Well-defined Absorption Bands Research Articles

Cholesterol and Vitamin D

BILLS, Honeywell and MacNair have recently demonstrated (Jour. Biol. Ghem., 76, 251 ; 1928) that both ergosterol and ordinary purified cholesterol, in addition to the previously observed well-defined absorption bands at 293.5, 281.5, and 270 μμ (Morton, Heilbron and Kamm, Biochem. Jour., 21, 78; 1927), exhibit a faint but distinct band at 260 μμ. They have also discovered that cholesterol purified by a thrice repeated conversion into the dibromide and recovery from same by treatment in boiling alcohol with zinc dust (so-called cholesterol E) can, contrary to the contentions of Windaus and Hess (Nach. Ges. Wiss. Gottingen, math.-physik. Klasse, 175 ; 1927) and Rosenheim and Webster (Biochem. Jour., 21, 389 ; 1927), still be activated by ultra-violet rays. According to the American workers, this activatability is associated with faint absorption bands at 315 and 304μμ as well as the three characteristic ergosterol bands.