HYDROXYCINNAMIC ACID

CAS NO.: 7400-08-0
EC/LIST NO.: 231-000-0

Hydroxycinnamic acids (HCAs) are important natural phenolic compounds present in high concentrations in our food products. 
Dietary intake and nutritional importance of HCAs is briefly described along with their pharmacokinetic properties, which have a high impact on HCAs to reach the target tissue in order to exert their biological activities. 
A range of health beneficial effects were observed for HCAs and in recent years, also for their metabolites formed in gastrointestinal tract, liver and kidneys. 
Therefore, metabolism is of high importance since Hydroxycinnamic acids’ metabolites could retain, enhance or lose the biological activity of corresponding parental Hydroxycinnamic acids. 
The biological activities and health benefits of Hydroxycinnamic acids' metabolites are also briefly reviewed.

Hydroxycinnamic acids acid is a hydroxycinnamic acid, an organic compound that is a hydroxy derivative of cinnamic acid. 
There are three isomers of coumaric acid—o-coumaric acid, m-coumaric acid, and Hydroxycinnamic acids acid—that differ by the position of the hydroxy substitution of the phenyl group. 
Hydroxycinnamic acids is the most abundant isomer of the three in nature.
Hydroxycinnamic acids exists in two forms trans-Hydroxycinnamic acids acid and cis-Hydroxycinnamic acids acid.

Hydroxycinnamic acids is a crystalline solid that is slightly soluble in water, but very soluble in ethanol and diethyl ether.
Hydroxycinnamic acids can be found in a wide variety of edible plants and fungi such as peanuts, navy beans, tomatoes, carrots, basil and garlic.
Hydroxycinnamic acids is found in wine and vinegar.
Hydroxycinnamic acids is also found in barley grain.

Hydroxycinnamic acids acid from pollen is a constituent of honey

Hydroxycinnamic acids acid glucoside can also be found in commercial breads containing flaxseed.

Diesters of Hydroxycinnamic acids acid can be found in carnauba wax.

Hydroxycinnamic acids is biosynthesized from cinnamic acid by the action of the P450-dependent enzyme 4-cinnamic acid hydroxylase (C4H).

Hydroxycinnamic acids is also produced from L-tyrosine by the action of tyrosine ammonia lyase (TAL).

Hydroxycinnamic acids acid is the precursor of 4-ethylphenol produced by the yeast Brettanomyces in wine. 
The enzyme cinnamate decarboxylase catalyzes the conversion of Hydroxycinnamic acids acid into 4-vinylphenol.
Vinyl phenol reductase then catalyzes the reduction of 4-vinylphenol to 4-ethylphenol. 
Hydroxycinnamic acids is sometimes added to microbiological media, enabling the positive identification of Brettanomyces by smell.

cis-p-Coumarate glucosyltransferase is an enzyme that uses uridine diphosphate glucose and cis-p-coumarate to produce 4′-O-β-D-glucosyl-cis-p-coumarate and uridine diphosphate (UDP). 
This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases.

Phloretic acid, found in the rumen of sheep fed with dried grass, is produced by hydrogenation of the 2-propenoic side chain of Hydroxycinnamic acids acid.

The enzyme, resveratrol synthase, also known as stilbene synthase, catalyzes the synthesis of resveratrol ultimately from a tetraketide derived from 4-coumaroyl CoA.

Hydroxycinnamic acids acid is a cofactor of photoactive yellow proteins (PYP), a homologous group of proteins found in many eubacteria.

Hydroxycinnamic acids are a class of aromatic acids or phenylpropanoids that have a C₆-C₃ carbon skeleton.
These compounds are hydroxy derivatives of cinnamic acid.
In the category of phytochemicals that can be found in foods, :
α-Cyano-4-hydroxycinnamic acid
Caffeic acid - burdock, hawthorn, artichoke, pear, basil, oregano, thyme, apple
cycoric acid
Cinnamic acid - aloe
Chlorogenic acid - echinacea, strawberry, pineapple, coffee, sunflower, blueberry
Diferulic acids
Coumaric acid
Ferulic acid - oats, rice, artichokes, oranges, pineapple, apples, peanuts
sinapinic acid

Hydroxycinnamic acids (HCs) (coumaric acid, ferulic acid, sinapic acid, caffeic acid, chlorogenic acid, rosmarinic acid) are phenolic compounds found in fruits, vegetables, and beverages (coffee, tea, wine). 
Hydroxycinnamic acids are of particular interest because of their biological properties and potential applications. 
Several studies have reported that HCs and their derivatives act as powerful antioxidants and protect biologically important molecules from oxidation. 
This chapter elucidates the relationship among the antioxidant activity, chemical structure, and physicochemical parameters of HCs with the aim of understanding their mechanism of action and explaining some of their biological activities.

