260 THE BIOCHEMISTRY OF B VITAMINS 



select diets rich in some factor which may be deficient in their nutrition, 

 and this would seem to provide still another approach to the assessment 

 of the B vitamin requirements of certain species. However, because of 

 the imperfect understanding of the phenomena involved and due to the 

 relatively recent inception of this type of study, 71 little progress has been 

 made with regard to this particular aspect of self-selection diets. Scott 

 et al. 12 - 73 have shown clearly, however, that in rats fed appropriately 

 deficient diets (but not in normal controls) appetites are developed for 

 thiamine, riboflavin, and the vitamins B 6 , but not for pantothenic acid. 

 Much progress in this field will undoubtedly be made in the years im- 

 mediately ahead as our understanding of the physiological nature of 

 specific hungers is further developed. (See p. 433.) 



The Use of "Anti-Vitamins." Finally, it is worthy of mention that 

 the new and rapidly developing study of anti-vitamins has contributed 

 in some degree to our knowledge of B vitamin requirements and seems to 

 provide an unique approach to their study. Later sections of this mono- 

 graph will consider in detail how avidin has made possible the elucidation 

 of the biotin requirement of various species (p. 428), how live yeast 

 has been used to produce thiamine depletion (p. 291), and how the sulfa 

 drugs have been similarly employed (p. 298) . It seems possible that the 

 requirements for as yet unidentified members of the B vitamin group 

 may await studies of this kind. Challenging in its implications for future 

 possibilities along these lines is the recent work involving lyco-marasmine. 

 Plattner and Clausen-Kaas 74 isolated from Fusarium lycospersici Sacc. 

 a substance, "lyco-marasmine," which is responsible for the wilting of 



H 2 N— CO— CH 2 CH 3 



HOOC— CH— NH— CO— CHo— NH— C— OH 



COOH 

 Lycomarasmine (after Woolley) 



plants on which the Fusarium is parasitic. Analysis of this substance 

 has indicated the probability of a tripeptide nature involving serine, 

 glycine and aspartic acid,. Strepogenin (p. 15), a possible new member 

 of the B vitamin group, is considered to be similar in structure, and 

 because of this it was thought that an anti-vitamin relationship might 

 exist. This is apparently so, since strepogenin reverses the toxic action of 

 lycomarasmine, and it therefore seems likely that strepogenin is important 

 in the higher plants (as it is in bacteria). This conclusion is based on 

 reasoning by methods analogous to those used in explaining the reversal 

 of sulfa drug bacterial inhibition with p-aminobenzoic acid (Chapter 



IIID ) 75,76 



