Abstract
Coincident with the isolation of crystalline stercobilin,1, 2 a substance resembling mesobiliviolin as first described by Fischer and Niemann 3 was regularly found in human feces. 2 Mesobiliviolin, as described by Fischer and Niemann, 3 exhibited absorption in the region of 600 and 500 mm. and showed green fluorescence with Zn acetate, the solution of the zinc salt having absorption at 626, 573, and 500. The similar substance found in feces had very similar characteristics, 2 and was consequently given the name kopromesobiliviolin.
It has now been determined that this substance still contained stercobilin as an impurity which accounted for the absorption in the region of 500 mm. as well as the green fluorescence of the zinc salt. Their complete separation has now been effected by virtue of the somewhat greater solubility of mesobiliviolin in ether. After this separation, the violet pigment obtained possesses no “urobilin” absorption. Its hydrochloride has a more bluish violet color with 2 closely adjacent absorption bands, the narrower from 608-598 (max. 604) and the broader 594-550 (max. 575). The free substance has one broad band 587-570 (max. 578-582). On treatment with alcoholic zinc acetate the color of the solution becomes a light blue and a beautiful intense red fluorescence is exhibited. This solution has the following absorption: 625-627 (well defined, narrow), 583, max. (faint, broader).
The most highly purified substance was obtained in the following way: (1) repeated acetic ether extraction of the stool; (2) removal of the ether by vacuum distillation; (3) precipitation of fatty acids and koprosterin by dilution of the remaining acetic acid solution with a large volume of 1% HCl; (4) repeated ether extraction after making the aqueous filtrate congo negative with sodium acetate.
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