Among the fruit phenolics, hydroxycinnamic acid derivatives play an important role because of both their abundance and diversity. 
They all derive from cinnamic acid and are essentially present as combined forms of the four basic molecules Hydroxycinnamic acids, caffeic, ferulic , and sinapic acids. 
The free forms of these acids are very rare in fruits. 
Two main types of soluble derivatives have been identified: 
first, those involving an ester bond between the carboxylic function of phenolic acid and one of the alcoholic groups of an organic compound, for example chlorogenic acid, which has been identified in numerous fruits; 
second, those involving a glycosidic bond with one of the phenolic groups of the molecule (e.g., Hydroxycinnamic acids acid O-glucoside). 
The diversity of the hydroxycinnamic acids encountered in plants and particularly in fruits thus results from the nature of the bonds and that of the molecules involved.

Hydroxycinnamic acids occur most commonly in foods of plant origin. 
Of these, caffeic acid is the predominant hydroxycinnamic acid in many fruits, constituting over 75% of total hydroxycinnamic acids found in plums, apples, apricots, blueberries, and tomatoes. 
However,Hydroxycinnamic acids acid is the dominant hydroxycinnamic acid of citrus fruits and pineapple. 
Hydroxycinnamic acids are widely present in the bound form and are rarely found in free form. 
Processing of fruits and vegetables (freezing, sterilization, and fermentation) contributes to the formation of free hydroxycinnamic acids in such products . 
Hydroxycinnamic acid is found in many foods, including apples, apricots, berries, peaches, pears, plums, avocados, and carrots. 
Hydroxycinnamic acid is the key substrate for enzymatic browning, particularly in apples and pears. 
Hydroxycinnamic acids content is reduced by 70% during browning of the pear skins.

Hydroxycinnamic acid derivatives are important class of polyphenolic compounds originated from the Mavolanate-Shikimate biosynthesis pathways in plants. 
Several simple phenolic compounds such as cinnamic acid, Hydroxycinnamic acids , ferulic acid, caffeic acid, chlorgenic acid, and rosmarinic acid belong to this class. 
These phenolic compounds possess potent antioxidant and anti-inflammatory properties. 
These compounds were also showed potential therapeutic benefit in experimental diabetes and hyperlipidemia. 
Recent evidences also suggest that they may serve as valuable molecule for the treatment of obesity related health complications. 
In adipose tissues, hydroxycinnamic acid derivatives inhibit macrophage infiltration and nuclear factor κB (NF-κB) activation in obese animals. 
Hydroxycinnamic acid derivatives also reduce the expression of the potent proinflammatory adipokines tumor necrosis factor-α (TNFα), monocyte chemoattractant protein-1 (MCP-1), and plasminogen activator inhibitor type-1 (PAI-1), and they increase the secretion of an anti-inflammatory agent adiponectin from adipocytes.

Hydroxycinnamic acids possess phenylpropanoid C6-C3 structure as the main chemical scaffold and are recognized by the presence of hydroxyl group(s) on the aromatic ring(s) and a carboxyl group in the lateral chain. 
The number and position of hydroxyl groups and other substituents contribute to the diversity of Hydroxycinnamic acids. 
The most abundant Hydroxycinnamic acids in nature are para-coumaric, caffeic, ferulic, and sinapic acids.
In nature, all four acids are rarely present in a free form and are usually esterified with quinic and tartaric acids or various derivatives of carbohydrates. 
Chlorogenic acids are one the most abundant esters including the whole set of Hydroxycinnamic acids esters with quinic acid, namely caffeoyl-, feruloyl-, dicaffeoyl- and coumaroylquinic acids. 
The most common representative is 5-O-caffeoylquinic acid  often referred to as chlorogenic acid. 
An ester of caffeic acid and Hydroxycinnamic acid is called rosmarinic acid , which is one of the most abundant caffeic acid ester in the plant kingdom besides chlorogenic acids.

