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CAFFEIC ACID

Caffeic acid is an organic compound that is classified as a hydroxycinnamic acid.
This yellow solid consists of both phenolic and acrylic functional groups.
Caffeic acid is found in all plants because it is an intermediate in the biosynthesis of lignin, one of the principal components of woody plant biomass and its residues.

CAS Number: 331-39-5
EC Number: 206-361-2
IUPAC Name: (2E)-3-(3,4-Dihydroxyphenyl)prop-2-enoic acid
Chemical Formula: C9H8O4

Other names: caffeic acid, 3,4-Dihydroxycinnamic acid, 331-39-5, trans-caffeic acid, 501-16-6, 3-(3,4-dihydroxyphenyl)acrylic acid, 3,4-Dihydroxybenzeneacrylic acid, (2E)-3-(3,4-dihydroxyphenyl)prop-2-enoic acid, (E)-3-(3,4-dihydroxyphenyl)acrylic acid, 3-(3,4-Dihydroxyphenyl)-2-propenoic acid, Caffeicacid, Cinnamic acid, 3,4-dihydroxy-, 2-Propenoic acid, 3-(3,4-dihydroxyphenyl)-, (E)-3-(3,4-dihydroxyphenyl)prop-2-enoic acid, 4-(2-Carboxyethenyl)-1,2-dihydroxybenzene, trans-Caffeate, CCRIS 847, NSC 57197, 3,4-Dihydroxy-trans-cinnamate, 3-(3,4-Dihydroxyphenyl)propenoic acid, HSDB 7088, UNII-U2S3A33KVM, 4-(2'-Carboxyvinyl)-1,2-dihydroxybenzene, 2-Propenoic acid, 3-(3,4-dihydroxyphenyl)-, (E)-, 71693-97-5, EINECS 206-361-2, U2S3A33KVM, NSC-57197, Caffeate, NSC-623438, CHEBI:16433, (E)-3,4-dihydroxycinnamic acid, AI3-63211, trans-3,4-Dihydroxycinnamic Acid, 3-(3,4-Dihydroxy phenyl)-2-propenoic acid, NSC57197, CHEMBL145, 3-(3,4-dihydroxyphenyl)prop-2-enoic acid, MLS000069738, 331-89-5, CHEBI:36281, MFCD00004392, NSC623438, 2-Propenoic acid, 3-(3,4-dihydroxyphenyl)-, (2E)-, SMR000058214, (2E)-3-(3,4-dihydroxyphenyl)acrylic acid, CAFFEIC ACID (IARC), CAFFEIC ACID [IARC], Caffeic acid - Natural, SR-01000000203, caffeic acid, (E)-isomer, DTXSID5020231, caffeic-acid, Caffeic acid pure, Caffeic acid, 1, Caffeic acid 1000 microg/mL in Acetone, 3,4-dihydroxycinnamic acid (caffeic acid), Caffeic Acid,(S), Caffeic Acid1507, Caffeic acid, trans-, 3,4-dihydroxycinnamate, CAFFEIC ACID natural, Opera_ID_1700, CAFFEIC ACID [MI], CAFFEIC ACID [DSC], Cinnamic acid,4-dihydroxy-, 3,4-Dihydroxycinnamic acid, predominantly trans, CAFFEIC ACID [HSDB], 