Comprehensive analysis of phenolic compounds and abscisic acid profiles of twelve native Canadian berries

Wild berries, integral parts of North American Natives’ traditional nutrition, are a rich source of phytochemicals involved in the prevention of metabolic syndrome. Although phenolic compounds are generally considered to be the functional components in fruits, the identification of specific compounds in relation to this beneficial activity remains to be uncovered. With the long-term goal of establishing the contribution of phytochemical compounds to their beneficial health effects, we investigated in a comprehensive manner the composition of twelve native Canadian berries: Saskatoon berry, alpine bearberry, chokeberry, black crowberry, honeysuckle, chokecherry, cloudberry, elderberry, lowbush blueberry, alpine blueberry, lingonberry and highbush cranberry. All harvested in the province of Quebec, these fruits were analyzed for their phenolic composition (anthocyanins, flavonols, flavan-3-ols, phenolic acids, proanthocyanidins and ellagitannins) and their content in abscisic acid derivatives (cis- and trans-ABA, abscisic acid-glucose ester, 7′-hydroxy-abscisic acid, neo-phaseic acid, phaseic acid and dihydrophaseic acid). Over 60 different phenolic compounds were identified and quantified in berries. Along with the characterization of abscisic acid, this study reports for the first time a complete characterization of proanthocyanidins in these fruits, highbush cranberry presenting the highest content of this class of compounds.     

New HPTLC methods for analysis of major bioactive compounds in mate (Ilex paraguariensis) tea

New HPTLC (high-performance thin-layer chromatography) methods to evaluate major bioactive compounds in mate (Ilex paraguariensis) tea were developed. Identification of compounds was based on HPTLC-MS (high-performance thin-layer chromatography–mass spectrometry), parallel to other techniques. Quantitative evaluation of the main methylxanthines and phenolic compounds in this species was accomplished by two HPTLC methods which can be performed consecutively on one single plate. A solvent system for the separation of the identified saponins is also described for qualitative evaluations. The methods for quantification were validated in terms of: robustness; LOD and LOQ (limits of detection and quantification); repeatability; intra-day and inter-day variation; ruggedness; and accuracy. The methods have proven to be suitable for evaluation of mate tea aqueous and methanolic extracts, with the advantages of: high-throughput; reduced need of plates and application procedures; and high sensitivity – low LODs and LOQs were achieved. Aqueous extracts of nineteen mate teas of different type, geographical origin and age were evaluated in terms of methylxanthines, phenolic compounds and pH. By means of principal component analysis, distinctive characteristics between mate teas could be observed.     

Extraction and identification by GC-MS of phenolic acids in traditional balsamic vinegar from Modena

Traditional balsamic vinegar from Modena (Aceto balsamico tradizionale di Modena, ABTM) is a typical Italian product obtained by a traditional method from grape must. As the chemical composition of this vinegar has not yet been fully investigated, the present work aims to develop a method for investigating the presence of biologically active compounds such as phenolic acids. The physico-chemical characteristics of ABTM required the development of a specific method for phenolic acid extraction. Different materials, such as diatomaceous earth cartridges for liquid–liquid extraction and polyamidic SPE cartridges, have been tested. The identification of phenolic acids in extracts of ABTM has been carried out using a GC/MS method after derivatization with bis(trimethylsilyl)trifluoroacetamide (BTSFA). The developed procedure allowed the identification in ABTM of nine phenolic acids, confirming also the presence of these natural antioxidants at the end of the process that transforms grape must into ABTM.     

Influence of cooking process on phenolic marker compounds of vegetables

Phenolic compounds are secondary plant metabolites which have long been associated with flavor and color characteristics of fruits and vegetables. These phenolic compounds attract great interest due to their postulated health protecting properties. However, adequate intakes and absorption rate of phenolic compounds are necessary for these beneficial effects. Until now, little is known about alterations of phenolic compounds content by the cooking process. In the present study, the influence of different volumes of cooking water on the amount of selected phenolic marker compounds resting in the vegetables was assessed. In zucchini, rutin was quantified as a marker for flavonoid glycosides. Chlorogenic acid, representative of phenolic acids was analyzed in carrots. In beans, rutin and quercitrin, both belonging to flavonoid glycosides, were investigated. In potatoes, chlorogenic and caffeic acid were determined. The cooking of zucchini, beans and carrots with smaller amounts of water resulted in significant higher content of phenolic phytochemicals in the vegetables compared to cooking with larger water volumes. For potatoes, which showed great variations in content of phenolic acids after cooking, no significant differences in phenolic acids was observed. It can be concluded from these observations, that real intakes of phenolic compounds from cooked vegetables are lower and that the amounts consumed are therefore overestimated.     

