Two polysaaccharides designated I and I1 have been isolated from the gum component of olibanum, the gum oleoresin from Boswellia carteri. Polysaccharide I is neutral and composed of galactose and arabinose in equimolecular ratio. Polysaccharide I1 is acidic and composed of galactose and galacturonic acid in the molar ratio 2 : 1. OLIBANUM, the gum oleoresin exuded from the incense tree Boswellia, has been extensively studied. Most of the work dealt with the chemistry of its resin and its essential oils and little is known of its gum component. Tschirch and Halbey 1 isolated an acidic gum after removing the essential oils and resinous matter by extraction with 90% alcohol. The gum was in the form of a salt containing calcium and magnesium. Malandkar isolated from the Indian variety of olibanum, Boswellia serrata, a gum which was also acidic; on hydrolysis with 3% sulphuric acid it yielded arabinose, xylose, and galactose. The present work had as its objective the isolation of the pure gum components and a study of their structures.Commerical East African olibanum from Boswellia carteri was used. The essential oils and resins were removed by ether-extraction, leaving a water-soluble gum, completely precipitated by 3 volumes of ethanol and containing 11% of inorganic matter, mainly calcium. Demineralisation with cation-exchange resin then gave an acidic gum mixture. Precipitation with 3 volumes of ethanol yielded a neutral gum, polysaccharide I (26%), and the major portion (59%) was precipitated only after further addition of 3 volumes of acetone, yielding an acidic gum, polysaccharide 11. Both polysaccharides were purified by repeated precipitation with alcohol and acetone.Its mean reducing power determined by the methods of Meyer, Noelting, and BernfeldJ3 and Jendrassik and Polgar * was 4*1%, corre-Polysaccharide I had [a]: -114.7".Polysaccharide I1 had [a]: -9.2".

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Aus e‐Rhodomycinon (I) erhält man mit dem Glykosylchlorid (II) ein Substitutionsprodukt (III), das zu (IV) hydrolysiert wird.