Constituintes químicos e atividade antioxidante de folhas e galhos de Eugenia copacabanensis Kiaersk (Myrtaceae)

Phytochemical investigation of Eugenia copacabanensis allowed for the isolation and identification of following compounds: β-sitosterol, β-sitosterol-glucoside, eight triterpenes, (mixture of α- and β-amyrins, ursolic acid, 30-hydroxy-ursolic acid, betulin, friedelin, friedelan-3,4-lactone, and taraxerol), a mixture of three sesquiterpenes, (clovandiol, globulol, and viridiflorol), three flavonoids (kaempferol-3-O-β-D-rhamnoside, quercetin-3-O-α-L-arabinoside, and quercetin), and a mixture of four coumaroyl esters (octacosanyl, heptacosanyl, hexacosanyl, and tetracosanyl coumarates). The structures of these compounds were assigned based on comparison with literature data and spectroscopic analysis, including analysis by two-dimensional NMR techniques. Total phenolic content and total flavonoids were evaluated. Antioxidant activities of methanol extracts and fractions were measured by the 1,2-diphenyl-2-picryl-hidrazyl free radical scavenging assay.

ENCAPSULAÇÃO DO ÁCIDO L-ASCÓRBICO NO BIOPOLÍMERO NATURAL GALACTOMANANA POR SPRAY‑DRYING: PREPARAÇÃO, CARACTERIZAÇÃO E ATIVIDADE ANTIOXIDANTE

AbstractIn this study, the spray drying technique was used to prepare L-ascorbic acid (AA) microparticles encapsulated with galactomannan-an extract from the seeds of the Delonix regia species. The physico-chemical characteristics, antioxidant activity, and encapsulation efficiency of the AA microparticles were evaluated and characterized using thermogravimetric analysis, differential scanning calorimetry, infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The free-radical scavenging activity of the AA microparticles was determined at different environmental conditions using DPPH (1,1-diphenyl-2-picryl-hydrazyl). X-ray diffraction measurements demonstrated a loss of crystallinity in AA after the encapsulation process, and a DSC scan also showed the loss of the compound's melting peak. Thermogravimetric analysis showed small differences in the thermal stability of galactomannan before and after the incorporation of AA. The mean diameters of the obtained spherical microspheres were in the range of 1.39 ± 0.77 µm. The encapsulation efficiency of AA microparticles in different environmental conditions varied from 95.40 to 97.92, and the antioxidant activity showed values ranging from 0.487 to 0.550 mg mL-1.

Determination of phenolic compounds and evaluation of antioxidant capacity of Campomanesia adamantium leaves

Five flavanones and three chalcones were isolated from Campomanesia adamantium Berg. (Myrtaceae) leaves. The contents of these compounds were determined by HPLC. The phenolic contents were also determined. The monitoring of the antioxidant activity was carried out by inhibition of peroxidation using the linoleic acid system and radical-scavenging (DPPH). The plants were collected from 4 distinct cities of the Mato Grosso do Sul State, Brazil. The different samples exhibited a range of 4.67-232.35 mg/g chalcones and 15.62-50.71 mg/g flavanones and phenolic contents of the 7.24-21.19 mg/g gallic acid. All extracts showed high antioxidant activity with a wide range of the radical-scavenging (DPPH) from 52.0 to 92.2 % and inhibition oxidation of linoleic acid from 14.6 to 94.2%.