A Phenolic Extract Obtained from Methyl Jasmonate-Treated Strawberries Enhances Apoptosis in a Human Cervical Cancer Cell Line

In the present study, we evaluated the effect of methyl jasmonate (MeJA) treatment on strawberry phenolic composition. Strawberry extracts contain a mixture of phenolic compounds possessing several biological properties. We demonstrated that these extracts were more effective in inducing apoptosis in HeLa cells compared to phenolic preparations derived from untreated strawberries. Treatment of strawberries with 0.5% MeJA resulted in increased polyphenols content (from 7.4 to 8.6 mM quercetin equivalents) and antioxidant properties (from 3.9 to 4.6 mM quercetin equivalents). The identification and quantification of phenolic compounds by liquid chromatography–mass spectrometry in the strawberry extracts showed that cyanidin glucoside, pelargonidin glucoside, and ellagic glucoside acid were significantly higher in strawberries treated with MeJA. Phenolic extracts from MeJA-treated strawberries significantly decreased the cell viability in HeLa cells, compared to extracts derived from untreated fruits. We hypothesized that the enhanced apoptotic activity of MeJA-treated strawberries was due to a synergistic or additive effect of different phenolic compounds present in the extract, rather than the activity of a single molecule.     

Inhibition of blood platelet adhesion and secretion by different phenolics from Yucca schidigera Roezl. bark

OBJECTIVE: Yucca schidigera is a plant that grows in Mexico, and it has a very high level of saponins and phenolic compounds with antioxidant action. The products of Y. schidigera are used as food additives and have a generally recognized as safe label. This study investigated the antiplatelet mechanisms of four phenolic compounds. METHODS: We investigated antiplatelet mechanisms of the phenolic compounds trans-3,4',5-trihydroxystilbene (trans-resveratrol), trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene, and yuccaols A and C that had been isolated from the bark of Y. schidigera by studying their effects on the first step of platelet activation, i.e., platelet adhesion to collagen and fibrinogen. The effects of these compounds on the release of adenine nucleotides, proteins, and beta-N-acetyl-glycosaminidase (a marker of lysosomal secretion) from blood platelets activated by thrombin were also studied. RESULTS: These different phenolic compounds (1 to 25 microg/mL) and their extracts decreased platelet adhesion and secretion. CONCLUSIONS: Resveratrol and yucca extract were more reactive in decreasing these processes than were other tested phenolic compounds.     

Phenolic compounds in red wine digested in vitro in the presence of iron and other dietary factors

Quantitative and qualitative changes in the phenolic composition of red wine may occur during digestion in the lumen, particularly when other dietary components are present. In this study, mixtures of red wine, iron, and ascorbic acid, meat or casein were subjected to a simulated gastrointestinal digestion. This process involves incubation of samples for 4.5 h at 37 degrees C, at different pH values, in the presence of peptic enzymes and fractionation of digests through a dialysis membrane with a molecular weight cut-off of 6000-8000. Selected phenolic compounds were determined in undigested samples and in their dialysable digests by reversed-phase high-performance liquid chromatography. A dramatic decrease in the concentration of the selected phenolic compounds was observed in all samples after they were digested in vitro. Moreover, when iron and/or protein were added to red wine samples, changes in the phenolic profile of the undigested and of the in vitro digested samples were detected. These results suggest that interactions between red wine phenolic compounds and iron, protein and/or digestion components are important determinants of the physicochemical properties and the concentration of these phenolic compounds in the lumen. The in vitro methodology employed herein offers a tool for the study of phenolic compounds under conditions of simulated gastrointestinal digestion, incorporating lumenal events that may affect phenolic compounds.     

