Chickpeas from a Chilean Region Affected by a Climate-Related Catastrophe: Effects of Water Stress on Grain Yield and Flavonoid Composition.

The Valparaiso region in Chile was decreed a zone affected by catastrophe in 2019 as a consequence of one of the driest seasons of the last 50 years. In this study, three varieties ('Alfa-INIA', 'California-INIA', and one landrace, 'Local Navidad') of kabuli-type chickpea seeds produced in 2018 (control) and 2019 (climate-related catastrophe, hereafter named water stress) were evaluated for their grain yield. Furthermore, the flavonoid profile of both free and esterified phenolic extracts was determined using liquid chromatography-mass spectrometry, and the concentration of the main flavonoid, biochanin A, was determined using liquid chromatography with diode array detection. The grain yield was decreased by up to 25 times in 2019. The concentration of biochanin A was up to 3.2 times higher in samples from the second season (water stress). This study demonstrates that water stress induces biosynthesis of biochanin A. However, positive changes in the biochanin A concentration are overshadowed by negative changes in the grain yield. Therefore, water stress, which may be worsened by climate change in the upcoming years, may jeopardize both the production of chickpeas and the supply of biochanin A, a bioactive compound that can be used to produce dietary supplements and/or nutraceuticals.

Revisiting the Oxidation of Flavonoids: Loss, Conservation or Enhancement of Their Antioxidant Properties.

Flavonoids display a broad range of health-promoting bioactivities. Among these, their capacity to act as antioxidants has remained most prominent. The canonical reactive oxygen species (ROS)-scavenging mode of the antioxidant action of flavonoids relies on the high susceptibility of their phenolic moieties to undergo oxidation. As a consequence, upon reaction with ROS, the antioxidant capacity of flavonoids is severely compromised. Other phenol-compromising reactions, such as those involved in the biotransformation of flavonoids, can also markedly affect their antioxidant properties. In recent years, however, increasing evidence has indicated that, at least for some flavonoids, the oxidation of such residues can in fact markedly enhance their original antioxidant properties. In such apparent paradoxical cases, the antioxidant activity arises from the pro-oxidant and/or electrophilic character of some of their oxidation-derived metabolites and is exerted by activating the Nrf2-Keap1 pathway, which upregulates the cell's endogenous antioxidant capacity, and/or, by preventing the activation of the pro-oxidant and pro-inflammatory NF-κB pathway. This review focuses on the effects that the oxidative and/or non-oxidative modification of the phenolic groups of flavonoids may have on the ability of the resulting metabolites to promote direct and/or indirect antioxidant actions. Considering the case of a metabolite resulting from the oxidation of quercetin, we offer a comprehensive description of the evidence that increasingly supports the concept that, in the case of certain flavonoids, the oxidation of phenolics emerges as a mechanism that markedly amplifies their original antioxidant properties. An overlooked topic of great phytomedicine potential is thus unraveled.

Protection against indomethacin-induced loss of intestinal epithelial barrier function by a quercetin oxidation metabolite present in onion peel: In vitro and in vivo studies.

Oxidative stress is directly implicated in the loss of intestinal epithelial barrier function (IEBF) induced by non-steroidal anti-inflammatory drugs (NSAIDs). Previous studies by our research team demonstrated that 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (BZF), a quercetin oxidation metabolite that naturally occurs in onion peels, exhibits an antioxidant potency notably higher than quercetin. Thus, we assessed the potential of BZF and a BZF-rich onion peel aqueous extract (OAE) to protect against the loss of IEBF in Caco-2 cell monolayers and in rats exposed to indomethacin. In vitro, pure BZF and OAE standardized in BZF (100 nM), protected against the drop in transepithelial electrical resistance by 70 - 73%. Likewise, it prevented the increase in fluorescein-isothiocyanate labelled dextran (FITC-dextran) paracellular transport by 74% and oxidative stress by 84 - 86%. In vivo, BZF, given orally at a dose 80 µg/Kg bw as OAE, totally abolished a 30-fold increase in FITC-dextran serum concentration induced by indomethacin. This effect was dose-dependent and largely conserved (85%) when OAE was given 180-min prior to indomethacin. The IEBF-protective effect of OAE was accompanied by a full prevention of the NF-ĸB activation, and the increases in interleukine-8 secretion and myeloperoxidase activity induced by indomethacin. The protection was also associated with a 21-fold increase in Nrf2, and a 7-fold and 9-fold increase in heme oxygenase-1 and NAD(P)H-quinone oxidoreductase 1, respectively. The IEBF-protecting effect of OAE involves, most likely, its dual capacity to activate Nrf2 while inhibiting NF-ĸB activation. The extremely low doses of BZF needed to promote such actions warrants extending its IEBF-protective effects to other NSAIDs.

