ascorbic-acid-2-sulfate and ascorbate-2-phosphate

Inhibitory effects of 2-O-substituted ascorbic acid derivatives, ascorbic acid 2-glucoside (AA-2G), ascorbic acid 2-phosphate (AA-2P), and ascorbic acid 2-sulfate (AA-2S), on 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative hemolysis of sheep erythrocytes were studied and were compared with those of ascorbic acid (AA) and other antioxidants. The order of the inhibition efficiency was AA-2S> or =Trolox=uric acid> or =AA-2P> or =AA-2G=AA>glutathione. Although the reactivity of the AA derivatives against AAPH-derived peroxyl radical (ROO(*)) was much lower than that of AA, the derivatives exerted equal or more potent protective effects on AAPH-induced hemolysis and membrane protein oxidation. In addition, the AA derivatives were found to react per se with ROO(*), not via AA as an intermediate. These findings suggest that secondary reactions between the AA derivative radical and ROO(*) play a part in hemolysis inhibition. Delayed addition of the AA derivatives after AAPH-induced oxidation of erythrocytes had already proceeded showed weaker inhibition of hemolysis compared to that of AA. These results suggest that the AA derivatives per se act as biologically effective antioxidants under moderate oxidative stress and that AA-2G and AA-2P may be able to act under severe oxidative stress after enzymatic conversion to AA in vivo.

Topics: Amidines; Animals; Antioxidants; Ascorbic Acid; Erythrocyte Membrane; Free Radicals; Hemolysis; Sheep; Time Factors

Duplicate lots of 150 Atlantic salmon (Salmo salar), average weight 0.5 g, were fed NRC diet H-440 base containing L-ascorbic acid (C1) or L-ascorbyl-2-sulfate (C2S); or L-ascorbyl-2-monophosphate (C2MP): at 0 or 100 mg C1; 50, 100, 300 mg C2S; or 50, 100 mg C2MP per kg dry diet in 12 degrees C freshwater tanks. After 12 weeks, negative controls (no vitamin C) exhibited reduced growth, scoliosis, lordosis, and petechial hemorrhages typical of fish scurvy. All other lots grew normally. Four 100-fish lots of scorbutic salmon, average weight 3.3 g, were placed on recovery diets of 0, 50, or 300 mg C2S, or 100 mg C2MP per kg dry diet. After 5 weeks, fish fed either level of C2S intake had recovered and resumed growth. Negative controls continued to develop acute scurvy. The 41 survivors in this no-vitamin-C group all had advanced scurvy, whereas all fish in both C2S-fed recovery groups appeared normal. Tissue assays for C vitamers disclosed normal levels of C1 and C2S in the recovery groups. All other test treatment lots containing C1, C2S, or C2MP had fish with normal appearance and no significant differences in growth response for the 17-week test period. C2S at 50 mg or more per kg diet as the sole vitamin C source promoted normal growth in young Atlantic salmon for more than 20-fold increase in weight.

Topics: Animals; Ascorbic Acid; Body Weight; Fish Diseases; Liver; Salmon; Scurvy

Channel catfish (Ictalurus punctatus) fingerlings (13 g average initial weight) were fed semipurified diets supplemented with 0, 0.06, 0.12, 0.24 and 0.72 mmol/kg (0, 11, 22, 44 or 132 mg/kg) of ascorbic acid molar equivalent supplied by either L-ascorbic acid, L-ascorbyl-2-monophosphate (Mg salt) (AAP), or L-ascorbyl-2-sulfate (K salt) (AAS). After 14 wk, weight gains were equal for all fish fed diets containing L-ascorbic acid or AAP; however, growth rates were less for fish fed AAS at all dietary levels and for fish fed the ascorbic acid-free diet (control). There were no gross signs of vitamin C deficiency in any of the fish fed L-ascorbic acid or AAP, whereas spinal deformities were found in the controls and in fish fed all but the highest concentration of AAS. The percentage of spinal deformities decreased as dietary levels of AAS increased. Reduced bone collagen content and histopathology in liver and gill tissues also indicated ascorbic acid deficiency in the controls and in fish fed all but the highest concentration of AAS. Limited histopathology was found in fish fed the lowest level of L-ascorbic acid but not in those fed the lowest level of AAP. Regression analysis of weight gain data showed that the vitamin activity of ascorbic acid from AAS was only 5.2% of that from L-ascorbic acid for growth. This study indicates that AAP has equimolar activity to L-ascorbic acid as a vitamin C source for channel catfish and that AAS has vitamin activity for this species but at a much lower level than the other compounds.

Topics: Administration, Oral; Animals; Anticholesteremic Agents; Ascorbic Acid; Ascorbic Acid Deficiency; Ictaluridae; Liver