Antrocaryon amazonicum: An unexploited Amazonian fruit with high potential of scavenging reactive oxygen and nitrogen species.

Antrocaryon amazonicum fruits are unexploited sources of bioactive compounds found in the Amazonia region of Brazil. In this study, for the first time, the carotenoid and phenolic compound profiles of the pulp and peel of A. amazonicum fruits, from two varieties at two harvest periods, were determined by LC-MS. Additionally, the potential of the peel and pulp extracts to scavenge physiologically relevant reactive oxygen species (ROS) and reactive nitrogen species (RNS) was assessed. The major carotenoids in both parts of the fruits were lutein, accounting for ≈42% of the identified carotenoids in the peel and ≈25% in the pulp, whereas catechin and hydroxybenzoic acid derivatives were the major phenolics in both parts. The peel extract, which presented the highest bioactive compound contents, was more efficient to scavenge ROS than the pulp. The peel extract showed high scavenging efficiency (IC50 ) for singlet oxygen (1 O2 ; 16 µg/ml), hypochlorous acid (HOCl; 20 µg/ml), peroxynitrite (ONOO- ; 38 µg/ml), and superoxide radical (O2 •- ; 47 µg/ml), whereas the pulp extract exhibited high efficiency for ONOO- (13 µg/ml), followed by HOCl (30 µg/ml), ¹O2 (76 µg/ml), and less efficient for O2 •- (44 µg/ml). Therefore, A. amazonicum fruits can be seen as an expressive source of bioactive compounds with high antioxidant potential to be further investigated to inhibit or delay oxidative processes both in food and physiological systems triggered by ROS and RNS. PRACTICAL APPLICATION: Bioactive compound extracts of Antrocaryon amazonicum fruits have high potential to be exploited for inhibiting or delaying oxidative processes and increase food stability.

Detection and quantification of nitric oxide-derived oxidants in biological systems.

The free radical nitric oxide (NO•) exerts biological effects through the direct and reversible interaction with specific targets (e.g. soluble guanylate cyclase) or through the generation of secondary species, many of which can oxidize, nitrosate or nitrate biomolecules. The NO•-derived reactive species are typically short-lived, and their preferential fates depend on kinetic and compartmentalization aspects. Their detection and quantification are technically challenging. In general, the strategies employed are based either on the detection of relatively stable end products or on the use of synthetic probes, and they are not always selective for a particular species. In this study, we describe the biologically relevant characteristics of the reactive species formed downstream from NO•, and we discuss the approaches currently available for the analysis of NO•, nitrogen dioxide (NO2•), dinitrogen trioxide (N2O3), nitroxyl (HNO), and peroxynitrite (ONOO-/ONOOH), as well as peroxynitrite-derived hydroxyl (HO•) and carbonate anion (CO3•-) radicals. We also discuss the biological origins of and analytical tools for detecting nitrite (NO2-), nitrate (NO3-), nitrosyl-metal complexes, S-nitrosothiols, and 3-nitrotyrosine. Moreover, we highlight state-of-the-art methods, alert readers to caveats of widely used techniques, and encourage retirement of approaches that have been supplanted by more reliable and selective tools for detecting and measuring NO•-derived oxidants. We emphasize that the use of appropriate analytical methods needs to be strongly grounded in a chemical and biochemical understanding of the species and mechanistic pathways involved.

In vivo photoinduced [4 + 2] dimerization of a neo-clerodane diterpene in Baccharis flabellata. ROS and RNS scavenging abilities.

