VIII. PHARMACOLOGY 439 



feel that certain naphthoquinones act as plant respiratory pigments. This 

 is of interest, since the plant leaves in which vitamin K is found are capable 

 of synthesizing the vitamin to any extent only if exposed to sunlight.*-' ** 

 Wright*^ intimates that vitamin K may be an essential metabolite of all 

 forms of life. 



Bacteria are known to produce vitamin K, and the possibility that the 

 vitamin is a growth factor has been entertained. According to Gu^rillot- 

 Vinet*^ phthiocol and menadione in concentrations of 10~^ to 10~^ are growth 

 factors for Mycobacterium paratuherculosis and Aspergillus niger, but at the 

 concentration at which vitamin K is produced by bacteria (8 to 152 7 per 

 gram of dry weight) it is definitely bacteriostatic. The inhibition in vitro 

 of many bacteria by vitamin K analogs has been reported: Streptococcus, 

 pneumococcus, Salmonella typhosa and paratyphi, Brucella, Staphylococcus,^^ 

 anthrax,*^ mycobacteria,*® corynebacteria;*^ the mode of action on the vari- 

 ous bacteria may vary with the analog employed.*^ Hand*" doubts that the 

 vitamins K are true growth factors but suspects they may play some 

 metabolic role in the bacteria. The quinone growth-stimulating properties 

 may be unrelated to antihemorrhagic activity, since the 4-aminonaphthol 

 analog has only an inhibitory action.*® Bacterial inhibition by dicoumarol 

 is not reversed by vitamin K, but is reversed by vitamin P.'*^ However, the 

 strong bacteriostatic action of salicylic acid is opposed by vitamin K 

 (weakly), and, in the case of the inhibition of Fusaria by 2-chloromenadione, 

 menadione is strongly competitive.*^ Inhibition of streptococcal growth by 

 the pigment iodinin*- and of the growth of yeasts by 2,3-dichloro-l,4- 

 naphthoquinone** is counteracted by menadione. 



Other inhibitory actions of menadione have been demonstrated, again 

 without information as to the specificity of the inhibition. Menadione and 

 derivatives shorten the life of Daphnia magna f^ inhibit the gro^vth of roots 

 of Allium cepa, the onion roots becoming yellow and flaccid within a week;*^ 



32 H. J. Almquist and E. L. R. Stokstad, J. Nutrition 12, 329 (1936). 



33 H. Dam and J. Glavind, Biochem. J. 32, 485 (1938); J. Erkama and N. Pettersson, 

 Acta Chem. Scand. 4, 922 (1950). 



" L. D. Wright, J. Am. Dietet. Assoc. 23, 289 (1947). 



" M. Gu(5rillot-Vinet, Bull. soc. chim. biol. 30, 863 (1948). 



36 F. Mul6, II Policlinico {Rome) sez. prat. 53, 653 (1946). 



37 L. Donatelli and R. Davoli, Boll. soc. ital. biol. sper. 22, 134 (1946). 



38 A. Kimler, J. Bacteriol. 60, 469 (1950). 



33 L. Nassi, Boll. soc. ital. biol. sper. 22, 141 (1946). 



^0 C. N. Hand, Nature 161, 1010 (1948). 



<i J. Naghski, M. J. Copley, and J. F. Couch, Science [N. S.] 105, 125 (1947). 



« H. Mcllwain, Biochem. J. 37, 265 (1943). 



" D. W. Woolley, Proc. Soc. Expll. Biol. Med. 60, 225 (1945). 



" V. Schecter, Proc. Soc. Exptl. Biol. Med. 74, 747 (1950). 



" M. Levine and S. A. Rice, Proc. Soc. Exptl. Biol. Med. 74, 310 (1950). 



