Multiple catechols in human plasma after drinking caffeinated or decaffeinated coffee.

BACKGROUND: Coffee is one of the most frequently consumed beverages worldwide. Research on effects of coffee drinking has focused on caffeine; however, coffee contains myriad biochemicals that are chemically unrelated to caffeine, including 3,4-dihydroxyphenyl compounds (catechols) such as caffeic acid and dihydrocaffeic acid (DHCA). OBJECTIVE: This prospective within-subjects study examined effects of drinking caffeinated or decaffeinated coffee on plasma free (unconjugated) catechols measured by liquid chromatography with series electrochemical detection (LCED) after batch alumina extraction. To confirm coffee-related chromatographic peaks represented catechols, plasma was incubated with catechol-O-methyltransferase and S-adenosylmethionine before the alumina extraction; reductions in peak heights would identify catechols. METHODS: Ten healthy volunteers drank 2 cups each of caffeinated and decaffeinated coffee on separate days after fasting overnight. With subjects supine, blood was drawn through an intravenous catheter up to 240 min after coffee ingestion and the plasma assayed by alumina extraction followed by LCED. RESULTS: Within 15 min of drinking coffee of either type, >20 additional peaks were noted in chromatographs from the alumina eluates. Most of the coffee-related peaks corresponded to free catechols. Plasma levels of the catecholamines epinephrine and dopamine increased with both caffeinated and decaffeinated coffee. Levels of other endogenous catechols were unaffected. Plasma DHCA increased bi-phasically, in contrast with other coffee-related free catechols. INTERPRETATION: Drinking coffee-whether caffeinated or decaffeinated-results in the rapid appearance of numerous free catechols in the plasma. These might affect the disposition of circulating catecholamines. The bi-phasic increase in plasma DHCA is consistent with production by gut bacteria.

Danggui Buxue decoction ameliorates lipid metabolic defects involved in the initiation of diabetic atherosclerosis; identification of active compounds.

OBJECTIVE: To determine the constituent compounds of Danggui buxue decoction (DBD) involved and the potential mechanisms mediating its effects, with specific reference to lipids playing a role in the initiation of diabetic atherosclerosis. METHODS: Liquid chromatography-tandem mass spectrometry was used to identify and quantify the absorbed bioactive compounds (ABCs) present in DBD. Goto-Kakizaki (GK) rats were randomly allocated to a diabetes atherosclerosis (DA) group, a DBD group, and an ABC group (10 per group), which were all high-fat diet-fed. The treated rats were administered DBD (4 g/kg) or ABCs (in amounts equal to those present in DBD) once daily for 28 d, and a control group of Wistar rats were administered vehicle. Body mass gain, fasting blood glucose, and homeostasis assessment of insulin resistance (HOMA- IR) were measured. Serum triglyceride (TG), cholesterol (CHOL), high density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL- C) and tumor necrosis factor-α (TNF-α) concentrations were determined. Hematoxylin and eosin staining and microscopy were used to characterize the abdominal aorta and the expression of lipogenic genes was quantified in this vessel. RESULTS: Seven ABCs were identified in rat serum: ferulic acid, formononetin, calycosin, astragaloside, caffeic acid, ligustilide, and butyphthalide. DBD significantly reduced HOMA-IR, the serum concentrations of TG, CHOL, and LDL-C, and the expression of the lipogenic genes monocyte chemotactic protein 1, Fas, intercellular adhesion molecule 1, and Cd36 in aorta; and significantly increased the mRNA expression of Scd1 in aorta. CONCLUSION: DBD affects lipid metabolism in the early stage of atherosclerosis in diabetic GK rats, with the mechanism likely involving the regulation of lipid metabolic genes in vessels. The contribution of ABCs to the effect of DBD on lipid metabolism was 24%-101%.

The Presence of Caffeic Acid in Cerebrospinal Fluid: Evidence That Dietary Polyphenols Can Cross the Blood-Brain Barrier in Humans.

