5-Lipoxygenase (5-LO); TRPV1

Caffeic acid modulates histamine-induced reactions. When the concentration of light is increased from 0.1 to 1 mM, the modulatory impact of caffeic acid progressively increases, mimicking a normal dose-modulated response. Capsaicin-induced responses were considerably reduced in HEK293T-TRPV1 cells treated with 1 mM caffeine. Lower doses of caffeic acid inhibit capsaicin-induced reactions. Experiments have shown that caffeic acid can dramatically suppress histamine-sensitive dorsal root ganglion (DRG) neurons. The administration of caffeic acid (1 mM) reduced the percentage of DRG neurons responding to histamine application from 12.5% to 2.1%. The allyl isothiocyanate (AITC)-induced rise in intracellular calcium in TRPA1-expressing cells was thought to be considerably inhibited by 1 mM caffeic acid. Caffeic acid may also inhibit AITC-induced TRPA1 activation [1].

In the mouse model, histamine-induced scratching (30.50±10.87 times/1 hour, n=6) was seen when caffeic acid (500 mg/kg) was used. Furthermore, although there appeared to be a declining trend (49.40±12.35 times/1 h, n=5), the anti-scratch effect of a lower dose of caffeic acid (100 mg/kg) in histamine-induced scratching was not determined to be significant. Scratching caused by chlorine buffer can be considerably reduced by 500 mg/kg caffeic acid (161.6±31.42 times/1 h, n=5)[1]. In the hippocampal regions, caffeineic acid dramatically decreased 5-LO mRNA (P<0.01). The 5-LO protein expression in the I/R-caffeic acid group was significantly lower (P<0.05 or P<0.01) than in the potential reperfusion (I/R) untreated group. This was particularly true when comparing the I/R-caffeic acid and I/R untreated groups. The latency of finding the platform was significant throughout the process in both the low-dose and high-dose caffeic acid groups, and the entire platform latency was in I/R. Group R-caffeic acid (50 mg/kg). Hippocampal neuron nuclear pyknosis was dramatically reduced in the high-dose caffeic acid group, with a pyknosis rate of (13.3) ±3.0)%, while cell damage was still evident in the low-dose group (63.6±2.8)% [2].

Itch is an unpleasant sensation that evokes a desire to scratch. Although often regarded as a trivial 'alarming' sensation, itch may be debilitating and exhausting, leading to reduction in quality of life. In the current study, the question of whether caffeic acid can be used to alleviate itch sensation induced by various pruritic agents, including histamine, chloroquine, SLIGRL-NH2, and β-alanine was investigated. It turned out that histamine-induced intracellular calcium increase was significantly blocked by caffeic acid in HEK293T cells that express H1R and TRPV1, molecules required for transmission of histamine-induced itch in sensory neurons. In addition, inhibition of histamine-induced intracellular calcium increase by caffeic acid was demonstrated in primary cultures of mouse dorsal root ganglion (DRG). When chloroquine, an anti-malaria agent known to induce histamine-independent itch - was used, it was also found that caffeic acid inhibits the induced response in both DRG and HEK293T cells that express MRGPRA3 and TRPA1, underlying molecular entities responsible for chloroquine-mediated itch. Likewise, intracellular calcium changes by SLIGRL-NH2 - an itch-inducing agent via PAR2 and MRGPRC11 - were decreased by caffeic acid as well. However, it was found that caffeic acid is not capable of inhibiting β-alanine-induced responses via its specific receptor MRGPRD [1].

Experimental design [2]
Rats were divided into five groups: the sham group (n = 9), I/R non-treated group (n = 9), I/R-caffeic acid group (10 mg · kg−1) (n = 9), I/R-caffeic acid group (30 mg · kg−1) (n = 9) and I/R-caffeic acid group (50 mg · kg−1) (n = 9). In I/R-caffeic acid groups, the rats were administrated caffeic acid at 10, 30, 50 mg · kg−1 (prepared with 0.3% sodium carboxymethyl cellulose) by intraperitoneal injection at 30 min prior to ischemia. The sham group and I/R group were treated with an equal volume of 0.3% sodium carboxymethyl cellulose.

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Induction of global cerebral I/R model[2]
Rats were anesthetized by intraperitoneal injection of chloral hydrate (400 mg/kg), and fixed in a supine position. Global cerebral ischemia was induced as previously described. A midline incision was made in the neck, after that the incision was extended 1 cm to the right. Then both common carotid arteries and the right common jugular vein were exposed carefully by blunt dissection. The distal end of the common jugular vein was ligated following 2 ml heparinized saline (100 mL 0.9% saline containing heparin (250 U)) were perfused. The blood accounting for about 30 percent of the total blood volumes were taken from the right common jugular vein leading to hypotension. Global cerebral ischemia was induced by bilateral clamping of the common carotid arteries combined with hypotension. After ischemia for 20 min, the artery clamps were removed, and the extracted blood was reinfused. Rats in the sham group were subjected to the same operation as above, excepted for the bilateral carotid artery occlusion and hemospasia from the right common jugular vein.