Inhibitory effects of environmental chemicals on protein disulfide isomerase in vitro

BACKGROUND: The influence of endocrine disrupting chemicals (EDCs) upon physiological functions and their mechanisms is of concern. We have previously demonstrated that protein disulfide isomerase (PDI) was a target molecule of bisphenol A (BPA), which is considered to be EDC. PDI plays a key role in protein folding as an isomerase and also possesses a 3,3',5-triiodo-L-thyronine (T3)-binding activity. Since PDI activities were inhibited by BPA in our previous study, BPA might have adverse effects on physiological functions via the inhibition of PDI activities. We conducted this study to identify the compounds which disturb PDI activities as well as BPA, and to discuss their structural characteristics. METHODS: We examined the effects of 22 suspected EDC on both the T3-binding activity and isomerase activity of rat recombinant PDI. RESULTS: Among the 22 compounds, only phenolic compounds, namely BPA, p-octylphenol, p-nonylphenol, 2,4-dichlorophenol, pentachlorophenol, tetrabromobisphenol A, and tetrachlorobisphenol A, inhibited T3 binding to PDI. Furthermore non-halogenated compounds among these phenolic compounds, such as BPA, p-octylphenol, and p-nonylphenol, showed inhibitory effects on the isomerase activity of PDI. CONCLUSIONS: Our results suggest that phenolic groups might have important inhibitory effects on the T3-binding activity of PDI, and that compounds with phenolic groups might have the same effects on PDI. Furthermore, non-halogenated phenolic compounds had inhibitory effects on the isomerase activities of PDI in addition to T3-binding activity, indicating that these compounds might also have adverse effects on protein folding, which PDI participates in by catalyzing rearrangements of disulfide bonds as an isomerase.     

Air sampling and analytical procedures for benzidine, 3,3'-dichlorobenzidine and their salts

The purpose of the study was the development of new air-sampling and analytical procedures for benzidine, 3,3'-dichlorobenzidine and their salts. Air is drawn through a glass-fiber filter followed by a bed of silica gel to collect these substances as either particles or vapors. The compounds are extracted from the sampler and analyzed by HPLC with sensitivities in the range of 3 micrograms/m3 for 48-L air samples. The methods were evaluated in the laboratory with test aerosol atomospheres and found to be unaffected by temperature or humidity of the sampled environment. Tests of precision, sample stability and separation from interferants indicate that the method should provide reliable results for personal monitoring procedures.     

Phenolic compounds in wholegrain rye and its fractions

Rye (Secale cereale L.) has traditionally had an important role in the daily diet especially in Northern and Eastern Europe, and in addition to dietary fibre, rye grain is a good source of various phytochemicals in our diet. The focus of the present work was to find out how various phenolic compounds are distributed in rye grain fractions prepared by air-classification, and compare rye brans produced by different separation techniques (sieving or air classification). Of the phenolic compounds, phenolic acids were analyzed as organic solvent soluble (OSS) free, esterified and glycosylated residues, organic solvent in-soluble (OSI) esterified and etherified residues and OSI ferulic acid esterified to water extractable fibre. In addition alkylresorcinols, flavonoids, hydroxamic acid DIBOA (2,4-dihydroxy-1,4-benzoxazin-3-one), flavonoids and lignans were analyzed. Based on the determined concentrations, alkylresorcinols formed the most dominant group of OSS phenolic compounds in rye and its fractions, followed by smaller amounts of OSS esterified phenolic acids and hydroxamic acid DIBOA. In wholegrain rye and rye fractions, the major part (86–92%) of the total amount of phenolic acids was present as OSI-form bound to the fibre complex either via ester or β-aryl ether bonds. All of the analyzed phenolic compound groups were enriched in the bran fraction, which encourages usage of this part of rye grain in foods. The content and profile of phenolic compounds did not differ much between the two differently produced rye brans.     