Secondary metabolites play a major role in the adaptation of plants to the environment. Furan neo-clerodane diterpenes are characteristic secondary metabolites in Baccharis flabellata Hook. & Arn. var. flabellata. One of the main compounds is the diene ent-15,16-epoxy-19-hydroxy-1,3,13(16),14-clerodatetraen-18-oic acid (DAC). In this work a new dimeric compound (DACD) has been isolated and identified by NMR and MS techniques. The presence of other minor dimers was also observed in the same plant methanolic extracts. Assuming that they may be the products of [4 + 2] condensation of two monomeric moieties, the formation of adducts by photochemical dimerization was checked by inducing the in vitro [4 + 2] cycloaddition of DAC. Moreover, the DAC and DACD accumulation rates in aerial parts of B. flabellata specimens were analyzed monthly during a complete phenological cycle. The accumulation of monomer depends on the plant phonological stage; meanwhile the dimer proportion arises in detriment of the monomer as the solar UV radiation increases. Since plants exposed to strong UV intensities produce radical species, the scavenger properties of these compounds toward reactive nitrogen species (RNS), and reactive oxygen species (ROS), were analyzed. Albeit DAC and DACD show significant superoxide radical scavenger activities, the monomer proved to be more effective than the dimer toward ROS, while DACD was an excellent RNS scavenger.

Studies on free radical scavenging, cancer cell antiproliferation, and calf thymus DNA interaction of Schiff bases.

Thirty-nine Schiff bases were synthesized by performing microwave-assisted condensation of the corresponding aldehydes and aromatic amines. Their reactive nitrogen species (RNS) scavenging activity and inhibitory effects against cancer cell growth were then subsequently investigated. Additionally, the interaction between the calf thymus DNA (ctDNA) and selected Schiff bases was evaluated using fluorescence spectroscopy, and their binding parameters were determined. The yields of the various compounds ranged from moderate to excellent (43-99%) after only a 2-min reaction. The hydroxylated Schiff bases 2, 8, 15, 16, 18, 20, 29, 32, 34, and 37 were found to be potent scavengers of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals with half-maximal scavenging concentration (SC50) values lower than that of the positive control, resveratrol. The presence of hydroxyl substituents on the aromatic rings also proved essential to the cytotoxicity of the compounds. The binding constants (Kb) obtained using fluorescence spectroscopy ranged from 0.37 to 3.07×105Lmol-1, and were strongly influenced by the structure and hydroxylation degree. Schiff bases 3 and 8 showed promising cytotoxic activity, with half-maximal growth inhibitory (GI50) values in the same order of magnitude as those exhibited by the reference drug, doxorubicin against various cell lines. Interestingly, these compounds also showed the highest Kb, suggesting that the cytotoxic activity could be related to their interaction with the DNA of the tumor cells. The results of this study highlighted some Schiff bases as potential lead compounds for the design of new free radical scavengers and anticancer agents.

Solanum diploconos fruits: profile of bioactive compounds and in vitro antioxidant capacity of different parts of the fruit.

Solanum diploconos is an unexploited Brazilian native fruit that belongs to the same genus of important food crops, such as tomato (Solanum lycorpersicum) and potato (Solanum tuberosum). In this study, we determined, for the first time, the profile of bioactive compounds (phenolic compounds, carotenoids, ascorbic acid and tocopherols) of the freeze-dried pulp and peel of Solanum diploconos fruits, as well as of an extract obtained from the whole fruit. Additionally, the antioxidant potential of the whole fruit extract was evaluated in vitro, against reactive oxygen species (ROS) and reactive nitrogen species (RNS). Eighteen phenolic compounds were identified in the peel and pulp and 6 compounds were found in the whole fruit extract. Coumaric, ferulic and caffeic acid derivatives were revealed to be the major phenolic constituents. All-trans-ß-carotene was the major carotenoid (17-38 µg g(-1), dry basis), but all-trans-lutein and 9-cis-ß-carotene were also identified. The peel and pulp presented <2 µg per mL of tocopherols, and ascorbic acid was not detected. The whole fruit extract exhibited scavenging capacity against all tested ROS and RNS (IC50 = 14-461 µg mL(-1)) with high antioxidant efficiency against HOCl. Thus, Solanum diploconos fruits may be seen as a promising source of bioactive compounds with high antioxidant potential against the most physiologically relevant ROS and RNS.

The seed of the Amazonian fruit Couepia bracteosa exhibits higher scavenging capacity against ROS and RNS than its shell and pulp extracts.

