Isotopic signatures reveal zinc cycling in the natural habitat of hyperaccumulator Dichapetalum gelonioides subspecies from Malaysian Borneo.

BACKGROUND: Some subspecies of Dichapetalum gelonioides are the only tropical woody zinc (Zn)-hyperaccumulator plants described so far and the first Zn hyperaccumulators identified to occur exclusively on non-Zn enriched 'normal' soils. The aim of this study was to investigate Zn cycling in the parent rock-soil-plant interface in the native habitats of hyperaccumulating Dichapetalum gelonioides subspecies (subsp. pilosum and subsp. sumatranum). We measured the Zn isotope ratios (δ66Zn) of Dichapetalum plant material, and associated soil and parent rock materials collected from Sabah (Malaysian Borneo). RESULTS: We found enrichment in heavy Zn isotopes in the topsoil (δ66Zn 0.13 ‰) relative to deep soil (δ66Zn -0.15 ‰) and bedrock (δ66Zn -0.90 ‰). This finding suggests that both weathering and organic matter influenced the Zn isotope pattern in the soil-plant system, with leaf litter cycling contributing significantly to enriched heavier Zn in topsoil. Within the plant, the roots were enriched in heavy Zn isotopes (δ66Zn ~ 0.60 ‰) compared to mature leaves (δ66Zn ~ 0.30 ‰), which suggests highly expressed membrane transporters in these Dichapetalum subspecies preferentially transporting lighter Zn isotopes during root-to-shoot translocation. The shoots, mature leaves and phloem tissues were enriched in heavy Zn isotopes (δ66Zn 0.34-0.70 ‰) relative to young leaves (δ66Zn 0.25 ‰). Thisindicates that phloem sources are enriched in heavy Zn isotopes relative to phloem sinks, likely because of apoplastic retention and compartmentalization in the Dichapetalum subspecies. CONCLUSIONS: The findings of this study reveal Zn cycling in the rock-soil-plant continuum within the natural habitat of Zn hyperaccumulating subspecies of Dichapetalum gelonioides from Malaysian Borneo. This study broadens our understanding of the role of a tropical woody Zn hyperaccumulator plant in local Zn cycling, and highlights the important role of leaf litter recycling in the topsoil Zn budget. Within the plant, phloem plays key role in Zn accumulation and redistribution during growth and development. This study provides an improved understanding of the fate and behaviour of Zn in hyperaccumulator soil-plant systems, and these insights may be applied in the biofortification of crops with Zn.

Acerola (Malpighia glabra L.) and guava (Psidium guayaba L.) industrial processing by-products stimulate probiotic Lactobacillus and Bifidobacterium growth and induce beneficial changes in colonic microbiota.

AIMS: This study evaluated whether by-products from industrial processing of acerola (Malpighia glabra L.; AB) and guava (Psidium guajava L.; GB) fruit may stimulate the growth and metabolism of probiotic Lactobacillus and Bifidobacterium and induce changes in human colonic microbiota. METHODS AND RESULTS: The ability of non-digested and digested AB or GB to stimulate the growth ad metabolism of Lactobacillus acidophilus LA-05, Lactobacillus casei L-26 and Bifidobacterium animalis subsp. lactis BB-12 was evaluated. Changes in populations of distinct bacterial groups of human colonic microbiota induced by digested AB and GB were evaluated using an in vitro colonic fermentation system. Non-digested and digested AB and GB favoured probiotic growth. No difference among counts of probiotics in media with glucose, fructooligosaccharides and non-digested and digested AB and GB was found during a 48-h cultivation. Cultivation of probiotics in media with non-digested and digested AB and GB resulted in decreased pH, increased organic acid production and sugar consumption over time. Digested AB and GB caused overall beneficial changes in abundance of Bifidobacterium spp., Lactobacillus-Enterococcus, Eubacterium rectall-Clostridium coccoides and Bacteroides-Provotella populations, besides to decrease the pH and increase the short-chain fatty acid production during a 24-h in vitro colonic fermentation. CONCLUSION: AB and GB could be novel prebiotic ingredients because they can stimulate the growth and metabolism of probiotics and induce overall beneficial changes in human colonic microbiota. SIGNIFICANCE AND IMPACT OF THE STUDY: AB and GB stimulated the growth and metabolism of probiotics, in addition to induce beneficial alterations in human colonic microbiota composition and increase short-chain fatty acid production. These results characterize AB and GB as potential prebiotic ingredients and fruit processing by-products as sources of added-value compounds.

