دانلود رایگان مقاله ارزیابی بالینی مرکاپتو بنزو آمید برای مهار NCp7

Abstract

Although the effective use of highly active antiretroviral therapy results in the suppression of virus production in infected individuals, it does not eliminate the infection and low level virus production in cells harboring virus in sanctuary sites. Thus, the continued search for new antiretroviral agents with unique and different mechanisms of HIV inhibition remains critical, and compounds that can reduce the level of virus production from cells already infected with HIV, as opposed to preventing de novo infection, would be of great benefit. A mercaptobenzamide (MDH-1-38) and its prodrug (NS1040) are being developed as potential therapeutic compounds targeting the zinc finger of HIV nucleocapsid. In the presence of esterase enzymes, NS1040 is designed to be converted to MDH-1-38 which has antiviral activity. While we presume that NS1040 is rapidly converted to MDH-1-38 in all experiments, the two compounds were tested side-by-side to determine whether the presence of a prodrug affects the antiviral activity or mechanism of action. The two compounds were evaluated against a panel of HIV-1 clinical isolates in human PBMCs and monocyte-macrophages and yielded EC50 values ranging from 0.7 to 13 mM with no toxicity up to 100 mM. MDH-1-38 and NS1040 remained equally active in human PBMCs in the presence of added serum proteins as well as against HIV-1 isolates resistant to reverse transcriptase, integrase or protease inhibitors. Cell-based and biochemical mechanism of antiviral action assays demonstrated MDH-1-38 and NS1040 were virucidal at concentrations of 15 and 50 mM, respectively. Cell to cell transmission of HIV in multiple passages was significantly reduced in CEM-SS and human PBMCs by reducing progeny virus infectivity at compound concentrations greater than 2 mM. The combination of either MDH-1-38 or NS1040 with other FDA-approved HIV drugs yielded additive to synergistic antiviral interactions with no evidence of antiviral antagonism or synergistic toxicity. Serial dose escalation was used in attempts to select for HIV strains resistant to MDH-1-38 and NS1040. Virus at several passages failed to replicate in cells treated at increased compound concentrations, which is consistent with the proposed mechanism of action of the virus inactivating compounds. Through 14 passages, resistance to the compounds has not been achieved. Most HIV inhibitors with mechanism of antiviral action targeting a viral protein would have selected for a drug resistant virus within 14 passages. These studies indicate that these NCp7-targeted compounds represent new potent anti-HIV drug candidates which could be effectively used in combination with all approved anti-HIV drugs.

4. Discussion

MDH-1-38 and its prodrug NS1040 are being developed as potential therapeutic compounds targeting the zinc finger of HIV-1 nucleocapsid. The compounds were similarly and broadly active against a geographically diverse panel of clinical HIV-1 subtypes and inhibited CXCR4-tropic, CCR5-tropic and dual-tropic virus strains with equal efficacy. MDH-1-38 and its prodrug were equally active against monocyte-tropic strains of HIV-1 in fresh human monocytes. These data demonstrate that MDH-1-38 and its prodrug NS1040 would be expected to be active against HIV-1 strains found throughout the world as a therapeutic product. The lack of cross resistance to HIV strains conferring resistance to reverse transcriptase inhibitors, integrase inhibitors and protease inhibitors, as well as multidrug resistant isolates, indicates a distinct mechanism of antiviral action for MDH-1-38 and its prodrug when compared with approved HIV drugs. Following cell-based and biochemical inhibition assays to evaluate mechanism of antiviral action, it was concluded that MDH-1-38 and its prodrug act as a virucidal agent and reduces transmission of infectious virus over multiple rounds of virus replication. This reduction in virus infectivity proved a challenge when passaging virus in the presence of MDH-1-38 and NS1040 in attempts to select for drug resistant HIV.