Lamellarin alpha 20-sulfate, an inhibitor of HIV-1 integrase active against HIV-1 virus in cell culture.

HIV-1 integrase is an attractive target for anti-retroviral chemotherapy, but to date no clinically useful inhibitors have been developed. We have screened diverse marine natural products for compounds active against integrase in vitro and found a series of ascidian alkaloids, the lamellarins, that show selective inhibition. A new member of the family named lamellarin alpha 20-sulfate (1), the structure of which was determined from spectroscopic data, displayed the most favorable therapeutic index. The site of action of lamellarin alpha 20-sulfate on the integrase protein was mapped by testing activity against deletion mutants of integrase. Inhibition of isolated catalytic domain was detectable though weaker than inhibition of full length integrase; possibly lamellarin alpha 20-sulfate binds a site composed of multiple integrase domains. Lamellarin alpha 20-sulfate also inhibited integration in vitro by authentic HIV-1 replication intermediates isolated from infected cells. Lamellarin alpha 20-sulfate was tested against wild type HIV using the MAGI indicator cell assay and found to inhibit early steps of HIV replication. To clarify the inhibitor target, we tested inhibition against an HIV-based retroviral vector bearing a different viral envelope. Inhibition was observed, indicating that the HIV envelope cannot be the sole target of lamellarin alpha 20-sulfate in cell culture. In addition, these single round tests rule out action against viral assembly or budding. These findings provide a new class of compounds for potential development of clinically useful integrase inhibitors.     

New developments in diketo-containing inhibitors of HIV-1 integrase

HIV-1 integrase is one of the three enzymes, which are critical for viral replication. It catalyzes the integration of the HIV genome into the cellular chromosome. Since there is no known human homolog to integrase, its inhibition is one of the most promising novel drug targets for anti-retroviral therapy with potential advantage over existing therapies. To date, numerous compounds with diverse structural features have been reported as integrase inhibitors, among which the diketo-containing inhibitors of HIV-1 integrase represent a major lead for anti-HIV drug development. The discovery of diketo acids plays an important role in validating integrase as a legitimate target for treatment of AIDS. In this review, we summarize several drug candidates in clinical trials and new diketo-containing inhibitors of HIV-1 integrase discovered recently.     

二酮酸类HIV-1整合酶抑制剂的研究进展

HIV-1整合酶催化前病毒DNA整合进入宿主细胞基因组的过程是病毒复制必不可少的步骤,所以抑制HIV-1整合酶活性是治疗HIV-1感染的合理策略。目前已开发了大量HIV-1整合酶抑制剂,其中一些已进入临床研究阶段,从化学结构看,绝大多数已报道的HIV-1整合酶抑制剂属于二酮酸类或其生物电子等排体。该文对近3年来二酮酸类HIV-1整合酶抑制剂的研究进展做简要综述。     

Novel inhibitors of HIV integrase: the discovery of potential anti-HIV therapeutic agents

The viral enzyme, HIV integrase (MW 32 kDa), is one of the three key enzymes of the pol gene of HIV. HIV integrase is involved in the integration of HIV DNA into host chromosomal DNA. There is apparently no functional equivalent of this enzyme in human cells. Integration of HIV DNA into the host cell genome apparently occurs by a carefully defined sequence of DNA tailoring (3'-processing) and coupling (joining or integration) reactions. In spite of some effort in this area targeted at the discovery of therapeutically useful inhibitors of this viral enzyme, there are no drugs for HIV/AIDS in clinical use where the mechanism of action is inhibition of HIV integrase. It is clear that new knowledge on inhibitors of this enzyme is of critical importance in the anti-HIV drug discovery area. This review focuses on the major classes of compounds that have been discovered as inhibitors of HIV integrase. Some of these compounds are non-specific inhibitors of the enzyme while evidence suggests that others may possess some specificity. The various classes include nucleotides, oligonucleotides, dinucleotides, and miscellaneous small molecules including heterocyclic systems, natural products, diketo acids and sulfones. A major focus of the review is on discoveries from my laboratory in the area of non-natural, nuclease-resistant dinucleotide inhibitors of HIV integrase.     

