182 ASCORBIC ACID 



Szent-Gyorgyi that his hexuronic acid was also antiscorbutically ac- 

 tive,"' ^^''^ strongly suggested that these crystalline materials were in fact 

 vitamin C, a conclusion which was in line with a suggestion to this effect 

 made previously by Tillmans from a series of investigations on vitamin 

 C.^"' " However, there was still some doubt about this conclusion, because 

 relatively large doses of the so-called pure crystalline hexuronic acid wxre 

 re^^'iired to cure scurvy whereas with other deficiency diseases very much 

 sm'allet doses of the appropriate vitamin or vitamin concentrates were 

 already known to be capable of effecting a cure. This gave support to the 

 view that the active principle was present in the crystalline hexuronic acid 

 as a contaminant no matter how many times it was recrystallized. Against 

 this view, however, could be advanced the observation that all the samples 

 of hexuronic acid, irrespective of their source, had the same antiscorbutic 

 activity. It was further shown that, whereas the crystalline monoisopro- 

 pylidene derivative of hexuronic acid was inactive, the hexuronic acid re- 

 generated from it by hydrolysis had the same antiscorbutic activity as the 

 original material from which the isopropylidene derivative was prepared.^' 

 All doubts about hexuronic acid's being the true vitamin were finally re- 

 moved when it was found that synthetic hexuronic acid, or ascorbic acid 

 as it was later called, had exactly the same physiological activity as the 

 hexuronic acid isolated from natural sources.'^- -'• 



B. NATURAL OCCURRENCE OF l- ASCORBIC ACID 



Since the first isolation of this crystalline vitamin in 1928,^- a great deal 

 of work has been done in determining the ascorbic acid content of many 

 foods, fruits, vegetables, and plants, and it is now apparent that ascorbic 

 acid is widely distributed in the plant and animal kingdoms. The paprika 

 plant (Capsicum sp.) found by Szent-Gyorgyi to be an excellent source of 

 the vitamin'^ is now rivaled by such sources as rose hips (Rosa sp.),"' -^' -- 

 pine needles,^^ sea buckthorn berries (Hippophae rhamnoides) ,-^ and guava 

 (Psidium guayava L.).^** A search for alternative sources of ascorbic acid 



16 J. L. Svirbely and A. Szent-Gyorgyi, Nature 129, 576 (1932). 

 16 J. L. Svirbely and A. Szent-Gyorgyi, Nature 129, 690 (1932). 

 " J. L. Svirbely and A. Szent-Gyorgyi, Biochem. J. 26, 865 (1932). 



18 T. W. Birch, L. J. Harris, and S. N. Ray, Nature 131, 273 (1933). 



19 T. Reichstein, A. Griissner, and R. Oppenauer, Helv. Chim. Acta 16, 1019 (1933). 

 2" W. N. Haworth, E. L. Hirst, and S. S. Zilva, ./. Chem. Soc. 1934, 1155. 



21 G. Hunter and J. Tuba, Can. Med. Assoc. J. 48, 30 (1943) ; G. A. Kepkova, Compt. 

 rend. acad. sci. U.R.S.S. 48, 655 (1945) [r*. A. 40, 6124 (1946)]. 



22 O. Shnaidman, Pishchevaya Prom. 1943, No. 1/2, 5 [C.A. 40, 113 (1946)]. 



23 F. Rriihne, Dent. Apoth. Ztg. 58, No. 61/62; Dent. Heilpflanze 45 (1943) [C.A. 39, 

 2585 (1945)]; A. Jermstad and E. Brockmann-Hansen, Medd. Norsk Farm. Selskap 

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2< H. E. Munsell, Food Research 10, 42 (1945). 



