AEGiS-11IAC: Isolation and characterization of a novel class of human immunodeficiency virus integrase inhibitors from natural product screening.

11th International AIDS Conference

Vancouver, British Columbia — July 7-12, 1996

Isolation and characterization of a novel class of human immunodeficiency virus integrase inhibitors from natural product screening.

Int Conf AIDS 1996 Jul 7-12; 11:58 (abstract no. Mo.A.1020)
Hazuda D, Blau C, Felock P, Hastings J, Lineberger D, Wolfe A, Goetz M, Williams M, Zink D, Singh S; Merck Research Laboratories, West Point, PA, USA. Fax: 215-652-0994. E-mail: daria_hazuda@merck.com.

OBJECTIVE: Integration of a copy of the viral genome into the genome of the host cell is an essential and defining step in the replication of all retroviruses. Integration is catalyzed by a virally encoded enzyme, integrase. The absolute requirement for integrase activity in the propagation of HIV-1 in cell culture defines the enzyme as a potential biochemical target for HIV-1 antiviral chemotherapeutic intervention. Therefore, we have attempted to identify novel inhibitors of integrase for potential use as chemotherapeutic agents against HIV infection.

METHODS: Natural product extracts were randomly screened via a high throughput biochemical assay which measures both the 3' end processing and strand transfer activities of the enzyme.

RESULTS: Equisetin, previously isolated from Fusarium equiseti, was recovered from the fungus Fusarium heterosporum and shown to inhibit HIV-1 integrase in vitro. Novel compounds related to equisetin were also isolated and identified from the fungus Phoma sp. Equisetin and related compounds inhibited the 3' end-processing, strand transfer and disintegration activities of the wild type enzyme with comparable potency (5-10 uM). Equisetin also inhibited disintegration catalyzed by the truncated core domain protein (amino acids 50-212). Binding to the catalytic domain was also demonstrated in competition studies using a radiolabelled ATP affinity analog, fluorosulfonyl benzyl adenosine (FSBA); equisetin was observed to compete for FSBA binding to both the full length and truncated enzymes.

CONCLUSIONS: We have identified a novel class of integrase inhibitors which interact with the enzyme at the substrate binding site(s). These studies demonstrate that it is possible to isolate small molecular weight compounds which act as integrase inhibitors by randomly screening natural product extracts using this approach.

Keywords: AEGIS, Integrase Inhibitors, HIV Integrase, HIV Integrase Inhibitors, HIV-1, Integrase, Virus Replication, Antiviral Agents, Anti-HIV Agents, Mass Screening, Catalysis, HIV-1 Reverse Transcriptase, HIV Protease Inhibitors, Binding Sites, Human, In Vitro, isolation & purification, diagnosis, therapy, surgery, virology, drug therapy, ICA11

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MoA1020