The Phosphatides of Hevea Brasiliensis

The presence of phosphatide in Hevea latex had long been suspected, but it was not until 1931 that Rhodes and Bishop isolated phosphatidic material containing 0.59 per cent nitrogen and 1.72 per cent phosphorus from the serum of latex which had been coagulated with ethanol. The crude material of these authors represented 0.2 per cent of the latex and, on treatment with acetone, yielded an insoluble fraction containing 0.88 per cent nitrogen and 2.56 per cent phosphorus (40 per cent of the former product). This latter fraction was, according to the accepted analytical composition of phosphatide, still very impure. The work of Rhodes and Bishop was repeated by Altman and Kraay, who isolated in very small amounts a product which gave much the same analyses, and extended the findings of Rhodes and Bishop by showing that the crude phosphatide contained both choline and glycerophosphoric acid. It is very probable that the phosphatide, although present in such small amount, is one of the important nonrubber components of latex. Judging from the ease with which phosphatides emulsify in aqueous media, there seems little doubt that the phosphatidic material assists in the maintenance of latex as a stable emulsion. It has been suggested by Bollman that crude phosphatide preparations act as natural antioxidants in vegetable oils. This suggestion has been disputed by Diemair and Fox and other workers, who state that this property is not possessed by pure phosphatide, although the complex system from which the phosphatide had been separated was an active antioxidant. Diemair, Strohecker and Reuland have advanced the opinion that the active antioxidant is a protein-phosphatide complex. The present work was undertaken as part of an investigation of the non-rubber components of latex. The crude phosphatide was prepared by the method of Rhodes and Bishop, the preliminary treatment being carried out at the Rubber Research Laboratories, Ceylon, under the direction of Mr. O'Brien, to whom the author's thanks are due. The raw material was treated by the method outlined below. The crude phosphatide was fractionated by a method which was essentially that used by Channon and Foster in their work on the phosphatides of wheat germ. The fractionation resulted in the isolation of a fairly pure form of phosphatidic acid (the possible source of which is discussed later) and an impure form of lecithin. The lecithin fraction contained little or no kephalin (only about 5.5 per cent of the nitrogen in this fraction was amino-nitrogen), a finding which was unexpected.