We describe a sensitive and specific assay for the determination of the plant lignan secoisolariciresinol, one of the main dietary precursors to the mammalian derived lignans, enterodiol and enterolactone. Quantification of secoisolariciresinol aglycone is achieved by reversephase high-performance liquid chromatography with multichannel electrochemical detection after hydrolysis of the glycoside moieties. This approach affords greater specificity than conventional ultraviolet detection and has a detection limit of 2.8 pmol. The method is ideally suited to the determination of secoisolariciresinol in processed flaxseed samples and can be used to assess the level of incorporation of flaxseed in fortified foods.

No abstract

A method is presented which allows one to measure the permeable volume of the renal cortex to substances which are transported or actively accumulated by the renal cortex. This permeable volume in rat and rabbit renal cortical slices has been measured using PAH, Diodrast and Urokon as the transported substances. It is less than the volume of tissue water. Therefore, a volume of the renal cortex must be impermeable to these substances. It is postulated that all or part of the impermeable volume is made up of the tubular cells. The permeable volumes are 0.474 cc/gm tissue for PAH, 0.542 cc/gm tissue for Diodrast, and 0.447 cc/gm tissue for Urokon, as compared to 0.771 cc/gm for the tissue water. The active accumulation of these substances by rabbit renal cortical slices after 90– 130 minutes is 10.10 µm/gm for PAH, after 90 minutes is 1.90 µm/gm for Diodrast, and after 60–150 minutes is 3.20–3.53 µm/gm for Urokon.