3,4-Dihydroxybenzeneacrylate, SCHEMBL23358, MLS001076493, MLS002207132, MLS002222302, MLS006011849, BIDD, DTXCID10231, SPECTRUM1503987, CAFFEIC ACID [WHO-DD], 2-Propenoic acid,3-(3,4-dihydroxyphenyl)-, (2E)-, 3,4-Dihydroxycinnamate, XVII, BDBM4375, cid_689043, GTPL5155, AMY3943, Trans 3,4-Dihydroxycinnamic acid, DTXSID901316055, HMS2235G09, HMS3260J17, HMS3649O17, BCP28271, HY-N0172, Tox21_200648, Tox21_500208, BBL012113, Caffeic Acid - CAS 331-39-5, CCG-38895, s2277, STK397812, Caffeic acid, >=98.0% (HPLC), 2-Propenoic acid,4-dihydroxyphenyl)-, AKOS000144463, AC-8006, CS-8205, DB01880, LP00208, SDCCGMLS-0002982.P003, SDCCGSBI-0050196.P004, NCGC00017364-04, NCGC00017364-05, NCGC00017364-06, NCGC00017364-07, NCGC00017364-08, NCGC00017364-09, NCGC00017364-10, NCGC00017364-11, NCGC00017364-12, NCGC00017364-13, NCGC00017364-22, NCGC00022654-03, NCGC00022654-04, NCGC00022654-05, NCGC00022654-06, NCGC00022654-07, NCGC00022654-08, NCGC00022654-09, NCGC00258202-01, NCGC00260893-01, NCGC00263641-01, (E)-3-(3,4-dihydroxyphenyl)acrylicacid, AS-10895, BP-30112, CAS-331-39-5, SMR004703501, XC164210, 4-(2'Carboxyvinyl)-1,2-dihydroxybenzene, Caffeic acid, purum, >=95.0% (HPLC), DB-318886, DB-321780, HY-121231, AB00490047, CS-0081280, EU-0100208, NS00010313, SW197202-3, 2-Propenoic acid, 3-(3,4-dihdroxyphenyl)-, (E)-3-(3,4-dihydroxyphenyl)prop-2-enoicacid, C 0625, C-1500, C01197, C01481, EN300-1067793, (2E)-3-(3,4-Dihydroxyphenyl)-2-propenoic acid, A851723, CAFFEIC ACID (CONSTITUENT OF BLACK COHOSH), Q414116, SR-01000000203-2, SR-01000000203-6, SR-01000000203-7, SR-01000000203-8, BRD-K09900591-001-06-9, BRD-K09900591-001-25-9, BRD-K09900591-001-26-7, SR-01000000203-13, CAFFEIC ACID (CONSTITUENT OF BLACK COHOSH) [DSC], F3096-1708, Z240113804, 2',3-DIHYDROXY-4,4',6'-TRIMETHOXYCHALCONE_met021, 2',4-DIHYDROXY-3,4',6'-TRIMETHOXYCHALCONE_met023, 8B3E4DA7-F3B0-4972-A315-2E387071737F, trans-Caffeic acid, certified reference material, TraceCERT(R), Caffeic acid, matrix substance for MALDI-MS, >=99.0% (HPLC), Caffeic acid, United States Pharmacopeia (USP) Reference Standard, Caffeic acid, matrix substance for MALDI-MS, >=99.0% (HPLC), powder, light beige, InChI=1/C9H8O4/c10-7-3-1-6(5-8(7)11)2-4-9(12)13/h1-5,10-11H,(H,12,13)/b4-2