Andean indigenous food crops: nutritional value and bioactive compounds

The Andean area of South America is a very important center for the domestication of food crops. This area is the botanical origin of potato, peanut and tomato. Less well- known crops, such as quinoa (Chenopodium quinoa), kañiwa (Chenopodium pallidicaule) and kiwicha (Amaranthus caudatus), were also domesticated by ancient Andean farmers. These crops have a long history of safe use with the local populations and they have contributed to the nutrition and wellbeing of the people for centuries. Several studies have reported the nutritional value of Andean grains. They contain proteins with a balanced essential amino acid composition that are of high biological value, good quality oil and essential minerals, for example iron, calcium and zinc. They are potential sources of bioactive compounds such as polyphenols and dietary fiber. The main objective of the practical work was to assess the nutritional value of Andean native grains with a special emphasis on the bioactive components and the impact of processing. The compounds studied were phenolic acids, flavonoids, betalains and dietary fiber. The radical scavenging activity was measured as well. Iron, calcium and zinc content and their bioavailability were analyzed as well. The grains were processed by extrusion with the aim to study the effect of processing on the chemical composition. Quinoa, kañiwa and kiwicha are very good sources of dietary fiber, especially of insoluble dietary fiber. The phenolic acid content in Andean crops was low compared with common cereals like wheat and rye, but was similar to levels found in oat, barley, corn and rice. The flavonoid content of quinoa and kañiwa was exceptionally high. Kiwicha did not contain quantifiable amounts of these compounds. Only one variety of kiwicha contained low amounts of betalains. These compounds were not detected in kañiwa or quinoa. Quinoa, kañiwa and kiwicha are good sources of minerals. Their calcium, zinc and iron content are higher than the content of these minerals in common cereals. In general, roasting did not affect significantly mineral bioavailability. On the contrary, in cooked grains, there was an increase in bioavailability of zinc and, in the case of kañiwa, also in iron and calcium bioavailability. In all cases, the contents of total and insoluble dietary fiber decreased during the extrusion process. At the same time, the content of soluble dietary fiber increased. The content of total phenolics, phytic acid and the antioxidant activity decreased in kiwicha varieties during the extrusion process. In the case of quinoa, the content of total phenolic compounds and the radical scavenging activity increased during the extrusion process in all varieties. Taken together, the studies presented here demonstrate that the Andean indigenous crops have excellent potential as sources of minerals, flavonoids and dietary fiber. Further studies should be conducted to characterize the phenolic compound and antioxidant composition in processed grains and end products. Quinoa, kañiwa and kiwicha grains are consumed widely in Andean countries but they also have a significant, worldwide potential as a new cultivated crop species and as an imported commodity from South America. Their inclusion in the diet has the potential to improve the intake of minerals and health-promoting bioactive compounds. They may also be interesting raw materials for special dietary foods and functional foods offering natural sources of specific health-promoting components.

Antioxidant and antimicrobial activities of Bauhinia racemosa L. stem bark

The present study was carried out to evaluate the antioxidant and antimicrobial activities of a methanol extract of Bauhinia racemosa (MEBR) (Caesalpiniaceae) stem bark in various systems. 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) radical, superoxide anion radical, nitric oxide radical, and hydroxyl radical scavenging assays were carried out to evaluate the antioxidant potential of the extract. The antioxidant activity of the methanol extract increased in a concentration-dependent manner. About 50, 100, 250, and 500 µg MEBR inhibited the peroxidation of a linoleic acid emulsion by 62.43, 67.21, 71.04, and 76.83%, respectively. Similarly, the effect of MEBR on reducing power increased in a concentration-dependent manner. In DPPH radical scavenging assays the IC50 value of the extract was 152.29 µg/ml. MEBR inhibited the nitric oxide radicals generated from sodium nitroprusside with an IC50 of 78.34 µg/ml, as opposed to 20.4 µg/ml for curcumin. Moreover, MEBR scavenged the superoxide generated by the PMS/NADH-NBT system. MEBR also inhibited the hydroxyl radical generated by Fenton's reaction, with an IC50 value of more than 1000 µg/ml, as compared to 5 µg/ml for catechin. The amounts of total phenolic compounds were also determined and 64.7 µg pyrocatechol phenol equivalents were detected in MEBR (1 mg). The antimicrobial activities of MEBR were determined by disc diffusion with five Gram-positive, four Gram-negative and four fungal species. MEBR showed broad-spectrum antimicrobial activity against all tested microorganisms. The results obtained in the present study indicate that MEBR can be a potential source of natural antioxidant and antimicrobial agents.

