Macular pigment (MP) is composed of lutein (L), zeaxanthin (Z) and meso-zeaxanthin (MZ). The present study reports on serum response to three different MP supplements in normal subjects (n 27) and in subjects with age-related macular degeneration (AMD) (n 27). Subjects were randomly assigned to: Group 1 (20 mg L and 2 mg Z), Group 2 (10 mg L, 2 mg Z and 10 mg MZ) or Group 3 (3 mg L, 2 mg Z and 17 mg MZ). Serum carotenoids were quantified at baseline, and at 4 and 8 weeks using HPLC. Response data for normal and AMD subjects were comparable and therefore combined for analysis. We report response as the average of the 4-and 8-week concentrations (saturation plateau). Serum L increased significantly in Group 1 (0·036 mmol/l per mg (269 %); P,0·001) and Group 2 (0·079 mmol/l per mg (340 %); P,0·001), with no significant change in Group 3 (0·006 mmol/l per mg (7 %); P¼0·466). Serum Z increased significantly in Group 1 (0·037 mmol/l per mg (69 %); P¼ 0·001) and Group 2 (0·015 mmol/l per mg (75 %); P,0·001), with no significant change in Group 3 (20·0002 mmol/l per mg (26 %); P¼0·384). Serum MZ increased significantly in Group 1 (0·0094 mmol/l (absolute value); P¼ 0·015), Group 2 (0·005 mmol/l per mg; P,0·001) and Group 3 (0·004 mmol/l per mg; P,0·001). The formulation containing all three macular carotenoids (Group 2 supplement) was the most efficacious in terms of achieving the highest combined concentration of the three MP constituent carotenoids in serum, thereby potentially optimising the bioavailability of these compounds for capture by the target tissue (retina).
Dispersive liquid-liquid microextraction (DLLME) is an extraction technique developed within the last decade, which involves the dispersion of fine droplets of extraction solvent in an aqueous sample. Partitioning of analytes into the extraction phase is instantaneous due to the very high collective surface area of the droplets. This leads to very high enrichment factors and very low solvent consumption, relative to other liquid or solid phase extraction methods. A comprehensive review of the various modes of DLLME in the analysis of organic and inorganic analytes in dairy products (milk, cheese, infant formula, yogurt, and breast milk) is presented here. Dairy products present a complex sample matrix and the removal of interfering matrix components can prove troublesome. This review focuses on sample pretreatment prior to the appropriate DLLME procedure, the extraction and dispersive solvents chosen, derivatisation methods, and analytical figures of merit. Where possible, a critical comparison of DLLME methods has been undertaken. The overall suitability, and limitations, of DLLME as a sample preparation technique for dairy products has been assessed.
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