Natural occurrences
Caffeic acid can be found in the bark of Eucalyptus globulus the barley grain Hordeum vulgare and the herb Dipsacus asperoides.
Caffeic acid can also be found in the freshwater fern Salvinia molest and in the mushroom Phellinus linteus.

Occurrences in food
Caffeic acid is found at a very modest level in coffee, at 0.03 mg per 100 ml.
Caffeic acid is one of the main natural phenols in argan oil.

Caffeic acid is found at a high level in some herbs, especially thyme, sage and spearmint (at about 20 mg per 100 g), at high levels in spices, especially Ceylon cinnamon and star anise (at about 22 mg per 100 g), found at fairly high level in sunflower seeds (8 mg per 100 g), and at modest levels in red wine (1.88 mg per 100 ml) and in apple sauce, apricots and prunes (at about 1 mg per 100 g).

Caffeic acid occurs at high levels in black chokeberry (141 mg per 100 g) and in fairly high level in lingonberry (6 mg per 100 g).
Caffeic acid is also quite high in the South American herb yerba mate (150 mg per 100 g based on thin layer chromatography densiometry and HPLC).
Caffeic acid is also found in barley and rye grain.

Biosynthesis
Caffeic acid, which is unrelated to caffeine, is biosynthesized by hydroxylation of coumaroyl ester of quinic acid (esterified through a side chain alcohol).
This hydroxylation produces the caffeic acid ester of shikimic acid, which converts to chlorogenic acid.
Caffeic acid is the precursor to ferulic acid, coniferyl alcohol, and sinapyl alcohol, all of which are significant building blocks in lignin.
The transformation to ferulic acid is catalyzed by the enzyme caffeate O-methyltransferase.

Caffeic acid and its derivative caffeic acid phenethyl ester (CAPE) are produced in many kinds of plants.

Dihydroxyphenylalanine ammonia-lyase was presumed to use 3,4-dihydroxy-L-phenylalanine (L-DOPA) to produce trans-caffeate and NH3.
However, the EC number for this purported enzyme was deleted in 2007, as no evidence has emerged for its existence.

Biotransformation
Caffeate O-methyltransferase is an enzyme responsible for the transformation of caffeic acid into ferulic acid.
Caffeic acid and related o-diphenols are rapidly oxidized by o-diphenol oxidases in tissue extracts.

Biodegradation
Caffeate 3,4-dioxygenase is an enzyme that uses caffeic acid and oxygen to produce 3-(2-carboxyethenyl)-cis,cis-muconate.

Glycosides
3-O-caffeoylshikimic acid (dactylifric acid) and its isomers, are enzymic browning substrates found in dates (Phoenix dactylifera fruits).

Pharmacology
Caffeic acid has a variety of potential pharmacological effects in in vitro studies and in animal models, and the inhibitory effect of caffeic acid on cancer cell proliferation by an oxidative mechanism in the human HT-1080 fibrosarcoma cell line has recently been established.

Molar mass: 180.16 g/mol
Density: 1.478 g/cm3
Melting point: 223 to 225 °C
XLogP3: 1.2

Hydrogen Bond Donor Count: 3
Hydrogen Bond Acceptor Count: 4
Rotatable Bond Count: 2
Exact Mass: 180.04225873 g/mol

Monoisotopic Mass: 180.04225873 g/mol
Topological Polar Surface Area: 77.8Å²
Heavy Atom Count: 13

Complexity: 212
Covalently-Bonded Unit Count: 1
Compound Is Canonicalized: Yes

Caffeic acid is an orally bioavailable, hydroxycinnamic acid derivative and polyphenol, with potential anti-oxidant, anti-inflammatory, and antineoplastic activities. Upon administration, caffeic acid acts as an antioxidant and prevents oxidative stress, thereby preventing DNA damage induced by free radicals.

Caffeic acid targets and inhibits the histone demethylase (HDM) oncoprotein gene amplified in squamous cell carcinoma 1 (GASC1; JMJD2C; KDM4C) and inhibits cancer cell proliferation.
GASC1, a member of the KDM4 subgroup of Jumonji (Jmj) domain-containing proteins, demethylates trimethylated lysine 9 and lysine 36 on histone H3 (H3K9 and H3K36), and plays a key role in tumor cell development.

Caffeic acid is a hydroxycinnamic acid that is cinnamic acid in which the phenyl ring is substituted by hydroxy groups at positions 3 and 4. It exists in cis and trans forms; the latter is the more common.
Caffeic acid has a role as a plant metabolite, an EC 1.13.11.33 (arachidonate 15-lipoxygenase) inhibitor, an EC 2.5.1.18 (glutathione transferase) inhibitor, an EC 1.13.11.34 (arachidonate 5-lipoxygenase) inhibitor, an antioxidant and an EC 3.5.1.98 (histone deacetylase) inhibitor. It is a hydroxycinnamic acid and a member of catechols.

