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.     

Chlorogenic acid biosynthesis in Cestrum poeppigii

The chlorogenic acid content of Cestrum poeppigii, and its ability to form the acid from labelled t-cinnamic acid, was determined at different stages of growth. In contrast to mature plants, young plants showed great seasonal variation in their chlorogenic acid content. The incorporation of radioactivity from t-cinnamic into chlorogenic acid also differed greatly during the growth period. Trapping experiments with caffeic and p-coumaric acids were performed to study the effect of large pools of these acids on the incorporation of t-cinnamic acid-3-[¹⁴C] into chlorogenic acid. The kinetics of incorporation exclude a major role for caffeic acid in the biosynthesis of chlorogenic acid.     

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.     

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.     

Hydroxytropane tiglates in the roots of Mandragora species

Roots of Mandragora autumnalis and M. vernalis contain hyoscyamine, hyoscine, cuscohygrine, apoatropine 3α-tigloyloxytropane and 3,6-ditigloyloxytropane. Belladonnine is present in the dried roots but could not be detected in fresh roots. No major differences were found in the alkaloids present in the two species. This is the first time the presence of tiglic acid esters has been reported in Mandragora species and the significance of this in the chemotaxonomy of the genus is indicated.     

Photocontrol of chlorogenic acid biosynthesis in potato tuber discs

The appearance of phenylalanine ammonia-lyase activity and the accumulation of chlorogenic acid in potato tuber discs are stimulated by illumination with white light, whereas the appearance of cinnamic acid 4-hydroxylase activity is unaffected by illumination. The photosensitive step in chlorogenic acid biosynthesis may be by-passed by treatment of discs with exogenous supplies of cinnamic acid, whereas treatment of discs with phenylalanine does not isolate the photosensitive step. Therefore, the site of photocontrol of chlorogenic acid biosynthesis in potato tuber discs is the reaction catalysed by phenylalanine ammonia-lyase. Cinnamic acid 4-hydroxylase activity in vitro is unaffected by p-coumaric acid, caffeic acid or chlorogenic acid. Phenylalanine ammonia-lyase activity in vitro is sensitive to inhibition by cinnamic acid. The in vitro properties of the two enzymes are also consistent with the hypothesis that phenylalanine ammonia-lyase rather than cinnamic acid 4-hydroxylase is important in the regulation of chlorogenic acid biosynthesis in potato tuber discs.     

Spectroscopic studies on a withanolide from Withania coagulans

The structure of a new withanolide was elucidated as 3β,14α,2Oα_F,27-tetrahydroxy-1-oxo-20R,22R-witha-5,24-dienolide using chemical and spectroscopic methods. The structure was corroborated by comparative studies with known closely related withanolides. Sitosterol-β-d-glucoside was identified through chemical and spectroscopic means.     

Incorporation of 14CO2, 14C-phenylalanine and 14C-cinnamate into soluble and insoluble cinnamic derivatives in Mentha arvensis

With the successful development of methods for the isolation and purification of ethanol-insoluble cinnamic acid esters in mint it became possible to initiate kinetic, isotopic studies on purified, ‘insoluble’ derivatives of caffeic acid, ferulic acid and p-coumaric acid. Pulse-feeding experiments were conducted with ¹⁴CO₂, phenylalanine-U-¹⁴C and cinnamic acid-3-¹⁴C. The ferulic acid derivative exhibited a significant turnover as compared to the other insoluble derivatives which were relatively stable. Time-course tracer studies were performed to compare the turnover of soluble caffeic acid derivatives with ‘insoluble’ forms of caffeic acid. Caffeic acid associated with a macromolecular fraction consistently showed a higher specific activity than either soluble caffeic acid or the caffeic acid associated with a second insoluble derivative.     

Differences in the incorporation pattern of labelled cinnamic acid and l-phenylalanine into the anthocyanins of Petunia hybrida

The incorporation of phenylalanine-[¹⁴C] into anthocyanins of petals of Petunia hybrida is greater than that of cinnamic acid-[¹⁴C]. Moreover, there is a preferential incorporation of phenylalanine-[¹⁴C] into delphinidin 3-monoglucoside, as compared with the incorporation into cyanidin and peonidin 3-monoglucosides.     

