30 II. CHEMISTRY OF FATTY ACIDS AND (3LYCEKOL 



structure has not been established. Convolvuhnohc acid is an unusual 

 biological acid, since it contains an odd number of carbon atoms. Ap- 

 parently it is present in the roots of plants of the Convolvulaceae family. '''- 

 As a result of the studies of Asahina and Akasu,^"^ the structure was es- 

 tablished as 1 1-hydroxypentadecanoic acid, CH3(CH2)3CHOH(CH2)9- 

 COOH. An optically active monohydroxypalmitic acid has been sep- 

 arated from butter fat by Bosworth and Helz,^"' but the position of the 

 hydroxyl group has not been established. The acid is believed to differ 

 from any palmitic acid previously reported. 



Dihydroxystearic acid is the only natural hydroxy-acid having two hy- 

 droxyl groups. It has been recognized as a component of a number of 

 fats, but its cliief source is castor oil.^"^^"'"^ It is of especial physiologic in- 

 terest because of the suggestion that it might have special nutritive proper- 

 ties.^"^ This question has, howe\'er, been answered in the negative. 



Several saturated acids and one unsatiu'ated hydroxy-acid are present 

 in the cerebrosides, which are largely found in the l)rain.'^-*'"'^ The 

 hydroxyl group is belie\'ed to be free in these compounds. It is not known 

 whether or not this fact contributes anything to the functional acti\'ity of 

 the nervous tissue. 



b. Unsaturated Hydroxy- and Keto-Acids. (a) Ricinoleic Acid. 

 Ricinoleic acid is the most imj)ortant of the lu'droxy-acids. It is the 

 only one of this group which is present in the oils in a large enough pro- 

 portion to be of economic importance. Bussy and Lecanu,"' as early as 

 1827, noted that the products of distillation of castor oil differed from 

 those of other fats. The structure of ricinoleic acid was established by 

 Goldsobel,"- in 1894, as I2-hydrox3^-9-octadecenoic acid, CH;5(CH2)5- 

 CHOHCHoCH : CH(("H2)7CO()H. 



Ricinoleic acid, as the triglyceride triricinolein, accounts for 80% of cas- 

 tor oil.'°^ Ricinoleic acid is also present in oil of ergot (Secak' cortDdum),^^^ 



i»2 M. Hoehnel, Arch. Fhurm., 234, 647-685 (1896). 



'03 Y. Asahina and M. Akasu, J. Pharm. Soc. Japan, No. 523, 779-786 (1925): Chnn. 

 AbsL, 20, 365 (1926). 



'0^ A. W. Bosworth and G. Iv Helz, J. Biol. Chem., 112, 489-492 (1936). 



"» A. Eil)nor and E. Miinzing, Chem. Umschau, 32, 153-162; 166-176 (1925); Chmi. 

 AbsL, 19, 3027 (1925). 



">« P. Panjutin and M. Kapopoit, Chem. Vnisehau, 37, 130-135 (1930); Chem. AbsL, 

 24, 3665 (1930). 



'»' H. P. Kaufmann and H. Boinhardt, Fetle n. Seifeu, 46, 444-446 (1939); Chem. 

 AbsL, 34, 3521 (1940). 



'"» R. S. Harris, H. Sherman, and E. Iv Lofkhart, Arch. Biochem., 6, 63-70 (1944). 



i»9 E. Klenk, Z. phtjsioL Chem., 153, 74-82 (1926); 166, 287 293 (1927); 17H, 312-319 

 1928); /S.5, 169-182 (1929); iW), 51-68 (1931); ,'^06', 25-40 (1932). 



"» A. C. Chibnall, S. H. Piper, and E. F. Williams, Biuchem. J., 30, 100-114 (1936). 



'" A. Bussv and L. R. Lecanu, J. pharm. chim. [2] 13, 57-81 (1827). 



"2 A. G. Goldsobel, Ber., 27, 3121-3129 (1894). 



"3 H. Alatthes and P. Schiitz, .4rc/*. Pharm., 265, 541-546 (1927). 