Vitamin E as an essential micronutrient for human health: Common, novel, and unexplored dietary sources.

Vitamin E comprises a group of vitamers that includes tocopherols and tocotrienols. They occur in four homologues according to the number and position of methyl groups attached to the chromanol ring. Vitamin E, a liposoluble antioxidant, may participate as an adjuvant in the prevention and treatment of cardiovascular, neurological, and aging-related diseases. Furthermore, vitamin E has applications in the food industry as a natural additive. In this contribution, the most recent information on the dietary sources of vitamin E, including common, novel, and unexplored sources, is presented. Common edible oils, such as those of corn, olive, palm, rice bran, and peanut, represent the most prominent sources of vitamin E. However, specialty and underutilized oils such as those obtained from tree nuts, fruit seeds, and by-products, emerge as novel sources of this important micronutrient. Complementary studies should examine the tocotrienol content of vitamin E dietary sources to better understand the different biological functions of these vitamers.

Quercetin Oxidation Metabolite Present in Onion Peel Protects Caco-2 Cells against the Oxidative Stress, NF-kB Activation, and Loss of Epithelial Barrier Function Induced by NSAIDs.

The potential of 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (BZF), a quercetin oxidation metabolite, and that of a BZF-rich onion peel aqueous extract (OAE) to protect Caco-2 monolayers against the oxidative stress (OS) and an increased permeability (IP) induced by five nonsteroidal anti-inflammatory drugs (NSAIDs) (indomethacin, diclofenac, piroxicam, ibuprofen, and metamizole) were investigated. Under identical OS conditions, the NSAIDs substantially differed in their ability to induce an IP and/or NF-kB activation. The OAE (100 nM BZF) protected in identical magnitude (84-86%) against OS but in a highly dissimilar manner against the IP (18-73%). While all NSAIDs activated NF-kB, the OAE prevented only that induced by indomethacin. Results reveal that the IP has no direct relationship with the OS and that with the exception of indomethacin, the prevention of NSAIDs-induced OS and/or NF-kB activation plays no fundamental role in the IP-protecting effect of OAE. These results warrant the in vivo evaluation of OAE against indomethacin-induced loss of intestinal barrier function.

Low nanomolar concentrations of a quercetin oxidation product, which naturally occurs in onion peel, protect cells against oxidative damage.

The occurrence of the quercetin oxidation metabolite 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (BZF), whose antioxidant potency is notably higher than the antioxidant potency of quercetin, was investigated in twenty quercetin-rich plant foods. BZF was identified (HPLC-DAD-ESI-MS/MS) only in the dry outer scales of onions and shallots. Aqueous extracts of onions (OAE) and shallots (SAE) were evaluated for their antioxidant and cytoprotective properties. OAE, whose potency did not differ from SAE, protected ROS-exposed Caco2 cells against oxidative (78%) and cellular (90%) damage at a 3 µg/L concentration (corresponding to 0.03 nM of BZF). After chromatographic resolution of OAE, the BZF peak accounted fully and exclusively for its antioxidant effect. The antioxidant effects of OAE and of a pure BZF were described by two perfectly overlapping curves whose concentration-dependence was within the 3 × 10-4 to 102 nM BZF range. Such unprecedented low concentrations place BZF-containing plants on the frontier of the search for novel sources of antioxidants.

An In Vitro Study of the Antioxidant and Antihemolytic Properties of Buddleja globosa (Matico).