Ginkgo biloba leaf extract (EGb 761) enhances catalepsy induced by haloperidol and L-nitroarginine in mice

Ginkgo biloba extract EGb 761 has been reported to have therapeutic effects which have been attributed to anti-oxidant and free radical-scavenging activities, including a direct action on nitric oxide production. L G-nitro-arginine (L-NOARG), a nitric oxide synthase inhibitor, and haloperidol, a drug that blocks dopamine receptors, are both known to induce catalepsy in rodents. Nitric oxide has been shown to influence dopaminergic transmission in the striatum. The purpose of the present study was to evaluate the effect of the extract obtained from leaves of Ginkgo biloba tree EGb 761 on catalepsy induced by haloperidol or by L-NOARG. Albino Swiss mice (35-45 g, N = 8-12) received by gavage a single or repeated oral dose (twice a day for 4 days) of EGb 761 followed by ip injection of haloperidol or L-NOARG. After the treatments, the animals were submitted to behavioral evaluation using the catalepsy test. Acute treatment with 80 mg/kg EGb did not modify the catalepsy induced by L-NOARG but, the dose of 40 mg/kg significantly enhanced haloperidol-induced catalepsy measured at the 10th min of the test. After repeated treatment with 80 mg/kg EGb 761, a significant increase in the cataleptic effect produced by both haloperidol and L-NOARG was observed. These data show that repeated EGb 761 administration increases the effects of drugs that modify motor behavior in mice. Since the catalepsy test has predictive value regarding extrapyramidal effects, the possibility of pharmacological interactions between haloperidol and Ginkgo biloba extracts should be further investigated in clinical studies.

Inhibition of cyclooxygenase activity by standardized hydroalcoholic extracts of four Asteraceae species from the Argentine Puna

We determined the anti-inflammatory activity of standardized extracts of four medicinal plant species (Baccharis incarum, B. boliviensis, Chuquiraga atacamensis, Parastrephia lucida) that grow in the Argentine Puna (3800 m above sea level) and that are used to reduce oxidative stress and alleviate gout and arthritic pain. The extracts of plant aerial parts were standardized in terms of total phenolic compounds and flavone/flavanone content and free radical scavenging activity. All extracts showed high phenolic compound concentration (0.5-1.6 mg/mL), mainly flavones and flavonols (0.1-0.8 mg/mL). The extracts showed hydrogen donating ability (DPPH and ABTS) and reactive oxygen species scavenging activity (O2●-, OH-, H2O2). The ability of the extracts to inhibit cyclooxygenase enzymes (COX-1 and COX-2) was determined by calculating percent inhibition of PGE2 production measured by enzyme immunoassay. All extracts inhibited both enzymes with IC50 values of 2.0 to 16.7 µg/mL. The anti-inflammatory activity of B. incarum and C. atacamensis extracts was higher than that of B. boliviensis and P. lucida. The IC50 values obtained for indomethacin were 0.11 and 0.78 µM for COX-1 and COX-2, respectively. The present results are consistent with the anecdotal use of these species in phytotherapic preparations.

Effects of melatonin on DNA damage induced by cyclophosphamide in rats

The antioxidant and free radical scavenger properties of melatonin have been well described in the literature. In this study, our objective was to determine the protective effect of the pineal gland hormone against the DNA damage induced by cyclophosphamide (CP), an anti-tumor agent that is widely applied in clinical practice. DNA damage was induced in rats by a single intraperitoneal injection of CP (20 or 50 mg/kg). Animals received melatonin during the dark period for 15 days (1 mg/kg in the drinking water). Rat bone marrow cells were used for the determination of chromosomal aberrations and of formamidopyrimidine DNA glycosylase enzyme (Fpg)-sensitive sites by the comet technique and ofXpf mRNA expression by qRT-PCR. The number (mean ± SE) of chromosomal aberrations in pinealectomized (PINX) animals treated with melatonin and CP (2.50 ± 0.50/100 cells) was lower than that obtained for PINX animals injected with CP (12 ± 1.8/100 cells), thus showing a reduction of 85.8% in the number of chromosomal aberrations. This melatonin-mediated protection was also observed when oxidative lesions were analyzed by the Fpg-sensitive assay, both 24 and 48 h after CP administration. The expression of Xpf mRNA, which is involved in the DNA nucleotide excision repair machinery, was up-regulated by melatonin. The results indicate that melatonin is able to protect bone marrow cells by completely blocking CP-induced chromosome aberrations. Therefore, melatonin administration could be an alternative and effective treatment during chemotherapy.