Among the large number of scientifically unstudied fruits from the Amazonia biome, Couepia bracteosa acts as an interesting source of bioactive compounds, such as phenolic compounds and carotenoids, which may be used for protecting human health against oxidative damage. For the first time, the phenolic compounds and carotenoids in extracts obtained from the pulp, shell and seeds of C. bracteosa fruits are reported, as well as their in vitro scavenging capacities against some reactive oxygen species (ROS) and reactive nitrogen species (RNS). The shell extract presented the highest phenolic compound and carotenoid contents (5540 and 328 µg per g extract, dry basis, respectively), followed by the pulp and seed extracts. The major phenolic compound was acacetin sulphate (one methoxy and two OH groups) (62%) in the shells; however, only seeds presented apigenin sulphate (three OH groups), in which it was the major compound (44%). The high content of apigenin sulphate may explain why the seed extract had the highest scavenging efficiency against all tested ROS/RNS among the studied extracts. Regarding carotenoids, all-trans-neochrome (17%) and all-trans-ß-carotene (16%) were the major carotenoids in the pulp extracts, while all-trans-lutein (44%) was the most prevalent in the shell extracts and all-trans-α-carotene (32%) and all-trans-ß-carotene (29%) were the major ones in the seed extracts.

Influence of coffee genotype on bioactive compounds and the in vitro capacity to scavenge reactive oxygen and nitrogen species.

The influence of green coffee genotype on the bioactive compounds and the in vitro antioxidant capacity against the principal reactive oxygen (ROO(•), H2O2, HO(•), and HOCl) and nitrogen (NO(•) and ONOO(-)) species of biological relevance was investigated. This is the first report on the capacity of green coffee to scavenge H2O2, HOCl, and NO(•). Variations in the contents of total chlorogenic acids (22.9-37.9 g/100 g), cinnamoyl-amino acid conjugates (0.03-1.12 g/100 g), trigonelline (3.1-6.7 g/100 g), and caffeine (3.9-11.8 g/100 g) were found. Hydrophilic extracts of Coffea canephora and Coffea kapakata were the most potent scavengers of ROO(•), H2O2, HO(•), NO(•), and ONOO(-) due to their chlorogenic acid contents, which were, on average, 30% higher than those found in Coffea arabica and Coffea racemosa. The results showed that genotype is a determinant characteristic in the bioactive compound contents and consequently in the antioxidant capacity of green coffee.

Psidium cattleianum fruit extracts are efficient in vitro scavengers of physiologically relevant reactive oxygen and nitrogen species.

Psidium cattleianum, an unexploited Brazilian native fruit, is considered a potential source of bioactive compounds. In the present study, the in vitro scavenging capacity of skin and pulp extracts from P. cattleianum fruits against reactive oxygen species (ROS) and reactive nitrogen species (RNS) was evaluated by in vitro screening assays. Additionally, the composition of phenolic compounds and carotenoids in both extracts was determined by LC-MS/MS. The major phenolic compounds identified and quantified (dry matter) in the skin and pulp extracts of P. cattleianum were ellagic acid (2213-3818 µg/g extracts), ellagic acid deoxyhexoside (1475-2,070 µg/g extracts) and epicatechin gallate (885-1,603 µg/g extracts); while all-trans-lutein (2-10 µg/g extracts), all-trans-antheraxanthin (1.6-9 µg/g extracts) and all-trans-ß-carotene (4-6 µg/g extracts) were the major carotenoids identified in both extracts. P. cattleianum pulp extract showed higher scavenging capacity than skin extract for all tested ROS and RNS. Considering the potential beneficial effects to human health, P. cattleianum may be considered as a good source of natural antioxidants and may be useful for the food and phytopharmaceutical industry.

Biological nitric oxide signalling: chemistry and terminology.

