546 THE BIOCHEMISTRY OF B VITAMINS 



however, if it is analogous to biotin, only one of the optically active 

 forms would be expected to be biologically active. 



As indicated in Table 12, this oxygen analogue of biotin is capable of 

 replacing the vitamin in the nutrition of a wide variety of organisms. 

 For Lactobacillus arabinosus and Lactobacillus pentosus 124-2, DL-oxy- 

 biotin is as active as DL-biotin, giving growth responses at various 

 concentrations identical with those obtained with biotin. However, the 



Table 12. The Biological Activity of Dh-Oxijbiotin (O-Helerobiotin). 



Activity 

 per cent 

 Organism of (+) biotin Reference 



Rat 6.0-2.9^ e 27 - 28 - 31 



Chicks 17* 27 ' 29 



20-2'. d 30 



Lactobacillus arabinosus 50* 24 ' 41 



Lactobacillus pentosus 124-2 50 33 



Lactobacillus casei 40 2i - 34 



22-25 23 ' 31 



Streptococcus faecalis R 0(pH 6.6)' 32 



7.5(pH 7.3)' 32 



Rhizobium trifolii 12-1.3" 34 



Saccharomyces cerevisiae 25-10 c 23 ' 24, 31 - 34 



Saccharomyces carlsbergensis 20 9 31 



° If the biological activity resides in only one of the optically active forms of the oxygen analogue, these 

 values should be doubled. 



4 Biotin deficiency induced by feeding raw egg white with biotin deficient diet; DL-oxybiotin injected 

 intramuscularly or subcutaneously. 



• The activity of the analogue relative to ( + ) biotin varies at different concentrations of the analogue; 

 i.e., the dose-response plots differ in shape for the two compounds. The relative activity of the analogue 

 tends to decrease with increases in concentrations. 



d Animals on biotin deficient diet only. 



« Activities of 29-44 per cent dependent upon pH of the medium have been reported. 32 



/ Activity reported to be dependent upon pH of medium. 



» Slight variations at different concentrations. 



activity of this analogue is not so pronounced for other organisms, and 

 relative to biotin, this analogue is often less effective in obtaining the 

 maximum response of the organism than in eliciting a suboptimal re- 

 sponse. This is particularly true of Rhizobium trifolii and Saccharomyces 

 cerevisiae. For Saccharomyces cerevisiae, oxybiotin is approximately 25 

 per cent as effective as ( + ) biotin in stimulating the fermentation rate 

 of biotin-deficient cells. 40 



It is interesting to note that the activity of oxybiotin for Streptococcus 

 faecalis R has been reported to be dependent upon the pH of the medium. 

 The analogue is approximately 7.5 per cent as active as ( + ) biotin at 

 pH 7.3, but it is essentially inactive at pH 6.6. 



In the rat oxybiotin administered by daily subcutaneous injections 

 completely cured the skin lesions resulting from biotin deficiency caused 

 by feeding raw egg white, and spastic paralysis of the hind legs observed 

 in a few animals was also completely cured with the oxygen analogue. 28 

 In stimulating growth, DL-oxybiotin was from 2.9 to 6.0 per cent as 



