+)-catechin (11) and 3-O-methylellagic acid-4′-O-ɑ-L-rhamnopyranoside (12). Among them, compounds 4–7 were first identified from the genus Potentilla. And the other compounds except compounds 8 and 11 were found in Potentilla fragarioides for the first time. Chemotaxonomic significance of these compounds was discussed.     

Formation of 12-oxo-trans-10-dodecenoic acid in chloroplasts from Thea sinensis leaves

Linolenic acid-[1-¹⁴C] was converted to 12-oxo-trans-10-dodecenoic acid, via 12-oxo-cis-9-dodecenoic acid by incubation with chloroplasts of Thea sinensis leaves. Thus, it was confirmed that linolenic acid is split into a C₁₂-oxo-acid, 12-oxo-trans-10-dodecenoic acid, and a C₆-aldehyde, trans-2-hexenal, leaf aldehyde, by an enzyme system in chloroplasts of tea leaves.     

Steroidal saponins from the leaves of Cordyline fruticosa (L.) A. Chev. and their cytotoxic and antimicrobial activity

Three new steroidal saponins, spirosta-5,25(27)-diene-1β,3β-diol-1-O-α-l-rhamnopyranosyl-(1→2)-β-d-fucopyranoside (fruticoside H) 1, 5α-spirost-25(27)-ene-1β,3β-diol-1-O-α-l-rhamnopyranosyl-(1→2)-(4-O-sulfo)-β-d-fucopyranoside (fruticoside I) 2, and (22S)-cholest-5-ene-1β,3β,16β,22-tetrol 1-O-β-galactopyranosyl-16-O-α-l-rhamnopyranoside (fruticoside J) 3, together with the known quercetin 3-O-β-d-glucopyranoside, quercetin 3-O-[6-trans-p-coumaroyl]-β-d-glucopyranoside, quercetin 3-rutinoside, apigenin 8-C-β-d-glucopyranoside and farrerol, were isolated from the leaves of Cordyline fruticosa. Their structures were elucidated by spectroscopic techniques (¹H NMR, ¹³C NMR, HSQC, ¹H–¹H COSY, HMBC, TOCSY, NOESY), mass spectrometry (HRESIMS, Tandem MS–MS), chemical methods and by comparison with published data. Compounds 1 and 2 showed moderate cytotoxic activity against MDA-MB 231 human breast adenocarcinoma cell line, HCT 116 human colon carcinoma cell line, and A375 human malignant melanoma cell line, while compound 3 was not active. Compound 2 also showed a moderate antibacterial activity against the Gram-positive Enterococcus faecalis.     

Arvensoside A and B,triterpenoid saponins from Calendula arvensis

Two new triterpenoid glycosides from the aerial parts of Calendula arvensis were identified as oleanolic acid-28-O-β-D-glucopyranoside-3-β-O-(O-β-D-galactopyranosyl(1 → 3)-β-D-glucopyranoside) and oleanolic acid 3-β-O-(O-β-D-galactopyranosyl(1 → 3)-β-D-glucopyranoside) by FAB, FAB MIKE mass spectrometry and ¹³C NMR spectroscopy.     

Biosynthesis of sterols and triterpenes in Pelargonium hortorum

Although all parts of the geranium plant (Pelargonium hortorum) are capable of synthesizing sterols and triterpenes and their esters in vitro from mevalonic acid-[2-¹⁴C], the aerial portions are more active than other tissues. All plant parts were shown to incorporate mevalonic acid-[2-¹⁴C] into isoprenoids for at least 3 days. The leaves and petioles had the greatest incorporation on a wet weight basis. Chopped preparations showed comparable incorporations of mevalonate whereby rootlets incorporated about one half as much as most parts; the flower petals incorporated five times the average amount. In leaves the principal sterol synthesized was sitosterol. Metabolic studies with isolated leaves indicated a fairly rapid conversion of free tetracyclic triterpenes to 4-desmethyl-sterols, while β-amyrin was synthesized at a different rate than α-amyrin. Esterified tetracyclic triterpenes exhibited only a slight amount of conversion to 4-desmethylsterols.     

