636 X. VITAMINS D 



ergostero], 7-dehydrocholesterol, and 22-dihydroergosterol have been re- 

 ported from various sources. Boer and his group'''*''°^''-^ described the 

 preparation of provitamins D in patents granted. They obtained the 

 provitamins from various invertebrates: the stick-insect (Carausius moro- 

 sus), the leech (Hirudo medicinalis), the meahvorm (Tenebrio molitor), 

 the diving water-beetle {Dytiscus marginatus) , the earthworm (Lumbricus, 

 spp.), the periwinkle (Littorina littorea), the swan mussel (Anodonta cygnea), 

 the whelk (Buccinum undatum), the field slug (Limax agrestis), the edible 

 crab (Cancer pagurus) , the European flat oyster {Ostrea edulis) , the edible 

 sea-mussel {My tilts edulis) and the waterworm {Tubifex, spp.).^''^'"'^'^^^ 

 The provitamin D obtained from the earthworm, Lumbricus terrestris, is 

 believed to be a mixture of ergosterol and a second undefined provitamin D. 

 A second one from the waterworm, Tubifex, according to Bills,- is probably 

 a mixture, although van Vliet^^ reported an efficacy ratio of 100% for the 

 activated material. Mytilis edulis is believed by van Vliet^^ to consist of 

 three components, which are 7-dehydrocholestero], ergosterol, and a sub- 

 stance tentatively identified as 22-dehydro-7-dehydrocholesterol.2 Rosen- 

 berg and Waddell^^^ report an efficacy ratio of 71% for this provitamin D; 

 in all probability this low ratio is ascribable to its high ergosterol content. - 

 Kind and Harman'^^ are of the opinion that the provitamin D in the Euro- 

 pean perinwinkle, Littorina littorea, is 7-dehydroclionasterol, although the 

 purified activated product was reported ^^ to have an efficacy ratio of 100%. 

 Bills^ considers that this activity is inconsistent with the presence of an 

 ethyl group in the side chain, which would rule out 7-dehydrochonasterol 

 as the mother substance. The so-called provitamin Dm (in which "m" 

 refers to Modiolus), was isolated from the provitamin D of the ribbed 

 mussel (formerly known as Modiolus demissus, Dillwyn, but designated in 

 the new terminology as Arcuatula demissa), by Petering and Waddell.^^ 

 It is believed to have twenty-nine carbons. It yields a vitamin D which 

 has an efficacy ratio 10 to 20% higher than that of cod-liver oil.'-^ A num- 

 ber of workers have prepared the provitamin D from the ribbed 

 mussel.^2,126.128 



(3) The Vitamins D 



A number of different compounds have been found to possess antirachitic 

 potency, although they are known to vary from each other both quahta- 



12B A. G. Boer, J. van Niekerk, E. H. Reerink, and A. van Wijk, U. S. Patent No. 2- 

 216,719 (Oct. 8, 1940). 



126 H. R. Rosenberg and J. Waddell, /. Biol. Chem., 191, 757-763 (1951). 

 1" C. A. Kind and S. C. Harman, /. Org. Chem., 13, 867-869 (1948). 

 1*8 H. R. Rosenberg, U. S. Patent No. 2,475,917 (July 12, 1949). 



