Homogeneous polymeric proanthocyanidins have been isolated from 22 plant sources and all are based on a C(4)-C(8) [or C(S)] linked polyflavan-3-01 structure. I3C N.m.r. spectroscopy in 2[H,]acetone-water is used to calculate the ratio of procyanidin to prodelphinidin monomer units, the average heterocyclic ring stereochemistry of the monomers, and the ratio of monomers to chain-terminating units. The majority of polymers isolated in this study possess monomers with predominantly a 2,3-cis stereochemistry [the same configuration as (-) -epicatechin],The number-average molecular weight, calculated from monomer to terminal unit ratios, of the polymers is 1 500-5 000. The structure of the chain-terminating group is established by thiolysis degradation and g.1.c. analysis of the products.

Two populations of Polynesians living on atolls near the equator provide an opportunity to investigate the relative effects of saturated fat and dietary cholesterol in determining serum cholesterol levels. The habitual diets of the toll dwellers from both Pukapuka and Tokelau are high in saturated fat but low in dietary cholesterol and sucrose. Coconut is the chief source of energy for both groups. Tokelauans obtain a much higher percentage of energy from coconut than the Pukapukans, 63% compared with 34%, so their intake of saturated fat is higher. The serum cholesterol levels are 35 to 40 mg higher in Tokelauans than in Pukapukans. These major differences in serum cholesterol levels are considered to be due to the higher saturated fat intake of the Tokelauans. Analysis of a variety of food samples, and human fat biopsies show a high lauric (12:0) and myristic (14:0) content. Vascular disease is uncommon in both populations and there is no evidence of the high saturated fat intake having a harmful effect in these populations.

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1. The carcass composition, the composition and characteristics of the subcutaneous and longissimus dorsi muscle fats, the volatile fatty acids of the rumen-reticulum fluid and the degree of flavour and odour of the cooked 12th rib chops of two groups each of fifteen Southdown–Romney cross ewe and wether lambs fed respectively white clover and perennial ryegrass have been determined. The lambs had been on treatment for 5 months and were slaughtered when about 9 months of age.2. The white clover-fed lambs had a mean live weight at slaughter of 94 lb ± 9 lb compared with 67 lb ± 7 lb for the perennial ryegrass-fed lambs. The carcasses of the white clover-fed lambs had greater (P < 0·01) amounts of fat.3. The iodine values of the subcutaneous fats of the white clover-fed lambs were highly significantly greater than those of the ryegrass-fed lambs and this result was consistent with the greater deposition of endogenous fat.4. The extra fatness of the white clover-fed lambs was consistent with their greater production of rumen-reticulum volatile fatty acids.5. The maj or differences in fatty acid composition of subcutaneous and intramuscular fats between pasture treatments were the highly significant increases in shorter-chain saturated and C15 branched-chain acids of the ryegrass-fed lambs. In addition, the subcutaneous fat of the ryegrass group contained highly significantly more octadecadienoic and octadecatrienoic acids while the 1. dorsi fat of the ryegrass group was highly significantly richer in stearic and oleic acids.

Sunzmary A combination of 13C n.m.r., chiroptical, and chemical degradation evidence proves t h a t polymeric proan thocyanidins consist exclusively of repeating flavan-3-Oi units.RECENT work has elucidated the chemistry of dimeric procyanidins,1*2 but little is known of the corresponding polymers which, quantitatively, are of greater significance in most plants.2 Current techniques enable the isolation and purification of the polymers in an undegraded state3 and the structural homogeneity of proanthocyanidins so isolated is now demonstrated.