Article

Palmitic Acid Is a Novel CD4 Fusion Inhibitor That Blocks HIV Entry and Infection.

Mailman Research Center, McLean Hospital, Harvard Medical School, Belmont, Massachusetts 02478, USA.
AIDS research and human retroviruses (Impact Factor: 2.18). 12/2009; 25(12):1231-41. DOI: 10.1089/aid.2009.0019
Source: PubMed

ABSTRACT The high rate of HIV-1 mutation and the frequent sexual transmission highlight the need for novel therapeutic modalities with broad activity against both CXCR4 (X4) and CCR5 (R5)-tropic viruses. We investigated a large number of natural products, and from Sargassum fusiforme we isolated and identified palmitic acid (PA) as a natural small bioactive molecule with activity against HIV-1 infection. Treatment with 100 microM PA inhibited both X4 and R5 independent infection in the T cell line up to 70%. Treatment with 22 microM PA inhibited X4 infection in primary peripheral blood lymphocytes (PBL) up to 95% and 100 microM PA inhibited R5 infection in primary macrophages by over 90%. Inhibition of infection was concentration dependent, and cell viability for all treatments tested remained above 80%, similar to treatment with 10(-6)M nucleoside analogue 2', 3'-dideoxycytidine (ddC). Micromolar PA concentrations also inhibited cell-to-cell fusion and specific virus-to-cell fusion up to 62%. PA treatment did not result in internalization of the cell surface CD4 receptor or lipid raft disruption, and it did not inhibit intracellular virus replication. PA directly inhibited gp120-CD4 complex formation in a dose-dependent manner. We used fluorescence spectroscopy to determine that PA binds to the CD4 receptor with K(d) approximately 1.5 +/- 0.2 microM, and we used one-dimensional saturation transfer difference NMR (STD-NMR) to determined that the PA binding epitope for CD4 consists of the hydrophobic methyl and methelene groups located away from the PA carboxyl terminal, which blocks efficient gp120-CD4 attachment. These findings introduce a novel class of antiviral compound that binds directly to the CD4 receptor, blocking HIV-1 entry and infection. Understanding the structure-affinity relationship (SAR) between PA and CD4 should lead to the development of PA analogs with greater potency against HIV-1 entry.

1 Bookmark
 · 
114 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Total lipids from the Brazilian brown seaweed Sargassum vulgare were extracted with chloroform/methanol 2:1 and 1:2 (v/v) at room temperature. After performing Folch partition of the crude lipid extract, the lipids recovered from the Folch lower layer were fractionated on a silica gel column eluted with chloroform, acetone and methanol. The fraction eluted with methanol, presented a strong orcinol-positive band characteristic of the presence of sulfatides when examined by TLC. This fraction was then purified by two successive silica gel column chromatography giving rise to fractions F4I86 and F4II90 that exhibited strong activity against herpes simplex virus type 1 and 2. The chemical structures present in both fractions were elucidated by ESI-MS and 1H/13C NMR analysis HSQC fingerprints based on their tandem-MS behavior as Sulfoquinovosyldiacylglycerols (SQDGs). The main SQDG present in both fractions and responsible for the anti-herpes activity observed was identified as 1,2-di-O-palmitoyl-3-O-(6-sulfo-α-d-quinovopyranosyl)-glycerol.
    Marine Drugs 11/2013; 11(11):4628-4640. DOI:10.3390/md11114628 · 3.51 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: AIDS is a global pandemic that has seen the development of novel and effective treatments to improve the quality of life of those infected and reduction of spread of the disease. Palmitic Acid (PA), which we identified and isolated from Sargassum fusiforme, is a naturally occurring fatty acid that specifically inhibits HIV entry by binding to a novel pocket on the CD4 receptor. We also identified a structural analogue, 2-bromopalmitate (2-BP), as a more effective HIV entry inhibitor with a 20-fold increase in efficacy. We have used the structure-activity relationship (SAR) of 2-BP as a platform to identify new small chemical molecules that fit into the various identified active sites in an effort to identify more potent CD4 entry inhibitors. To validate further drug development, we tested the PA and 2-BP scaffold molecules for genotoxic potential. The FDA and International Conference on Harmonisation (ICH) recommends using a standardized 3-test battery for testing compound genotoxicity consisting of the bacterial reverse mutation assay, mouse lymphoma assay, and rat micronucleus assay. PA and 2-BP and their metabolites tested negative in all three genotoxicty tests. 2-BP is the first derivative of PA to undergo pre-clinical screening, which will enable us to now test multiple simultaneous small chemical structures based on activity in scaffold modeling across the dimension of pre-clinical testing to enable transition to human testing.
    PLoS ONE 03/2014; 9(3):e93108. DOI:10.1371/journal.pone.0093108 · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: AIDS is a global pandemic that has seen the development of novel and effective treatments to improve the quality of life of those infected and reduction in the spread of the disease. While great advancements have been made in HIV/AIDS therapeutics, there is still no cure or viable vaccine in development. The high rate of HIV-1 mutation contributing to virus immune escape, combined with increase in sexual transmission and the significant clinical therapeutics side effects of the currently available treatments highlights the need for novel therapeutics with broad anti-viral activity against both CXCR4 (X4) and CCR5 (R5)-tropic viruses. In our search for novel modalities against HIV infection, we investigated several aqueous extracts from Traditional Chinese Medicine (TCM) collection and identified Sargassum fusiforme (S. fusiforme) as a potent inhibitor of HIV infection. Following the Western approach of drug discovery and development, we isolated several bioactive molecules from S. fusiforme and determined their mechanism of action. TCM and Western approaches to disease treatment and drug development have been shown to be complementary to each other. The former provides a rich medicinal history for natural compounds that can have clinical impact on a variety of illnesses, while the latter enables the application of chemical informatics with rational drug design approach coupled to mechanistic underpinnings of such therapeutics. This multistep paradigm is demonstrated in the example of S. fusiforme as a treatment to prevent HIV infection, as described in this review.
    11/2014; DOI:10.1016/S1674-6384(14)60041-1

Full-text (2 Sources)

Download
76 Downloads
Available from
May 21, 2014