Acid-soluble Pigments of Molluscan Shells

1. The isolation and properties of roseins I and II from the mycelium ofTrichothecium rogeum and of rosein III from the culture filtrate are described. 2. Rosein I, colourless tetrahedra, m.p. 2100, [oc]4112-5 in chloroform (c, 1) has the molecular formula C019H2603. It is a neutral ketone, which reacted with one equivalent of hot ethanolic alkali and yielded a lactone, i8orosein I, m.p. 144°, on acidification. The latter has an hydroxyl but no ketonic group. On oxidation with potassium permanganate, rosein I gave a monobasic acid, C16,H24, m.p. 2420. 3. Rosein II, C19H2803, crystallized in colourless fibrous needles, m.p. 1860, [CC]23° + 5.90 in chloroform (c, 2). It has no ketonic or hydroxyl groups, but its properties correspond to those of a lactone. Oxidation with potassium permanganate gave a monobasic acid, C018H2605, m.p. 2960. 4. Rosein III, C20H2804, crystallized from toluene in colourless plates, m.p. 2210, [oc]°1240inchloroform (c, 1). It was a neutral ketone which, on treatment with hot alkali, yielded i8orosein III, m.p. 155°. 5. Rosein II inhibited growth of Bacillu8 8ubtiha at 5 p.p.m. It was slightly active against Mycobacterium tuberculosis, inhibited Myco. phlei at 1 in 81,000 and had no effect on Myco. butyricum at 1 in 1000. Roseins I and III had no effect on three test bacteria and on Penicillium digitatum. 6. The bitter principle of Trichothecium ro8eum observed by Iwanoff (1904), and others has been shown to contain trichothecin.