KETONIC ACIDS DERIVED FROM CHOLIC ACID 111 washed with water. This gum gave an H-test showing yellow-greenish-violet (dichroic) colours. It was dissolved in acetic acid (10 ml.) and the cold solution treated with 20% CrO (1 ml.). After 15 min. it was diluted: the partly crystalline precipitate was collected after 2-3 hr., washed, and recrystallized from dilute ethanol. Yield, 0 55 g. of needles, m.p. 185B188°, raised to 190-191°by recrystallization from l.p./benzene and ethyl acetate. (Found: C, 69 3; H, 8*8. Calc. for C29H,o07: C, 69*0; H, 8.8%.) H-test, negative. This ester (0.3 g.) was heated in a sealed metal bomb for 4 hr. at 200-210O with a solution of NTa (0.1 g.) in ethanol (2 ml.) with hydrazine hydrate (0.3 ml. of 95-99%). Acidification of the diluted contents of the cooled bomb precipitated a solid which separated from dilute ethanol as long white needles (0.15 g.) of 7:12-dihvdroxy-cholanic acid (III), m.p. 205°. SUMMARY 1. The series of six% possible acids obtainable by the oxidation to carbonyl of one or two secondary hydroxyl groups in natural cholic acid has been completed by the preparation of 12-hydroxy-3:7diketo-cholanic acid. 2. New derivatives of this acid, of 3:12-dihydroxy-7-keto-, 7:12-dihydroxy-3-keto-, and 3-hydroxy-7:12-diketo-cholanic acids are described; methods for obtaining such substances have been further explored. The author thanks Allen and Hanburys Ltd. for a gift of cholic acid.
Three growth patterns (no effect, slight inhibition, or complete inhibition) were observed when bacterial species common to the dairy-food industry were grown in media containing 50 or 100 ppm DDT, dieldrin, or endrin. The pattern obtained appeared to depend on species and type and concentration of pesticide. All pesticides studied had a greater inhibitory effect on gram positive species than they had on gram negative species when grown in broth. Acid production by lactic acid bacteria was inhibited in broth plus 5 ppm chlordane or heptachlor but unaffected in skimmilk plus up to 100 ppm of these pesticides. Generation times for gram negative species grown in broth plus 10 ppm chlordane or heptachlor were similar to those obtained in controls. Growth of gram positive species was inhibited in broth plus 10 ppm of these pesticides but unaffected in skimmilk containing similar pesticide concentrations. Generation times for several gram negative species were increased by 10 ppm heptachlor in skimmilk.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.