Caffeic acid presents up to 70% of whole Hydroxycinnamic acids in fruits, whereas ferulic acid is the prevalent Hydroxycinnamic acid in cereal grains. 
The daily consumption of Hydroxycinnamic acids varies significantly between individuals, which is attributed not only to different intake but also diverse metabolism and absorption from the gut. 
The bioavailability and metabolism of Hydroxycinnamic acids and their conjugates is thus of high importance for health benefits for particular individual.

Herein, we will briefly present natural sources and pharmacokinetic properties of Hydroxycinnamic acids and their esters. 
Afterwards, the main focus will be on their metabolism, biological activities and health benefits with emphasis on specific effects of Hydroxycinnamic acids mediated by their metabolites.

Hydroxycinnamic acids are the most widely distributed phenolic acids in plants. 
Broadly speaking, they can be defined as compounds derived from cinnamic acid. 
They are present at high concentrations in many food products, including fruits, vegetables, tea, cocoa, and wine. 
Cinnamic acid has received great attention in oriental research where it has been used as an antioxidant in food additives in Asia and especially in medical studies in China after being proven to be an effective component of medicinal herbs used by traditional medicine. 
Cinnamic acid is a phenolic acid widely distributed in the plant kingdom. 
Hydroxycinnamic acids presents a wide range of potential therapeutic effects useful in the treatments of cancer, diabetes, lung, and cardiovascular diseases, as well as hepatic, neuro-, and photoprotective effects and antimicrobial and antiinflammatory activities.
Overall, the pharmaceutical potential of cinnamic acid can be attributed to its ability to scavenge free radicals. However, recent studies have revealed that cinnamic acid presents pharmacological properties beyond those related to its antioxidant activity, such as the ability to competitively inhibit HMG-CoA reductase and activate glucokinase, contributing to reduce hypercholesterolemia and hyperglycemia, respectively. 
A diet rich in hydroxycinnamic acids is thought to be associated with beneficial health effects such as a reduced risk of cardiovascular disease. 
The impact of hydroxycinnamic acids on health depends on their intake and pharmacokinetic properties. 

Hydroxycinnamic acids can be found free, dimerized or esterified with proteins and polysaccharides in the cell wall, such as arabinoxylans in grasses and xyloglucans in bamboo. 
Cinnamic acid is an important biological and structural component of the plant cell wall. 
Due to its ability to stop radical chain reactions by resonance followed by polymerization, cinnamic acid offers protection against UV radiation and is responsible for cross-linking polysaccharides and other cell wall polymers. 
Cinnamic acid can be absorbed by the small intestine and excreted in the urine, where therapeutic efficacy is dependent on its physiological concentrations and pharmacokinetic properties, which include absorption, distribution, metabolism, and excretion of metabolites. 
Mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy, especially 2D NMR (COSY, NOESY, HMQC, and HMBC), are the most useful analytical techniques for the structural elucidation of hydroxycinnamic acids besides UV, IR, CD, X-ray analysis, and chemical degradation. 
In this chapter, we update the reader about the therapeutic properties of cinnamic acid, reviewing its dietary sources, the pharmacokinetic profile, antioxidant action mechanisms, and therapeutic effects in the treatment and prevention of various diseases, in order to provide a basis for understanding its pharmaceutical potential.

Hydroxycinnamic acids or hydroxycinnamates are phenolic compounds belonging to non-flavonoid polyphenols.
They are present in all parts of fruits and vegetables although the highest concentrations are found in the outer part of ripe fruits, concentrations that decrease during ripening, while the total amount increases as the size of the fruits increases.

Hydroxycinnamic acid, also known as Hydroxycinnamic acids, is a coumaric acid in which the hydroxy substituent is located at C-4 of the phenyl ring. 
Hydroxycinnamic acids has a role as a plant metabolite. 
Hydroxycinnamic acids is a conjugate acid of a Hydroxycinnamic acid. 
Hydroxycinnamic acids is an organic compound that is a hydroxy derivative of cinnamic acid. 
There are three isomers of coumaric acid: 

