The lyophilized stone matrix, prepared by exhaustive dialysis of pulverized stones against 10 per cent
EDTA and water, yielded 9.6 +/- 0.9 mg per cent of
lipids. Following fractionation of the
lipid extract on
silicic acid columns, 57 per cent of
lipids were found in the neutral
lipid fraction, 40 per cent in the
glycolipid fraction and 3 per cent in the
phospholipid fraction. Of the total neutral
lipids, 77.3 per cent were represented by
free fatty acids, 14.7 per cent by
cholesterol, 4.1 per cent by
triglycerides and 3.2 per cent by
cholesterol esters. The
glycolipid fraction was comprised of simple
glycosphingolipids (11.3 per cent), mainly lactosyl- and
glucosylceramides, and of neutral and sulphated
glyceroglucolipids (88.7 per cent). The sulphated
glyceroglucolipids consisted of tri- and tetraglucosyl
glyceroglucolipids, whereas hexa- and octaglucosyl
glyceroglucolipids were the predominant constituents of the neutral glyceroglucolipid fraction. The
phospholipids exhibited a high content of
sphingomyelin (22.3 per cent),
phosphatidylcholine (12.1 per cent),
phosphatidylethanolamine (11.4 per cent),
phosphatidylserine (10.5 per cent) and
lysophosphatidylcholine (13.3 per cent). The major
fatty acids of the neutral
lipid fraction were hexadecanoate,
octadecanoate and octadecenoate. The
glycolipids contained large quantities of hexadecanoate and tetracosanoate, while the hexadecanoate,
octadecanoate and tetracosanoate were the principal
fatty acids of the
phospholipid fraction.