UVC light modulates vitamin C and phenolic biosynthesis in acerola fruit: role of increased mitochondria activity and ROS production.

The effects of ultraviolet-C light (UVC) on vitamin C and phenolic compounds in acerola during postharvest storage were investigated in order to elucidate the mechanism inducing the antioxidant systems. The fruits, stored at 10 °C for 7 days after a hormetic UVC irradiation (two pulses of 0.3 J/cm2), showed significantly less degradation of vitamin C and phenolic compounds than the control without the UVC challenge. UVC activated the L-galactono-1,4-lactone dehydrogenase (GalDH), a key enzyme for vitamin C biosynthesis, and altered the composition of phenolic compounds, through phenolic biosynthesis, in acerola during postharvest storage. UVC also induced reactive oxygen species (ROS) productions at immediate (day 0) and late (day 7) times during postharvest storage through the mitochondrial electron transport chain and NADPH oxidase, respectively. Results suggest that UVC helps in the retention of vitamin C and phenolic content in acerola by altering ascorbic acid and phenolic metabolism through an increase in mitochondrial activity and a ROS-mediated mechanism. Data showed the beneficial effects of UVC on maintenance of nutraceutical quality in acerola during postharvest storage and supplied new insights into understanding the mechanism by which UVC irradiation enhance the antioxidant system in fruits.

Secondary metabolites from acridocarpus orientalis inhibits 4T1 cells and promotes mesenchymal stem cells (MSCs) proliferation.

Among medicinal plants, Acridocarpus orientalis (AO) possesses a remarkable anti-cancer potential, possibly because of its anti-oxidant property. In this study, the leaf and stem extracts from AO were assessed to find the bioactive compound with selective anti-cancer properties. The MTT viability and live and dead assays revealed that around 80% and 98% of 4T1 cells survival were declined after 48 h incubation with leaf and stem extracts, respectively. The leaf extract increased stem cell proliferation by 20% whereas the stem extract inhibited around 22% of stem cells proliferation after 48 h treatment. The live and dead assay of MSCs confirmed that 40% of the MSCs died when treated with AO stem extract. On the other hand, there were no dead cells after two days of treatment with the leaf extract. Followed by the induction of cell cycle arrest in G0/G1-phase, the real-time PCR demonstrated apoptosis properties in 4T1 cells through overexpression of Bax and down-regulation of BCL2 genes. Interestingly, within the pure compounds isolated from AO leaf extract, Morin was responsible for the inhibition of 4T1 cells proliferation as well as MSCs expansion, predicting to play an essential role in the treatment of cancer. The promising in vitro anti-cancer and stem cell-inductive properties of morin isolated from AO extract may provide a great potential to produce selective herbal derived drugs.

Metabolomic analysis of acerola cherry (Malpighia emarginata) fruit during ripening development via UPLC-Q-TOF and contribution to the antioxidant activity.

