The reverse transcriptase (RT) of human immunodeficiency virus type-1 (HIV-1) converts the single-stranded (ϩ) viral RNA genome into a double-stranded proviral DNA prior to its integration into the host genomic DNA. The RT is a multifunctional enzyme with three recognized enzymatic activities of RNA-dependent DNA polymerase (RDDP), DNA-dependent DNA polymerase (DDDP), and ribonuclease H activities. HIV-1 protease is an aspartic protease required for the proteolytic processing of the large Gag and Gag-Pol viral polyprotein precursors into the mature virion structural proteins, as well as the virion enzymes. These two enzymes, HIV-1 RT and protease, have key roles in HIV replication and inhibition of these enzymes along with HIV-1 integrase has been a major target of acquired immunodeficiency syndrome (AIDS) therapy. 1)In addition to the well-known nucleoside RT inhibitors (NRTIs), zidovudine (AZT), didanosine (ddC), zalcitabine (ddT), stavudine (d4T), lamivudine (3TC), and abacavir (ABC), non-nucleoside RT inhibitors (NNRTIs), such as nevirapine, delavirdine, and efavirenz have been formally approved to treat HIV infection. On the other hand, saquinavir, ritonavir, and indinavir are the three main HIV protease inhibitors available today. A number of inhibitors interacting with RT have been isolated from plants (baicalin, avarol, avarone, and psychotrine) and marine resources (illimaquinone, peyssonol, and KM043). [2][3][4] In the case of HIV-1 protease, natural products, such as mangostin, ursolic, and maslinic acid, have been reported to show inhibitory activity against this enzyme. 5) We previously reported the results of screening inhibitory activities of 47 types of Korean seaweed on HIV-1 RT and found that the EtOAc fraction of Ecklonia cava strongly inhibited the RDDP activity of this enzyme. 6) In this study, we report the isolation of four phlorotannin compounds containing dibenzo [1,4]dioxin elements in common from E. cava and the kinetic study of HIV-1 RT by 8,8Ј-bieckol (2) that showed the most potent inhibitory effect on this enzyme. MATERIALS AND METHODS MaterialsThe thalli of E. cava KJELLMAN were collected from the coasts of Korea including Sungsanpo, Wando, and Namhaedo from January 1999 to June 2000. After cleaning the surface of the thalli with water to remove visible epiphytes and dirt, samples were dried at 60°C for 12 h in an oven and then ground in a coffee grinder. This seaweed was identified by Prof. S. M. Boo of the Department of Biology, Chungnam National University, Korea, and Prof. Y. S. Oh of the Department of Aquaculture, Gyeongsang National University, Korea. A voucher specimen (SSI-06) was deposited in the Herbarium of the Department of Biological Sciences, Sungkyunkwan University.Extraction and Isolation The dried thalli (1 kg) of E. cava were extracted three times with 100% MeOH and evaporated in vacuo. The MeOH extract (180 g) was dissolved in water and partitioned with n-hexane. After the H 2 O layer was further partitioned with ethyl acetate, the organic solvent fraction was c...

Chloroquine has been used for many decades in the prophylaxis and treatment of malaria. It is metabolized in humans through the N-dealkylation pathway, to desethylchloroquine (DCQ) and bisdesethylchloroquine (BDCQ), by cytochrome P450 (CYP). However, until recently, no data are available on the metabolic pathway of chloroquine. Therefore, the metabolic pathway of chloroquine was evaluated using human liver microsomes and cDNA-expressed CYPs. Chloroquine is mainly metabolized to DCQ, and its Eadie-Hofstee plots were biphasic, indicating the involvement of multiple enzymes, with apparent Km and Vmax values of 0.21 mM and 1.02 nmol/min/mg protein 3.43 mM and 10.47 nmol/min/mg protein for high and low affinity components, respectively. Of the cDNA-expressing CYPs examined, CYP1A2, 2C8, 2C19, 2D6 and 3A4/5 exhibited significant DCQ formation. A study using chemical inhibitors showed only quercetin (a CYP2C8 inhibitor) and ketoconazole (a CYP3A4/5 inhibitor) inhibited the DCQ formation. In addition, the DCQ formation significantly correlated with the CYP3A4/5-catalyzed midazolam 1-hydroxylation (r = 0.868) and CYP2C8-catalyzed paclitaxel 6alpha-hydroxylation (r = 0.900). In conclusion, the results of the present study demonstrated that CYP2C8 and CYP3A4/5 are the major enzymes responsible for the chloroquine N-deethylation to DCQ in human liver microsomes.

Abstract. To investigate whether bee venom (BV) induces apoptosis, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, terminal deoxynucleotidyl transferasemediated dUTP nick end-labeling assay, 4,6-diamidino-2-phenylindole staining, flow cytometric analysis, and DNA fragmentation assay were performed on NCI-H1299 lung cancer cells treated with BV. Through morphological and biochemical analyses, it was demonstrated that NCI-H1299 cells treated with BV exhibit several features of apoptosis. In addition, reverse transcription-polymerase chain reaction and prostaglandin E 2 (PGE 2 ) immunoassay were performed to verify whether BV possesses an inhibitory effect on the expression of cyclooxygenase (COX) and PGE 2 synthesis. Expression of COX-2 mRNA and synthesis of PGE 2 were inhibited by BV. These results suggest the possibility that BV may exert an anti-tumor effect on human lung cancer.

The bioassay-directed isolation of Terminalia chebula fruits afforded four human immunodeficiency virus type 1 (HIV-1) integrase inhibitors, gallic acid ( 1) and three galloyl glucoses ( 2 - 4). In addition, four flavonol glycoside gallates ( 5 - 8) from Euphorbia pekinensis containing the galloyl moiety also showed the inhibitory activity at a level comparable to those of 2 - 4. By comparison with the activities of the compounds not bearing this moiety, it is proposed that the galloyl moiety plays a major role for inhibition against the 3'-processing of HIV-1 integrase of these compounds.

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