Epidemiological data indicate that a diet rich in plant polyphenols has a positive effect on brain functions, improving memory and cognition in humans. Direct activity of ingested phenolics on brain neurons may be one of plausible mechanisms explaining these data. This also suggests that some phenolics can cross the blood-brain barrier and be present in the brain or cerebrospinal fluid. We measured 12 phenolics (a combination of the solid-phase extraction technique with high-performance liquid chromatography) in cerebrospinal fluid and matched plasma samples from 28 patients undergoing diagnostic lumbar puncture due to neurological disorders. Homovanillic acid, 3-hydroxyphenyl acetic acid and caffeic acid were detectable in cerebrospinal fluid reaching concentrations (median; interquartile range) 0.18; 0.14 µmol/L, 4.35; 7.36 µmol/L and 0.02; 0.01 µmol/L, respectively. Plasma concentrations of caffeic acid (0.03; 0.01 µmol/L) did not correlate with those in cerebrospinal fluid (ρ = -0.109, p = 0.58). Because food (fruits and vegetables) is the only source of caffeic acid in human body fluids, our results indicate that the same dietary phenolics can cross blood-brain barrier in humans, and that transportation of caffeic acid through this barrier is not the result of simple or facilitated diffusion.

Chicoric acid (CA) induces autophagy in gastric cancer through promoting endoplasmic reticulum (ER) stress regulated by AMPK.

Gastric cancer is one of the most common cancers leading to tumor-related deaths worldwide. Chicoric acid (CA) exhibits a variety of protective effects in different diseases. However, its role in regulating tumor progression has not been reported. Autophagy, as a conserved catabolic process, sustains cellular homoeostasis responding to stress to modulate cell fate. In the study, the effects of CA on gastric cancer were investigated. The results indicated that CA treatment markedly reduced the cell viability and induced apoptosis in gastric cancer cells, and prevented tumor growth in an established xenograft gastric cancer model. Furthermore, CA exposure significantly induced autophagy both in gastric cancer cells and tumor samples, as evidenced by the up-regulated expression of LC3II. Moreover, phosphorylated AMP-activated protein kinase (AMPK) and p70S6 kinase (p70s6k) expression were obviously promoted by CA in vitro and in vivo. Importantly, blocking AMPK activation abrogated CA-induced expression of LC3II in gastric cancer cells. In addition, endoplasmic reticulum (ER) stress in tumor samples or cells was markedly induced by CA treatment through promoting the expression of associated signals such as Parkin, protein kinase RNA-like ER kinase (PERK), activating transcription factors 4 (ATF4) and ATF6. Importantly, these effects were abolished by the inhibition of AMPK signaling. Collectively, our findings indicated that CA prevents human gastric cancer progression by inducing autophagy partly through the activation of AMPK, and represents an effective therapeutic strategy against gastric cancer development.

Simultaneous determination of eight bioactive components of Qishen Yiqi dripping pills in rat plasma using UFLC-MS/MS and its application to a pharmacokinetic study.

In this study, a rapid and reliable ultra-fast liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous determination of eight active ingredients, including astragaloside IV, ononin, tanshinol, protocatechualdehyde, protocatechuic acid, salvianolic acid D, rosmarinic acid and ginsenoside Rg1 , in rat plasma. The plasma samples were pretreated by protein precipitation with acetonitrile. Chromatographic separation was performed on a Waters Acquity UPLC® BEH C18 column (1.7 µm particles, 2.1 × 100 mm). The mobile phase consisted of 0.1% aqueous formic acid (A)-acetonitrile with 0.1% formic acid (B) at a flow rate of 0.4 mL/min. Quantification was performed on a triple quadruple tandem mass spectrometry with electrospray ionization by multiple reaction monitoring both in the negative and in the positive ion mode. The lower limit of quantification of tanshinol was 2.0 ng/mL and the others were 5.0 ng/mL. The extraction recoveries, matrix effects, intra- and inter-day precision and accuracy of eight tested components were all within acceptable limits. The validated method was successfully applied to the pharmacokinetic study of the eight active constituents after intragastric administration of three doses (1.0, 3.0, 6.0 g/kg body weight) of Qishen Yiqi Dripping Pills to rats.

Bioavailability of chlorogenic acids in rats after acute ingestion of maté tea (Ilex paraguariensis) or 5-caffeoylquinic acid.

