The present study was carried out to investigate the antioxidative and neuroprotective effects of sea buckthorn ( L.) leaves (SBL) harvested at different times. Reversed-phase high-performance liquid chromatography analysis revealed five major phenolic compounds: ellagic acid, gallic acid, isorhamnetin, kaempferol, and quercetin. SBL harvested in August had the highest total phenolic and flavonoid contents and antioxidant capacity. Treatment of neuronal PC-12 cells with the ethyl acetate fraction of SBL harvested in August increased their viability and membrane integrity and reduced intracellular oxidative stress in a dose-dependent manner. The relative populations of both early and late apoptotic PC-12 cells were decreased by treatment with the SBL ethyl acetate fraction, based on flow cytometry analysis using annexin V-FITC/PI staining. These findings suggest that SBL can serve as a good source of antioxidants and medicinal agents that attenuate oxidative stress.

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Oxidative stress, caused by the excessive production of reactive oxygen species (ROS), results in cellular damage. Therefore, functional materials with antioxidant properties are necessary to maintain redox balance. Turmeric leaves (Curcuma longa L. leaves; TL) are known to have antioxidant properties, including 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2′-Azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS), and Hydrogen peroxide (H2O2) radical scavenging activity in several studies. The antioxidant effects of TL come from distinct bioactive compounds, such as curcumin, total phenolic compounds, and flavonoids. Therefore, in this study, the antioxidant effects of a water extract of TL (TLE) against H2O2 treatment were assessed in vitro Vero cells and in vivo zebrafish models. The intracellular ROS generation and the proportion of sub-G1 phase cells were evaluated in H2O2- or/and TLE-treated Vero cells to measure the antioxidant activity of TLE. TLE showed outstanding intracellular ROS scavenging activity and significantly decreased the proportion of cells in the sub-G1 phase in a dose-dependent manner. Furthermore, cell death, ROS generation, and lipid peroxidation in the H2O2-treated zebrafish model were attenuated as a consequence of TLE treatment. Collectively, the results from this study suggested that TLE may be an alternative material to relieve ROS generation through its antioxidant properties or a suitable material for the application in a functional food industry.

α-Flavone glycosides have beneficial properties for applications in the pharmaceutical, cosmetic, and food industries. However, their chemical syntheses are often limited by a low efficiency or scarcity of substrates. In this study, α-flavone glucosides were enzymatically synthesized by amylosucrase from Deinococcus geothermalis (DGAS) using sucrose and various flavones as a donor for glucosyl units and acceptors, respectively. Luteolin was the most effective acceptor in the transglucosylation reaction using DGAS among nine flavone materials (apigenin, chrysin, 6,7-dihydroxyflavone, homoorientin, 7-hydroxyflavone, isorhoifolin, luteolin, luteolin-3′,7-diglucoside, and orientin). The highest production yield of luteolin glucoside was 86%, with a 7:1 molar ratio of donor to acceptor molecules, in 50 mM Tris-HCl buffer (pH 7) at 37°C for 24 h using 2 U of DGAS. The synthesized luteolin glucoside was identified as luteolin-4′-O-α-D-glucopyranoside with a glucose molecule linked to the C-4′ position on the B-ring of luteolin via an α-glucosidic bond, as determined by 1H and 13C nuclear magnetic resonance. This result clearly confirmed that the glucosylated luteolin was successfully synthesized by DGAS and it can be applied as a functional ingredient. Furthermore, this approach using DGAS has the potential to be utilized for the synthesis of various glucosylated products using different types of polyphenols to enhance their functionalities.

Red ginseng, a steamed and sun-dried ginseng, is a popular health-promoting food in Korea and other Asian countries. We introduced nanofertilizer technology using gold nanoparticles in an effort to develop red ginseng with an elevated level of ginsenosides, the main active compounds of ginseng. Shoots of 6-year-old ginseng plants were fertilized three times with colloidal gold nanoparticle sprays. Red ginseng extract was prepared from the main roots. The concentrations of gold and ginsenosides were measured following gold nanoparticle treatment. To evaluate the anti-inflammatory effects, mouse peritoneal macrophages of male BALB/c mouse were stimulated with lipopolysaccharide plus interferon-γ in the presence of extracts from red ginseng with or without gold nanoparticle treatment. The content of ginsenosides, such as Rg1, Re, Rf, and Rb1, increased in ginseng treated with gold nanofertilizer whereas the steaming process increased only the levels of Rd and Rg3. The levels of nitric oxide, inducible nitric oxide synthase, and interleukin-6, but not tumor necrosis factor-α, were more suppressed in macrophages treated with extract from gold nanoparticle-treated red ginseng. Our results show that the use of a colloidal gold nanoparticle fertilizer improved the synthesis of ginsenosides in ginseng and enhanced the anti-inflammatory effects of red ginseng. Further research is required to elucidate the causal factors for the gold-induced change in ginsenoside synthesis and to determine the in vivo effect of gold nanoparticle-treated ginseng.