Acerola cherry (Malpighia emarginata D.C.) is a tropical fruit of great economic and nutritional value due to its high content of vitamin C. However, there is little information available about which ripening stage of Acerola cherry can provide the best nutrients. In the current study, the chemical variation at two developmental stages (immature and mature) were investigated by metabolic profiling, and the biological properties of Acerola cherry and its antioxidant assays at four developmental stages were measured, respectively. Through comprehensive metabolites analysis via ultra-high-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry system (UPLC-QTOF), 1896 annotated metabolite features were obtained, and 133 metabolites were finally identified according to the MS/MS fragments compared with these standards in in-house database. Statistically differences in the levels of amino acids, flavonoids, lipids, terpenoids and ascorbic acids were found between mature and immature fruits. Interestingly, most of differential accumulated amino acids, flavonoids, lipids, and terpenoids predominantly accumulated in the mature fruits and ascorbic acid predominantly accumulated in the immature fruits. On the other hand, their antioxidant activities were compared. The alcoholic extract of immature acerola fruit possessed better scavenging ability of DPPH and ABTS than the mature one. The well correlations were found between the antioxidant potential with its content of ascorbic acid (r = 0.9803 and 0.9897, respectively). In conclusion, Acerola cherry showed very different metabolite profile and antioxidant activities during the fruit ripening development. The maturity of Acerola cherry has to be considered when it is being used for health food products.

Malagasy Dye Plant Species: A Promising Source of Novel Natural Colorants with Potential Applications - A Review.

Due to the potentially harmful effects of some synthetic dyes, there is an increasing demand for natural colorants. Recent literature has emphasized the necessity of investigating new sources of dyes. This review discusses the biological sources of dyes derived from the rich plant diversity of Madagascar. As one of the first contributions on the use of these dyestuffs for dyeing textiles, it provides an overview of 128 dye plant species with other potential applications for coloring materials in industry. A detailed description of the botanical and chemical properties of these dyestuffs is given. We believe that the Madagascar plant diversity may be a promising source of novel colorants not yet investigated. We considered it worthwhile to carry out a thorough scientific study of a set of Malagasy plants carefully selected for their coloring properties together with their potential use and valorization in specialized industries where use of natural colorants would be a particular interest.

Transcriptome analysis of acerola fruit ripening: insights into ascorbate, ethylene, respiration, and softening metabolisms.

KEY MESSAGE: The first transcriptome coupled to metabolite analyses reveals major trends during acerola fruit ripening and shed lights on ascorbate, ethylene signalling, cellular respiration, sugar accumulation, and softening key regulatory genes. Acerola is a fast growing and ripening fruit that exhibits high amounts of ascorbate. During ripening, the fruit experience high respiratory rates leading to ascorbate depletion and a quickly fragile and perishable state. Despite its growing economic importance, understanding of its developmental metabolism remains obscure due to the absence of genomic and transcriptomic data. We performed an acerola transcriptome sequencing that generated over 600 million reads, 40,830 contigs, and provided the annotation of 25,298 unique transcripts. Overall, this study revealed the main metabolic changes that occur in the acerola ripening. This transcriptional profile linked to metabolite measurements, allowed us to focus on ascorbate, ethylene, respiration, sugar, and firmness, the major metabolism indicators for acerola quality. Our results suggest a cooperative role of several genes involved in AsA biosynthesis (PMM, GMP1 and 3, GME1 and 2, GGP1 and 2), translocation (NAT3, 4, 6 and 6-like) and recycling (MDHAR2 and DHAR1) pathways for AsA accumulation in unripe fruits. Moreover, the association of metabolites with transcript profiles provided a comprehensive understanding of ethylene signalling, respiration, sugar accumulation and softening of acerola, shedding light on promising key regulatory genes. Overall, this study provides a foundation for further examination of the functional significance of these genes to improve fruit quality traits.

Raman spectroscopy for monitoring carotenoids in processed Bunchosia glandulifera pulps.

Raman spectroscopy is a rapid and non-destructive analytical technique that has found a growing interest in the characterization and quantification of microconstituents in foods. In this work, Raman spectroscopy was used to evaluate the carotenoids content of processed Bunchosia glandulifera, a native fruit from the Brazilian Atlantic Forest. The B. glandulifera pulps were dried in hot air at 65 and 85 °C, resulting in carotenoids degradation of about 75 and 80%, respectively. The degradation profile of carotenoids over time was analyzed by Raman spectroscopy, with and without the use of an internal standard (TiO2). The reproducibility of the analyses was evaluated by PCA of spectral data. PLS regression was applied for modelling the total carotenoids in B. glandulifera. Resulting models show the Raman data correlate with carotenoids content on samples resulting in a satisfactory coefficient of determination for all sets of samples.