Caffeic acid is an antioxidant in vitro and also in vivo.
Caffeic acid also shows immunomodulatory and anti-inflammatory activity.
Caffeic acid outperformed the other antioxidants, reducing aflatoxin production by more than 95 percent.
The studies are the first to show that oxidative stress that would otherwise trigger or enhance Aspergillus flavus aflatoxin production can be stymied by caffeic acid.
This opens the door to use as a natural fungicide by supplementing trees with antioxidants.

Chemistry
Caffeic acid is susceptible to autoxidation.
With transition metals, it forms transition metal-carboxylate complexes, but not salts. Glutathione and thiol compounds (cysteine, thioglycolic acid or thiocresol) or ascorbic acid have a protective effect on browning and disappearance of caffeic acid.

This browning is due to the conversion of o-diphenols into reactive o-quinones.
Chemical oxidation of caffeic acid in acidic conditions using sodium periodate leads to the formation of dimers with a furan structure (isomers of 2,5-(3′,4′-dihydroxyphenyl)tetrahydrofuran 3,4-dicarboxylic acid).
Caffeic acid can also be polymerized using the horseradish peroxidase/H2O2 oxidizing system.

Other uses
Caffeic acid may be the active ingredient in caffenol, a do-it-yourself black-and-white photographic developer made from instant coffee.
The developing chemistry is similar to that of catechol or pyrogallol.

Caffeic acid is also used as a matrix in MALDI mass spectrometry analyses.

Isomers
Isomers with the same molecular formula and in the hydroxycinammic acids family are:

Application: caffeic acid is safe to be applied in cosmetics and has a broader antibacterial and antiviral activity. Caffeic acid can also absorb ultraviolet radiation.
A low concentration
of it already has inhibitory efficacy on the generation of skin melanin.
Its applied amount in the beauty products for whitening is at the range of 0.5 to 2%.
Caffeic acid can also be used as additive for the oxidized hair dyes which is good for enhancing the strength of the color.
Preparation: it can be produced from the Perkin’s reaction between protocatechuic aldehyde and acetic acid

Extraction Method
Caffeic acid belongs to common phenolic compounds with effects of increasing the levels of white blood cells.
Caffeic acid is easily to be confused with caffeine and is widely distributed in the plant kingdom.
Its major plant sources include lemon peel, Ranunculaceae cimicifuga rhizome, and valerian root.
Caffeic acid, together with ferulic acid, erucic acid, and p-hydroxy cinnamic acid are ubiquitous hydroxy cinnamic acid-class molecule distributed in various kinds of plants.

This kind of products has conjugated double bonds in the side chain of the molecular structure, and thus exhibiting significant fluorescence upon ultraviolet light, mostly showing bluish color fluorescence.
This is a advantage for paper chromatography tests or thin layer chromatography tests.

Single spike cimicifuga rhizome is extracted with methanol which is removed through concentration under reduced pressure.
Add hot water to the residue to dissolve it.
Heating the water to dissolve the residue, and further filter the insolubles upon heating.
After cooling, add benzene for extraction with the benzene solution being washed with 1% aqueous sodium bicarbonate and further collecting the washed solution.

Add dilute hydrochloric acid for acidification, and then apply benzene to remove the free organic acid; Concentrate under reduced pressure to get rid of the benzene with the residue being the enriched product of caffeic acid.

Chemical Properties
Caffeic acid is yellow crystals and can be dissolved in water and ethanol.
Light yellow to greenish-yellow powder

Uses:
Reagents for Organic Synthesis.
Intermediate of caffeic acid; can be used in organic synthesis.
Used for Biochemical studies.

Uses:
antineoplastic, PGE2 synthase inhibitor, PK inhibitor
Caffeic Acid is a constituent of plants, probably occurs in plants only in conjugated forms.
Caffeic acid is found in all plants because it is a key intermediate in the biosynthesis of lignin, one of the principal sources of biomass.
Caffeic acid is one of the main natural phenols in argan oi.

Indications
Caffeic acid is used for preventing or stopping bleeding during surgery, as well as hemostasis in the department of medicine, obstetrics and gynecology, etc.
Caffeic acid is also used for various causes of neutropenia and thrombocytopenia.