Hydroxycinnamic acids m-coumaric acid, and Hydroxycinnamic acids, that differ by the position of the hydroxy substitution of the phenyl group. 
Hydroxycinnamic acids is the most abundant isomer of the three in nature. 
Hydroxycinnamic acids exists in two forms trans-p-coumaric acid and cis-p-coumaric acid. 
Hydroxycinnamic acids is a crystalline solid that is slightly soluble in water, but very soluble in ethanol and diethyl ether. 
Hydroxycinnamic acid belongs to the class of organic compounds known as hydroxycinnamic acids. 
Hydroxycinnamic acids are compounds containing an cinnamic acid where the benzene ring is hydroxylated. 
Hydroxycinnamic acid exists in all living species, ranging from bacteria to humans. 
Outside of the human body, Hydroxycinnamic acid is found, on average, in the highest concentration within a few different foods, such as pepper (Capsicum frutescens), pineapples, and sunflowers and in a lower concentration in spinachs, kiwis, and sweet oranges. 
Hydroxycinnamic acid has also been detected, but not quantified in several different foods, such as wild rices, soursops, garden onions, hyssops, and avocado

The study of hydroxycinnamic acid amides (HCAAs) which are a group of secondary metabolites has been an interesting one and has become one of the important researches at present.
Accumulation of several plant amides was detected in various plants, which play important role in plant growth and development. 
This paper aims to review the biosynthesis, physiology, and functions of Hydroxycinnamic acid accumulation in plants during plant growth and development as well as in response to senescence and drought stress. 
Hydroxycinnamic acids are secondary metabolites derived from phenylalanine and tyrosine pathway. 
Phenylalanine ammonia lyase (PAL) and Hydroxycinnamic acid CoA ligase (4CL) hydroxycinnamoyl-CoA:tyramine N-(hydroxycinnamoyl) transferase (THT) and tyrosine decarboxylase (TyDC) are essential enzymes for HCAA biosynthesis. 
Hydroxycinnamic acids contribute to many developmental processes as well as plant responses against biotic and abiotic stress responses. 
However, there is a need to specifically investigate the role of many Hydroxycinnamic acids in view of plant molecular biology since it is still not fully conceptualized and explained at present.

Hydroxycinnamic acid, a common dietary phenol, could inhibit platelet activity, with IC50s of 371 μM, 126 μM for thromboxane B2 production and lipopolysaccharide-induced prostaglandin E2 generation, respectively.

Hydroxycinnamic acid (Hydroxycinnamic acids), is a ubiquitous plant metabolite with antioxidant and anti-inflammatory properties.
Hydroxycinnamic acid (500 μM and 1 mM) reduces ADP-induced platelet aggregation (55•2 (SE 4•01) % and 35•6 (SE 2•35) % relative to basal level, respectively). 
Hydroxycinnamic acid is able to modify platelet function, a shear-inducing device that simulates primary haemostasis. 
Hydroxycinnamic acid interferes also with arachidonic acid cascade, reducing thromboxane B2 production and lipopolysaccharide-induced prostaglandin E2 generation (IC50 371 and 126 μM, respectively)

Hydroxycinnamic acids (HCs) (coumaric acid, ferulic acid, sinapic acid, caffeic acid, chlorogenic acid, rosmarinic acid) are phenolic compounds found in fruits, vegetables, and beverages (coffee, tea, wine). 
Hydroxycinnamic acid are of particular interest because of their biological properties and potential applications. 
Several studies have reported that HCs and their derivatives act as powerful antioxidants and protect biologically important molecules from oxidation. 
This chapter elucidates the relationship among the antioxidant activity, chemical structure, and physicochemical parameters of HCs with the aim of understanding their mechanism of action and explaining some of their biological activities.

Hydroxycinnamic acids are found in abundance in coffee, where these compounds are esterified with quinic acid. 
Following intake of chlorogenic acids, up to one-third is absorbed in the upper gastrointestinal tract, and subsequently subject to the action of esterases, prior to the release of the free hydroxycinnamic acids. 
Subsequent metabolism results in extensive methylation, sulfation, and to a lesser extent, glucuronidation of these hydroxycinnamic acids released into the circulatory system, along with trace quantities of the parent chlorogenic acids. 
The remaining two-thirds of chlorogenic acids reach the colon where they are further metabolized. 
The appearance of peak plasma concentrations for caffeic acid and ferulic acid after 1 hour and peak plasma concentrations for dihydrocaffeic and dihydroferulic acids after 4 to 5 hours suggests a biphasic profile of absorption, with primary absorption and metabolism occurring in the small intestine and further metabolism occurring in the colon. 
Overall coffee chlorogenic acids are highly bioavailable, with up to 30% of intake being excreted as metabolites within 24 hours of ingestion.