Acylated malvidin 3-rutinosides in dusky violet flowers of Petunia integrifolia subsp. inflata

A new acylated anthocyanin was isolated from a strain of Petunia integrifolia subsp. inflata with dusky violet flowers (B1204d), and identified as malvidin 3-O-[6-O-(4-O-(4-O-(6-O-(trans-caffeoyl)-β-d-glucopyranosyl)-trans-p-coumaroyl)-α-l-rhamnopyranosyl)-β-d-glucopyranoside] as a major pigment. Also, two known pigments were found in these flowers, and determined to be malvidin 3-caffeoylrutinoside and 3-p-coumaroylrutinoside.     

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.     

Biotransformation of (RS)-tropic acid in suspension cultures of Coffea arabica,Datura innoxia,Eucalyptus perriniana and Nicotiana tabacum

Suspension cultures of Datura innoxia and Nicotiana tabacum are able to convert (RS)-tropic acid into its glucose esters (2RS)-3-hydroxy-2-phenylpropionyl β-d-glucopyranoside and (2RS)-2-O-(3-hydroxy-2-phenylpropionyl)-d-glucose whereas a cultures of Eucalyptus perriniana converts it into its glucoside (2RS)-3-O-β-d-glucopyranosyl-2-phenylpropionic acid in addition to glucose esters. Suspension cultures of Coffea arabica converts: (RS)-tropic acid into its glucose, sucrose and isotrehalose esters and a small amount of its glucoside; (RS)-2-(4-hydroxyphenyl)propionic acid into its glucose and sucrose esters and a small amount of its glucoside; and (RS)-ethyl 2-(4-hydroxyphenyl)propionate into its gentiobioside. The formation of sucrose esters and linkage of the aglycone to the C-6 position of glucose are characteristic of the biotransformation of carboxylic acids by suspension cultures of C. arabica. The suspension culture of C. arabica selectively converted (R)-tropic acid into its isotrehalose ester on administration of (RS)-tropic acid.     

Conversion of [1-3H2,G-14C]geranyl pyrophosphate to cyclic monoterpenes without loss of tritium

Soluble enzyme preparations from Salvia officinalis convert the acyclic precursor [1-³H₂,G-¹⁴C]geranyl pyrophosphate to cyclic monoterpenes of the pinane (α-pinene,β-pinene), isocamphane (camphene), p-menthane (limonene,1,8-cineole), and bornane (bornyl pyrophosphate, determined as borneol) type without loss of tritium, and without significant conversion to other free acyclic intermediates. Similarly, [1-³H₂,G-¹⁴C]geraniol is converted in intact S. officinalis leaves to the cyclic monoterpene olefins and 1,8-cineole, as well as to isothujone and camphor, without loss of tritium from C(1). These results clearly eliminate transcis isomerization of geranyl pyrophosphate to neryl pyrophosphate via aldehyde intermediates prior to cyclization, and they support a scheme whereby the trans precursor is cyclized directly by way of a bound linaloyl intermediate.     

Quinovic acid glycosides from Guettarda angelica

Two new triterpene glycosides isolated from the root bark Guettarda angelica were proven to be quinovic acid-3β-O-[β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranoside] and quinovic acid-3β-O-β-d-glucopyranosyl-(28 → 1)-β-d-glucopyranosyl ester. In addition quinovic acid and two known glycoside derivatives (quinovic acid-3β-O-β-d-glucopyranoside and quinovic acid-3β-O-α-l-rhamnopyranoside) were isolated. The structures were elucidated by spectroscopic analysis of the peracetyl methyl ester derivatives.     

C-glycosylflavones from Oryza sativa

Eight flavone C-glycosides isolated from rice plant were found to act as probing stimulants for planthoppers. They have been identified as the known compounds schaftoside, neoschaftoside, carlinoside, isoorientin 2″-glucoside and the new constituents neocarlinoside (6-C-β-D-glucopyranosyl-8-C-β-L-arabinopyranosylluteolin), isoscoparin 2″-glucoside (chrysoeriol 6-C-β-D-(2-O-β-D-glucopyranosyl)glucopyranoside) and its 6?-p-coumaric and ferulic acid esters.     

trans- and cis-Linalool 3,6-Oxide 6-O-β-d-Xylopyranosyl-β-d-glucopyranosides Isolated as Aroma Precursors from Leaves for Oolong Tea

