Effects of kale (Brassica oleracea L. var. acephala DC) leaves extracts on the susceptibility of very low and low density lipoproteins to oxidation.

Of Brassicaceous plants, kale (Brassica oleraceae L. var. acephala DC) contains polyphenols, flavonoids, isoflavones and glucosinolates and so has antioxidant and anticarcinogenic properties. Antioxidants inhibit negative effects of free radicals and may, therefore, protect tissues against oxidative damage. Oxidation of lipoproteins is a key event in the development of atherosclerosis. In the current study, the levels of total phenolic and flavonoid contents and total antioxidant capacity of methanolic and aqueous extracts of kale leaves were determined. In addition, the susceptibility of isolated lipoproteins — very low density lipoprotein (VLDL) and low density lipoprotein (LDL) to the Cu2+-induced oxidation with various concentrations of metanolic and aqueous extracts was evaluated as t-lag values. Although aqueous extract had higher total antioxidant capacity, methanolic extract had higher total phenolic and flavonoid content (P<0.05). On the other hand, both extracts inhibited lipid peroxidation in both isolated VLDL and LDL. Inhibitory effect of extracts or increasing t-lag values, mainly in methanolic extract was found to be related to increasing the concentration of extracts. It was concluded that because of high antioxidant capacity and phenolic content, kale showed a protective effect on the oxidation of lipoproteins. Therefore, it may be speculated that kale consumption may play an important protective role in the cardiovascular and other related diseases resulting from imbalance of oxidant and antioxidant status.

Alterations in dense LDL subfractions in normolipidemic IDDM patients

Low density lipoproteins (LDL) of human plasma, consist of a continuum of particles subclasses with distinct physicochemical, immunological and hydrodynamic characteristics. Such structural differences are intimately linked to atherogenesis. The current sludy was designated to investigate the LDL subclasses profile in 12 normolipidemic IDDM patients, and compare it with 11 healthy controls. Four plasma LDL subfractions were isolated by sequential ultracentrifugation in the density range (1.025- 1.063 g/ml) and were characterized by their content of free and esterified cholesterol, triglycerides, phospholipids, and proteins. The net electrical charge was evaluated. Plasma concentration of the two denser LDL subfractions were higher in IDDM patients vs control subjects, due to an increase in cholesterol (free and esterified and phospholipids, while more buoyant subfractions in the two groups were not diferent. In IDDM patients the LDL profile was skewed towards the dense subclasses LDL-III and LDL-IV, being significant this increase for LDL-IV: 22.3 ñ 5.2 vs 18.3 ñ 4.0 per cent, p<0.05, XñDS. In the healthy controls the LDL profile was skewed toward the lighter subclasses (LDL-I and LDL-II), being significant for LDL-II: 30.0 ñ 4.3 vs 23.3 ñ 4.2 per cent, p<0.005. Diabetic patients, even those who are normolipidemic, present increased risk of premature atherosclerosis. This suggest that normal values in lipid and lipoprotein profile can mask deeper alterations, such as changes in the composition and distribution of the denser subclasses, whose characteristics make them potentially more atherogenic. Despite the apparently normolipidemic status, dense LDL particles considered to be atherogenic, are increased in IDDM patients.