We have reported that the protein-protein interaction between UDP-glucuronosyltransferase (UGT) 2B7 and cytochrome P450 3A4 (CYP3A4) alters UGT2B7 function. However, the domain(s) involved in the interaction are largely unknown. To address this issue, we examined in more detail the CYP3A4-UGT2B7 association by means of immunoprecipitation, overlay assay, and cross-linking involving 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. Purified CYP3A4 or glutathione transferase (GST)-tagged CYP3A4 was cross-linked to UGT2B7 in solubilized baculosomes. The formation of the cross-linked complex was detected by immunoblotting using both antibodies against CYP3A4 and UGTs. Although the GST-tagged CYP3A4 containing the region ranging from Tyr25 to Ala503 was cross-linked to UGT2B7, the same did not occur when another construct containing Met145 to His267 was used. This observation was consistent with the result of the overlay assay indicating that CYP3A4 lacking the N-terminal hydrophobic segment retains the ability to associate with UGT2B7, whereas the Met145-to-His267 region loses this capacity. Although the Met145-to-His267 peptide was recognized by one anti-CYP3A4 antibody that has the ability to coimmunoprecipitate UGT2B7, it was not recognized by another antibody incapable of coimmunoprecipitating UGT2B7. The epitope of the latter antibody was mapped to the Leu331-to-Lys342 region, which is located on the J-helix of CYP3A4. Taken together, the results obtained suggest that 1) CYP3A4 and UGT2B7 are a pair of enzymes in proximity to each other and 2) either the Leu331-to-Lys342 domain or the surrounding region plays a role in the interaction with UGT2B7, whereas the hydrophobic Met145-to-His267 region does not contribute to this interaction.Cytochrome P450 (P450) and UDP-glucuronosyltransferase (UGT) are two major enzyme groups responsible for phase I and II reactions, respectively (Guengerich, 1989;Oguri et al., 1994;Gonzalez and Lee, 1996;Ritter, 2000). These enzymes are localized on the cytosolic (P450) and luminal sides (UGT) of the endoplasmic reticulum (ER) membrane. UGT plays an important role in detoxifying drugs, including potent carcinogenic metabolites formed by P450 (Tukey and Strassburg, 2000). To minimize toxicity, it would be reasonable to expect that the reactive metabolite produced by P450 is directly transferred to the other enzymes participating in its subsequent metabolism (e.g., the UGTs) via protein-protein interactions. Our recent studies have suggested that CYP3A4 and other P450 isoforms interact with UGT2B7 to modulate the activity of the UGT (Ishii et al., 2005; Takeda et al., 2005a,b). The interactions between P450 and UGT occur also in rats, and the UGT in a P450-UGT complex is catalytically active (Ishii et al., 2007). These series

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Glucuronidation is one of the major pathways of metabolism of endo- and xenobiotics. UDP-Glucuronosyltransferase (UGT)-catalyzed glucuronidation accounts for up to 35% of phase II reactions. The expression and function of UGT is modulated by gene regulation, post-translational modifications and protein-protein association. Many studies have focused on drug-drug interactions involving UGT, and there are a number of reports describing the inhibition of UGT by xenobiotics. However, studies about the role of endogenous compounds as an inhibitor or activator of UGT are limited, and it is important to understand any change in the function and regulation of UGT by endogenous compounds. Recent studies in our laboratory have shown that fatty acyl-CoAs are endogenous activators of UGT, although fatty acyl-CoAs had been considered as inhibitors of UGT. Further, we have also suggested that adenine and related compounds are endogenous allosteric inhibitors of UGT. In this review, we summarize the endogenous modulators of UGT and discuss their relevance to UGT function.

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All of our findings suggests that PGV-0 could protect the liver cells from CCl4-induced liver damages and the mechanism may through the antioxidative effect of PGV-0 to prevent the accumulation of free radicals and protect the liver damage.

The present study aimed to examine the immunomodulatory effect of ethanolic extract of Typhonium flagelliforme (Lodd) Blume in cyclophosphamide-treated rats. The immunomodulatory effects were determined by lymphocytes proliferation, phagocytic activity of macrophages, plasma cytokines of tumor necrosis factor-α, interleukin-1α, interleukin-10 levels, and killer T cells (CD8+ T cells) counts. The results showed that the administration of ethanolic extract of T flagelliforme reduced immunosupessive effect on lymphocyte proliferation, increase the number and phagocytic activity of macrophages in cyclophosphamide-treated rats. Moreover, the ethanolic extract of T flagelliforme also significantly (P < .05) improved the immune system activities especially the proliferation of CD8+T cells and reduced the suppressive effects on cytokines such as tumor necrosis factor-α and interleukin-1α. In conclusion, the ethanolic extract of T flagelliforme has immunomodulatory properties in cyclophosphamide-treated rats. The results suggest that T flagelliforme can reduce immunosuppresive effect caused by a chemotherapeutic agent.

Platelet plays a crucial role in cardiovascular diseases (CVDs) development. Abnormalities in platelet aggregation provokes thromboembolism, eventually leading to death. In Indonesia, breadfruit (Artocarpus altilis) leaf is traditionally used to treat CVDs. This study aimed to evaluate the antiplatelet activity of A. altilis leaf extract (AAE) and to identify its active compound. A. altilis leaves were extracted with ethanol, and the antiplatelet activity was assessed using ADP-induced platelet aggregation. The major compound was isolated with column chromatography followed by preparative TLC, and the structure was determined on the basis of UV, MS, IR, and NMR spectra. The binding mode of the active compound to platelet receptors was characterized in in silico study. AAE exhibited an antiplatelet activity (IC50 of 252.23 µg/mL). A geranylated chalcone, 2-geranyl-2ʹ,3,3,4ʹ-tetrahydroxydihydrochalcone (GTDC) was identified as the antiplatelet compound (IC50 of 9.09 µM). GTDC actions with P2Y12 platelet receptor involving three amino acid residues.