Bioavailability of coffee chlorogenic acids and green tea flavan-3-ols

This paper reviews recent human studies on the bioavailability of chlorogenic acids in coffee and green tea flavan-3-ols in which the identification of metabolites, catabolites and parent compounds in plasma, urine and ileal fluid was based on mass spectrometric methodology. Both the chlorogenic acids and the flavan-3-ols are absorbed in the small intestine and appear in the circulatory system predominantly as glucuronide, sulfate and methylated metabolites. Even when absorption occurs in the small intestine, feeding studies with ileostomists reveal that substantial amounts of the parent compounds and some of their metabolites appear in ileal fluid indicating that in volunteers with a functioning colon these compounds will pass to the large intestine where they are subjected to the action of the colonic microflora. A diversity of colonic-derived catabolites are absorbed into the bloodstream and pass through the body prior to excretion in urine. There is growing evidence that these compounds, which were little investigated until recently, are produced in quantity in the colon and form a key part of the bioavailability equation of flavonoids and related compounds that occur in fruits, vegetables and beverages. Recent evidence indicates that some colon-derived phenolic acids have in vitro anti-inflammatory activity.     

Bioavailability of phenols from a phenol-enriched olive oil

Phenolic compounds are one of the main reasons behind the healthy properties of virgin olive oil (VOO). However, their daily intake from VOO is low compared with that obtained from other phenolic sources. Therefore, the intake of VOO enriched with its own phenolic compounds could be of interest to increase the daily dose of these beneficial compounds. To evaluate the effectiveness of enrichment on their bioavailability, the concentration of phenolic compounds and their metabolites in human plasma (0, 60, 120, 240 and 300 min) from thirteen healthy volunteers (seven men and six women, aged 25 and 69 years) was determined after the ingestion of a single dose (30 ml) of either enriched virgin olive oil (EVOO) (961·17 mg/kg oil) or control VOO (288·89 mg/kg oil) in a cross-over study. Compared with VOO, EVOO increased plasma concentration of the phenol metabolites, particularly hydroxytyrosol sulphate and vanillin sulphate (P < 0·05). After the consumption of VOO, the maximum concentration of these peaks was reached at 60 min, while EVOO shifted this maximum to 120 min. Despite these differences, the wide variability of results indicates that the absorption and metabolism of olive oil phenols are highly dependent on the individual.     

Antioxidant actions of phenolic compounds found in dietary plants on low-density lipoprotein and erythrocytes in vitro

OBJECTIVE: There is increasing interest in the study of the antioxidant actions of plant phenolic compounds as evidence shows that consumption of plant products rich in these compounds contributes to protection from a number of ailments including cardiovascular diseases. In the present study, the antioxidant effects of selected phenolic compounds from dietary sources, namely barbaloin, 6-gingerol and rhapontin, were investigated. METHODS: Low-density lipoprotein (LDL), erythrocytes and erythrocyte membranes were subjected to several in vitro oxidative systems. The antioxidant effects of the phenolic compounds were assessed by their abilities in inhibiting hemolysis and lipid peroxidation of LDL and erythrocyte membranes, and in protecting ATPase activities and protein sulfhydryl groups of erythrocyte membranes. RESULTS: 6-Gingerol and rhapontin were found to exhibit strong inhibition against lipid peroxidation in LDL induced by 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH) and hemin while barbaloin possessed weaker effects. A similar order of antioxidant potencies among the three compounds was observed on the lipid peroxidation of erythrocyte membranes in a tert-butylhydroperoxide (tBHP)/hemin oxidation system. On the other hand, barbaloin and rhapontin were comparatively stronger antioxidants than 6-gingerol in preventing AAPH-induced hemolysis of erythrocytes. Among the three compounds, only barbaloin protected Ca2+-ATPase and protein sulfhydryl groups on erythrocyte membranes against oxidative attack by tBHP/hemin. Interestingly, rhapontin demonstrated protective actions on Na+/K+-ATPase in a sulfhydryl group-independent manner under the same experimental conditions. CONCLUSIONS: In view of their protective effects on LDL and erythrocytes against oxidative damage, these phenolic compounds might have potential applications in prooxidant state-related cardiovascular disorders.     