PURPOSE: Yerba maté is widely consumed in South America as different beverages, such as maté tea (roasted leaves) and chimarrão (green dried leaves), and linked to health benefits, mainly attributed to chlorogenic acids (CGAs). Health effects of CGAs depend on their bioavailability, but such data are scarce. The aim of this study was to investigate the distribution of CGAs and metabolites in tissues, hepatic and plasmatic kinetic profile and urinary excretion after ingestion of maté tea or 5-caffeoylquinic acid (5-CQA). METHODS: Wistar rats ingested maté tea (MT) or 5-CQA (ST) and were killed after 1.5 h for tissue distribution analysis (pilot study) or at 0.5, 1, 2, 4 and 8 h for liver and plasma kinetics (main experiment). Urine was collected in metabolic cages. Biological samples were analyzed by UPLC-DAD-MS with and without incubation with ß-glucuronidase and sulfatase. RESULTS: CGAs and metabolites were detected in all tissues. Caffeic acid was the main compound in plasma up to 2 h after ingestion of maté tea, while 5-CQA predominated in ST group. Concentration of microbial metabolites increased 4 h after gavage and reached higher amounts in MT plasma and liver, when compared to ST group. Approximately 4.0 % of compounds ingested by MT and 3.3 % by ST were recovered in urine up to 8 h after the gavage. CONCLUSION: The study confirms that not only absorption, but also metabolization of CGAs begins in stomach. There were differences in compounds formed from maté tea or isolated 5-CQA, showing that CGAs profile in food may influence qualitatively and quantitatively the metabolites formed in the body.

Plasma concentrations of coffee polyphenols and plasma biomarkers of diabetes risk in healthy Japanese women.

Coffee consumption has been reported to reduce the risk of type 2 diabetes in experimental and epidemiological studies. This anti-diabetic effect of coffee may be attributed to its high content in polyphenols especially caffeic acid and chlorogenic acid. However, the association between plasma coffee polyphenols and diabetic risks has never been investigated in the literature. In this study, fasting plasma samples were collected from 57 generally healthy females aged 38-73 (mean 52, s.d. 8) years recruited in Himeji, Japan. The concentrations of plasma coffee polyphenols were determined by liquid chromatography coupled with mass tandem spectrometer. Diabetes biomarkers in the plasma/serum samples were analysed by a commercial diagnostic laboratory. Statistical associations were assessed using Spearman's correlation coefficients. The results showed that plasma chlorogenic acid exhibited negative associations with fasting blood glucose, glycated hemoglobin and C-reactive protein, whereas plasma total coffee polyphenol and plasma caffeic acid were weakly associated with these biomarkers. Our preliminary data support previous findings that coffee polyphenols have anti-diabetic effects but further replications with large samples of both genders are recommended.

Coffee Consumption Increases the Antioxidant Capacity of Plasma and Has No Effect on the Lipid Profile or Vascular Function in Healthy Adults in a Randomized Controlled Trial.

BACKGROUND: Coffee, a source of antioxidants, has controversial effects on cardiovascular health. OBJECTIVE: We evaluated the bioavailability of chlorogenic acids (CGAs) in 2 coffees and the effects of their consumption on the plasma antioxidant capacity (AC), the serum lipid profile, and the vascular function in healthy adults. METHODS: Thirty-eight men and 37 women with a mean ± SD age of 38.5 ± 9 y and body mass index of 24.1 ± 2.6 kg/m(2) were randomly assigned to 3 groups: a control group that did not consume coffee or a placebo and 2 groups that consumed 400 mL coffee/d for 8 wk containing a medium (MCCGA; 420 mg) or high (HCCGA; 780 mg) CGA content. Both were low in diterpenes (0.83 mg/d) and caffeine (193 mg/d). Plasma caffeic and ferulic acid concentrations were measured by GC, and the plasma AC was evaluated with use of the ferric-reducing antioxidant power method. The serum lipid profile, nitric oxide (NO) plasma metabolites, vascular endothelial function (flow-mediated dilation; FMD), and blood pressure (BP) were evaluated. RESULTS: After coffee consumption (1 h and 8 wk), caffeic and ferulic acid concentrations increased in the coffee-drinking groups, although the values of the 2 groups were significantly different (P < 0.001); caffeic and ferulic acid concentrations were undetectable in the control group. At 1 h after consumption, the plasma AC in the control group was significantly lower than the baseline value (-2%) and significantly increased in the MCCGA (6%) and HCCGA (5%) groups (P < 0.05). After 8 wk, no significant differences in the lipid, FMD, BP, or NO plasma metabolite values were observed between the groups. CONCLUSIONS: Both coffees, which contained CGAs and were low in diterpenes and caffeine, provided bioavailable CGAs and had a positive acute effect on the plasma AC in healthy adults and no effect on blood lipids or vascular function. The group that did not drink coffee showed no improvement in serum lipid profile, FMD, BP, or NO plasma metabolites. This trial was registered at registroclinico.sld.cu as RPCEC00000168.