Hydroxycinnamic acid amides (HCAAs) are a widely distributed group of plant secondary metabolites purported to function in several growth and developmental processes including floral induction, flower formation, sexual differentiation, tuberization, cell division, and cytomorphogenesis. 
Although most of these putative physiological roles for Hydroxycinnamic acids remain controversial, the biosynthesis of amides and their subsequent polymerization in the plant cell wall are generally accepted as integral components of plant defense responses to pathogen challenge and wounding. 
Tyramine-derived Hydroxycinnamic acids are commonly associated with the cell wall of tissues near pathogen-infected or wound healing regions. 
Moreover, feruloyltyramine and feruloyloctapamine are covalent cell wall constituents of both natural and wound periderms of potato (Solanum tuberosum) tubers, and are putative components of the aromatic domain of suberin. 
The deposition of Hydroxycinnamic acidss is thought to create a barrier against pathogens by reducing cell wall digestibility. 
Hydroxycinnamic acidss are formed by the condensation of hydroxycinnamoyl-CoA thioesters with phenylethylamines such as tyramine, or polyamines such as putrescine. 
The ultimate step in tyramine-derived Hydroxycinnamic acids biosynthesis is catalyzed by hydro xycinnamoyl-CoA:
tyramine N-(hydroxycinnamoyl)transferase (THT; E.C. 2.3.1.110). 
The enzyme has been isolated and purified from a variety of plants, and the corresponding cDNAs cloned from potato, tobacco (Nicotiana tabacum), and pepper (Capsicum annuum). 
THT exhibits homology with mammalian spermidine-spermine acetyl transferases and putative N-acetyltransferases from microorganisms. 
In this review, recent advances in our understanding of the physiology and biochemistry of Hydroxycinnamic acids biosynthesis in plants are discussed.

Hydroxycinnamic acids (HCAs) are natural phenylpropenoic acid compounds, which occur as esters, glycosides, and/or conjugates of proteins. 
A few also exist as natural free acids . 
They are major intermediates in the biosynthetic pathways of polyphenols. 
They have been recognized as an important source of antioxidants and play an influential role in the stability, flavor, color, and nutritional bioavailability of foods rich in the compounds.

Hydroxycinnamic acidss are derived from phenylalanine and tyrosine, comprising a nine carbon (C6single bondC3) skeleton with a side chain double bond (with cis or a trans configuration), representing a phenylpropanoid structure . 
The hydroxyl functional groups on the benzene ring and the unsaturated bond of its ethylenic side chain are important sites for reactions with reactive oxygen species (ROS), portraying a structure-activity relationship . 
Thus, their biological activity depends on the pattern of substitution of the aromatic moiety .

The most common Hydroxycinnamic acidss are cinnamic acid, caffeic acid, sinapic acid, o-coumaric acid, m-coumaric acid, Hydroxycinnamic acids, and ferulic acid. 
Adefegha and Oboh  reported the presence of caffeic and chlorogenic acids in a phenolic rich extract of C. volubile leaves. 
This was confirmed by Oboh et al.
who also reported the presence of Hydroxycinnamic acids in the phenolic rich extract. 
Molehin et al. 
also reported the presence of caffeic acid in the ethyl acetate, ethanol, and methanol extracts of the leaves.

Key words: 
hydroxycinnamic acid amides, hydroxycinnamoyl-CoA thioesters, metabolic engineering, phenylethylamines, plant cell wall, polyamines, secondary metabolism, tyramine.

Appearance :Powder
Physical State :Solid
Solubility :Soluble in water (slightly), methanol, ether, ethanol, and benzene.
Storage :Store at room temperature
Melting Point :193-195° C (lit.)
Boiling Point :~373.2° C at 760 mmHg (Predicted)
Density :~1.3 g/cm3 (Predicted)
Refractive Index :n20D 1.66 (Predicted)
IC50 :Mus musculus: IC50 = 180 nM; 
DAAO: IC50 = 6.269 mM (human); 
Serine racemase: IC50 = 8.386 mM (human);
DDO: IC50 = 10 mM (human)