High levels of expression of multiple enzymes in the Smirnoff-Wheeler pathway are important for high accumulation of ascorbic acid in acerola fruits.

Acerola fruits contain abundant ascorbic acid (AsA). The gene expression levels of three upstream enzymes in the primary AsA biosynthesis pathway were correlated with AsA contents in the fruits of two acerola cultivars. Multiple overexpression of the enzymes increased AsA contents, suggesting their high expression is important for high AsA accumulation in acerola fruits and the breeding of AsA-rich plants. Abbreviations: AsA: ascorbic acid; PMI: phosphomannose isomerase; PMM: phosphomannomutase; GMP: GDP-d-mannose pyrophosphorylase; GME: GDP-d-mannose 3',5'-epimerase; GGP: GDP-l-galactose phosphorylase; GPP: l-galactose-1-phosphate phosphatase; GDH: l-galactose dehydrogenase; GLDH: l-galactono-1,4-lactone dehydrogenase.

Important issues in plant tissues analyses by HR-MAS NMR.

INTRODUCTION: High-resolution magic-angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy enables the analysis of the metabolic profile of plant and animal tissues under close to natural conditions, as well as of other heterogeneous natural or synthetic materials. Neither sample pretreatment is required after fragmentation nor powdering of the sample before insertion into the rotor. However, the efficiency of the method depends strongly on the sample preparation, rotor insertion procedure, and analysis conditions. OBJECTIVE: To identify some of the variables that affect the spectral data and to propose solutions that minimise their impact on the quality of the analyses and results. METHODS: Dried plant tissues were powdered, weighed, and homogenised in a 50 µL rotor with an optimised volume of deuterated solvent and sample in order to prevent material from escaping during spacer insertion, avoiding variations in magnetic susceptibility. Factors affecting the quality of HR-MAS NMR analysis such as particle size, sample and solvent amounts, solvent polarity, swelling time, rotor manipulation and pulse sequence setting were evaluated. RESULTS: A strong correlation was observed between the signal area and the particle size of the powdered sample. The spectral profile varied depending on the deuterated solvent used. An incubation period was necessary to achieve adequate swelling of the sample and to ensure good data reproducibility. Proper sealing of the rotor, number of cycles and τ time on cpmgpr1d pulse sequence were found to affect the signal areas. CONCLUSION: The study highlights the need for standardised sample preparation and instrumental setup protocols in order to achieve high reproducibility and obtain reliable data from HR-MAS NMR analyses.

Using natural deep eutectic solvents for the extraction of metabolites in Byrsonima intermedia leaves.

Natural deep eutectic solvents have been used as an alternative to organic solvents for the extraction of plants metabolites, allowing for the extraction of compounds of different polarities, while being inexpensive, non-toxic, and easy to prepare. This work presents the comparison of the chromatographic profiles by high-performance liquid chromatography with diode-array detection obtained from Byrsonima intermedia (Malpighiaceae) using five choline chloride-based natural deep eutectic solvents, in addition to the most used traditional extraction solvents, methanol/water 7:3 and ethanol/water 7:3 v/v. A reference extract was used to tentatively identify compounds by high-performance liquid chromatography with tandem mass spectrometry. The water content appeared to be important for the extraction efficiency and the mixture choline chloride/glycerol was shown to be the best candidate for efficiently extracting this matrix when compared with the traditional extraction media in addition to being far greener as shown by the environmental analysis tool. Seven phenolic compounds (digalloyl quinic acid, proanthocyanidin dimer, galloylproanthocyanidin dimer, quercetin-O-hexoside, galloyl quercetin hexoside, quercetin-O-pentoside, and galloyl quercetin pentoside) were tentatively identified in all extracts. Moreover, the influence of these solvents on the antioxidant activity of the extracts was studied and the results for choline chloride/glycerol extracts were very similar to that of the traditional extraction solvents.