Variability in the Beneficial Effects of Phenolic Compounds: A Review

When analysing the beneficial effects of phenolic compounds, several factors that exert a clear influence should be taken into account. The content of phenolic compounds in foods is highly variable, directly affecting individual dietary intake. Once ingested, these compounds have a greater or lesser bioaccessibility, defined as the amount available for absorption in the intestine after digestion, and a certain bioavailability, defined as the proportion of the molecule that is available after digestion, absorption and metabolism. Among the external factors that modify the content of phenolic compounds in food are the variety, the cultivation technique and the climate. Regarding functional foods, it is important to take into account the role of the selected food matrix, such as dairy matrices, liquid or solid matrices. It is also essential to consider the interactions between phenolic compounds as well as the interplay that occurs between these and several other components of the diet (macro- and micronutrients) at absorption, metabolism and mechanism of action levels. Furthermore, there is a great inter-individual variability in terms of phase II metabolism of these compounds, composition of the microbiota, and metabolic state or metabotype to which the subject belongs. All these factors introduce variability in the responses observed after ingestion of foods or nutraceuticals containing phenolic compounds.     

The influence of interactions among phenolic compounds on the antiradical activity of chokeberries (Aronia melanocarpa)

In the present work, interactions between phenolic compounds from chokeberries and their influence on the antiradical activity was studied. Three fractions were isolated from chokeberries containing different classes of phenolic compounds. The first fraction contained a major part of phenolic acids and flavonols, the second anthocyanins, and the third insoluble phenols and proanthocyanidins. The phenolic compound content was determined using high-performance liquid chromatography, and the antiradical activity using the DPPH test. In order to evaluate the effects of interactions between phenolic compounds on the antiradical activity, the antiradical activity of individual phenolic fractions was compared with that obtained by mixing phenolic fractions. Phenolic mixtures showed the decrease in the antiradical activity in comparison with the individual phenolic fractions. These results suggest the existence of complex interactions among phenolic compounds that caused the decrease of the antiradical activity. Interactions among chokeberry phenols promoted a negative synergism.     

Influence of environment and genotype on polyphenol compounds and in vitro antioxidant capacity of native Andean potatoes (Solanum tuberosum L.)

The influence of environment and genetics on total phenolic content and hydrophilic antioxidant capacity (H-ORAC) of potato tubers was evaluated using 13 native Andean genotypes. Cultivars were grown at two highland locations in Peru: Huancayo and Huancani. Environmental conditions significantly affected the total phenolic contents and H-ORAC values in a cultivar-dependent manner. However, the potato genotype was the most determining factor of the observed variations. The effects of environment on individual phenolic compounds were also significant in terms of quantity, whereas the chemical profile remained stable across environmental conditions. To gain an insight into the observed antioxidant capacity of potato extracts, the individual and combined antioxidant effects of the main potato phenolic compounds were investigated. The ORAC values of reconstituted polyphenol mixtures reflecting the authentic phenolic composition of potato extracts were higher than expected from the summing of the ORAC values of individual phenolic compounds, indicating synergistic effects. The authentic potato extracts showed either a higher or a lower ORAC value than their reconstituted counterparts, suggesting positive or negative interactions with other compounds. Taken together, our results lead us to the following conclusions: (i) the hydrophilic antioxidant capacity observed in potato extracts is the result of various and complex interactions that could be attributed to phenolic compounds, to other non-identified molecules, and to synergistic as well as antagonistic effects between all these components and (ii) the high stability of the ranking of cultivars across environment in terms of phenolic content and antioxidant capacity indicates that the native Andean cultivars could be confidently used within breeding programs aiming at improving the health-promoting value of potato.     

Ellagic acid,phenolic acids,and flavonoids in Malaysian honey extracts demonstrate in vitro anti-inflammatory activity