Metabolism / Metabolites
Enzymes involved in its /caffeic acid/ metabolism have not been identified. In the following, caffeic (CA), chlorogenic (CGA), and dihydrocaffeic (DHCA) acids were incubated with hepatocytes and shown to undergo metabolism by cytochrome P450, catechol-O-methyltransferase (COMT), and beta-oxidation enzymes. Ferulic (FA) or dihydroferulic (DHFA) acids, formed as the result of CA- or DHCA-O-methylation by COMT, were also O-demethylated by CYP1A1/2 but not CYP2E1. DHCA or DHFA also underwent side chain dehydrogenation to form CA and FA, respectively, which was prevented by thioglycolic acid, an inhibitor of the beta-oxidation enzyme acyl CoA dehydrogenase. The rates of glutathione conjugate formation catalyzed by NADPH/microsomes (CYP2E1) in decreasing order DHCA>CA>CGA trend which was in reverse order to the rates of their O-methylation by COMT. The CA- and DHCA-o-quinones formed by NADPH/P450 likely inhibited COMT but can readily form glutathione conjugates. CA, DHCA and DHFA were inter-metabolized to each other and to FA by isolated rat hepatocytes whereas FA was metabolized only to CA but not to DHCA or DHFA. CA, DHCA, FA, DHFA and CGA showed a dose-dependent hepatocyte toxicity and the LD(50) (2 h), determined were in decreasing order of effectiveness DHCA>CA>DHFA>CGA>FA. In summary, evidence has been provided that O-methylation, GSH conjugation, hydrogenation and dehydrogenation are involved in the hepatic metabolism of CA and DHCA. The O-methylation pathway for CA and DHCA is a detoxification route whereas o-quinones formation catalyzed by P450 is the toxification route.
In rats, chlorogenic acid is hydrolysed in the stomach and intestine to caffeic and quinic acids. A number of metabolites have been identified. Glucuronides of meta-coumaric acid and meta-hydroxyhippuric acid appear to be the main metabolites in humans. After oral administration of caffeic acid to human volunteers, O-methylated derivatives (ferulic, dihydroferulic and vanillic acids) were excreted rapidly in the urine, while the meta-hydroxyphenyl derivatives appeared later. The dehydroxylation reactions were ascribed to the action of intestinal bacteria.
Caffeic Acid has known human metabolites that include (2S,3S,4S,5R)-6-[4-[(E)-2-carboxyethenyl]-2-hydroxyphenoxy]-3,4,5-trihydroxyoxane-2-carboxylic acid and (2S,3S,4S,5R)-6-[5-[(E)-2-carboxyethenyl]-2-hydroxyphenoxy]-3,4,5-trihydroxyoxane-2-carboxylic acid.

Interactions
Caffeic acid enhanced the uptake of radioactive glucose into C2C12 cells in a concentration-dependent manner. Similar effect of phenylephrine on the uptake of radioactive glucose was also observed in C2C12 cells. Prazosin attenuated the action of caffeic acid in a way parallel to the blockade of phenylephrine.
Female ICR/Ha mice, nine weeks of age, were fed a diet containing 0.06 mmol/g (10 g/kg of diet) caffeic acid (purity, 99%). From experimental day 8, the mice were also given 1 mg benzo(a)pyrene by gavage twice a week for four weeks. The diet containing caffeic acid was removed three days after the last benzo(a)pyrene treatment. Mice were killed at 211 days of age. In the 17 effective mice, the number of forestomach tumors (> or = 1 mm)/mouse (histology unspecified) was significantly decreased by caffeic acid (p < 0.05) (3.1 versus 5.0 tumors/mouse among 38 mice treated with benzo(a)pyrene alone).

[1]. Caffeic acid exhibits anti-pruritic effects by inhibition of multiple itch transmission pathways in mice. Eur J Pharmacol. 2015 Sep 5;762:313-21.

[2]. The protective effect of caffeic acid on global cerebral ischemia-reperfusion injury in rats. Behav Brain Funct. 2015 Apr 18;11:18.

Caffeic Acid can cause cancer according to The World Health Organization's International Agency for Research on Cancer (IARC).
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. (NTP, 1992)
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. It 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 has been reported in Salvia miltiorrhiza, Salvia plebeia, and other organisms with data available.
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 metabolite found in or produced by Saccharomyces cerevisiae.
See also: Black Cohosh (part of); Comfrey Root (part of); Arctium lappa Root (part of) ... View More ...