Stability of caffeic acid phenethyl amide (CAPA) in rat plasma.

A validated C18 reverse-phase HPLC method with UV detection at 320 nm was developed and used for the stability evaluation of caffeic acid phenethyl amide (CAPA) and caffeic acid phenethyl ester (CAPE) in rat plasma. CAPA is the amide derivative of CAPE, a naturally occurring polyphenolic compound that has been found to be active in a variety of biological pathways. CAPA has been shown to protect endothelial cells against hydrogen peroxide-induced oxidative stress to a similar degree to CAPE. CAPE has been reported to be rapidly hydrolyzed in rat plasma via esterase enzymes. CAPA is expected to display a longer half-life than CAPE by avoiding hydrolysis via plasma esterases. The stability of CAPA and CAPE in rat plasma was investigated at three temperatures. The half-lives for CAPA were found to be 41.5, 10 and 0.82 h at 25, 37 and 60 °C, respectively. The half-lives for CAPE were found to be 1.95, 0.35 and 0.13 h at 4, 25 and 37 °C, respectively. The energy of activation was found to be 22.1 kcal/mol for CAPA and 14.1 kcal/mol for CAPE. A more stable compound could potentially extend the beneficial effects of CAPE.

Hydrolysis influence on phytochemical composition, antioxidant activity, plasma concentration, and tissue distribution of hydroethanolic Ilex paraguariensis extract components.

The infusion of aerial parts of Ilex paraguariensis is widely consumed. Its antioxidant activity suggests an important role of this plant in the treatment/prevention of oxidative stress related diseases. Plant extract active compounds are frequently found in esterified form that may be poorly absorbed. Hydrolysis of the extract is a possible approach to increase its bioavailability. The aim of this study was to perform a phytochemical analysis and evaluate in rats the plasma concentration and tissue distribution of antioxidant compounds in the hydroethanolic extract of Ilex paraguariensis, before and after enzymatic hydrolysis. Both extracts presented high antioxidant activity and phenolic content. Rats given single or repeated doses of the hydrolyzed extract showed increased plasma antioxidant activity and higher plasma levels of caffeic acid. However, no changes of endogenous antioxidants were observed. In conclusion, hydrolysis of the extract of Ilex paraguariensis is a strategy to improve its bioavailability and in vivo antioxidant activity.

First synthesis, characterization, and evidence for the presence of hydroxycinnamic acid sulfate and glucuronide conjugates in human biological fluids as a result of coffee consumption.

A systematic investigation of the human metabolism of hydroxycinnamic acid conjugates was carried out. A set of 24 potential human metabolites of coffee polyphenols has been chemically prepared, and used as analytical standards for unequivocal identifications. These included glucuronide conjugates and sulfate esters of caffeic, ferulic, isoferulic, m-coumaric and p-coumaric acids as well as their dihydro derivatives. A particular focus has been made on caffeic and 3,4-dihydroxyphenylpropionic acid derivatives, especially the sulfate conjugates, for which regioselective preparation was particularly challenging, and have so far never been identified as human metabolites. Ten out of the 24 synthesized conjugates have been identified in human plasma and/or urine after coffee consumption. A number of these conjugates were synthesized, characterized and detected as hydroxycinnamic acid metabolites for the first time. This was the case of dihydroisoferulic acid 3'-O-glucuronide, caffeic acid 3'-sulfate, as well as the sulfate and glucuronide derivatives of 3,4-dihydroxyphenylpropionic acid.