Comparison of the antioxidant property of acerola extracts with synthetic antioxidants using an in vivo method with yeasts.

In this study, we compared the antioxidant activity of ripe and unripe acerola extracts with synthetic antioxidants (BHA and BHT). This activity was assessed by classical approaches (DPPH and ABTS) and by an in vivo method using yeasts. Acerola extracts contain phenolic compounds and ascorbic acid that exhibit radical scavenger capacity and reducing power. The results obtained with yeasts revealed that the acerola extracts and BHT either acted as antioxidants or presented no activity depending on the nature of the oxidant molecule used. BHA decreased yeast resistance to oxidative treatments and also showed deleterious effects even when oxidative treatments were not applied. The unripe acerola was the most efficient antioxidant in the in vitro experiments but not necessarily in the in vivo assays, showing the weakness of in vitro systems in predicting antioxidant responses for biological purposes. BHA presented cell damaging effects even in the absence of oxidizing reagents.

Strategies of leaf water uptake based on anatomical traits.

The ability of leaves to absorb fog water can positively contribute to the water and carbon balance of plants in montane ecosystems, especially in periods of soil water deficit. However, the ecophysiological traits and mechanisms responsible for variations in the speed and total water absorption capacity of leaves are still poorly known. This study investigated leaf anatomical attributes of seven species occurring in seasonal tropical high-altitude ecosystems (rocky outcrop and forest), which could explain differences in leaf water uptake (LWU) capacities. We tested the hypothesis that different sets of anatomical leaf attributes will be more marked in plant individuals living under these contrasting environmental conditions. Anatomical variations will affect the initial rate of water absorption and the total storage capacity, resulting in different strategies for using the water supplied by fog events. Water absorption by leaves was inferred indirectly, based on leaf anatomical structure and visual observation of the main access routes (using an apoplastic marker), the diffusion of water through the cuticle, and non-glandular or glandular trichomes in all species. The results suggest that three LWU strategies coexist in the species studied. The different anatomical patterns influenced the speed and maximum LWU capacity. The three LWU strategies can provide different adaptive advantages to adjust to temporal and spatial variations of water availability in these tropical high-altitude environments.

Structure of the stigma and style of Callaeum psilophyllum (Malpighiaceae) and its relation with potential pollinators.

The family Malpighiaceae, particularly in the Neotropic, shows a similar floral morphology. Although floral attraction and rewards to pollinators are alike, stigmas and styles show more diversity. The stigmas were described covered with a thin and impermeable cuticle that needs to be ruptured by the mechanical action of the pollinators. However, this characteristic was only mentioned for a few species and the anatomy and ultrastructure of the stigmas were not explored. In this work, we analyze the morphology, anatomy, and ultrastructure of the stigma and style of Callaeum psilophyllum. Moreover, we identify the potential pollinators in order to evaluate how the disposition of the stigmas is related with their size and its role in the exposure of the receptive stigmatic surface. Our observations indicate that Centris flavifrons, C. fuscata, C. tarsata, and C. trigonoides are probably efficient pollinators of C. psilophyllum. The three stigmas are covered by a cuticle that remained intact in bagged flowers. The flowers exposed to visitors show the cuticle broken, more secretion in the intercellular spaces between sub-stigmatic cells and abundant electron-dense components inside vacuoles in stigmatic papillae. This indicates that the stigmas prepares in similar ways to receive pollen grains, but the pollinator action is required to break the cuticle, and once pollen tubes start growing, stigmatic and sub-stigmatic cells release more secretion by a granulocrine process.

Effects of Acerola (Malpighia emarginata DC.) Juice Intake on Brain Energy Metabolism of Mice Fed a Cafeteria Diet.