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Mechanism of Action
Caffeic acid phenethyl ester (CAPE) was synthesized from caffeic acid and phenethyl alcohol (ratio 1:5) at room temperature with dicyclohexyl carbodiimide (DCC) as a condensing reagent. The yield was about 38%. CAPE was found to arrest the growth of human leukemia HL-60 cells. It also inhibits DNA, RNA and protein synthesis in HL-60 cells with IC50 of 1.0 M, 5.0 M and 1.5 M, respectively.
In an attempt to understand the antihyperglycemic action of caffeic acid, the myoblast C2C12 cells were employed to investigate the glucose uptake in the present study. Caffeic acid enhanced the uptake of radioactive glucose into C2C12 cells in a concentration-dependent manner. Similar effect of phenylephrine on the uptake of radioactive glucose was also observed in C2C12 cells. Prazosin attenuated the action of caffeic acid in a way parallel to the blockade of phenylephrine. Effect of caffeic acid on alpha1-adrenoceptors was further supported by the displacement of [3H]prazosin binding in C2C12 cells. Moreover, the glucose uptake-increasing action of phenylephrine in C2C12 cells was inhibited by the antagonists of alpha1A-adrenoceptors, both tamsulosin and WB 4101, but not by the antagonist of alpha1B-adrenoceptors, chlorethylclonidine (CEC). The presence of alpha1A-adrenoceptors in C2C12 cells can thus be considered. Similar inhibition of the action of caffeic acid was also obtained in C2C12 cells co-incubating these antagonists. An activation of alpha1A-adrenoceptors seems responsible for the action of caffeic acid in C2C12 cells. In the presence of U73312, the specific inhibitor of phospholipase C, caffeic acid-stimulated uptake of radioactive glucose into C2C12 cells was reduced in a concentration-dependent manner and it was not affected by U73343, the negative control of U73312. Moreover, chelerythrine and GF 109203X diminished the action of caffeic acid at concentrations sufficient to inhibit protein kinase C. Therefore, the obtained data suggest that an activation of alpha1A-adrenoceptors in C2C12 cells by caffeic acid may increase the glucose uptake via phospholipase C-protein kinase C pathway.
Caffeic acid (CA, 3,4-dihydroxycinnamic acid), at 2% in the diet, had been shown to be carcinogenic in forestomach and kidney of F344 rats and B6C3F1 mice. Based on its occurrence in coffee and numerous foods and using a linear interpolation for cancer incidence between dose 0 and 2%, the cancer risk in humans would be considerable. In both target organs, tumor formation was preceded by hyperplasia, which could represent the main mechanism of carcinogenic action. The dose-response relationship for this effect was investigated in male F344 rats after 4-week feeding with CA at different dietary concentrations (0, 0.05, 0.14, 0.40, and 1.64%). Cells in S-phase of DNA replication were visualized by immunohistochemical analysis of incorporated 5-bromo-2'-deoxyuridine (BrdU), 2 hr after intraperitoneal injection. In the forestomach, both the total number of epithelial cells per millimeter section length and the unit length labeling index of BrdU-positive cells (ULLI) were increased, about 2.5-fold, at 0.40 and 1.64%. The lowest concentration (0.05%) had no effect. At 0.14%, both variables were decreased by about one-third. In the kidney, the labeling index in proximal tubular cells also indicated a J-shaped (or U-shaped) dose response with a 1.8-fold increase at 1.64%. In the glandular stomach and in the liver, which are not target organs, no dose-related effect was seen. The data show a good correlation between the organ specificity for cancer induction and stimulation of cell division. With respect to the dose-response relationship and the corresponding extrapolation of the animal tumor data to a human cancer risk, a linear extrapolation appears not to be appropriate.

C9H8O4

180.1574

180.042

331-39-5

trans-Caffeic acid;501-16-6;Caffeic acid phenethyl ester;104594-70-9;Caffeic acid-13C3;1185245-82-2

689043

Off-white to light yellow solid

1.5±0.1 g/cm3

416.8±35.0 °C at 760 mmHg

211-213 °C (dec.)(lit.)

220.0±22.4 °C

0.0±1.0 mmHg at 25°C

1.707

1.42

3

4

2

13

212

0

O=C(O)/C=C/C1=CC=C(O)C(O)=C1

QAIPRVGONGVQAS-DUXPYHPUSA-N

InChI=1S/C9H8O4/c10-7-3-1-6(5-8(7)11)2-4-9(12)13/h1-5,10-11H,(H,12,13)/b4-2+

(E)-3-(3,4-dihydroxyphenyl)prop-2-enoic acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~100 mg/mL (~555.06 mM)
H2O : < 0.1 mg/mL

Solubility in Formulation 1: ≥ 2.5 mg/mL (13.88 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (13.88 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 3: ≥ 2.08 mg/mL (11.55 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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 (Please use freshly prepared in vivo formulations for optimal results.)