Coffee consumption enhances high-density lipoprotein-mediated cholesterol efflux in macrophages.

RATIONALE: Association of habitual coffee consumption with coronary heart disease morbidity and mortality has not been established. We hypothesized that coffee may enhance reverse cholesterol transport (RCT) as the antiatherogenic properties of high-density lipoprotein (HDL). OBJECTIVE: This study was to investigate whether the phenolic acids of coffee and coffee regulates RCT from macrophages in vitro, ex vivo and in vivo. METHODS AND RESULTS: Caffeic acid and ferulic acid, the major phenolic acids of coffee, enhanced cholesterol efflux from THP-1 macrophages mediated by HDL, but not apoA-I. Furthermore, these phenolic acids increased both the mRNA and protein levels of ATP-binding cassette transporter (ABC)G1 and scavenger receptor class B type I (SR-BI), but not ABCA1. Eight healthy volunteers were recruited for the ex vivo study, and blood samples were taken before and 30 minutes after consumption of coffee or water in a crossover study. The mRNA as well as protein levels of ABCG1, SR-BI, and cholesterol efflux by HDL were increased in the macrophages differentiated under autologous sera obtained after coffee consumption compared to baseline sera. Finally, effects of coffee and phenolic acid on in vivo RCT were assessed by intraperitoneally injecting [(3)H]cholesterol-labeled acetyl low-density lipoprotein-loaded RAW264.7 cells into mice, then monitoring appearance of (3)H tracer in plasma, liver, and feces. Supporting in vitro and ex vivo data, ferulic acid was found to significantly increase the levels of (3)H tracer in feces. CONCLUSIONS: Coffee intake might have an antiatherogenic property by increasing ABCG1 and SR-BI expression and enhancing HDL-mediated cholesterol efflux from the macrophages via its plasma phenolic acids.

Investigation of the metabolic fate of dihydrocaffeic acid.

The antioxidant dihydrocaffeic acid is a dietary constituent and a microbial metabolite of flavonoids. Orally administered to rats, dihydrocaffeic acid was very rapidly absorbed most probably by the gastric or duodenal epithelium and excreted in urine as free and conjugated forms. LC-MS2 analysis of plasma and urine samples allowed confident identification of the dihydrocaffeic acid metabolites. The parent compound was glucuronidated, sulphated or methylated, on one of the hydroxyl groups present on its phenyl ring. All the dihydrocaffeic acid metabolites peaked in plasma within the first 30min following ingestion, suggesting a metabolism possibly by the gastric or duodenal cells and by the liver. Using in vitro and ex vivo models of the intestinal epithelium and the liver, the identity and source of the metabolites detected in vivo were examined. The data obtained suggest that, in rats, intestinal cells are more able to glucuronidate dihydrocaffeic acid, whereas liver favours sulphation. Moreover, glucuronidation, sulphation and methylation seem to be regio-selective, preferably on the 3-OH of dihydrocaffeic acid. The methyl conjugate, dihydroferulic acid, was shown to be oxidized into ferulic acid by intestinal and hepatic cells, which were also able to perform the reverse reaction, the reduction of ferulic acid into dihydroferulic acid. As a conclusion, the main form of dihydrocaffeic acid circulating in plasma after its ingestion is a mixture of different primary and secondary metabolites.

Absorption and metabolism of bioactive molecules after oral consumption of cooked edible heads of Cynara scolymus L. (cultivar Violetto di Provenza) in human subjects: a pilot study.