New glycosidic aroma precursors (1 and 2) of the main volatile constituents, trans- and cis-linalool 3,6-oxides (linalool oxides I and II), were isolated from oolong tea leaves (Camellia sinensis var. sinensis cv. Maoxie). The isolation was guided by an enzymatic hydrolysis with acetone powder prepared from fresh tea leaves (cv. Yabukita) followed by GC or GC-MS analyses. Chromatographic purification of hot water extracts of the tea leaves on active charcoal, Amberlite XAD-2, and Sephadex LH-20 columns as well as HPLC gave two new glycosides, trans- and cis-linalool 3,6-oxide 6-O-β-d-xylopyranosyl-β-d-glucopyra-nosides (1 and 2).     

Synthesis of glycosyl esters of oleanolic acid

The trisaccharide, O-(2,3,4-tri-O-benzoyl-β-L-rhamnopyranosyl)-(1→4)-O-(2,3,6-tri-O-benzoyl-β-D-glucopyranosyl)-(1→6)-1,2,3,4-tetra-O-acetyl-β-D-glucopyranose has been prepared by two different routes. Condensation of this trisaccharide with oleanolic acid afforded the corresponding 1,2-trans glycosyl ester. Some other glycosyl esters of oleanolic acid were also prepared by the same method.     

Covalent anthocyanin–flavonol complexes from the violet-blue flowers of Allium ‘Blue Perfume’

Three covalent anthocyanin–flavonol complexes (pigments 1–3) were extracted from the violet-blue flower of Allium ‘Blue Perfume’ with 5% acetic acid-MeOH solution, in which pigment 1 was the dominant pigment. These three pigments are based on delphinidin 3-glucoside as their deacylanthocyanin and were acylated with malonyl kaempferol 3-sophoroside-7-glucosiduronic acid or malonyl-kaempferol 3-p-coumaroyl-tetraglycoside-7-glucosiduronic acid in addition to acylation with acetic acid.By spectroscopic and chemical methods, the structures of these three pigments 1–3 were determined to be: pigment 1, (6^I-O-(delphinidin 3-O-(3^I-O-(acetyl)-β-glucopyranoside^I)))(2^VI-O-(kaempferol 3-O-(2^II-O-(3^III-O-(β-glucopyranosyl^V)-β-glucopyranosyl^III)-4^II-O-(trans-p-coumaroyl)-6^II-O-(β-glucopyranosyl^IV)-β-glucopyranoside^II)-7-O-(β-glucosiduronic acid^VI))) malonate; pigment 2, (6^I-O-(delphinidin 3-O-(3^I-O-(acetyl)-β-glucopyranoside^I)))(2^VI-O-(kaempferol 3-O-(2^II-O-β-glucopyranosyl^III)-β-glucopyranoside^II)-7-O-(β-glucosiduronic acid^VI))); and pigment 3, (6^I-O-(delphinidin 3-O-(3^I-O-(acetyl)-β-glucopyranoside^I)))(2^VI-O-(kaempferol 3-O-(2^II-O-(3^III-O-(β-glucopyranosyl^V)-β-glucopyranosyl^III)-4^II-O-(cis-p-coumaroyl)-6^II-O-(β-glucopyranosyl^IV)-β-glucopyranoside^II)-7-O-(β-glucosiduronic acid^VI))) malonate.The structure of pigment 2 was analogous to that of a covalent anthocyanin–flavonol complex isolated from Allium schoenoprasum where delphinidin was observed in place of cyanidin. The three covalent anthocyanin–flavonol complexes (pigment 1–3) had a stable violet-blue color with three characteristic absorption maxima at 540, 547 and 618 nm in pH 5–6 buffer solution. From circular dichroism measurement of pigment 1 in the pH 6.0 buffer solution, cotton effects were observed at 533 (+), 604 (−) and 638 (−) nm. Based on these results, these covalent anthocyanin–flavonol complexes were presumed to maintain a stable intramolecular association between delphinidin and kaempferol units closely related to that observed between anthocyanin and hydroxycinnamic acid residues in polyacylated anthocyanins. Additionally, an acylated kaempferol glycoside (pigment 4) was isolated from the same flower extract, and its structure was determined to be kaempferol 3-O-sophoroside-7-O-(3-O-(malonyl)-β-glucopyranosiduronic acid).     

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.