The antioxidant and antihemolytic properties contained in the leaves of Buddleja globosa (B. globosa), also known as "Matico," were determined. Aqueous extracts of leaves were assayed in human erythrocytes and molecular models of its membrane. The latter were bilayers built-up of lipids located in the outer and inner leaflets of the erythrocyte membrane. Observations by scanning electron microscopy showed that the extract altered the morphology of erythrocytes inducing the formation of crenated echinocytes. This result implied that the extract components were inserted into the outer leaflet of the cell membrane. This conclusion was confirmed by experiments carried out by fluorescence spectroscopy of red cell membranes and vesicles (LUV) of dimyristoylphosphatidylcholine (DMPC) and by X-ray diffraction of DMPC and dimyristoylphosphatidylethanolamine bilayers. Human erythrocytes were in vitro exposed to HClO, which is a natural powerful oxidant. Results demonstrated that low concentrations of B. globosa aqueous extract neutralized the harmful capacity of HClO. Hemolysis experiments also showed that the extract in very low concentrations reduced hemolysis induced by HClO.

International Regulations of Propolis Quality: Required Assays do not Necessarily Reflect their Polyphenolic-Related In Vitro Activities.

Propolis has been proposed as a polyphenolic-rich natural product potentially able to be used for human consumption or even for medicinal proposes. To guarantee a minimum phenolic and flavonoid content and as consequence of their related-biological activities, international requirements of propolis quality are commonly applied. In this work we assessed phenolic and flavonoid contents of propolis; the antioxidant capacity (toward peroxyl radicals and hypochlorous acid); the ability to generate nitric oxide (NO); and, finally the antimicrobial activity of 6 propolis samples from the VI region of Chile. Our results show that the total phenolic and flavonoid content of propolis samples are not always in agreement with their polyphenolic-associated in vitro activities. For example, P03 and P06 samples showed the lowest (25 ± 4 GAE/g propolis) and the highest (105 ± 3 GAE/g propolis) total phenolic content, respectively. This was in agreement with flavonoid content and their Oxygen Radical Absorbance Capacity (ORAC) activity. However, this dependence was not observed toward HOCl, NO release and antimicrobial activity. Based on our results, we consider that, in order to guarantee the antioxidant or antimicrobial in vitro effects, the international regulations of propolis quality should contemplate the convenience of incorporating other simple analytical test such as ORAC or antimicrobial tests.

Probiotic screening and safety evaluation of Lactobacillus strains from plants, artisanal goat cheese, human stools, and breast milk.

The aim of this study was to select autochthonous strains of Lactobacillus from stools of healthy infants and adults, human milk, artisanal goat cheese, and fruits and vegetables according to their probiotic properties and safety. From 421 strains of Lactobacillus isolated, 102 (24.2%) were shown to be tolerant to gastric pH and bile salts; they were used to determine their anti-Helicobacter pylori (agar diffusion assay), antioxidant (oxygen radical absorption capacity), and anti-inflammatory (inhibition of interleukin-8 release by tumor necrosis factor-α-stimulated HT-29 cells) activities as well as their ability to adhere to intestinal (Caco-2) and gastric (AGS) epithelial cells. Results obtained were compared with three commercial probiotic Lactobacillus rhamnosus GG, L. plantarum 299v, and L. johnsonii NCC533. The five strains most efficient according to these activities were subsequently identified by sequencing their 16S rRNA gene, their susceptibility to antibiotics was determined, and their safety evaluated in mice. One strain of L. plantarum was discarded due to the higher prevalence of liver bacterial translocation observed in the animals fed this strain. In conclusion, four autochthonous strains of L. rhamnosus were finally selected with probiotic properties and safety allowing their eventual use in human studies. These results contribute to increase the diversity of probiotic strains available for the development of nutraceuticals and functional foods.

Use of pyrogallol red and pyranine as probes to evaluate antioxidant capacities towards hypochlorite.