General Description
Yellow prisms or plates (from chloroform or ligroin) or pale yellow granules.
Alkaline solutions turn from yellow to orange.

Caffeic Acid is an orally bioavailable, hydroxycinnamic acid derivative and polyphenol, with potential anti-oxidant, anti-inflammatory, and antineoplastic activities.
Upon administration, caffeic acid acts as an antioxidant and prevents oxidative stress, thereby preventing DNA damage induced by free radicals.

3,4-dihydroxycinnamic acid appears as yellow prisms or plates (from chloroform or ligroin) or pale yellow granules.
Alkaline solutions turn from yellow to orange.

Use and Manufacturing
Caffeic acid is not know to be a significant commercial product.
Caffeic acid is available as the trans isomer in research quantities at purities ranging from 97% to greater than 99%; the cis isomer of caffeic acid is not available commercially.

What is caffeic acid?
Caffeic acid (3,4-dihydroxy-cinnamic acid) is an organic compound and a potent antioxidant.
Caffeic acid can be found naturally in a wide range of plants.

Caffeic acid is a type of polyphenol, a class of micronutrients known for their antioxidant properties.
The nutrient is claimed to have many health benefits, including anti-inflammatory, anticancer, and antiviral abilities.
Caffeic acid may help boost the performance of athletes.
However, it isn’t considered “essential” for human health. In other words, you don’t need it to survive.

The most common source of caffeic acid in the human diet is from drinking coffee.
It’s also found in certain vegetables, fruits, and herbs.
Some examples of foods containing caffeic acid include:

coffee
wine
turmeric
basil
thyme
oregano
sage
cabbage
apples
strawberries
cauliflower
radishes
mushrooms
kale
pears
olive oil
Despite its name, caffeic acid is unrelated to caffeine.

What are the claimed benefits of caffeic acid?
Caffeic acid is a known antioxidant.
Antioxidants help prevent the oxidation of other molecules in the body.
Oxidation produces free radicals, which can damage cells.
This in turn can lead to inflammation, heart disease, or even cancer.

Caffeic acid is also claimed to:
reduce inflammation
prevent cancer
prevent toxicity associated with chemotherapy and radiation
prevent diabetes
prevent premature aging
prevent neurodegenerative diseases, like Parkinson’s disease
reduce exercise-related fatigue
Like other antioxidants, caffeic acid may be helpful in improving overall health as we age.
Its antioxidant properties may help reduce chances of developing cancer, heart disease, and other illnesses of old age, like Alzheimer’s disease.
In addition, it may keep skin looking younger by protecting it from damage from the sun.

How do you get caffeic acid?
The best way to get caffeic acid is from food.
If you eat a diet rich in fruits and vegetables, or you drink coffee on a regular basis, you’re probably getting a fair amount of caffeic acid in your diet already.

Caffeic acid is also marketed as a supplement:
to boost athletic performance
to aid in weight loss
to treat certain viruses, including herpes and HIV
as part of a cancer treatment regimen
in skin care serums
However, more evidence is needed to support these uses and to determine the proper dosage needed to produce the most benefits.

Is there evidence to support the claimed benefits?
More research is needed to assess how caffeic acid is absorbed in the human body.
A small study in seven people found that over 90 percent of caffeic acid ingested was absorbed by the small intestine.

Boosting athletic performance
A small studyTrusted Source was performed to see if caffeic acid could help competitive athletes during prolonged periods of endurance exercise.
The study used caffeic acid phenethyl ester (CAPE), a caffeic acid derivative.

After extracting cells from the blood of competitive cyclists, some of the cells were treated with CAPE, while others were not.
Then all of the cells were subjected to hyperthermal (heat) stress.
The researchers found that cells treated with CAPE were better able to handle and recover from the stress.
More research is needed to replicate these findings outside of the laboratory.

Reducing cancer risk
ResearchTrusted Source on coffee has shown a link between regular consumption of coffee and incidence of certain types of cancer compared to people who don’t drink coffee.
Studies have suggested that daily coffee intake, including decaffeinated coffee, is associated with a reduced incidence of colon and rectal cancer.
Researchers think that these effects are attributed to polyphenol compounds, like caffeic acid.