The current growing interest for natural antioxidants has led to a renewed scientific attention for artichoke, due not only to its nutritional value, but, overall, to its polyphenolic content, showing strong antioxidant properties. The major constituents of artichoke extracts are hydroxycinnamic acids such as chlorogenic acid, dicaffeoylquinic acids caffeic acid and ferulic acid, and flavonoids such as luteolin and apigenin glycosides. In vitro studies, using cultured rat hepatocytes, have shown its hepatoprotective functions and in vivo studies have shown the inhibition of cholesterol biosynthesis in human subjects. Several studies have shown the effect on animal models of artichoke extracts, while information on human bioavailability and metabolism of hydroxycinnamates derivatives is still lacking. Results showed a plasma maximum concentration of 6.4 (SD 1.8) ng/ml for chlorogenic acid after 1 h and its disappearance within 2 h (P< 0.05). Peak plasma concentrations of 19.5 (SD 6.9) ng/ml for total caffeic acid were reached within 1 h, while ferulic acid plasma concentrations showed a biphasic profile with 6.4 (SD1.5) ng/ml and 8.4 (SD4.6) ng/ml within 1 h and after 8 h respectively. We observed a significant increase of dihydrocaffeic acid and dihydroferulic acid total levels after 8 h (P<0.05). No circulating plasma levels of luteolin and apigenin were present. Our study confirms the bioavailability of metabolites of hydroxycinnamic acids after ingestion of cooked edible Cynara scolymus L. (cultivar Violetto di Provenza).

Differential anti-inflammatory effects of phenolic compounds from extra virgin olive oil identified in human whole blood cultures.

OBJECTIVE: The olive oil-rich Mediterranean diet protects against cardiovascular disease, which involves inflammatory processes. This study investigated the effects of phenolic compounds found in extra virgin olive oil on inflammatory mediator production by human mononuclear cells. METHODS: Diluted human blood cultures were stimulated with lipopolysaccharide in the presence of phenolics (vanillic, p-coumaric, syringic, homovanillic and caffeic acids, kaempferol, oleuropein glycoside, and tyrosol) at concentrations of 10(-7) to 10(-4) M. Concentrations of the inflammatory cytokines tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 and of the inflammatory eicosanoid prostaglandin E2 were measured by enzyme-linked immunosorbent assay. RESULTS: Oleuropein glycoside and caffeic acid decreased the concentration of interleukin-1beta. At a concentration of 10(-4) M, oleuropein glycoside inhibited interleukin-1beta production by 80%, whereas caffeic acid inhibited production by 40%. Kaempferol decreased the concentration of prostaglandin E2. At a concentration of 10(-4) M, kaempferol inhibited prostaglandin E2 production by 95%. No effects were seen on concentrations of interleukin-6 or tumor necrosis factor-alpha and there were no effects of the other phenolic compounds. CONCLUSIONS: Some, but not all, phenolic compounds derived from extra virgin olive oil decrease inflammatory mediator production by human whole blood cultures. This may contribute to the antiatherogenic properties ascribed to extra virgin olive oil.

Antitumor activity of wheats with high orthophenolic content.

The purpose of the present study is to develop in vitro assays for rapid screening of a large number of food samples that contain components that prevent tumor formation in vivo and to identify the components that contribute to this antitumor effect. Wheat samples representing numerous strains and cultivars were screened for their in vitro ability to kill a human colon cancer cell, CaCo2, in culture by trypan blue dye exclusion assay. Wheat samples were assayed for orthophenolic acid content by use of a colorimetric assay using a bathochromatic shift at 350 nm. Blood levels of specific orthophenols were determined by high-performance liquid chromatography/mass spectrometry. Wheat samples, which contained low, mid-, and high in vitro protective ability, were used to formulate balanced diets fed to Min mice. Wheat samples with high ability to kill CaCo2 cells in culture had high levels of orthophenolic acids and produced elevated blood caffeic acid levels when used in diets. These factors correlated positively with their ability to prevent tumor formation in Min mice. When fiber content was equal in diets the content of orthophenolic acids in wheats predicted the antitumor activity in vivo.

Effect of acute ingestion of fresh and stored lettuce (Lactuca sativa) on plasma total antioxidant capacity and antioxidant levels in human subjects.