Hypochlorite is a strong oxidant able to induce deleterious effects in biological systems. The goal of this work was to investigate the use of PGR and PYR as probes in assays aimed at evaluating antioxidant activities towards hypochorite and apply it to plant extracts employed in Chilean folk medicine. The consumption of PGR and PYR was evaluated from the decrease in the visible absorbance and fluorescence intensity, respectively. Total phenolic content was determined by the Folin Ciocalteau assay. PGR and PYR react with hypochlorite with different kinetics, being considerably faster the consumption of PGR. Different stoichiometric values were also determined: 0.7 molecules of PGR and 0.33 molecules of PYR were bleached per each molecule of added hypochlorite. Both probes were protected by antioxidants, but the rate of PGR bleaching was too fast to perform a kinetic analysis. For PYR, the protection took place without changes in its initial consumption rate, suggesting a competition between the dye and the antioxidant for hypochlorite. Plant extracts protected PYR giving a PYR-HOCl index that follows the order: Fuchsia magellanica ≈ Marrubium vulgare ≈ Tagetes minuta > Chenopodium ambrosoides ≈ Satureja montana > Thymus praecox. Based on both the kinetic data and the protection afforded by pure antioxidants, we selected PYR as the best probe. The proposed methodology allows evaluating an antioxidant capacity index of plant extracts related to the reactivity of the samples towards hypochlorite.

Inhibition of mitochondrial complex I by various non-steroidal anti-inflammatory drugs and its protection by quercetin via a coenzyme Q-like action.

Mitochondrial dysfunction plays a major role in the development of oxidative stress and cytotoxicity induced by non-steroidal anti-inflammatory drugs (NSAIDs). A major objective of the present study was to investigate whether in vitro the NSAIDs, aspirin, indomethacin, diclofenac, piroxicam and ibuprofen, which feature different chemical structures, are able to inhibit mitochondrial complex I. All NSAIDs were effective inhibitors when added both, directly to mitochondria isolated from rat duodenum epithelium (50 µM) or to Caco-2 cells (250 µM). In the former system, complex I inhibition was concentration-dependent and susceptible to competition and reversion by the addition of coenzyme Q (32.5-520 µM). Based on reports suggesting a potential gastro-protective activity of quercetin, the ability of this flavonoid to protect isolated mitochondria against NSAIDs-induced complex I inhibition was evaluated. Low micromolar concentrations of quercetin (1-20 µM) protected against such inhibition, in a concentration dependent manner. In the case of aspirin, quercetin (5 µM) increased the IC50 by 10-fold. In addition, the present study shows that quercetin (5-10 µM) can behave as a "coenzyme Q-mimetic" molecule, allowing a normal electron flow along the whole electron transporting chain (complexes I, II, III and IV). The exposed findings reveal that complex I inhibition is a common deleterious effect of NSAIDs at the mitochondrial level, and that such effect is, for all tested agents, susceptible to be prevented by quercetin. Data provided here supports the contention that the protective action of quercetin resides on its, here for first time-shown, ability to behave as a coenzyme Q-like molecule.

Differential protective effects of quercetin, resveratrol, rutin and epigallocatechin gallate against mitochondrial dysfunction induced by indomethacin in Caco-2 cells.

The beneficial effects of dietary polyphenols on health are due not only to their antioxidant properties but also to their antibacterial, anti-inflammatory and/or anti-tumoral activities. It has recently been proposed that protection of mitochondrial function (which is altered in several diseases such as Alzheimer, Parkinson, obesity and diabetes) by these compounds, may be important in explaining the beneficial effects of polyphenols on health. The aim of this study was to evaluate the protective effects of dietary polyphenols quercetin, rutin, resveratrol and epigallocatechin gallate against the alterations of mitochondrial function induced by indomethacin (INDO) in intestinal epithelial Caco-2 cells, and to address the mechanism involved in such damaging effect by INDO, which generates oxidative stress. INDO concentration dependently decreases cellular ATP levels and mitochondrial membrane potential in Caco-2 cells after 20min of incubation. INDO also inhibits the activity of mitochondrial complex I and causes accumulation of NADH; leading to overproduction of mitochondrial O(2)()(-), since it is prevented by pyruvate. Quercetin (0.01mg/ml), resveratrol (0.1mg/ml) and rutin (1mg/ml) protected Caco-2 cells against INDO-induced mitochondrial dysfunction, while no protection was observed with epigallocatechin gallate. Quercetin was the most efficient in protecting against mitochondrial dysfunction; this could be due to its ability to enter cells and accumulate in mitochondria. Additionally its structural similarity with rotenone could favor its binding to the ubiquinone site of complex I, protecting it from inhibitors such as INDO or rotenone. These findings suggest a possible new protective role for dietary polyphenols for mitochondria, complementary of their antioxidant property. This new role might expand the preventive and/or therapeutic use of PPs in conditions involving mitochondrial dysfunction and associated with increased oxidative stress at the cellular or tissue levels.