Anti-aging
Due to its antioxidant and anti-inflammatory properties, caffeic acid is often found in skin care regimens.

Treating HIV
Caffeic acid and its derivatives have been shown to inhibit the virus known as HIV.
While researchers don’t propose using caffeic acid alone to treat HIV, they suggest that including more caffeic acid-rich foods in the diet could help improve overall treatment for the infection.
More research is needed to confirm these benefits.

Caffeic acid is a phenolic compound synthesized by all plant species and is present in foods such as coffee, wine, tea, and popular medicines such as propolis.
This phenolic acid and its derivatives have antioxidant, anti-inflammatory and anticarcinogenic activity.
In vitro and in vivo studies have demonstrated the anticarcinogenic activity of this compound against an important type of cancer, hepatocarcinoma (HCC), considered to be of high incidence, highly aggressive and causing considerable mortality across the world.

The anticancer properties of Caffeic acid are associated with its antioxidant and pro-oxidant capacity, attributed to its chemical structure that has free phenolic hydroxyls, the number and position of OH in the catechol group and the double bond in the carbonic chain.
Pharmacokinetic studies indicate that this compound is hydrolyzed by the microflora of colonies and metabolized mainly in the intestinal mucosa through phase II enzymes, submitted to conjugation and methylation processes, forming sulphated, glucuronic and/or methylated conjugates by the action of sulfotransferases, UDP-glucotransferases, and o-methyltransferases, respectively.

The transmembrane flux of Caffeic acid in intestinal cells occurs through active transport mediated by monocarboxylic acid carriers.
Caffeic acid can act by preventing the production of ROS (reactive oxygen species), inducing DNA oxidation of cancer cells, as well as reducing tumor cell angiogenesis, blocking STATS (transcription factor and signal translation 3) and suppression of MMP2 and MMP-9 (collagen IV metalloproteases).

Caffeic acid (CA) is a polyphenol produced through the secondary metabolism of vegetables,including olives, coffee beans, fruits, potatoes, carrots and propolis, and constitutes the main hydroxycinnamic acid found in the diet of humans.
This phenolic compound is found in the simple form (monomers) as organic acid esters, sugar esters, amides and glycosides, or in more complex forms such as dimers, trimers and flavonoid derivatives, or they may also be bound to proteins and other polymers in the cell wall of the vegetable.

Caffeic acid participates in the defense mechanism of plants against predators, pests and infections, as it has an inhibitory effect on the growth of insects, fungi and bacteria and also promote the protection of plant leaves against ultraviolet radiation B (UV-B).

In vitro and in vivo experiments have been performed, proving innumerable physiological effects of Caffeic acid and its derivatives, such as antibacterial activity, antiviral activity , antioxidant activity, anti-inflammatory activity, anti-atherosclerotic activity, immunostimulatory activity, antidiabetic activity, cardioprotective activity, antiproliferative activity), hepatoprotective activity (14, 15), anticancer activity, and anti-hepatocellular carcinoma activity.

Among these properties, anti-hepatocarcinoma activity is highlighted, because hepatocarcinoma (HCC) is one of the main causes of cancer mortality in the world.
Therefore, further studies on the chemical and pharmacological aspects of Caffeic acid are necessary to contribute in the future to the development of a new drug and consequently the expansion of therapeutic possibilities.

Thus, this review provides an overview of the chemical and pharmacological parameters of Caffeic acid and its derivatives, reporting its main mechanisms of action and pharmacokinetic aspects, as well as to critically analyse its performance in the fight against HCC.

Caffeic acid is a chemical found in many plants and foods.
Coffee is the primary source of caffeic acid in the human diet.
However, it can be found in other food sources such as apples, artichoke, berries, olives, and pears.
Wine also contains a significant amount of caffeic acid.