HIV-1 assembly and budding as targets for drug discovery

Research conducted during the past several years has led to an increased understanding of the roles played by the viral protein Gag and specific cellular factors in HIV assembly/budding. The identification of compounds that interfere with this process validates this late step in virus replication as a target for HIV therapeutic discovery. In this review, current understanding of HIV-1 assembly/budding is described and several developmental stage drugs that target this process are reviewed.     

Dicaffeoyltartaric acid analogues inhibit human immunodeficiency virus type 1 (HIV-1) integrase and HIV-1 replication at nontoxic concentrations

The human immunodeficiency virus type 1 (HIV-1) is a major health problem worldwide. In this study, 17 analogues of L-chicoric acid, a potent inhibitor of HIV integrase, were studied. Of these analogues, five submicromolar inhibitors of integrase were discovered and 13 compounds with activity against integrase at less than 10 microM were identified. Six demonstrated greater than 10-fold selectivity for HIV replication over cellular toxicity. Ten analogues inhibited HIV replication at nontoxic concentrations. Alteration of the linkages between the two bis-catechol rings, including the use of amides, mixed amide esters, cholate, and alkyl bridges, was explored. Amides were as active as esters but were more toxic in tissue culture. Alkyl and cholate bridges were significantly less potent against HIV-1 integrase in vitro and were inactive against HIV-1 replication. Two amino acid derivates and one digalloylderivative of L-chicoric acid (L-CA) showed improved selectivity over L-CA against integration in cell culture. These data suggest that in addition to the bis-catechols and free carboxylic acid groups reported previously, polar linkages are important constituents for optimal activity against HIV-1 integrase and that new derivatives can be developed with increased specificity for integration over HIV entry in vivo.     

HIV integrase inhibitors with nucleobase scaffolds: discovery of a highly potent anti-HIV agent

HIV integrase is essential for HIV replication. However, there are currently no integrase inhibitors in clinical use for AIDS. We have discovered a conceptually new beta-diketo acid that is a powerful inhibitor of both the 3'-processing and strand transfer steps of HIV-1 integrase. The in vitro anti-HIV data of this inhibitor were remarkable as exemplified by its highly potent antiviral therapeutic efficacy against HIV(TEKI) and HIV-1(NL4)(-)(3) replication in PBMC (TI >4,000 and >10,000, respectively).     

Raltegravir (MK-0518): an integrase inhibitor for the treatment of HIV-1

In the developed world, access to highly active antiretroviral therapy (HAART) has led to significant reductions in the morbidity and mortality attributed to HIV/AIDS. However, the continual emergence of HIV-1 strains resistant to currently available classes of antiretrovirals highlights the need to develop agents with novel mechanisms of action. Successful completion of the HIV-1 viral life cycle depends in part on the integration of complementary DNA mediated by the enzyme HIV-1 integrase, one of three essential enzymes encoded in the viral genome. The integrase inhibitors have demonstrated the ability to act specifically at the strand transfer step during integration, making HIV-1 integrase a valid and attractive chemotherapeutic target for the treatment of HIV/AIDS. In clinical trials, raltegravir has been shown to be a potent drug with a pharmacokinetic profile that supports a twice-daily dosing schedule. In addition, it has demonstrated a favorable side-effect profile in treatment-naive and -experienced patients and a subset of heavy treatment-experienced patients have been able a achieve virologic suppression with raltegravir as part of combination therapy despite limited treatment options. In October 2007, raltegravir was approved by the U.S. Food and Drug Administration (FDA) for the treatment of HIV-1 as part of combination antiretroviral therapy in treatment-experienced patients-providing an additional option for the management of the HIV-1 infected individual.