Dihydrocaffeic Acid Research Articles

The antioxidative effect of lipophilized rutin and dihydrocaffeic acid in fish oil enriched milk

AbstractThe antioxidative effect of phenolipids was evaluated in fish oil enriched milk emulsions as a model for a complex food system. Two different phenolipids modified from dihydrocaffeic acid (with C8 or C18:1) and rutin (with C12 or C16) were evaluated. Both dihydrocaffeate esters and rutin laurate showed significantly better antioxidant properties in milk emulsion compared with the original phenolics. However, rutin palmitate only performed slightly better as antioxidant than rutin. The results with rutin indicated that a cut‐off effect exists in relation to the alkyl chain length with respect to optimal antioxidant activity in milk emulsions. Thus, the optimal alkyl chain length is at least below 16 carbon atoms, and maybe even less for rutin esters. For dihydrocaffeate esters it was not possible to conclude on a cut‐off effect in relation to alkyl chain length and antioxidative effect due to the almost similar antioxidant effect of the two phenolipids. However, there was a tendency towards octyl dihydrocaffeate being slightly more efficient than oleyl dihydrocaffeate.Practical application: The finding that phenolipids are better antioxidants in milk emulsions than the original phenolic acid provides new knowledge that can be used to develop new antioxidant strategies to protect foods against lipid oxidation. However, the results indicate that both optimization of alkyl chain length for each type of phenolic, and optimization for each type of emulsion will be necessary in order to get the best oxidative stability of an emulsion with these phenolipids. Use of efficient antioxidants may lower the amount of antioxidant needed to protect against lipid oxidation and may in addition decrease the costs.

Purification and characterisation of polyphenol oxidase (PPO) from eggplant (Solanum melongena)

Eggplant (Solanum melongena) is a very rich source of polyphenol oxidase (PPO), which negatively affects its quality upon cutting and postharvest processing due to enzymatic browning. PPO inhibitors, from natural or synthetic sources, are used to tackle this problem. One isoform of PPO was 259-fold purified using standard chromatographic procedures. The PPO was found to be a 112 kDa homodimer. The enzyme showed very low K(m) (0.34 mM) and high catalytic efficiency (3.3×10(6)) with 4-methyl catechol. The substrate specificity was in the order: 4-methyl catechol>tert-butylcatechol>dihydrocaffeic acid>pyrocatechol. Cysteine hydrochloride, potassium metabilsulphite, ascorbic acid, erythorbic acid, resorcylic acid and kojic acid showed competitive inhibition, whereas, citric acid and sodium azide showed mixed inhibition of PPO activity. Cysteine hydrochloride was found to be an excellent inhibitor with the low inhibitor constant of 1.8 μM.

Bioactivities, phenolic compounds and in-vitro propagation of Lippia citriodora Kunth cultivated in Egypt

The aqueous and alcoholic extracts of the fresh aerial parts of Lippia citriodora Kunth, family Verbenaceae, cultivated in Egypt, exhibited variable antiinflammatory, antipyretic, analgesic and antioxidant properties. Three phenolic compounds; two phenolic acids, dihydrocaffeic acid (1) and 4-hydroxycinnamic acid (3) and a flavonoid glycoside, luteolin-7-O-glucoside (2), were isolated and identified from the ethyl acetate fraction of the plant. The structures of the isolated compounds were elucidated on the basis of spectral analysis. The effects of explant type, method of sterilization and growth regulators on the in-vitro callus formation of L. citriodora were studied. Shoot tips and leaf explants (cut in the midrib region) sterilized by soaking in 0.2% mercuric chloride for 5min, then washed twice with sterilized distilled water gave callus, on Murashige and Skoog (MS) medium impregnated with 4mg/L 6-benzyl amino purine (BAP). Spectrophotometric estimation of the total flavonoids showed that the fresh in-vitro formed callus contained 68.4% of the total flavonoids of the fresh aerial parts of the conventional plant.

