Oxygen radical absorbance capacity (ORAC) of cyclodextrin-solubilized flavonoids, resveratrol and astaxanthin as measured with the ORAC-EPR method

Recently, we proposed an oxygen radical absorbance capacity method that directly quantifies the antioxidant’s scavenging capacity against free radicals and evaluated the radical scavenging abilities for water soluble antioxidant compounds. In this study, we determined the radical scavenging abilities of lipophilic antioxidants which were solubilized by cyclodextrin in water. Commonly employed fluorescence-based method measures the antioxidant’s protection capability for the fluorescent probe, while we directly quantify free-radical level using electron paramagnetic resonance spin trapping technique. In addition, the spin trapping-based method adopted controlled UV-photolysis of azo-initiator for free radical generation, but in fluorescence-based method, thermal decomposition of azo-initiator was utilized. We determined the radical scavenging abilities of seven well-known lipophilic antioxidants (five flavonoids, resveratrol and astaxanthin), using methylated β-cyclodextrin as a solubilizer. The results indicated that the agreement between spin trapping-based and fluorescence-based values was only fair partly because of a large variation in the previous fluorescence-based data. Typical radical scavenging abilities in trolox equivalent unit are: catechin 0.96; epicatechin 0.94; epigallocatechin gallate 1.3; kaempferol 0.37; myricetin 3.2; resveratrol 0.64; and astaxanthin 0.28, indicating that myricetin possesses the highest antioxidant capacity among the compounds tested. We sorted out the possible causes of the deviation between the two methods

Redox regulation in radiation-induced cytochrome-c release from mitochondria of human lung carcinoma A549 cells.

Mitochondria in mammalian cells were well-known to play an important role in the intrinsic pathway of genotoxic-agent-induced apoptosis by releasing cytochrome c into cytosol and to be a major source of reactive oxygen species (ROS). The aim of this study is to examine whether mitochondrial ROS involved in radiation-induced apoptotic signaling in A549 cells. The post-irradiation-treatment of N-acetyl-L-cystein (NAC) inhibited cytochrome c release from mitochondria but did not affect expression level of Bcl-2, Bcl-XL and Bax, suggesting late production of ROS triggered cytochrome c release. The experiments using DCFDA (a classical ROS fluorescence probe) and MitoAR (a novel mitochondrial ROS probe) demonstrated that intracellular and mitochondrial ROS were enhanced 6 h after X irradiation. Furthermore, the O2^[-.] production ability of mitochondria isolated from A549 cells was evaluated by ESR spectroscopy combined with a spin-trapping reagent (CYPMPO). When isolated mitochondria were incubated with NADH, succinate and CYPMPO, the ESR spectrum due to CYPMPO-OOH was detected. This NADH/succinate-dependent O2^[-.] production from mitochondria of irradiated cells was significantly increased in comparison with that of unirradiated cells. These results indicated that ionizing radiation enhanced O2^[-.] production from mitochondria to trigger cytochrome c release in A549 cells

Amelioration of kidney damage in spontaneously diabetic WBN/Kob rats after treatment with Keishi-bukuryo-gan

In this study, we investigated whether Keishi-bukuryo-gan can retard the occurrence and progression of diabetic nephropathy in spontaneously diabetic WBN/Kob rats. Administration of Keishi-bukuryo-gan did not affect body weight loss or blood glucose levels but effectively lowered urinary protein excretion and serum creatinine levels, and ameliorated glomerular, vascular and tubulointerstitial lesions. In addition, treatment of the diabetic rats with Keishi-bukuryo-gan reduced renal levels of thiobarbituric acid reactive substances and advanced glycation end products significantly and elevated renal superoxide dismutase activity significantly. These results suggest that Keishi-bukuryo-gan exerts antioxidant effects in the kidneys of diabetics and may prove that the herbal medicine is useful for inhibiting the progression of diabetic kidney disease. 本研究では,自然発症糖尿病WBN/Kobラットを用い,桂枝茯苓丸が糖尿病性腎症の発症・進展を遅延するか否かについて検討した。その結果,体重と血糖値に対しては,桂枝茯苓丸投与による変化は見られなかったが,尿蛋白排泄量と血清クレアチニンレベルが有意に低下し,病理組織所見(糸球体硬化,血管病変,間質・尿細管障害)も改善していた。一方,腎組織中の過酸化脂質とadvanced glycation end productsレベルは,桂枝茯苓丸投与群で有意に低下し,スーパーオキシドジスムターゼ活性は有意に上昇していた。これらの結果より,桂枝茯苓丸は糖尿病ラットの腎臓において抗酸化作用を発揮し,腎症の進展抑制に有用であることが示唆された