Rosemary (Rosmarinus officinalis): a study of the composition, antioxidant and antimicrobial activities of extracts obtained with supercritical carbon dioxide

Rosemary leaf extracts were obtained by supercritical fluid extraction (SFE) and Soxhlet extraction. Their chemical compositions were evaluated by GC-MS. The extracts were analyzed for compounds reported in the literature as showing antimicrobial and antioxidant activities. The rosemary extracts were tested with regard to antioxidant (DPPH radical scavenging and total phenolic content - Folin-Denis reagent), antibacterial (Gram-positive bacteria - Staphylococcus aureus ATCC 25923 and Bacillus cereus ATCC 11778 - and Gram-negative bacteria - Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) and antifungal (Candida albicans) activities. Antioxidant, antibacterial and antifungal activities of the SFE extracts were confirmed.

Flavonoids, total phenolics and antioxidant capacity: comparison between commercial green tea preparations

The potential health benefits attributed to green tea and its catechins such as antioxidant effects, cancer chemoprevention, and weight loss have led to a huge increase of green tea products in the food market. The objectives of this work were to analyze and compare these products in terms of phenolic contents and in vitro antioxidant capacity including tea bags, dehydrated leaves, and ready-to-drink preparations after standardization of the infusion preparation procedure. Total phenolics content in 1 cup of the different teas varied from 90 to 341 mg of catechin equivalents, and the highest and the lowest values were both those of the ready-to-drink products. Infusions prepared from tea bags had contents varying from 96 to 201 mg.200 mL-1, and there were no significant differences among batches. The DPPH radical scavenging and the Oxygen Radical Absorbing Capacities (ORAC) varied largely among the different tea preparations, from 23 to 131 mmoles of Trolox Equivalents (TE).200 mL-1 (DPPH), and from 1.2 to 5.1 mmoles of TE.200 mL-1 (ORAC), but again there were no differences among infusions or ready-to-drink commercial preparations. However, the antioxidant capacity of ready-to-drink products was partially due to the presence of other non-phenolic compounds such as ascorbic acid

Antioxidant capacity of anthocyanins from acerola genotypes

Anthocyanins from 12 acerola genotypes cultivated at the Active Germplasm Bank at Federal Rural University of Pernambuco were isolated for antioxidant potential evaluation. The antioxidant activity and radical scavenging capacity of the anthocyanin isolates were measured according to the β-carotene bleaching method and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay, respectively. The antioxidant activity varied from 25.58 to 47.04% at 0.2 mg.mL-1, and it was measured using the β-carotene bleaching method. The free radical scavenging capacity increased according to the increase in concentration and reaction time by the DPPH assay. At 16.7 μg.mL-1 concentration and after 5 minutes and 2 hours reaction time, the percentage of scavenged radicals varied from 36.97 to 63.92% and 73.27 to 94.54%, respectively. Therefore, the antioxidant capacity of acerola anthocyanins varied amongst acerola genotypes and methods used. The anthocyanins present in this fruit may supply substantial dietary source of antioxidant which may promote health and produce disease prevention effects.