Ionic Liquid‐Assisted Solubilization for Improved Enzymatic Esterification of Phenolic Acids

AbstractLipophilic derivatives of phenolic acids could greatly extend their applications in the lipophilic bio‐environment and food processing, therefore, developing an efficient lipophilization reaction system constitutes an interesting topic of biocatalysis. Low solubility of phenolic acids in most enzyme‐benign solvents represents the main reason for the inefficiency of enzymatic production of lipophilic phenolic derivatives. This work reports a novel approach to improve Candida antartica lipase B (Novozym 435) catalyzed lipophilization of phenolic acids by means of ionic liquids (IL), trioctylmethylammonium trifluoroacetate (tOMA.TFA) assisted solubilization of the substrate. In this approach, the IL plays two major roles, namely, to dissolve phenolic acids at high concentration so as to create a homogeneous system with another substrate—1‐octanol, and to be benign to the enzyme to keep the biocatalyst active; which is proved itself to be a correct strategy as improved conversion and volumetric productivity are obtained. The results showed that dosage of IL (denoted as the volume ratio of 1‐octanol/tOMA.TFA), concentration of dihydrocaffeic acid (DHCA) and temperature are the key parameters governing the reaction efficiency. A maximum conversion of DHCA was achieved at the ratio of 1‐octanol/tOMA.TFA 12:1 (v/v) (1‐octanol/DHCA, 38:1 (mol/mol)). A temperature of 70 °C was correct to obtain optimal conversion of DHCA. Even though the conversion of DHCA was higher at lower concentrations of DHCA, the overall volumetric productivity (reaction rate) was much higher when a high concentration of DHCA (1.6 M) was applied, due to IL‐assisted solubilization of DHCA. Remarkable enhancement of the conversions of ferulic and caffeic acids were achieved, when the same reaction approach (tOMA.TFA assisted solubilization) was applied to these two phenolic acids, indicating the general applicability of this novel approach.

On the peroxyl scavenging activity of hydroxycinnamic acid derivatives: mechanisms, kinetics, and importance of the acid–base equilibrium

The peroxyl radical scavenging activity of four hydroxycinnamic acid derivatives (HCAD) has been studied in non-polar and aqueous solutions, using the density functional theory. The studied HCAD are: ferulic acid (4-hydroxy-3-methoxycinnamic acid), p-coumaric acid (trans-4-hydroxycinnamic acid), caffeic acid (3,4-dihydroxycinnamic acid), and dihydrocaffeic acid (3-(3,4-dihydroxyphenyl)-2-propionic acid). It was found that the polarity of the environment plays an important role in the relative efficiency of these compounds as peroxyl scavengers. It was also found that in aqueous solution the pH is a key factor for the overall reactivity of HCAD towards peroxyl radicals, for their relative antioxidant capacity, and for the relative importance of the different mechanisms of reaction. The H transfer from the phenolic OH has been identified as the main mechanism of reaction in non-polar media and in aqueous solution at acid pHs. On the other hand, the single electron transfer mechanism from the phenoxide anion is proposed to be the one contributing the most to the overall peroxyl scavenging activity of HCAD in aqueous solution at physiological pH (7.4). This process is also predicted to be a key factor in the reactivity of these compounds towards a large variety of free radicals.

Lipophilization of dihydrocaffeic acid affects its antioxidative properties in fish‐oil‐enriched emulsions