Obesity is a multifactorial disease that comes from an imbalance between food intake and energy expenditure. Moreover, studies have shown a relationship between mitochondrial dysfunction and obesity. In the present study, we investigated the effect of acerola juices (unripe, ripe, and industrial) and its main pharmacologically active components (vitamin C and rutin) on the activity of enzymes of energy metabolism in the brain of mice fed a palatable cafeteria diet. Two groups of male Swiss mice were fed on a standard diet (STA) or a cafeteria diet (CAF) for 13 weeks. Afterwards, the CAF-fed animals were divided into six subgroups, each of which received a different supplement for one further month (water, unripe, ripe or industrial acerola juices, vitamin C, or rutin) by gavage. Our results demonstrated that CAF diet inhibited the activity of citrate synthase in the prefrontal cortex, hippocampus, and hypothalamus. Moreover, CAF diet decreased the complex I activity in the hypothalamus, complex II in the prefrontal cortex, complex II-III in the hypothalamus, and complex IV in the posterior cortex and striatum. The activity of succinate dehydrogenase and creatine kinase was not altered by the CAF diet. However, unripe acerola juice reversed the inhibition of the citrate synthase activity in the prefrontal cortex and hypothalamus. Ripe acerola juice reversed the inhibition of citrate synthase in the hypothalamus. The industrial acerola juice reversed the inhibition of complex I activity in the hypothalamus. The other changes were not reversed by any of the tested substances. In conclusion, we suggest that alterations in energy metabolism caused by obesity can be partially reversed by ripe, unripe, and industrial acerola juice.

Characterisation of the FAD2 gene family from Hiptage benghalensis: a ricinoleic acid accumulating plant.

We have characterised the FAD2 gene family from Hiptage benghalensis, a tropical plant that accumulates high levels of ricinoleic acid in its seeds. Functional characterisation of six FAD2 gene family members showed that two of them were capable of functioning as Δ12-hydroxylases while the other FAD2 members were confirmed to be Δ12-desaturases. The Δ12-hydroxylation function of these two genes was confirmed in yeast cells, using C16:1(Δ9) and C18:1(Δ9) monounsaturated fatty acids as substrates. These Δ12-hydroxylases, like the other Δ12-hydroxylases previously cloned from plants Ricinus communis (castor), Physaria fendleri and fungus Claviceps purpurea, also showed some Δ12-desaturase activity. The hydroxylation activity of the two Hiptage hydroxylases was further confirmed by their expression in the Arabidopsis fad2/fae1 double mutant where they were able to produce equivalent or higher levels hydroxylated fatty acids in the seed oil when compared with the other known hydroxylases.

A comparative study of aluminium and nutrient concentrations in mistletoes on aluminium-accumulating and non-accumulating hosts.

Mistletoes offer a unique model to study interactions among Al and nutrients in vascular plants, because they grow and reproduce on hosts with distinct Al uptake strategies. We investigated Al distribution and nutrient relations of mistletoes on Al-accumulating and non-accumulating hosts. We hypothesised that mistletoes would exhibit similar leaf nutrient and Al concentrations as their host plants, but a strong compartmentalisation of Al when growing on Al-accumulators. We measured concentrations of N, P, K, Ca, Mg, Cu, Fe, Mn, Zn in leaves and Al in leaves, seeds and branches of Phthirusa ovata and Psittacanthus robustus infecting Miconia albicans, an Al-accumulator, and Ph. ovata infecting Byrsonima verbascifolia, a non-Al-accumulator. High leaf concentrations of Al in Ph. ovata only occurred while parasitizing the Al-accumulating host; there was no accumulation in branches or seeds. In P. robustus, large concentrations of Al were found in leaves, branches and seeds. Mistletoe seed viability and leaf nutrient concentrations were not affected by Al accumulation. Passive uptake of Al, Ca, Mg, Mn and Cu in mistletoes was evidenced by significant correlations between mistletoes and host leaf concentrations, but not of N, P and K. Al was retranslocated to different plant organs in P. robustus, whereas it was mostly restricted to leaves in Ph. ovata. We suggest that Al might have some specific function in P. robustus, which only parasitizes Al-accumulator hosts, while the host generalist Ph. ovata can be considered a facultative Al-accumulator.

Cytotoxic and mutagenic effects of iodine-131 and radioprotection of acerola (Malpighia glabra L.) and beta-carotene in vitro.