Caffeic acid is used in supplements for athletic performance, exercise-related fatigue, weight loss, and other conditions.
However, there is no good scientific evidence to support its use for any condition.

How does it work ?
Caffeic acid is thought to have many effects in the body including antioxidant and anti-inflammatory effects.
Caffeic acid might also affect the immune system in the body.
Test tube studies show that it might decrease the growth of cancer cells and viruses.

Insufficient Evidence for
Athletic performance.
Exercise-related fatigue.
Obesity.
Cancer.
HIV/AIDS.

What are the uses of caffeic acid?
There are a number of different uses of caffeic acid, including:

Fighting cancer
Although the research is preliminary, some studies suggest that caffeic acid might slow cancer development or prevent the disease altogether.

One study from 2015 used 1,090 people with breast cancer to look at the effect of caffeine and caffeic acid on breast cancer growth in relation to the condition’s estrogen receptor status.
Caffeic acid concluded that caffeine and caffeic acid demonstrated anticancer properties and suppressed the growth of estrogen receptor cells.

However, the fact that caffeic acid did not harm healthy cells may suggest that it could be a safe alternative to chemotherapy.

A 2003 study explored caffeic acid’s role as a treatment for breast cancer.
That study found that caffeic acid could target a chemical that helps a specific type of breast cancer cell reproduce.
In so doing, caffeic acid also prevented breast cancer from continuing to grow.

Again, these results suggest that caffeic acid might be a viable treatment for some types of breast cancer.

So far, there is no evidence that caffeic acid can replace other cancer treatments, so people with cancer should not consider it as an alternative.

The promising nature of the research, however, suggests that eating foods high in caffeic acid might support other cancer treatments a person may be receiving.

Other benefits of caffeic acid
Further areas where caffeic acid might be beneficial include:

Chronic inflammation: Caffeic acid’s anti-inflammatory power is one way it might fight or prevent cancer.

How to use caffeic acid
Studies that have looked at caffeic acid have used a variety of doses and sometimes mixed it with other plant chemicals that may increase its potency.

As researchers have taken such different approaches to caffeic acid dosing, it is unclear whether any specific dose of this plant polyphenol is necessary to gain its benefits.

No studies currently support a daily limit on caffeic acid intake but, as with any chemical, large doses might be harmful.

The safest option is for someone to eat a variety of foods rich in caffeic acid.
Alternatively, people can consider a caffeic acid supplement.

Can I get enough caffeic acid from my diet?
As caffeic acid is present in a large number of foods, people who eat a varied and healthful diet and who lack significant food allergies, are unlikely to have an allergic reaction.

As with any nutritional supplement, someone should talk to a doctor about risks and benefits before increasing caffeic acid intake.

Caffeic acid is never a good substitute for standard medical care, and even the most promising research into its effects does not suggest that it alone can cure any specific disease.

Sources of caffeic acid
Coffee is a key source of caffeic acid, but numerous other plant-based foods contain small quantities.
Some of the richest sources of caffeic acid include:
ale
berries
dried fruits
seed oils
sage
thyme
oregano
spearmint
cinnamon
caraway
nutmeg
sunflower seeds
black olives
Various products are available that contain caffeic acid as one of their ingredients.

Some research suggests that antioxidants applied directly to the skin may slow aging or improve skin health.
Research on the specific effects of caffeic acid, however, is in its infancy.
So, while evidence supporting antioxidant use is strong, there is little research comparing caffeic acid to other antioxidants.

Although caffeic acid is generally safe and well tolerated by most people, there is not enough research to recommend a daily target dose or a maximum safe dose.

General description
Caffeic acid exists in its free and ester form.
Caffeic acid is considered as the predominant polyphenol, contributing to the hydroxycinnamic acid content in various fruits. Coffee is one of the major source of caffeic acid.
Application
Caffeic acid has been used as a standard of phenolic acid in the study to determine the total phenolic acid content in vegetables after subjecting to alkaline and acid hydrolysis.
Caffeic acid has also been used to determine its antioxidant activity by various assay methods.