AbstractThe aim of the present study was to evaluate the antioxidative effect of lipophilized dihydrocaffeic acid, i.e., octyl dihydrocaffeate and oleyl dihydrocaffeate. Furthermore, the relationship between the measured efficacy of the antioxidants in emulsions, their partitioning into different phases of an emulsion system and their in vitro antioxidant properties was also evaluated. Lipid oxidation in the emulsions was affected by the antioxidants applied. Thus, despite a reduced antioxidant activity of lipophilized dihydrocaffeic acid in the antioxidant assays, lipophilized dihydrocaffeic acid was more efficient than caffeic and dihydrocaffeic acids. Octyl dihydrocaffeate had a significantly higher antioxidative effect than oleyl dihydrocaffeate in emulsions. The results partly supported the polar paradox hypothesis, since lipophilized compounds resulted in increased oxidative stability. However, the decreased antioxidative efficacy with increasing alkyl chain length esterified to dihydrocaffeic acid supported a newly suggested cut‐off effect hypothesis. This hypothesis suggests that when a certain level of hydrophobicity is obtained for lipophilized phenolic acids, the ester forms micelles in the aqueous phase rather than being located at the interface or oil phase. This phenomenon is suggested to explain the reduced antioxidant activity of oleyl dihydrocaffeate compared with octyl dihydrocaffeate.Practical application: The finding that lipophilization of phenolic compounds increase their efficacy opens up new possibilities for producing new and more efficient antioxidants for food systems. However, the results also show that optimization of the chain length for each type of phenolic compound may be necessary. Since these compounds may have a much higher efficacy against lipid oxidation a lower amount of antioxidant will be necessary to obtain the same effect. This would decrease the costs. In addition, the use of synthetic antioxidants, that might have toxic effect in vivo, can be avoided. The raw materials used for the lipophilized compounds are natural compounds, however the fate of the lipophilized compounds in vivo should eventually be evaluated.

Enzymatic lipophilisation of phenolic acids through esterification with fatty alcohols in organic solvents

We investigated and optimised the synthesis of lipophilized esters between selected phenolic acids and fatty alcohols in a binary solvent system, composed of hexane and butanone. The effect of proportions of hexane and butanone was first studied by varying the volume ratio of hexane/butanone from 85:15 to 45:55. It was found that the conversion of phenolic acids strongly depended on the proportions of hexane and butanone. To examine the effect of carbon chain length of fatty alcohols on the reaction rate, the esterifications of C4–C18 straight-chain fatty alcohol with dihydrocaffeic acid (DHCA), as a model phenolic acid, were systematically evaluated. The results indicated that the conversion of DHCA was significantly affected by the number of carbon chain of fatty alcohols. Roughly 95% conversion was achieved within 3days when hexanol was used as an acyl acceptor; while only 56% and 44% conversions were achieved when 1-butanol and octadecanol were employed, respectively. However, the conversions of ferulic and caffeic acids under the same conditions were much lower than was that of DHCA. The optimal mixture ratio of hexane to butanone was found to be 65:35. Using the reaction of octanol and DHCA as a model, the reaction parameters, such as temperature, enzyme load, reaction time and substrate molar ratio, were optimised with response surface methodology (RSM). A second polynomial model was generated and optimised reaction conditions were obtained as: temperature 60°C, reaction time 3.9days, enzyme load 238mg, and substrate molar ratio 3.6 (octanol/DHCA). A validation reaction, based on the optimal conditions, was conducted, to yield 94.5% conversion of DHCA, indicating the suitability of the RSM model.

Antioxidative properties of phenolic acids and interaction with endogenous minor components during frying

AbstractThe ability of selected phenolic acids to improve the frying performance of canola oil was evaluated in a frying test. The frying performance of the oil was assessed by analysis of total polar components (TPC), level of 4‐hydroxynonenal (HNE), and the rate of formation of volatile carbonyl compounds (VCC). All the tested phenolic acids; ferulic acid (FA), caffeic acid (CA), dihydrocaffeic acid (HCA), gallic acid (GA), and vanillic acid (VA) significantly increased the frying performance of canola oil triacylglycerols (CTG). At the end of the frying test, the amount of TPC in CTG was 22.9 ± 1.0% compared to a maximum of 18.8 ± 0.8% in CTG fortified with the phenolic acids. Similarly, the level of HNE was reduced by up to 45% when it was supplemented with phenolic acids. The results showed that ethyl ferulate (EF) was a better antioxidant than FA under frying conditions; HCA offered a slightly better protection than CA; and the cinnamic acid derivative, FA was better than VA, its benzoic acid analogue. A significant synergy was observed between phenolic acids and the sterol fraction isolated from canola oil. The observed synergy was attributed to the possible formation of steryl phenolates during the frying test.Practical applications: The poor thermal stability of polyunsaturated oils limits their application for prolonged frying. PUFA offer important health benefits and can improve nutritional value of fried foods. Contrary to the commonly applied synthetic antioxidants, the phenolic acids tested in this study often are part of endogenous oil components present in oilseeds and also in some oils, and are known for their positive health benefits. Thus, the simple phenolic acids, especially the cinnamic acid derivatives may be applied as potent antioxidants to protect oils during thermal processes used for food production.