The radioisotope iodine-131 [(131)I] can damage DNA. One way to prevent this is to increase the amount of antioxidants via dietary consumption. The goal of this study was to evaluate the radioprotective effect of fresh acerola pulp and synthetic beta-carotene in Rattus norvegicus hepatoma cells (HTC) in response to [(131)I] exposure in vitro. Cellular DNA damage was subsequently assessed using a cytokinesis block micronucleus assay. The mutagenic and cytotoxic activities of doses of [(131)I] (0.1, 0.5, 1, 5, and 10 µCi), acerola (0.025, 0.125, and 0.25 g acerola pulp/mL), and beta-carotene (0.2, 1, and 2 µM) were evaluated. Radioprotective tests were performed by simultaneous treatment with acerola (0.25 g/mL) plus [(131)I] (10 µCi) and beta-carotene (0.2 µM) plus [(131)I] (10 µCi). Acerola, beta-carotene, and low concentrations of [(131)I] did not induce micronucleus formation in HTC cells; in contrast, high concentrations of [(131)I] (10 µCi) were mutagenic and induced DNA damage. Moreover, neither acerola nor beta-carotene treatment was cytotoxic. However, acerola reduced the percentage of [(131)I]-induced damage, although beta-carotene did not show a similar effect. Thus, our results suggest that acerola diet supplementation may benefit patients who are exposed to [(131)I] during thyroid diagnostics and therapy.

Effect of Byrsonima crassa and phenolic constituents on Helicobacter pylori-induced neutrophils oxidative burst.

Byrsonima crassa Niedenzu (Malpighiaceae) is used in Brazilian folk medicine for the treatment of diseases related mainly to gastric ulcers. In a previous study, our group described the gastric protective effect of the methanolic extract from the leaves of B. crassa. The present study was carried out to investigate the effects of methanolic extract and its phenolic compounds on the respiratory burst of neutrophils stimulated by H. pylori using a luminol-based chemiluminescence assay as well as their anti-H. pylori activity. The suppressive activity on oxidative burst of H. pylori-stimulated neutrophils was in the order of methyl gallate > (+)-catechin > methanol extract > quercetin 3-O-α-l-arabinopyranoside > quercetin 3-O-ß-d-galactopyranoside > amentoflavone. Methyl gallate, compound that induced the highest suppressive activity with IC(50) value of 3.4 µg/mL, did not show anti-H. pylori activity. B. crassa could be considered as a potential source of natural antioxidant in gastric ulcers by attenuating the effects on the damage to gastric mucosa caused by neutrophil generated reactive oxygen species, even when H. pylori displays its evasion mechanisms.

Gene expression of monodehydroascorbate reductase and dehydroascorbate reductase during fruit ripening and in response to environmental stresses in acerola (Malpighia glabra).

Acerola (Malpighia glabra) is an exotic fruit cultivated primarily for its abundant ascorbic acid (AsA) content. The molecular mechanisms that regulate the metabolism of AsA in acerola have yet to be defined. Monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) are key enzymes of the ascorbate-glutathione cycle that maintain reduced pools of ascorbic acid and serve as important antioxidants. cDNAs encoding MDHAR and DHAR were isolated from acerola using RT-PCR and RACE. Phylogenetic trees associated acerola MDHAR and DHAR with other plant cytosolic MDHARs and DHARs. Expressions of the two genes correlated with their enzymatic activities and were differentially regulated during fruit ripening. Interestingly, MDHAR expression was only detected in overripe fruits, whereas the transcript level of DHAR was highest at the intermediate stage of fruit ripening. Under dark conditions, there was a sharp and significant decline in the total and reduced ascorbate contents, accompanied by a decrease in the level of transcripts and enzyme activities of the two genes in acerola leaves. MDHAR and DHAR transcripts and enzyme activities were significantly up-regulated in the leaves of acerola under cold and salt stress conditions, indicating that expression of both genes are transcriptionally regulated under these stresses.