Natural honey has been used in traditional medicine of different cultures throughout the world. This study looked into the extraction of Malaysian honey and the evaluation of the anti-inflammatory activity of these extracts. It was hypothesized that honey extracts contain varying amounts of phenolic compounds and that they possess different in vitro anti-inflammatory activities. Honey extracts were analyzed using liquid chromatography–mass spectrometry to identify and compare phenolic compounds, whereas high-performance liquid chromatography was used for their quantification. Subsequently, honey methanol extract (HME) and honey ethyl acetate extract (HEAE) were tested in vitro for their effect on nitric oxide production in stimulated macrophages. The extracts were also tested for their effects on tumor necrosis factor–α (TNF) cytotoxicity in L929 cells. The major phenolics in the extracts were ellagic, gallic, and ferulic acids; myricetin; chlorogenic acid; and caffeic acid. Other compounds found in lower concentrations were hesperetin, p-coumaric acid, chrysin, quercetin, luteolin, and kaempferol. Ellagic acid was the most abundant of the phenolic compounds recorded, with mean concentrations of 3295.83 and 626.74 μg/100 g of honey in HME and HEAE, respectively. The median maximal effective concentrations for in vitro nitric oxide inhibition by HEAE and HME were calculated to be 37.5 and 271.7 μg/mL, respectively. The median maximal effective concentrations for protection from TNF cytotoxicity by HEAE and HME were 168.1 and 235.4 μg/mL, respectively. In conclusion, HEAE exhibited greater activity in vitro, whereas HME contained a higher concentration of phenolic compounds per 100 g of honey.     

Berry flavonoids and phenolics: bioavailability and evidence of protective effects

Berries contain vitamin C and are also a rich source of phytochemicals, especially anthocyanins which occur along with other classes of phenolic compounds, including ellagitannins, flavan-3-ols, procyanidins, flavonols and hydroxybenzoate derivatives. This review examines studies with both human subjects and animals on the absorption of these compounds, and their glucuronide, sulphate and methylated metabolites, into the circulatory system from the gastrointestinal tract and the evidence for their localisation within the body in organs such as the brain and eyes. The involvement of the colonic microflora in catabolising dietary flavonoids that pass from the small to the large intestine is discussed along with the potential fate and role of the resultant phenolic acids that can be produced in substantial quantities. The in vitro and in vivo bioactivities of these polyphenol metabolites and catabolites are assessed, and the current evidence for their involvement in the protective effects of dietary polyphenols, within the gastrointestinal tract and other parts of the body to which they are transported by the circulatory system, is reviewed.     

Safety evaluation of olive phenolic compounds as natural antioxidants

Free and total polyphenolic compounds were extracted from the fruits and leaves of the Picual cultivar. The safety limits of these compounds were recognized by measuring the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the levels of high-density lipoprotein (HDL) cholesterol and total lipids of rat serum. The free and total phenolic compounds (400, 800, and 1600 ppm) and butylated hydroxy toluene (BHT) (200 ppm) were daily ingested for 7 weeks. The administration of olive total and free phenolic compounds at 400 and 800 ppm did not cause any significant changes on ALT and AST activities and serum total lipids. These compounds at 1600 ppm caused significant increase in ALT and AST activities and the content of total lipids. Both olive phenolic compounds were superior to that of BHT in increasing HDL-cholesterol level. Nutritional experiments demonstrated that BHT at 200 ppm caused an enlargement in the kidney and liver of the rat compared with the administration of total and free olive phenolic compounds at 1200 and 1600 ppm. Microscopical examination of kidney and liver tissues of rats administered free and total phenolic compounds at 1200 ppm had the same histological character as that of control rats, while the administration of BHT (200 ppm) and phenolic compounds (1600 ppm) induced severe damage to the tissues of the rat kidney and liver.     

Role of Chrononutrition in the Antihypertensive Effects of Natural Bioactive Compounds

Hypertension (HTN) is one of the main cardiovascular risk factors and is considered a major public health problem. Numerous approaches have been developed to lower blood pressure (BP) in hypertensive patients, most of them involving pharmacological treatments. Within this context, natural bioactive compounds have emerged as a promising alternative to drugs in HTN prevention. This work reviews not only the mechanisms of BP regulation by these antihypertensive compounds, but also their efficacy depending on consumption time. Although a plethora of studies has investigated food-derived compounds, such as phenolic compounds or peptides and their impact on BP, only a few addressed the relevance of time consumption. However, it is known that BP and its main regulatory mechanisms show a 24-h oscillation. Moreover, evidence shows that phenolic compounds can interact with clock genes, which regulate the biological rhythm followed by many physiological processes. Therefore, further research might be carried out to completely elucidate the interactions along the time–nutrition–hypertension axis within the framework of chrononutrition.