Melatonin treatment maintains nutraceutical properties of pomegranate fruits during cold storage.

In this study, the mechanism activated by melatonin treatment at 100 µM for maintaining nutraceutical properties in pomegranate fruits during storage at 4 °C for 120 days was investigated. Our results showed that the higher G6PDH and 6PGDH activities in pomegranate fruits treated with melatonin may be responsible for sufficient supply of intracellular NADPH. Also, higher AA and GSH accumulation in pomegranate fruits treated with melatonin may ascribe to higher APX and GR activities coincided with lower AAO activity. In addition, pomegranate fruits treated with melatonin exhibited significantly higher PAL activity resulting in higher phenols and anthocyanins accumulation as well as higher DPPH scavenging capacity. Additionally, higher AOX gene expression in pomegranate fruits treated with melatonin may be beneficial for ROS scavenging molecules accumulation. Therefore, maintaining nutraceutical properties of pomegranate fruits treated with melatonin may ascribe to sufficient intracellular NADPH supply by promoting G6PDH and 6PGDH activities during cold storage.

Exogenous adenosine triphosphate application retards cap browning in Agaricus bisporus during low temperature storage.

Exogenous adenosine triphosphate (ATP) treatment at 0, 250, 500, 750, and 1000 µM retarded cap browning in mushrooms by 0, 34, 26, 51 and 32 %, respectively, during storage at 4 °C for 18 days. Triggering signaling H2O2 accumulation arising from elevating NADPH oxidase enzyme activity during 6 days of storage at 4 °C may be pivotal for promoting shikimate dehydrogenase enzyme activity in mushrooms treated with ATP during 18 days of storage at 4 °C. Promoting melatonin accumulation (390 µg kg-1 FW vs. 160 µg kg-1 FW) in mushrooms treated with ATP during cold storage may attribute to signaling H2O2 accumulation. Higher DPPH scavenging capacity (72 % vs. 65 %) in mushrooms treated with ATP may attribute to higher phenols accumulation arising from higher phenylalanine ammonialyase/polyphenol oxidase enzymes activity concomitant with higher alternative oxidase gene expression during 18 days of storage at 4 °C.

Influence of Gum Arabic Enriched with GABA Coating on Oxidative Damage of Walnut Kernels.

Because of the higher content of unsaturated fatty acids (UNSFA) and phenolics, walnut kernels are vulnerable to oxidative rancidity and browning due to unfavorable postharvest handling procedures. This study investigates the impact of gum arabic coating enriched with γ-aminobutyric acid (GABA) on oxidative rancidity and browning of kernels during storage at 20 °C. The results showed that the walnut kernels coated with gum arabic (5%) enriched with GABA (0.1 mM) exhibited lower oxidative rancidity and browning, manifested by lower peroxide value and malondialdehyde accumulation along with higher whiteness index. Moreover, kernels had higher UNSFA/SFA ratio as a response to lower lipoxygenase activity and H2O2 accumulation. The reduced oxidative browning in coated kernels was accompanied with lower polyphenol oxidase and higher phenylalanine ammonia-lyase activity leading to higher accumulation of phenolics and increased DPPH• scavenging capacity. Based on our findings, gum arabic coating (5%) enriched with GABA (0.1 mM) may have a commercial potential for maintaining nutritional quality of walnut kernels.

Phenolic composition and antioxidant activity of colored oats.

Phenolic composition and antioxidant capacity of 20 oat genotypes differing in hull color were investigated. Phenolic aldehydes, phenolic acids, avenanthramides and mono-, and diglycerides were identified in the soluble phenolic fraction of the genotypes. The bound phenolic fraction proved to be less diverse with phenolic aldehydes, phenolic acids and a ferulic acid dehydrodimer detected. Investigating the scavenging capacity of the hull and groat toward 2,2-diphenyl-1-picrylhydrazyl (DPPH), an increased antioxidant activity (AOA) of hull compared to groats and a color dependence of the hull AOA could be observed. Principal component analysis on the determined variables revealed that the black-hulled samples were different from the white ones due to their increased phenolic content detected in the hull. However, reddish-hulled varieties were grouping with the accessions of the other colored groups. In addition, a distinction between spring and winter cultivars was also observed.

Preliminary in vitro assessment of the potential toxicity and antioxidant activity of Ceiba speciosa (A. St.-Hill) Ravenna (Paineira)

ABSTRACT The bark tea of Ceiba speciosa, a tropical tree of the Malvaceae family, is used in the Northwestern Region of Rio Grande do Sul state, Brazil, to reduce blood cholesterol levels. However, there are no scientific data on the efficacy and safety of this plant. The aim of the present study was to evaluate the in vitro antioxidant and toxic potential of bark extracts of C. speciosa. We performed a preliminary phytochemical analysis by high-performance liquid chromatography-diode array detection (HPLC-DAD) and evaluated the oxidative damage to proteins and lipids, the radical scavenging effect, and genotoxicity of the lyophilized aqueous extract (LAECs) and the precipitate obtained from the raw ethanol extract (Cs1). The phytochemical profile demonstrated the presence of phenolic and flavonoid compounds. The LAECs and Cs1 prevented damage to lipids and proteins at concentrations of 50 and 10 µg/mL. They also showed a scavenging effect on 2,2-diphenyl-1-pricril-hydrazyl (DPPH) radicals in a concentration-dependent manner. Furthermore, no genotoxic effect was observed at concentrations of 10, 5 and 2 µg/mL in the Comet assay. The present study is the first evaluation regarding the characterization of C. speciosa and its safety, and the results demonstrate its antioxidant potential and suggest that its therapeutic use may be relatively safe.