Chemical Name or Material : trans-2-Hydroxycinnamic acid
Quantity : 25g
Molecular Formula : C9H8O3
Beilstein : 1100900 
IUPAC Name : (E)-3-(2-hydroxyphenyl)prop-2-enoic acid
Formula Weight :  164.16

The influence of hydroxycinnamic acids (HCA) on the oxy-radical generated system, potassium iodide/hydrogen peroxide, was investigated through the enhancement of triiodide (I3−) yield. 
Caffeic acid, chlorogenic acid, and Hydroxycinnamic acids were used as typical representatives of Hydroxycinnamic acids.
A linear correlation, with positive slopes, was found between absorption maximum of I3− at 351 nm and Hydroxycinnamic acids concentration in all cases. 
The magnitude of enhanced I3− production was found to increase in the following order: Hydroxycinnamic acids < chlorogenic acid ≤ caffeic acid. 
A reaction mechanism, which includes negative influence of oxygen-centered free radicals on the I3− yield, was proposed. 
The enhanced production of I3− by Hydroxycinnamic acids is attributed to their radical scavenging activity. 
Supported by literature data, results obtained in this study have showed the correlation between radical scavenging activities of Hydroxycinnamic acids and their ability to enhanced I3− generation.

Hydroxycinnamic acid derivatives play an important role in plant life, not only as anti-pathogenic compounds and feeding deterrents but also as intermediates in the biosynthesis of lignin. 
Several classes of hydroxycinnamoyltransferases using differently activated (hydroxy)cinnamic acids are known from plant metabolism .
We are especially interested in the BAHD-family of hydroxycinnamoyltransferases which are part of the biosyntheses of e.g. rosmarinic acid and cimicifugic acids as well as the formation of monolignols. 
The evolution of monolignol biosynthesis is a crucial step for the ability of plants to conquer the land by being able to synthesise stabilising lignin as well as UV-protectants and antibacterial/antifungal compounds.

Hydroxycinnamic acid derivatives are important class of polyphenolic compounds originated from the Mavolanate-Shikimate biosynthesis pathways in plants. 
Several simple phenolic compounds such as cinnamic acid, Hydroxycinnamic acids, ferulic acid, caffeic acid, chlorgenic acid, and rosmarinic acid belong to this class. 
These phenolic compounds possess potent antioxidant and anti-inflammatory properties. 
These compounds were also showed potential therapeutic benefit in experimental diabetes and hyperlipidemia. 
Recent evidences also suggest that they may serve as valuable molecule for the treatment of obesity related health complications. 
In adipose tissues, hydroxycinnamic acid derivatives inhibit macrophage infiltration and nuclear factor κB (NF-κB) activation in obese animals. 
Hydroxycinnamic acid derivatives also reduce the expression of the potent proinflammatory adipokines tumor necrosis factor-α (TNFα), monocyte chemoattractant protein-1 (MCP-1), and plasminogen activator inhibitor type-1 (PAI-1), and they increase the secretion of an anti-inflammatory agent adiponectin from adipocytes. 
Furthermore, hydroxycinnamic acid derivatives also prevent adipocyte differentiation and lower lipid profile in experimental animals. 
Through these diverse mechanisms hydroxycinnamic acid derivatives reduce obesity and curtail associated adverse health complications.

Various investigations related to the biosynthesis of o-hydroxycinnamic acid in sweetclover require that simple, rapid methods of assay be available for both the cis isomer (coumarinic acid) and the trans isomer (o-coumaric acid). 
In one procedure, designatled method I, o-coumaric acid and total o-hydroxycinnamic acid are determined, and coumarinic acid is estimated by difference; while in the other procedure, method 11, coumarinic acid and total 2-hydroxycinnamic acid are determined, and o-coumaric acid levels are calculated by difference. 
Both methods depend upon the ultraviolet- mediated interconversion of the non-fluorescent cis isomer and the fluorescent trans form illustrated in 
In addition, method II depends upon the fact that o-hydroxycinmmic acid occurs in sweetclover almost exclusively in the form of glucosides , and sweetclover β- glucosidase readily hydrolyzes coumarinyl glucosl.de but is virtually inert toward o-coumarin glucoside