Biological nitrogen oxide signalling and stress is an area of extreme clinical, pharmacological, toxicological, biochemical and chemical research interest. The utility of nitric oxide and derived species as signalling agents is due to their novel and vast chemical interactions with a variety of biological targets. Herein, the chemistry associated with the interaction of the biologically relevant nitrogen oxide species with fundamental biochemical targets is discussed. Specifically, the chemical interactions of nitrogen oxides with nucleophiles (e.g. thiols), metals (e.g. hemeproteins) and paramagnetic species (e.g. dioxygen and superoxide) are addressed. Importantly, the terms associated with the mechanisms by which NO (and derived species) react with their respective biological targets have been defined by numerous past chemical studies. Thus, in order to assist researchers in referring to chemical processes associated with nitrogen oxide biology, the vernacular associated with these chemical interactions is addressed.

Carotenoids and phenolic compounds from Solanum sessiliflorum, an unexploited Amazonian fruit, and their scavenging capacities against reactive oxygen and nitrogen species.

The composition of carotenoids and phenolic compounds from mana-cubiu (Solanum sessiliflorum), a fruit native to Amazonia, was determined by high-performance liquid chromatography coupled to diode array and mass spectrometry detectors (HPLC-DAD-MS(n)). The antioxidant capacities of the hydrophilic and carotenoid extracts against some reactive oxygen (ROO(•), H(2)O(2), HOCl, and HO(•)) and nitrogen (ONOO(-)) species were also determined. Seventeen carotenoids and three phenolic compounds were found in mana-cubiu. The major carotenoids were (all-E)-ß-carotene (7.15 µg/g of dry weight) and (all-E)-lutein (2.41 µg/g of dry weight). The 5-caffeoylquinic acid (1351 µg/g of dry weight) was the major phenolic compound, representing more than 78% (w/w) of the total phenolic compounds. Moreover, two dihydrocaffeoyl spermidines were found in the hydrophilic extract. Both mana-cubiu extracts were able to scavenge all the tested reactive species. The carotenoid extract was shown to be a potent scavenger of peroxyl radical, while the hydrophilic extract was a potent hydrogen peroxide and hypochlorous acid scavenger.

Biological activities of eco-friendly synthesized Hantzsch adducts.

Fourteen Hantzsch adducts with different substituents at the C-4 position were synthesized through multicomponent reactions by using citric or lactic acid as catalysts. To the best of our knowledge, this is the first report on the synthesis of such a class of compounds based on multicomponent reactions catalyzed by non-toxic organic acids. The potential to scavenge reactive nitrogen/oxygen species (RNS/ROS) and the ability to inhibit cancer cell growth were then investigated. Among the synthesized compounds, adduct 15 was the most promising free radical scavenger, while adduct 20 was shown to have a wider spectrum of action on the cancer cells studied. These results highlight Hantzsch adducts as lead compounds for obtaining new free radical scavengers and anticancer agents.

Microcapsules containing antioxidant molecules as scavengers of reactive oxygen and nitrogen species.

The antioxidant capacities of gum arabic and maltodextrin microcapsules containing antioxidant molecules (trolox, α-tocopherol, ß-carotene, apo-8'-carotenal and apo-12'-carotenal) against reactive oxygen and nitrogen species were evaluated. The scavenging capacities were influenced by the wall material, the reactive species, namely ROO(), H(2)O(2), HO(), HOCl and ONOO(-), and the antioxidant molecule. In general, a more pronounced enhancement of the antioxidant capacity due to incorporation of antioxidant molecules was observed in gum arabic microcapsules. The empty microcapsules showed capacity to scavenge all the studied ROS and RNS, being gum arabic a more potent antioxidant than maltodextrin. Apo-8'-carotenal incorporation promoted the highest increase in the scavenging capacities among the evaluated antioxidants, varying from 50% to 132% and from 39% to 85% for gum arabic and maltodextrin microcapsules, respectively, suggesting that this carotenoid presented the best balance between the molecule localization inside the microcapsules and the reactivity against the specific reactive species.

The potential of extracts of Caryocar villosum pulp to scavenge reactive oxygen and nitrogen species.