Application of a microplate-based ORAC-pyrogallol red assay for the estimation ofantioxidant capacity: First Action 2012.03.

A method was developed for microplate-based oxygen radicals absorbance capacity (ORAC) using pyrogallol red (PGR) as probe (ORAC-PGR). The method was evaluated for linearity, precision, and accuracy. In addition, the antioxidant capacity of commercial beverages, such as wines, fruit juices, and iced teas, was measured. Linearity of the area under the curve (AUC) versus Trolox concentration plots was [AUC = (845 +/- 110) + (23 +/- 2) [Trolox, microM]; R = 0.9961, n = 19]. Analyses showed better precision and accuracy at the highest Trolox concentration (40 microM) with RSD and recovery (REC) values of 1.7 and 101.0%, respectively. The method also showed good linearity for red wine [AUC = (787 +/- 77) + (690 +/- 60) [red wine, microL/mL]; R = 0.9926, n = 17], precision and accuracy with RSD values from 1.4 to 8.3%, and REC values that ranged from 89.7 to 103.8%. Red wines showed higher ORAC-PGR values than white wines, while the ORAC-PGR index of fruit juices and iced teas presented a wide range of results, from 0.6 to 21.6 mM of Trolox equivalents. Product-to-product variability was also observed for juices of the same fruit, showing the differences between brands on the ORAC-PGR index.

Development of an ingredient containing apple peel, as a source of polyphenols and dietary fiber.

Apple peel is a waste product from dried apple manufacture. The content of phenolic compounds, dietary fiber, and mineral are higher in apple peel, compared to other edible parts of this fruits. The objective of this study was to develop an ingredient from Granny Smith apple peel, using a pilot scale double drum-dryer, as drying technology. The control of all steps to maximize the retention of phenolic compounds and dietary fiber was considered. Operational conditions, such as drying temperature and time were determined, as well as important preprocessing steps like grinding and PPO inhibition. In addition, the physical-chemical characteristics, mineral and sugar content, and technological functional properties such as water retention capacity, solubility index, and dispersability among others, were analyzed. A simple, economical, and suitable pilot scale process, to produce a powder ingredient from apple peel by-product, was obtained. The drying process includes the application of ascorbic acid at 0.5% in the fresh apple peel slurry, drum-dryer operational conditions were 110 degrees C, 0.15 rpm and 0.2 mm drum clearance. The ingredient developed could be considered as a source of phenolic compounds (38.6 mg gallic acid equivalent/g dry base) and dietary fiber (39.7% dry base) in the formulation of foods. Practical Application: A method to develop an ingredient from Granny Smith apple peel using a pilot scale double drum-dryer as drying technology was developed. The method is simple, economical, feasible, and suitable and maximizes the retention of phenolic compounds and dietary fiber present in the raw matter. The ingredient could be used in the formulation of foods.

Protection by apple peel polyphenols against indometacin-induced oxidative stress, mitochondrial damage and cytotoxicity in Caco-2 cells.

