ABSTRACT
The human UDP-glucuronosyltransferase 1A1 (UGT1A1), one of the most essential conjugative enzymes, is responsible for the metabolism and detoxification of bilirubin and other endogenous substances, as well as many different xenobiotic compounds. Deciphering UGT1A1 relevance to human diseases and characterizing the effects of small molecules on the activities of UGT1A1 requires reliable tools for probing the function of this key enzyme in complex biological matrices. Herein, an easy-to-use assay for highly-selective and sensitive monitoring of UGT1A1 activities in various biological matrices, using liquid chromatography with fluorescence detection (LC-FD), has been developed and validated. The newly developed LC-FD based assay has been confirmed in terms of sensitivity, specificity, precision, quanti-tative linear range and stability. One of its main advantages is lowering the limits of detection and quantification by about 100-fold in comparison to the previous assay that used the same probe substrate, enabling reliable quantification of lower amounts of active enzyme than any other method. The precision test demonstrated that both intra- and inter-day variations for this assay were less than 5.5％. Further-more, the newly developed assay has also been successfully used to screen and characterize the regu-latory effects of small molecules on the expression level of UGT1A1 in living cells. Overall, an easy-to-use LC-FD based assay has been developed for ultra-sensitive UGT1A1 activities measurements in various biological systems, providing an inexpensive and practical approach for exploring the role of UGT1A1 in human diseases, interactions with xenobiotics, and characterization modulatory effects of small mole-cules on this conjugative enzyme.
ABSTRACT
Schisandra is the mature fruit of Schisandra chinensis(known as "north Schisandra") or S. shenanthera(known as "south Schisandra"). S. chinensis contains a variety of lignans, volatile oils, polysaccharides, organic acids and other chemical constituents; among them, lignans are recognized as the characteristic active components. Clinical studies have found that Schisandra and Schisandra-related products have a better effect in the prevention and treatment of viral hepatitis, drug-induced liver injury, liver cirrhosis, liver failure and other liver diseases. Modern pharmacological studies have demonstrated that Schisandra has a variety of pharmacological activities, such as anti-inflammation, antioxidation, anticancer, regulation of nuclear receptor, antivirus, regulation of cytochrome P450 enzyme, inhibition of liver cell apoptosis and promotion of liver regeneration. This paper reviews the studies about the applications and mechanism of Schisandra in the prevention and treatment of liver diseases, in the expectation of providing guidance for the development of hepatoprotective drugs from Schisandra and the clinical applications of Schisandra-related products.