Anti-HIV-1 Activities And Mechanism Of Compounds From Schisandra Rebriflora And Hemsleya Jinfushanensis

Although the anti-retroviral therapy of the combination of the chemical drugs greatly reduce morbidity and mortality in HIV-1 infected individual. But emergence of HIV drug resistance, side effects and necessary for long-term anti-retroviral treatment limit the use of these drugs. So continuous development of new anti-HIV-1 drugs appears to be inevitable. Natural products as the most consistently successful source in drug discovery may offer opportunities for finding anti-HIV drugs or lead compounds. In recently years, millions of natural compounds with anti-HIV activity have been isolated and indentified, such as flavonoid, coumarin, terpenoid, alkaloid, polyphenol, polysaccharide, protein, miscellaneou. In this study, we tested the anti-HIV-1 effects and mechanism of compounds isolated from Schisandra rebriflora and Hemsleya jinfushanensis.Through the primary screen, we found two lignans from Schisandra rebriflora (swl 1 and swl 11) with anti-HIV-1 activities with a selective index of 26.64 and 45.58 in syncytia formation assay and selective index of 26.4 and 6.8 in MTT protection assay. Both of them can decrease HIV-1 p24 antigen production with EC50 of 7.06 and 1.93μg/ml. Then we tested their mechanism of anti-HIV-1 through fusion inhibition assay, RT and PR inhibition assay, zinc ejection assay, late replication assay and time addition assay. The results show: 1) At 200μg/ml, swl 1 can inhibit 56.64% of RT activity and 27.14% of PR activity. It also can eject zinc from NCp7 with EC50 of 93.71μg/ml and inhibit fusion in coculture with EC50 of 20.74 μg/ml. In the same time, swll shows decreasing activity on HIV-1 replication added after 8 hours exposure and no effect on replication of HIV-1 in chronically infected H9 cell (H9/HIV-1_IIIB) which indicate the late step of HIV-1 replication. All results suggest that swl 1 may have more than one target and various effect on HIV-1 replication and the major effect of swl 1 on HIV-1 replication is acting on metaphase of virus replication;2 ) Differently, at 200μg/ml, swl 11 only inhibit 33.4% of RT and has no effect on PR activity and structure of NCp7. Swl 11 also has no effect on replicationof HIV-1 in H9/HIV-1iiib. But it can inhibit fusion in co-culture at EC50 of 37.24ug/ml and decreasing activity added after 2 hours. All the results suggest that swl 11 is an inhibitor of HIV-1 replication and they may act on early step of HIV-1 replication.From the screening for 21 compounds from Hemsleya jinfushanensis, we acquired 4 cucurbitacin: jf 1, jf 2, jf 4 and jf 35 with effect on inhibition of syncytia formation. They also can decrease p24 antigen production in HIV-1 acutely infected C8166 cells and MT2 cells. In the mechanism studies, all four of them have no inhition on activity of RT and ejecting zinc from NCp7. To some extent, they have improvement activity of RT. In PR inhibition assay, both four of them have weak inhibition on activity of PR. They also have no inhibition activity on HIV-1 replication in H9/HIV-1hib- In selective cytotoxicity assay, they also have no different cytotoxicity between H9 and H9/HIV-lmB, except jf 4. But all of them have excellent effect on inhibition fusion between normal cell and H9/HIV, and all of them indicate more effective in pretreating group than no pretreting group. All result suggest that jf 1, jf 2, jf 4 and jf 35 are inhibitors of HIV entry and their activity may relate with interaction of surface molecular of host cell.