FAO Nutrition Meetings
    Report Series No. 40A,B,C
    WHO/Food Add./67.29




    TOXICOLOGICAL EVALUATION OF SOME
    ANTIMICROBIALS, ANTIOXIDANTS, EMULSIFIERS,
    STABILIZERS, FLOUR-TREATMENT AGENTS, ACIDS AND BASES





    The content of this document is the result of the deliberations of the
    Joint FAO/WHO Expert Committee on Food Additives which met at Rome,
    13-20 December, 19651 Geneva, 11-18 October, 19662




                   

    1 Ninth Report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, 1966 No. 40; 
    Wld Hlth Org. techn. Rep. Ser., 1966, 339

    2 Tenth Report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, 1967, in press; 


    Food and Agriculture Organization of the United Nations
    World Health Organization
    1967


    GLUCONO-DELTA-LACTONE (GLUCONIC ACID)

    Synonym                       Deltagluconolactone

    Chemical name                 Glucono-delta-lactone; D-gluconic acid
                                  delta-lactone

    Empirical formula             C6H10O6

    Structural formula

    

    Molecular weight              178.14

    Description                   A fine, white, nearly odourless,
                                  crystalline powder with a sweet taste
                                  and an acid after-taste.

    Biological Data

    Biochemical aspects

         Glucono-delta-lactone, in an aqueous medium, readily forms an
    equilibrium mixture of the lactone and gluconic acid. These are
    intermediates in the oxidation of glucose through the pentose
    phosphate cycle, which, while not the main pathway of glucose
    metabolism, is well recognized.

         When three men were given 10 g (167 mg/kg) of
    glucono-delta-lactone orally as a 10 per cent. solution, the amounts
    recovered in the urine in 7 hours represented 7.7-15 per cent. of the
    dose. No pathological urine constituents were noted. When 5 g (84
    mg/kg) was given orally none was recovered in the urine. The largest
    dose given to man was 30 g (500 mg/kg) (Chenoweth et al., 1941).

    Acute toxicity

                                                                       

    Animal    Compound           Route    LD50           References
                                          (mg/kg 
                                          body-weight)
                                                                       

    Rabbit    Sodium gluconate   i.v.     7 630          Gajatto, 1939
                                                                       

         The administration for 3-6 days of large oral doses (5-10 g/day)
    of gluconic acid to five normal humans did not produce any renal
    changes, as by the absence of blood, protein, casts and sugar in the
    urine (Chenoweth et al., 1941).

    Short-term studies

         Rat. Groups of 20 male and 20 female rats were fed gluconic
    acid (as glucono-delta-lactone) for 26 weeks at levels of 0 and 10 000
    ppm in the diet without ill effects or demonstrable changes in the
    main organs on microscopic examination (Harper & Gaunt, 1962).

    Long-term studies

         No data are available.

    Evaluation

         Consideration of glucono-delta-lactone and gluconic acid is based
    mainly on the metabolic evidence that these compounds are
    intermediates in a normal pathway of glucose metabolism in mammalian
    species. There is also considerable experience with the comparatively
    low toxicity of gluconate to man and animals.

    Estimate of acceptable daily intakes for man

                                       mg/kg body-weight

        Unconditional acceptance             0-15
        Conditional acceptance               15-50

    REFERENCES

    Chenoweth, M. B., Civin, H., Salzman, C., Cohn, M. & Gold, H. (1941)
    J. Lab. Clin. Med., 26, 1574

    Gajatto, S. (1939) Arch. Farmacol. 68, 1

    Harper, K. H. & Gaunt, I. F. (1962) Unpublished report of Huntingdon
    Research Centre
    

    See Also:
       Toxicological Abbreviations