Modification of Radiolethality by Vitamin K₅ and Certain Analogs in Model Systems and in Foods^a

Abstract

SUMMARY Spores of Bacillus subtilis var. niger and B. stearothermophilus irradiated in nitrogen were killed in greater numbers in the presence of vitamin KC, 4.amino‐1‐naphthol, or 2‐amino‐1‐naphthol than when irradiated without chemical. When irradiation was performed in air, the chemicals were without effect, or even protective. Spores of both organisms were particularly sensitive when irradiated in nitrogen with 4‐amino‐1‐naphthol. Irradiation of Micrococcus radiodurans in anoxia with these naphthol derivatives gave losses in cell recovery that resulted in much lower populations than could he attributed to chemical toxicity per se. These chemicals were found to be toxic to a yeast that had been isolated from frozen orange juice when the preparations were in buffer of pH 7.0 and 4.0. When the yeast was suspended in orange juice, on the other hand, the chemicals were neither toxic nor radiosensitizers. Milk was also found to interfere with the bactericidal and radiolethal activities of these chemicals. Sulfhydryl compounds were shown to decrease radiolethal action.

Effect of Irradiation Temperature on the Radiosensitizing Activity of Vitamin K5

“…The protective effect of vitamin K5 during irradiation is rather obvious. Silverman et al (1963) reported a similar protective effect of vitamin K, during irradiation of certain bacterial spores in an air atmosphere. Thus, during irradiation in air in a simple system suc11 as phosphate buffer, vitamin KS behaves like any other complex organic molecule by competing for free radicals formed.…”

“…El-Tabey Shehata (1961) suggested that this decrease in the sensitizing action of vitamin KG might be due to a reaction between the vitamin and sulfhydryl-containing compounds. Silverman et al (1963) found that cysteine or glutathione added to a model system neutralized the toxic effect of vitamin Ks.…”

“…Vitamin K5, in whole egg irradiated in air or vacuum, either had no effect on the I radiosurvival of S. typhiwzuriurvt over the temperature range investigated, or possibly I a slight protective effect. El-Tabey Shehata (1961) and Silverman et al (1963) also found that' the radiosensitizing action of vitamin K5 was not as effective in food systems such' as orange juice or raw milk as in model buffer systems. El-Tabey Shehata (1961) suggested that this decrease in the sensitizing action of vitamin KG might be due to a reaction between the vitamin and sulfhydryl-containing compounds.…”

Radiosensitization of Streptococcus faecalis and Escherichia colia

“…Dean and Alexander (1962) believe that iodoacetamide acts primarily in preventing restoration of the original physiological state of the cell surface and membrane. In a recent study, Silverman et al (1963) demonstrated the neutralizing effects of the sulfhydryl moiety (cysteine and glutathione) and food constituents on radiosensitization by KR, 4AlN, and lA2N. Until further work is done to correlate the sulfhydryl binding capacities of those compounds examined in this study with their sensitizing activity, the possibility still exists that neutralization by sulfhydryl compounds may reflect an associated reaction and not the specific mechanism involved in radiosensitization by naphthalene compounds.…”

Factors Affecting the Antimicrobial Activity of Vitamin K51

“…The antimicrobial activity of vitamin K5 under anaerobic conditions was investigated for the following reasons. (i) It was found that air oxidation enhanced the antimicrobial activity of vitamin K5 (Armstrong, Spink, and Kahnke, 1943;Shwartzman, 1948), and (ii) in an investigation of the sensitizing action of vitamin K5 in conjunction with y-radiation, vitamin K5 was found to be more effective against bacteria in the absence of oxygen (Noaman et al, 1964;Shehata, 1961;Silverman, Shehata, and Goldblith, 1962;Silverman, Davis, and Goldblith, 1963). Table 3 shows the effect of vitamin K5 against the bacteria grown in air, and Table 4 shows the results against bacteria grown in nitrogen.…”