PubMed · 6565018
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C Young. Ascorbic acid.. https://pubmed.ncbi.nlm.nih.gov/6565018/
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Ascorbic acid (AsA) is an essential nutritional component and powerful antioxidant in vegetables, and in plants, AsA levels are regulated by light. AsA levels in the leaves of Chinese chive (Allium tuberosum Rottler ex Spr), a popular vegetable, are poorly understood. Thus, this study was performed to assess the influence of light on AsA biosynthesis in chive and select related genes (AtuGGP1 and AtuGME1); in addition, bioinformatic analyses and gene expression level assays were performed. The biological information obtained for AtuGGP1 and AtuGME1 was analysed with several tools, including NCBI, DNAMAN, and MEGA11. After different light treatments were performed, the Chive AsA content and AtuGGP1 and AtuGME1 expression levels were determined. These results suggest that 1) compared with natural light, continuous darkness inhibited AsA synthesis in chives. 2) The amino acid sequences of AtuGGP1 and AtuGME1 are very similar to those of other plants. 3) The trends observed for the expression levels of AtuGGP1 and AtuGME1 were consistent with the AsA content observed in chives. Hence, we speculated that light controls AsA biosynthesis in chives by regulating AtuGGP1 and AtuGME1 expression. This study provided impactful and informative evidence regarding the functions of GGP and GME in chives.
Lipid peroxidation in human LDL (0.05 mg protein/mL) incubated with Cu(2+)-ions (5 microM) in vitro was dose-dependently inhibited by the flavonoid myrigalone B (MyB) and by ascorbic acid. MyB at 6 microM increased the oxidation lag time by 135 +/- 24 min (approximately 5-fold compared to controls) and reduced the maximum oxidation rate by 46 +/- 5%. Ascorbic acid, at 9 microM, increased the lag time by 179 +/- 29 min (6-fold compared to controls) but did not affect the maximum oxidation rate. The increase in lag time induced by MyB was enhanced in the presence of ascorbic acid. Their effects were additive, except when both were present at the highest concentration tested, when a significant potentiation, giving an increase in lag time of approximately 2 hr more than the sum of separate effects, occurred. Concentration-time curves for MyB in the absence and presence of ascorbic acid showed that the vitamin protected MyB against deterioration during incubation, and indicated that the net consumption of MyB in the oxidation process was reduced. No differences were observed when ordinary ascorbic acid and Ester-C, a commercial vitamin C product, were compared. In conclusion, MyB and ascorbic acid seem to interact in a way that further improves the antioxidant status of the LDL particle relative to each substance separately.
Hydrogen peroxide oxidation of human erythrocytes induces a transfer of phospholipid from the membrane into the cytosol [Brunauer, L.S., Moxness, M.S., & Huestis, W.H. (1994) Biochemistry 33, 4527-4532]. The current study examines the mechanism of lipid reorganization in oxidized cells. Exogenous phosphatidylserine was introduced into the inner monolayer of erythrocytes, and its distribution was monitored by microscopy and radioisotopic labeling. Pretreatment of cells with carbon monoxide prevented both hemoglobin oxidation and the transfer of phosphatidyserine into the cytosolic compartment. The roles of the various hemoglobin oxidation products in lipid extraction were investigated using selective oxidants. Nitrite treatment of intact cells produced almost complete conversion to methemoglobin, but no detectable lipid extraction. Treatments designed to produce the green hemoglobin derivatives, sulfhemoglobin and choleglobin, resulted in cytosolic extraction of phosphatidylserine. Ion exchange and size exclusion chromatography of oxidized cytosolic components revealed a lipid-hemoglobin complex. The interaction between lipid and hemoglobin oxidation products was verified in a model system. Purified hemoglobin, enriched in sulfhemoglobin and choleglobin by treatment with H2O2, H2S, or ascorbate, extracted phospholipid from small unilamellar phospholipid vesicles. Electron paramagnetic resonance studies demonstrated that hemoglobin oxidation products also adsorb fatty acids from solution. This newly described activity of hemoglobin may play a role in the clearance of oxidatively damaged and senescent cells from circulation.