Coffee Components Inhibit Amyloid Formation of Human Islet Amyloid Polypeptide in Vitro: Possible Link between Coffee Consumption and Diabetes Mellitus

Global epidemic studies have suggested that coffee consumption is reversely correlated with the incidence of type 2 diabetes mellitus (T2DM), a metabolic disease. The misfolding of human islet amyloid polypeptide (hIAPP) is regarded as one of the causative factors of T2DM. Coffee extracts have three major active components: caffeine, caffeic acid (CA), and chlorogenic acid (CGA). In this study, the effects of these major coffee components, as well as dihydrocaffeic acid (DHCA) (a major metabolite of CGA and CA), on the amyloidogenicity of hIAPP were investigated by thioflavin-T based fluorescence emission, transmission electronic microscopy, circular dichroism, light-induced cross-linking, dynamic light scattering, and MTT-based cell viability assays. The results suggest that all components show varied inhibitory effects on the formation of toxic hIAPP amyloids, in which CA shows the highest potency in delaying the conformational transition of the hIAPP molecule with the most prolonged lag time, whereas caffeine shows the lowest potency. At a 5-fold excess molar ratio of compound to hIAPP, all coffee-derived compounds affect the secondary structures of incubated hIAPP as suggested by the circular dichroism spectra and CDPro deconvolution analysis. Further photoinduced cross-linking based oligomerization and dynamic light scattering studies suggested CA and CGA significantly suppressed the formation of hIAPP oligomers, whereas caffeine showed no significant effect on oligomerization. Cell protection effects were also observed for all three compounds, with the protection efficiency being greatest for CA and least for CGA. These findings suggest that the beneficial effects of coffee consumption on T2DM may be partly due to the ability of the major coffee components and metabolites to inhibit the toxic aggregation of hIAPP.

A seven-transmembrane receptor that mediates avoidance response to dihydrocaffeic acid, a water-soluble repellent in Caenorhabditis elegans.

The ability to detect harmful chemicals rapidly is essential for the survival of all animals. In Caenorhabditis elegans (C. elegans), repellents trigger an avoidance response, causing animals to move away from repellents. Dihydrocaffeic acid (DHCA) is a water-soluble repellent and nonflavonoid catecholic compound that can be found in plant products. Using a Xenopus laevis (X. laevis) oocyte expression system, we identified a candidate dihydrocaffeic acid receptor (DCAR), DCAR-1. DCAR-1 is a novel seven-transmembrane protein that is expressed in the ASH avoidance sensory neurons of C. elegans. dcar-1 mutant animals are defective in avoidance response to DHCA, and cell-specific expression of dcar-1 in the ASH neurons of dcar-1 mutant animals rescued the defect in avoidance response to DHCA. Our findings identify DCAR-1 as the first seven-transmembrane receptor required for avoidance of a water-soluble repellent, DHCA, in C. elegans.

Novel caffeic acid amide antioxidants: Synthesis, radical scavenging activity and performance under storage and frying conditions

Twelve novel dihydro-caffeic acid amides were synthesised in good yields and fully characterised by 1H NMR, 13C NMR, and MS. Their radical scavenging activities were assessed by DPPH assay. Additionally, their abilities to protect polyunsaturated oils under accelerated storage and frying conditions were evaluated. All the new compounds possessed significantly higher radical scavenging activities than α-tocopherol and butylated hydroxytoluene (BHT). The radical scavenging activity of N-decyl-N-(3,5-dimethoxy-4-hydroxybenzyl)-3-(3,4-dihydroxyphenyl) propanamide was 1.7 and 4 times higher than α-tocopherol and BHT, respectively. At the end of the storage period, the respective amounts of hydroperoxides in canola oil triacylglycerols (CTAG) fortified with α-tocopherol and BHT was 6.1 and 1.4 times higher, respectively, than CTAG containing the amide. The frying test showed that CTAG containing N-decyl-N-benzyl-3-(3,4-dihydroxybenzyl) propanamide was 1.3, 1.4, and 1.6 times more stable compared to oil fortified with dihydro-caffeic acid, α-tocopherol and BHT, respectively, as assessed by the amounts of the total polar compounds. Moreover, these compounds were remarkably thermally stable, making them suitable for frying applications.