OBJECTIVES: Exposure of Caco-2 cells to indometacin can be a useful model to assess some of the cytotoxic events that appear to underlie the gastrointestinal lesions associated with the use of this anti-inflammatory agent. Using such a cellular model, we addressed here the cytoprotective potential of a recently standardized apple peel polyphenol extract, APPE. METHODS: We firstly characterized APPE in terms of its free radical scavenging and antioxidant properties, and subsequently investigated its potential to protect Caco-2 cells against the deleterious effects of indometacin on cellular oxidative status (redox state, malondialdehyde, glutathione (GSH) and oxidized glutathione (GSSG) levels), mitochondrial function (ATP and mitochondrial membrane potential) and cell viability (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction and lactate dehydrogenase (LDH) leakage). For comparative purposes, the free radical scavenging properties and reducing capacity of quercetin, epicatechin and rutin were also estimated. KEY FINDINGS: In the absence of APPE, indometacin induced mitochondrial perturbations (reducing ATP and the mitochondrial membrane potential), enhanced the oxidative status (decreasing the GSH/GSSG ratio and increasing dichlorofluorescein oxidation and malondialdehyde) and lowered the cell viability (decreasing MTT reduction and increasing LDH leakage). APPE, whether pre-added or co-incubated with indometacin, concentration-dependently prevented these mitochondrial, oxidative and cell viability alterations. Prompted by the recently recognized ability of indometacin to enhance the mitochondrial formation of reactive oxygen species, APPE was also characterized in terms of its free radical-scavenging capacity. APPE was found to actively scavenge O(2).(-), HO. and peroxyl radicals. Such free radical-scavenging activity of APPE suggests that its ability to protect mitochondria and prevent the oxidative and lytic damage induced by indometacin arises from its potent antioxidant capacity. CONCLUSIONS: In Caco-2 cells APPE prevented mitochondrial oxidative and cell viability alterations induced by indometacin possibly through its ability to scavenge reactive oxygen species. These findings are of interest in view of the high prevalence of gastrointestinal side-effects associated with the use of conventional anti-inflammatory agents.

In vitro inhibitory effect of apple peel extract on the growth of Helicobacter pylori and respiratory burst induced on human neutrophils.

In the present work, the in vitro effect of a standardized extract of apple peel APPE (60% of total polyphenols; 58% of flavonoids; 30% of flavan-3-ols and procyanidins) was evaluated with regard to the viability of Helicobacter pylori. The cytotoxic effect of APPE on H. pylori was also evaluated through the resazurin assay and ATP level determination. In both assays, APPE showed an early cytotoxic effect, which was both concentration and time-dependent. Additionally, the effect of APPE on the intra and extracellular production of reactive oxygen species (ROS) was evaluated in human neutrophils stimulated by H. pylori, phorbol myristate acetate (PMA), and formyl-methionyl-leucyl-phenylalanine (fMLP). The extracellular and intracellular production of ROS was evaluated through chemiluminiscence with the isoluminol-horseradish peroxidase (HRP) and luminol-superoxide dismutase (SOD)-catalase systems, respectively. APPE showed an inhibiting effect on the multiplication of two H. pylori strains (ATCC 43504 and TX136) with a miminnum inhibitory concentration (MIC) value of 112.5 microg gallic acid equivalent (GAE)/mL. APPE inhibited the respiratory burst of neutrophils induced by H. pylori, PMA, and fMLP in concentration-dependent form. Interestingly, this effect was observed on both the interior and exterior of the neutrophil. This result suggests that apple peel polyphenols have an attenuating effect on the damage to gastric mucosa caused by neutrophil generated ROS and, particularly, when H. pylori displays its evasion mechanisms.

Association between polymerization degree of apple peel polyphenols and inhibition of Helicobacter pylori urease.

Apple peel extracts and their fractions pooled according to their molecular size were prepared and evaluated for their inhibitory activity against Helicobacter pylori and Jack bean ureases. Urease Inhibitory effect of apple peel polyphenols (APPE) extracted from the Granny Smith variety was concentration-dependent and reversible. High molecular weight polyphenols (HMW) were more active against Helicobacter pylori and Jack bean ureases than low molecular weight polyphenols with IC50 values of 119 and 800 microg GAE/mL, respectively. The results suggest that monomeric compounds (mainly flavan-3-ols-and quercetin-O-glycosides) will not be implicated in the antiurease effect displayed by the apple peel polyphenolic extract. Thus, as a byproduct, apple peel is suitable for developing functional ingredients that could be useful for neutralizing an important Helicobacter pylori colonization factor.

Antioxidant screening of medicinal herbal teas.