阿魏酸和肉桂酸对杉木种子发芽的效应

杉木〔Ｃｕｎｎｉｎｇｈａｍｉａｌａｎｃｅｏｌａｔａ (Ｌａｍｂ .)Ｈｏｏｋ .〕连栽导致地力衰退问题 ,国内大多从提高土壤肥力和完善栽培制度方面进行研究[1 ] ,对化感自毒物质的毒害作用却注意不够。据报道杉木根桩与周围土壤酚类物质对杉木存在自毒作用[2 ] ,但除酚剂 (乙烯吡咯啉酮Ｋ30 0 )能降低杉木及其林下土壤的这种自毒作用[3 ] ,这暗示杉木叶、根等器官中含有酚类化感物质 ;香草醛 (ｖａｎｉｌｌｉｎ)对杉木幼苗生长也具有毒害作用[4] 。阿魏酸 (ｆｅｒｕｌｉｃａｃｉｄ)、肉桂酸 (ｃｉｎｎａｍｉｃａｃｉｄ)和香草醛同属于化感…     

Effect of phenolic compounds in Lycopersicon esculeutum on the synthesis of ethylene

Caffeic, coumaric, sinapic and ferulic acids and naringenin were found in green tomato fruit, Chlorogenic acid accounted for 75% of the total phenolics in mature green fruit but only 35% in ripe fruit. There was very little change in the phenolic composition of the flesh of the fruit during ripening, whereas in the skin, naringenin increased markedly at the onset of the climacteric and three unidentified compounds increased during the climacteric rise. The increase in the concentration of naringenin was accompanied by an increase in the production of ethylene in the skin. Investigation of three systems producing ethylene from 4-methylmercapto-2-oxobutyric acid in the presence of peroxidase, showed that only p`-coumaric acid or naringenin were capable of acting as phenolic substrates, the other phenolic compounds being inhibitory.     

The properties of cinnamic acid 4-hydroxylase of aged swede root disks

The cinnamic acid 4-hydroxylase of swede root disks is a microsomal enzyme with a specific requirement for NADPH and cinnamic acid. The enzyme is inhib     

Phytate metabolism in Petunia pollen

Phytic acid has been detected in the anthers of young flower buds of Petunia hybrida, the amount increasing slowly as the flower develops until anther dehydration, when there was a more rapid increase in phytic acid content. In mature pollen, the phytic acid content was found to be 2.0 % by weight, of which 90 % was water soluble, while free myo-inositol was a relatively low 0.06 % by weight. Breakdown of phytic acid was initiated soon after pollen germination began, and its degradation products, myo-inositol and inorganic phosphate, were rapidly mobilized for phospholipid and pectin biosynthesis. Both are in high demand during pollen tube elongation. Utilization of myo-[2-³H]inositol for phospholipid biosynthesis was about five times that for pectin synthesis during the first few hours of pollen germination. The label in the phospholipid was identified as the myo-inositol moiety of phosphaltidylinositol, while the pectin material contained predominantly labelled arabinose, with smaller amounts of label in galacturonic acid, glucose and xylose. A chase experiment showed that the myo-inositol moiety of phosphatidylinositol was subject to a relatively rapid turnover, while the label in pectin was not. Labelling germinating pollen with [³²P]orthophosphate gave label in phosphatidic acid, phosphatidylinositol, phosphatidylethanolamine and phosphatidylcholine of the phospholipids. Phosphatidylinositol contained 30 % of this label initially, a proportion which declined to 10 % over longer periods of germination.     

Biosynthetic conversion of α-methylbutyric acid to tiglic acid in Datura meteloides

The administration of RS-α-methylbutyric-[1-¹⁴C] acid to Datura meteloides plants resulted in the formation of radioactive meteloidine. A systematic degradation indicated that essentially all the activity was located at C-1 of the tiglic acid moiety of the alkaloid.     

The effect of blue light on free and esterified phenolic acids in etiolated gherkin tissues

The major phenolic acid found in gherkin tissues is p-coumaric acid, although cinnamic and caffeic acids are also present; these occur both free an     

A genetic investigation of the esters of caffeic acid with rhamnose or glucose in leaves of Plantago major

The genetic relationship between two sugar esters of caffeic acid in the leaves of Plantago major has been investigated. The difference is shown to be due to a single gene. Glucose accounts for the sugar part in the dominant phenotype while in the recessive type the sugar is rhamnose. This difference is only partly correlated with the division of the species into subspecies. The rhamnose type is found only in P. major ssp. pleiosperma Pilger, although only in less than half of the plants investigated.     