Identification of novel circulating coffee metabolites in human plasma by liquid chromatography–mass spectrometry

This study reports a liquid chromatography–mass spectrometry method for the detection of polyphenol-derived metabolites in human plasma without enzymatic treatment after coffee consumption. Separation of available standards was achieved by reversed-phase ultra performance liquid chromatography and detection was performed by high resolution mass spectrometry in negative electrospray ionization mode. This analytical method was then applied for the identification and relative quantification of circulating coffee metabolites. A total of 34 coffee metabolites (mainly reduced, sulfated and methylated forms of caffeic acid, coumaric acid, caffeoylquinic acid and caffeoylquinic acid lactone) were identified based on mass accuracy (<4 ppm for most metabolites), specific fragmentation pattern and co-chromatography (when standard available). Among them, 19 circulating coffee metabolites were identified for the first time in human plasma such as feruloylquinic acid lactone, sulfated and glucuronidated forms of feruloylquinic acid lactone and sulfated forms of coumaric acid. Phenolic acid derivatives such as dihydroferulic acid, dihydroferulic acid 4′- O-sulfate, caffeic acid 3′- O-sulfate, dimethoxycinnamic acid, dihydrocaffeic acid and coumaric acid O-sulfate appeared to be the main metabolites circulating in human plasma after coffee consumption. The described method is a sensitive and reliable approach for the identification of coffee metabolites in biological fluids. In future, this analytical method will give more confidence in compound identification to provide a more comprehensive assessment of coffee polyphenol bioavailability studies in humans.

Synthesis of Octyl Dihydrocaffeate and Its Transesterification with Tricaprylin Catalyzed by Candida antarctica Lipase

This work aimed at producing a phenolic ester from dihydrocaffeic acid (DHCA), besides carrying out transesterification reactions of this ester with tricaprylin. The esterification reaction was performed in two ratios (1:1 and 1:3 DHCA:octanol), and the transesterification was done in four ratios (1:1, 1:2, 1:5, and 1:10) between the produced ester and tricaprylin. In the last, a Central Composite Rotatable Design was employed, varying the amount of enzyme (1.6–18.4%), reaction time (9.9–35.1 h), and temperature (43.2–76.8 °C) on reagent consumption percentage. Novozym 435 was the catalyst in all reactions. The highest ester yield (50%) occurred in 8 days. In transesterification reactions, higher consumption of the produced ester was achieved at ratios 1:5 and 1:10, obtaining, respectively, 29.6% and 21.1% of octyl dihydrocaffeate residual, in 24 h. At higher temperatures and time above 26 h, there was less octyl dihydrocaffeate residual (18.7%). Three different phenolic compounds were identified.

Evaluation of allergens in propolis by ultra‐performance liquid chromatography/tandem mass spectrometry

The purified extract of propolis is used as a traditional remedy for the treatment of several diseases. Its beneficial activities are mainly attributed to the polyphenolic fraction. Nevertheless, propolis can cause allergic dermatitis and the sensitization rate in humans is increasing significantly mainly in younger subjects. The aim of this study was to develop and validate a selective and sensitive ultra-performance liquid chromatography tandem mass spectrometry analysis (UPLC/MS/MS) for the evaluation of the amount of caffeic acid and its esters with allergenic action in raw propolis samples and commercial formulations. The separation was carried out on a 1.7 μm C(18) BEH Shield column and the detection performed by means of electrospray ionization in negative ion mode with multiple reaction monitoring. The confirmation of formulae of the precursor and product ions was accomplished by injection into a high-resolution system (FTICR-MS) using accurate mass measurements. The error was below 1.4 ppm.The range of the standard curves was 0.5-10 μg/mL and dihydrocaffeic acid was used as internal standard (IS). The lower limit of detection (LLOD) for 3-methyl-2-butenyl-(3M2B), 3-methyl-3-butenyl-(3M3B), 2-methyl-2-butenyl-(2M2B), benzyl-(CABE), phenylethylcaffeic acid (CAPE) and for caffeic acid (CA) and the IS was 0.1 and 0.3 μg/mL, respectively. The recoveries were in the range 96-104% and the intra- and inter-day precisions were within 6.2%. In the European (n=8) and Asiatic (n=3) propolis the most abundant allergens were CABE>3M2B>CAPE>3M3B>CA>2M2B. These compounds were not found in the red (n=1) and green (n=1) Brazilian propolis. Hydroalcoholic extracts (n=6) and tablets (n=6) were analyzed by the proposed UPLC/MS/MS method. The results showed that in the commercial products CABE, 3M2B, CAPE and 3M3B were also the most abundant.