Herbal tea consumption is deeply and widely rooted amongst South-American populations. In view of the involvement of oxygen- and nitrogen-reactive species in the ethiogenesis of several diseases, the antioxidant properties of some of the herbal teas most commonly consumed in the southern regions was assessed in vitro. Around one-third of the 13 examined herbs, displayed a substantially higher ability to scavenge ABTS(+.) radicals (TEAC assay), and to quench the pro-oxidant species, hypochlorite (HClO) and peroxynitrite (ONOO(-)). Amongst the tested herbs, teas prepared from Haplopappus baylahuen, Rosa moschata and Peumus boldus showed the highest TEAC and HClO-quenching activities. These herbs were around 5- to 7-fold more potent than the least active herbs. Based on the TEAC assay, 150 mL of tea prepared from H. baylahuen, R. moschata and P. boldus would be equivalent to around 200 mg of Trolox). Teas from H. baylahuen and P. boldus were also found to be particularly potent in quenching HClO. In the ONOO(-) assay, H. baylahuen and Buddleia globosa showed the highest activities. The results obtained suggest that the regular consumption of teas prepared from some of these herbs may be useful potentially to provide the organism with molecules capable of protecting the gastrointestinal tract against certain pathologically relevant oxidant species.

Boldine and its antioxidant or health-promoting properties.

The increasing recognition of the participation of free radical-mediated oxidative events in the initiation and/or progression of cardiovascular, tumoural, inflammatory and neurodegenerative disorders, has given rise to the search for new antioxidant molecules. An important source of such molecules has been plants for which there is an ethno-cultural base for health promotion. An important example of this is boldo (Peumus boldus Mol.), a chilean tree whose leaves have been traditionally employed in folk medicine and is now widely recognized as a herbal remedy by a number of pharmacopoeias. Boldo leaves are rich in several aporphine-like alkaloids, of which boldine is the most abundant one. Research conducted during the early 1990s led to the discovery that boldine is one of the most potent natural antioxidants. Prompted by the latter, a large and increasing number of studies emerged, which have focused on characterizing some of the pharmacological properties that may arise from the free radical-scavenging properties of boldine. The present review attempts to exhaustively cover and discuss such studies, placing particular attention on research conducted during the last decade. Mechanistic aspects and structure-activity data are discussed. The review encompasses pharmacological actions, which arise from its antioxidant properties (e.g., cyto-protective, anti-tumour promoting, anti-inflammatory, anti-diabetic and anti-atherogenic actions), as well as those that do not seem to be associated with such activity (e.g., vasorelaxing, anti-trypanocidal, immuno- and neuro-modulator, cholagogic and/or choleretic actions). Based on the pharmacological and toxicological data now available, further research needs and recommendations are suggested to define the actual potential of boldine for its use in humans.

Effects of some antioxidative aporphine derivatives on striatal dopaminergic transmission and on MPTP-induced striatal dopamine depletion in B6CBA mice.

(S)-(+)-boldine, an aporphine alkaloid displaying antioxidative and dopaminergic properties, and six of its derivatives (glaucine, 3-bromoboldine, 3-iodoboldine, 8-aminoboldine, 8-nitrosoboldine and 2,9-O,O'-dipivaloylboldine) were tested for these properties in comparison with their parent compound. All the tested compounds displayed in vitro antioxidative properties equal to or slightly weaker than those of boldine, and equal to or stronger than (+/-)-6-hydroxy-2,5,7,8,-tetramethylchromane-2-carboxylic acid (Trolox), a water-soluble vitamin E analogue, used as a reference compound. All the aporphine compounds tested displaced [3H]SCH 23390 and [3H]raclopride from their specific binding sites in rat striatum. When tested on dopamine (DA) metabolism in the striatum of B6CBA mice, all the compounds, except 8-aminoboldine, increased striatal levels of DOPAC and HVA, and the HVA/DA ratio, indicating that they cross the blood-brain barrier and that they seem to act as dopamine antagonists in vivo. B6CBA mice were sensitive to the neurotoxic action of MPTP on dopaminergic neurons as indicated by the strongly decreased striatal levels of DA, DOPAC and HVA following administration of MPTP (20 mg/kg, i.p.). Among these aporphine derivatives, only 3-bromoboldine was able to reduce the MPTP-induced decrease of striatal levels of DA and DOPAC, whereas (R)-apomorphine (5 mg/kg, s.c.) and acetylsalicylic acid (100 mg/kg, i.p.), used as reference compounds, were very active. These data suggest that potent in vitro antioxidative properties and the ability to cross the blood-brain barrier are not sufficient criteria to predict the inhibition of neuronal degeneration induced by MPTP.