CHEMICAL STRUCTURE AND BIOLOGICAL ACTIVITY 857 



potency. Results of tests on such partially hydrogenated compounds are 

 summarized in Table 10. 



The 5,8-dihydrovitamin Ki has 25% of the activity of vitamin Ki while 

 the isomer, /3,7-dihydrovitamin Ki, in which the hydrogens are added to 

 the side chain, is only 12.5% as active as is the corresponding unreduced 

 vitamin K. The surprisingly high activity of 5,8-dihydrovitamin Ki is to 

 be explained on the basis that such partially hydrogenated quinones can be 

 readily aromatized by chemical oxidation, since the hydrogens at positions 



TABLE 11 



.\NTlHi.MORRHAGIC ACTIVITY OF MeTHYLNAPHTHOLS, MetHYLTETRALONES, AND SoME 



Related Compounds 



' L. F. Fieser, M. Tishler, and W. L. Sampson, J. Biol. Chem., 137, 659-692 (1941). 



^ M. Tishler, L. F. Fieser, and W. L. Sampson, /. Am. Chem. Soc, 62, 1881-1882 

 (1940). 



■= M. Tishler, L. F. Fieser, and N. L. Wendler, J. Am. Chem. Soc, 62, 2866-2871 

 (1940). 



"i E. A. Doisy, D. W. MacCorquodale, S. A. Thayer, S. B. Bmkley, and R. W. McKee, 

 Science 90 407 (1939). 



' H. J. Almquist and A. A. Klose, Proc. Soc. Exptl. Biol. Med., 45, 55-59 (1940). 



^ D. Richtert, S. A. Thayer, R. W. McKee, S. B. Binkley, and E. A. Doisy, Proc. Soc. 

 Exptl. Biol. Med., 44, 601-604 (1940). 



" A. D. Emmett, O. Kamm, and E. A. Shaip, ./. Biol. Chem., 133, 285-286 (1940). 



* H. R. Rosenberg, Chemistry and Physiology of the Vitamins, Interscience, New York, 

 1945, pp. 491, 499, 500. 



5 and 8 are highly active. On the other hand, the jS,7,5,6,7,8-hexahydro- 

 vitamin Ki shows practically no activity when given in the amount of 

 1000 ng.; in fact, Fernholz et al.^^ observed no effect on a 2000-Mg. dosage. 

 It should be recalled that the /3,7-dihydrovitamin Ki is active in amounts 

 of 8 fjLg. The inactivity of such tetradehydronaphthoquinones must be due 



'1 E. Fernholz, H. B. MacPhillamy, and S. .\nsbacher, /. Am. Chem. Soc, 62, 1619- 

 1620 (1940). 