Hydroxycinnamic acid bound arabinoxylans (HCA-AXs) were extracted from brans of five Indian millet varieties and response surface methodology was used to optimize the extraction conditions. 
The optimal condition to obtain highest yield of millet HCA-AXs was determined as follows: time 61min, temperature 66°C, ratio of solvent to sample 12ml/g. 
Linkage analysis indicated that hydroxycinnamic acid bound arabinoxylan from kodo millet (KM-HCA-AX) contained comparatively low branched arabinoxylan consisting of 14.6% mono-substituted, 1.2% di-substituted and 41.2% un-substituted Xylp residues. 
The HPLC analysis of millet HCA-AXs showed significant variation in the content of three major bound hydroxycinnamic acids (caffeic, p-coumaric and ferulic acid). 
The antioxidant activity of millet HCA-AXs were evaluated using three in vitro assay methods (DPPH, FRAP and β-carotene linoleate emulsion assays) which suggested both phenolic acid composition and structural characteristics of arabinoxylans could be correlated to their antioxidant potential, the detailed structural analysis revealed that low substituted KM-HCA-AX exhibited relatively higher antioxidant activity compared to other medium and highly substituted Hydroxycinnamic acids-AXs from finger (FM), proso (PM), barnyard (BM) and foxtail (FOXM) millet.

Hydroxycinnamic acids and flavonoids are dietary phenolic antioxidants that are abundant in our diet. 
Hydroxycinnamic acids are highly sulfated in vivo, and sulfotransferases (SULTs), in particular SULT1A1, play a major role in their metabolism. 
Flavonoids are potent inhibitors of human SULTs. 
In this study, the potential metabolic interaction between dietary hydroxycinnamic acids and flavonoids was investigated. 
Flavonoids, such as luteolin, quercetin, daidzein, and genistein, are identified as potent inhibitors of hydroxycinnamic acid sulfation in human liver S9 homogenate with IC values <1 μM. 
The inhibitory activity was less potent in the human intestinal S9 homogenate. 
We also demonstrate that quercetin conjugates found in vivo (quercetin-3-O-glucuronide, quercetin-7-O-glucuronide, and quercetin-3'-O-sulfate) moderately inhibited the sulfation of hydroxycinnamic acids in human liver S9. 
In an intact cellular system, human HepG2 cells, caffeic acid and ferulic acid sulfation was inhibited by luteolin and quercetin (IC: 1.6-3.9 μM). 
Quercetin-3'-O-sulfate weakly inhibited sulfation. Quercetin glucuronides, limited by their low cellular uptake, were ineffective. 
These data suggest that the inhibition of SULTs by flavonoids and in vivo flavonoid conjugates may modify the bioavailability of dietary hydroxycinnamic acids by suppressing their conversion to sulfated metabolites.

trans-4-Coumaric acid or (e)-Hydroxycinnamic acids, the trans-isomer of 4-coumaric acid, also known as Hydroxycinnamic acid, belongs to the class of organic compounds known as hydroxycinnamic acids. 
Hydroxycinnamic acids are compounds containing a cinnamic acid where the benzene ring is hydroxylated. 
Hydroxycinnamic acid is a neutral compound. 
Hydroxycinnamic acid exists in all living species, from bacteria to humans.
Hydroxycinnamic acid is found in highest concentrations in pepper (c. frutescens), pineapples, and sunflowers and in lower concentration in spinachs, kiwis, and sweet oranges. 
Hydroxycinnamic acid has also been detected in wild rices, soursops, garden onions, hyssops, and avocado. 
This could makeHydroxycinnamic acid a potential biomarker for the consumption of these foods.

IUPAC NAME :
(2E)-3-(4-hydroxyphenyl)prop-2-enoic acid

3-(4-hydroxyphenyl)acrylic acid

4-hydroxycinnamic acid

4-Hydroxyzimtsäure

Parahydroxycinnamic Acid

SYNONYMS:
(2e)-3-(4-Hydroxyphenyl)acrylate    
(2e)-3-(4-Hydroxyphenyl)acrylic acid    
(e)-3-(4-Hydroxyphenyl)-2-propenoate    
(e)-3-(4-Hydroxyphenyl)-2-propenoic acid    
(e)-P-Coumarate    
(e)-P-Hydroxycinnamate
3-(4-Hydroxyphenyl)-2-propenoate    
3-(4-Hydroxyphenyl)-2-propenoic acid    
3-(4-Hydroxyphenyl)acrylate    
3-(4-Hydroxyphenyl)acrylic acid