Lipase-catalyzed acylation of quercetin with cinnamic acid

Acylation of quercetin with cinnamic acid catalyzed by Candida antarctica lipase B (CAL-B) or Pseudomonas cepacia lipase C (PCL-C) was investigated. Specifically, the effects of reaction duration, incubation temperature, and molar ratio of substrates on bioconversion yield, initial rate of reaction, and regioselectivity were investigated. Three new acylated quercetin analogues were produced: quercetin 4′-cinnamate (C₂₄H₁₆O₈), quercetin 3′,4′-dicinnamate (C₃₃H₂₂O₉), and quercetin 7,3′,4′-tricinnamate (C₄₂H₂₈O₁₀). The effects of the lipase-catalyzed acylation conditions on the bioconversion yields varied across the conditions. The initial rate of reaction of acylation of quercetin with cinnamic acid catalyzed by CAL-B and PCL-C was similar. In the presence of CAL-B, acylation mainly took place at the C-4′-OH, generating mostly quercetin 4′-cinnamate; whereas with PCL-C, acylation mainly took place at both the 4′- and 3′-hydroxyls, generating quercetin 3′,4′-dicinnamate. Thin-layer-chromatography analysis showed that the three acylated quercetin analogues had higher lipophilicity when compared with quercetin. In silico investigation revealed that quercetin 4’-cinnamate and quercetin 3′,4′-dicinnamate are likely to be orally active pharmacological drugs.     

茄子根系分泌物中香草醛和肉桂酸对黄萎菌的化感效应

采用室内培养和生物测定的试验方法,研究了不同浓度的香草醛和肉桂酸对黄萎菌（Verticillium dahliae）及茄子种子萌发、幼苗生长的化感效应.结果表明,香草醛和肉桂酸对茄子黄萎菌的化感效应存在差异,表现为所有浓度的肉桂酸都抑制了黄萎菌孢子萌发,当浓度为0.5mmol/L时抑制作用最大;香草醛在浓度为0.1mmol/L时抑制孢子萌发,其余浓度则表现出促进作用.对香草醛和肉桂酸的生物测定结果显示,当浓度为0.1mmol/L时,肉桂酸促进茄子种子萌发和幼苗生长,其余浓度则表现为抑制作用,并且随着浓度的加大抑制作用增强;香草醛在各浓度水平下都促进了茄子种子萌发和幼苗生长,当浓度为0.5mmol/L时促进作用最大.     

Control of phenylalanine ammonia-lyase and cinnamic acid 4-hydroxylase in gherkin tissues

Blue light mediates a transient increase in the extractable activity of phenylalanine ammonia-lyase from both cotyledons and hypocotyls of etiolated gherkin seedlings, but concurrent changes in extractable cinnamic acid 4-hydroxylase activity only occur in cotyledons. Excision, followed by incubation in the dark, also results in stimulation of the lyase activity in both tissues, but the hydroxylase activity is only stimulated in cotyledons, again concurrently with the lyase. Stimulated levels of hydroxycinnamic acid esters are, however, only formed following light treatment, indicating the presence of another light-sensitive step in their biosynthesis. Treatment of gherkin tissues with 2-aminooxyacetic acid or α-aminooxy-β-phenylpropionic acid inhibits phenylalanine ammonia-lyase activity in situ, reduces the accumulation of hydroxycinnamic acid esters and presumably reduces the endogenous cinnamic acid pool. This treatment increases extractable lyase activity and delays its peak in activity. In cotyledons, these changes in the lyase are associated with concurrent and similar changes in extractable hydroxylase activity, whilst in hypocotyls the hydroxylase is relatively unaffacted. The increase in phenylalanine ammonia-lyase activity following excision of cotyledons and hypocotyls is prevented by cinnamic acid; in cotyledons the hydroxylase is similarly affected, but after a longer lag. Thus whilst cinnamic acid can modify the extractable activity of the lyase, it cannot itself mediate changes in the extractable activity of the hydroxylase.     

Biosynthesis of azetidine-2-carboxylic acid from methionine in Nicotiana tabacum

The administration of dl-methionine-[1¹⁴C] to Nicotia tabacum resulted in the formation of radioactive azetidine-2-carboxylic acid (isolated by dilution) which was specifically labelled on its carboxyl group. This result and other evidence strongly indicates that this imino acid is a normal component of tobacco.