Bioavailability and metabolism of coffee chlorogenic acids in humans

Chlorogenic acids are coffee bioactives that are becoming of great interest for their health promoting effects. However, human bioavailability of these compounds is not fully understood. We investigated plasma appearance of coffee chlorogenic (CGAs) and phenolic (PAs) acids after ingestion of coffee by healthy volunteers. Two groups of metabolites appeared over the 24h after coffee ingestion where plasma CGAs and PAs were measured after enzymatic treatment. Caffeoyl quinic, feruloyl quinic, caffeic, ferulic (FA) and isoferulic acid appeared rapidly with mean Cmax less than 2 hours after ingestion, indicative of intestinal absorption. Dihydrocaffeic and dihydroferulic acid peaked between 10 and 12h, which might suggest colonic metabolism and absorption. While colonic metabolites were present in high amounts (Cmax > 1μM), other PAs acids were present in lesser quantities (Cmax < 500nM). CGAs were present in low quantities (Cmax < 100nM), while di-caffeoylquinic acids were only detected in trace amounts. Surprisingly, FA and isoFA showed strong biphasic plasmatic curve while the methylated form of FA (dimethoxycaffeic acid) did not. Taken together, these data show the complexity of absorption and metabolism of coffee polyphenols in healthy humans. It also highlights the importance of this beverage as a significant dietary source of bioactive compounds.

Antiglycative and neuroprotective activity of colon‐derived polyphenol catabolites

Dietary flavonoids and allied phenolic compounds are thought to be beneficial in the control of diabetes and its complications, because of their ability to inhibit oxidative stress, protein glycation and to act as neuroprotectants. Following ingestion by humans, polyphenolic compounds entering the large intestine undergo extensive metabolism by interaction with colonic microbiota and it is metabolites and catabolites of the parent compounds that enter the circulatory system. The aim of this study was to investigate the inhibitory activity of some colonic microbiota-derived polyphenol catabolites against advanced glycation endproducts formation in vitro and to determine their ability, at physiological concentrations, to counteract mild oxidative stress of cultured human neuron cells. This study demonstrated that ellagitannin-derived catabolites (urolithins and pyrogallol) are the most effective antiglycative agents, whereas chlorogenic acid-derived catabolites (dihydrocaffeic acid, dihydroferulic acid and feruloylglycine) were most effective in combination in protecting neuronal cells in a conservative in vitro experimental model. Some polyphenolic catabolites, generated in vivo in the colon, were able in vitro to counteract two key features of diabetic complications, i.e. protein glycation and neurodegeneration. These observations could lead to a better control of these events, which are usually correlated with hyperglycemia.

Improved enzymatic production of phenolated acylglycerols through alkyl phenolate intermediates

A novel approach is reported for the synthesis of dihydrocaffoylated glycerols that consists of two steps: enzymatic synthesis of octyl dihydrocaffeate (as a synthetic intermediate) from octanol and dihydrocaffeic acid, and enzymatic interesterification of triacylglycerols with octyl dihydrocaffeate. Due to the good compatibility of the intermediate with triacylglycerols, an improved volumetric productivity [147 mol h(-1)(kg Novozym 435)(-1)] and high enzyme specific activity [up to 9.6 μmol(-1) min(-1)(g Novozym 435)(-1)] have been obtained.