Quinoa (Chenopodium quinoa, Willd.) as a source of dietary fiber and other functional components

Four varieties of an Andean indigenous crop, quinoa (Chenopodium quinoa Willd.), were evaluated as a source of dietary fiber, phenolic compounds and antioxidant activity. The crops were processed by extrusion-cooking and the final products were analyzed to determine the dietary fiber, total polyphenols, radical scavenging activity, and in vitro digestibility of starch and protein. There were no significant differences in the contents of total dietary fiber between varieties of quinoa. In all cases, the contents of total and insoluble dietary fiber decreased during the extrusion process. At the same time, the content of soluble dietary fiber increased. The content of total phenolic compounds and the radical scavenging activity increased during the extrusion process in the case of all 4 varieties. There were significant differences between the varieties and the content of total polyphenols. The in vitro protein digestibility of quinoa varieties was between 76.3 and 80.5% and the in vitro starch digestibility was between 65.1 and 68.7%. Our study demonstrates that quinoa can be considered a good source of dietary fiber, polyphenols and other antioxidant compounds and that extrusion improves the nutritional value.

Antioxidant activities of kombucha prepared from three different substrates and changes in content of probiotics during storage

Kombucha is a health-promoting fermented beverage worldwide. The present study compared the free-radical scavenging abilities and total reducing power (TRP) of kombucha prepared from low-cost green tea (LGTK), black tea (BTK), and tea powder (TPK). LGTK had the highest scavenging abilities against 2,2-diphenyl-1-picrylhydrazyl (DPPH), superoxide anion and hydroxyl radicals, while BTK showed the highest TRP. Changes in content of probiotics in LGTK were investigated during storage as well. The number of acetic acid bacteria decreased moderately up to 10 days of storage. The number of lactic acid bacteria (LAB) decreased significantly, and their survival rate was only 0.98% at the 8th day of storage.

Antioxidant activities of fractions from longan pericarps

The antioxidant activities of ethanolic crude extract (LPCE) and its four different solvent sub-fractions (namely, diethyl ether fraction (LPDF), ethyl acetate fraction (LPEF), n-butyl alcohol fraction (LPBF) and residue fraction (LPR)) from longan pericarps were investigated employing various systems including 2,2-diphenyl-1-picrylhydrazyl (DPPH)/ 2,2'-amino-di(2-ethyl-benzothiazoline sulphonic acid-6)ammonium salt (ABTS)/hydroxyl radical scavenging activity, total phenolic content and reducing power. Each extract showed concentration-dependent antioxidant activity. LPEF showed the highest scavenging activity against DPPH, ABTS and hydroxyl radicals with EC50 values of 0.506, 0.228 and 4.489 mg/mL, respectively. LPEF showed the highest reducing power with EC50 values of 0.253 mg/mL. The next was LPDF with EC50 values of 0.260 mg/mL. LPEF possessed the highest total phenolic content (230.816 mg/g, expressed as gallic acid equivalents), followed by LPDF, LPBF, LPCE and LPR. The results suggested that longan pericarp fractions possessed significant antioxidant activities and could be a promising source of natural antioxidant.

Extraction optimization of antioxidant polysaccharides from leaves of Gynura bicolor (Roxb. & Willd.) DC

Orthogonal design was employed to study the effect of extraction time, temperature and liquid-to-solid ratio on the production of antioxidant polysaccharides from leaves of Gynura bicolor (PLG). Analysis of variance was performed on the data obtained. The most relevant variable was extraction time. A liquid-solid ratio of 30:1 (v/w), a temperature of 80 °C and an extraction time of 3 h were found to be optimal for PLG. The optimal extraction yield of 4.9% was obtained through additional verification test. Hydroxyl radical-scavenging activity, reducing power and ferrous ion chelating ability of PLG were determined. PLG possess concentration-dependent antioxidant potency and IC50 of PLG was 4.67, 0.24 and 4.31 mg/mL for hydroxyl radical-scavenging and ferric ion chelating abilities as well as reducing power, respectively. The results suggest that G. bicolor polysaccharides could be potential source of natural antioxidant and be contributor to the health benefits of G. bicolor.