The present study investigated whether storage under modified-atmosphere packaging (MAP) affected the antioxidant properties of fresh lettuce (Lactuca sativa). Eleven healthy volunteers (six men, five women) consumed 250 g fresh lettuce, and blood was sampled before (0 h) and 2, 3 and 6 h after consumption. The protocol was repeated 3 d later with the same lettuce stored at 5 degrees C under MAP conditions (O2-N2 (5:95, v/v)). Results showed that after ingestion of fresh lettuce, plasma total radical-trapping antioxidant potential (TRAP), measured as area under the curve, was significantly higher (1.3 (sem 0.3) mmol/l per 6 h; P<0.05) than the value obtained with MAP-stored lettuce (0.1 (sem 0.2) mmol/l per 6 h). Plasma TRAP, quercetin and p-coumaric acid were significantly different from baseline values (P

Absorption of phenolic acids in humans after coffee consumption.

Despite extensive literature describing the biological effects of polyphenols, little is known about their absorption from diet, one major unresolved point consisting of the absorption of the bound forms of polyphenols. In this view, in the present work we studied the absorption in humans of phenolic acids from coffee, a common beverage particularly rich in bound phenolic acids, such as caffeic acid, ferulic acid, and p-coumaric acid. Coffee brew was analyzed for free and total (free + bound) phenolic acids. Chlorogenic acid (5'-caffeoylquinic acid), a bound form of caffeic acid, was present in coffee at high levels, while free phenolic acids were undetectable. After alkaline hydrolysis, which released bound phenolic acids, ferulic acid, p-coumaric acid, and high levels of caffeic acid were detected. Plasma samples were collected before and 1 and 2 h after coffee administration and analyzed for free and total phenolic acid content. Two different procedures were applied to release bound phenolic acids in plasma: beta-glucuronidase treatment and alkaline hydrolysis. Coffee administration resulted in increased total plasma caffeic acid concentration, with an absorption peak at 1 h. Caffeic acid was the only phenolic acid found in plasma samples after coffee administration, while chlorogenic acid was undetectable. Most of caffeic acid was present in plasma in bound form, mainly in the glucuronate/sulfate forms. Due to the absence of free caffeic acid in coffee, plasma caffeic acid is likely to be derived from hydrolysis of chlorogenic acid in the gastrointestinal tract.

Polyphenols from alcoholic apple cider are absorbed, metabolized and excreted by humans.

We determined the uptake and excretion of low doses of polyphenols in six subjects who each consumed 1.1 L of an alcoholic cider beverage. Over a 24-h period, no phloretin was detected in plasma (detection limit = 0.036 micromol/L), but 21 +/- 5% of the dose (4.8 mg) was excreted in the urine. In contrast, from a low dose of 1.6-mg quercetin equivalents, no quercetin was found in urine or plasma, but 3'-methyl quercetin was detected in plasma [C(max) (maximum concentration) = 0.14 +/- 0.19 micromol/L; range: 0 to 0.44 micromol/L]. No flavanol monomers (dose of free (+)-catechin and (-)-epicatechin = 3.5 mg) were detected in urine or plasma (detection limit: 0.01 micromol/L). Caffeic acid (total dose including esters = 11 mg) was detected only in plasma within 2 h, with C(max) = 0.43 +/- 0.3 micromol/L (range: 0.18 to 0.84 micromol/L). An almost 3-fold increase in hippuric acid was detected in 24-h urine (74 +/- 29 micromol/L; range: 38-116 micromol/L), compared with a prestudy value of 19 +/- 9 micromol/L. These data show that polyphenols are taken up from cider, that phloretin is excreted in the urine and suggest that low doses of quercetin are extensively methylated in humans.

Plasma levels of caffeic acid and antioxidant status after red wine intake.

The aim of this study was to evaluate the bioavailability of caffeic acid and the modification of plasma antioxidant status following red wine intake. Five healthy male volunteers consumed 100, 200, and 300 mL of red wine corresponding to approximately 0.9, 1.8, and 2.7 mg of caffeic acid, respectively. Plasma samples collected at different times (0-300 min) were evaluated for their content of caffeic acid and their total antioxidant status. Both these parameters, i.e., plasma concentration of caffeic acid and antioxidant potential, were dose-dependent and the C(max) was reached at about 60 min after red wine intake. The results indicate that caffeic acid is bioavailable and it may be correlated with the antioxidant potential of plasma.