Colonic metabolites of berry polyphenols: the missing link to biological activity?

The absorption of dietary phenols, polyphenols and tannins (PPT) is an essential step for biological activity and effects on health. Although a proportion of these dietary bioactive compounds are absorbed intact, depending on their chemical structure and the nature of any attached moiety (e.g. sugar, organic acid), substantial amounts of lower molecular weight catabolites are absorbed after biotransformation by the colon microflora. The main products in the colon are (a) benzoic acids (C6-C1), especially benzoic acid and protocatechuic acid; (b) phenylacetic acids (C6-C2), especially phenylacetic acid per se; (c) phenylpropionic acids (C6-C3), where the latter are almost entirely in the dihydro form, notably dihydrocaffeic acid, dihydroferulic acid, phenylpropionic acid and 3-(3'-hydroxyphenyl)-propionic acid. As a result of this biotransformation, some of these compounds can each reach mm concentrations in faecal water. Many of these catabolites are efficiently absorbed in the colon, appear in the blood and are ultimately excreted in the urine. In the case of certain polyphenols, such as anthocyanins, these catabolites are major products in vivo; protocatechuic acid is reported to represent a substantial amount of the ingested dose of cyanidin-3-O-glucoside. The major catabolites of berries, and especially blackcurrants, are predicted based on compositional data for polyphenols from berries and other sources. Since microbial catabolites may be present at many sites of the body in higher concentration than the parent compound, it is proposed that at least a part of the biological activities ascribed to berry polyphenols and other PPT are due to their colonic catabolites.

Flavanol derivatives with antioxidant activity from the stem bark of &lt;i&gt;Xylocarpus granatum&lt;/i&gt;

A new flavanol derivative dihydrocaffeic acid-(3→8)-epicatechin together with two known derivatives, (+)-catechin and catechin-(4β→8)-catechin were isolated from the stem bark of a mangrove plant Xylocarpus granatum . Their structures were established using 1D and 2D NMR experiments as well as HRMS-FAB, EIMS, IR and UV spectra. The compounds were evaluated for DPPH radical scavenging activity and ferric reducing antioxidant power and they exhibited higher activity compared to butylated hydroxytoluene (BHT) which is a commercially available antioxidant. Catechin-(4β→8)-catechin showed the highest DPPH radical scavenging activity with IC50 of 4.5 μg/mL. © 2010 International Formulae Group. All rights reserved. Keywords: Xylocarpus granatum , flavanol derivative, antioxidant activity.

Plasma appearance and correlation between coffee and green tea metabolites in human subjects

Coffee and green tea are two of the most widely consumed hot beverages in the world. Their respective bioavailability has been studied separately, but absorption of their respective bioactive phenolics has not been compared. In a randomised cross-over design, nine healthy subjects drank instant coffee and green tea. Blood samples were collected over 12 h and at 24 h to assess return to baseline. After green tea consumption, (-)-epigallocatechin (EGC) was the major catechin, appearing rapidly in the plasma; (-)-EGC gallate (EGCg) and (-)-epicatechin (EC) were also present, but (-)-EC gallate and C were not detected. Dihydroferulic acid and dihydrocaffeic acid were the major metabolites that appeared after coffee consumption with a long time needed to reach maximum plasma concentration, suggesting metabolism and absorption in the colon. Other phenolic acid equivalents (caffeic acid (CA), ferulic acid (FA) and isoferulic acid (iFA)) were detected earlier, and they peaked at lower concentrations. Summations of the plasma area under the curves (AUC) for the measured metabolites showed 1.7-fold more coffee-derived phenolic acids than green tea-derived catechins (P = 0.0014). Furthermore, we found a significant correlation between coffee metabolites based on AUC. Inter-individual differences were observed, but individuals with a high level of CA also showed a correspondingly high level of FA. However, no such correlation was observed between the tea catechins and coffee phenolic acids. Correlation between AUC and maximum plasma concentration was also significant for CA, FA and iFA and for EGCg. This implies that the mechanisms of absorption for these two classes of compounds are different, and that a high absorber of phenolic acids is not necessarily a high absorber of catechins.