Caryocar villosum (piquiá) is a native fruit from the Amazonian region, considered to be an interesting source of bioactive compounds. In this paper, five extracts of C. villosum pulp were obtained, using solvents with different polarities and their in vitro scavenging capacity against reactive oxygen species (ROS) and reactive nitrogen species (RNS) was determined. Additionally, the phenolic compounds and carotenoids in each extract were identified and quantified by a high performance liquid chromatography coupled to diode array and mass spectrometer detectors (HPLC-DAD-MS/MS). The ethanol/water and water extracts, which presented the highest phenolic contents (5163 and 1745µg/g extract, respectively), with ellagic acid as the major phenolic compound, proved to have the highest ROS and RNS scavenging potential. Nevertheless, in general, ellagic acid was less effective in scavenging ROS (IC(50) from 1.7 to 108µg/ml) and RNS (IC(50) from 0.05 to 0.59µg/ml), when compared to gallic acid (IC(50) from 0.4 to 226µg/ml for ROS and IC(50) from 0.04 to 0.12µg/ml for RNS). The results obtained in the present study clearly demonstrated that the in vitro antioxidant efficiency of C. villosum extracts was closely related to their contents of phenolic compounds.

Structure of dihydrochalcones and related derivatives and their scavenging and antioxidant activity against oxygen and nitrogen radical species.

Quantum mechanical calculations at B3LYP/6-31G** level of theory were employed to obtain energy (E), ionization potential (IP), bond dissociation enthalpy (O-H BDE) and stabilization energies (DE(iso)) in order to infer the scavenging activity of dihydrochalcones (DHC) and structurally related compounds. Spin density calculations were also performed for the proposed antioxidant activity mechanism of 2,4,6-trihydroxyacetophenone (2,4,6-THA). The unpaired electron formed by the hydrogen abstraction from the phenolic hydroxyl group of 2,4,6-THA is localized on the phenolic oxygen at 2, 6, and 4 positions, the C3 and C6 carbon atoms at ortho positions, and the C5 carbon atom at para position. The lowest phenolic oxygen contribution corresponded to the highest scavenging activity value. It was found that antioxidant activity depends on the presence of a hydroxyl at the C2 and C4 positions and that there is a correlation between IP and O-H BDE and peroxynitrite scavenging activity and lipid peroxidation. These results identified the pharmacophore group for DHC.

ESR and electrochemical study of 1,2-disubstituted 5-nitroindazolin-3-ones and 2-substituted 3-alkoxy-5-nitro-2H-indazoles: reactivity and free radical production capacity in the presence of biological systems.

Two families of 5-nitroindazole derivatives were electrochemically studied in an aprotic solvent using cyclic voltammetry (CV) technique. The produced nitro-anion radical species were characterized using electron spin resonance spectroscopy (ESR). Also, we examined the interaction between the radical species generated from nitroindazole derivatives and glutathione (GSH). Moreover, the capacity of intraparasite and intramammals-free radical production, through ESR spectroscopy, was performed.

Relationship between the action of reactive oxygen and nitrogen species on bilayer membranes and antioxidants.

Membrane lipid peroxidation (LPO) induced by hydroxyl (*OH) and ascorbyl (*Asc) radicals and by peroxynitrite (ONOO-) was investigated in asolectin (ASO), egg phosphatidylcholine (PC) and PC/phosphatidic acid mixtures (PC:PA) liposomes and rat liver microsomes (MC). Enthalpy variation (DeltaH) of PC:PA at different molar ratios were obtained by differential scanning calorimetry. It was also evaluated the LPO inhibition by quercetin, melatonin and Vitamin B6. The oxidant effect power follows the order *OH approximately *Asc > ONOO- on PC and MC; whilst on ASO liposomes, it follows *Asc > *OH approximately ONOO-. Increasing amounts of PA in PC liposomes resulted in lower levels of LPO. The DeltaH values indicate a more ordered membrane arrangement as a function of PA amount. The results were discussed in order to provide a complete view involving the influence of membranes, oxidants and antioxidants intrinsic behavior on the LPO dynamics.