ABSTRACT
BACKGROUND: Several HIV protease mutations, which are resistant to clinical HIV protease inhibitors (PIs), have been identified. There is a great need for second-generation PIs with different chemical structures and/or with an alternative mode of inhibition. Ginkgolic acid is a natural herbal substance and a major component of the lipid fraction in the nutshells of the Ginkgo biloba tree. The objective of this study was to determine whether ginkgolic acid could inhibit HIV protease activity in a cell free system and HIV infection in human cells. MATERIAL/METHODS: Purified ginkgolic acid and recombinant HIV-1 HXB2 KIIA protease were used for the HIV protease activity assay. Human peripheral blood mononuclear cells (PBMCs) were used for HIV infection (HIV-1SF162 virus), determined by a p24gag ELISA. Cytotoxicity was also determined. RESULTS: Ginkgolic acid (31.2 µg/ml) inhibited HIV protease activity by 60%, compared with the negative control, and the effect was concentration-dependent. In addition, ginkgolic acid treatment (50 and 100 µg/ml) effectively inhibited the HIV infection at day 7 in a concentration-dependent manner. Ginkgolic acid at a concentration of up to 150 µg/ml demonstrated very limited cytotoxicity. CONCLUSIONS: Ginkgolic acid effectively inhibits HIV protease activity in a cell free system and HIV infection in PBMCs without significant cytotoxicity. Ginkgolic acid may inhibit HIV protease through different mechanisms than current FDA-approved HIV PI drugs. These properties of ginkgolic acid make it a promising therapy for HIV infection, especially as the clinical problem of viral resistance to HIV PIs continues to grow.
Subject(s)
HIV Infections/drug therapy , HIV Infections/virology , HIV Protease Inhibitors/pharmacology , HIV Protease Inhibitors/therapeutic use , HIV Protease/metabolism , Salicylates/pharmacology , Salicylates/therapeutic use , Cell Death/drug effects , Cell-Free System , Dose-Response Relationship, Drug , Ginkgolides/chemistry , Ginkgolides/pharmacology , Ginkgolides/therapeutic use , HIV Protease/drug effects , HIV Protease Inhibitors/chemistry , Humans , Jurkat Cells , Lactones/chemistry , Lactones/pharmacology , Lactones/therapeutic use , Salicylates/chemistryABSTRACT
The SWI/SNF enzymes belong to a family of ATP-dependent chromatin remodeling enzymes that have been functionally implicated in gene regulation, development, differentiation and oncogenesis. BRG1, the catalytic core subunit of some of the SWI/SNF enzymes, can interact with known tumor suppressor proteins and can act as a tumor suppressor itself. We report that cells that inducibly express ATPase-deficient versions of BRG1 increase in cell volume, area of attachment and nuclear size upon expression of the mutant BRG1 protein. Examination of focal adhesions reveals qualitative changes in paxillin distribution but no difference in the actin cytoskeletal structure. Increases in cell size and shape correlate with over-expression of two integrins and the urokinase-type plasminogen activator receptor (uPAR), which is also involved in cell adhesion and is often over-expressed in metastatic cancer cells. These findings demonstrate that gene expression pathways affected by chromatin remodeling enzymes can regulate the physical dimensions of mammalian cell morphology.
