Weihong Lai

Betulinic Acid Derivatives as Human Immunodeficiency Virus Type 2 (HIV-2) Inhibitors

We previously reported that [[N-[3beta-hydroxyllup-20(29)-en-28-oyl]-7-aminoheptyl]carbamoyl]methane (A43D, 4) was a potent HIV-1 entry inhibitor. However, 4 was inactive against HIV-2 virus, suggesting the structural requirements for targeting these two retroviruses are different. In this study, a series of new betulinic acid derivatives were synthesized, and some of them displayed selective anti-HIV-2 activity at nanomolar concentrations. In comparison to compounds with anti-HIV-1 activity, a shorter C-28 side chain is required for optimal anti-HIV-2 activity.

Betulinic Acid Derivatives That Target gp120 and Inhibit Multiple Genetic Subtypes of Human Immunodeficiency Virus Type 1

ABSTRACT Betulinic acid (BA) derivatives can inhibit human immunodeficiency virus type 1 (HIV-1) entry or maturation depending on side chain modifications. While BA derivatives with antimaturation activity have attracted considerable interest, the anti-HIV-1 profile and molecular mechanism of BA derivatives with anti-HIV-1 entry activity (termed BA entry inhibitors) have not been well defined. In this study, we have found that two BA entry inhibitors, IC9564 and A43D, exhibited a broad spectrum of anti-HIV-1 activity. Both compounds inhibited multiple strains of HIV-1 from clades A, B, and C at submicromolar concentrations. Clade C viruses were more sensitive to the compounds than clade A and B viruses. Interestingly, IC9564 at subinhibitory concentrations could alter the antifusion activities of other entry inhibitors. IC9564 was especially potent in increasing the sensitivity of HIV-1YU2 Env-mediated membrane fusion to the CCR5 inhibitor TAK-779. Results from this study suggest that the V3 loop of gp120 is a critical determinant for the anti-HIV-1 activity of IC9564. IC9564 escape viruses contained mutations near the tip of the V3 loop. Moreover, IC9564 could compete with the binding of V3 monoclonal antibodies 447-52D and 39F. IC9564 also competed with the binding of gp120/CD4 complexes to chemokine receptors. In summary, these results suggest that BA entry inhibitors can potently inhibit a broad spectrum of primary HIV-1 isolates by targeting the V3 loop of gp120.

Discovery of diarylpyridine derivatives as novel non-nucleoside HIV-1 reverse transcriptase inhibitors

Two series (4 and 5) of diarylpyridine derivatives were designed, synthesized, and evaluated for anti-HIV-1 activity. The most promising compound, 5e, inhibited HIV-1 IIIB, NL4-3, and RTMDR1 with low nanomolar EC50 values and selectivity indexes of >10,000. The results of this study indicate that diarylpyridine can be used as a novel scaffold to derive a new class of potent NNRTIs, active against both wild-type and drug-resistant HIV-1 strains.

Aloperine and Its Derivatives as a New Class of HIV-1 Entry Inhibitors

A quinolizidine-type alkaloid aloperine was found to inhibit HIV-1 infection by blocking HIV-1 entry. Aloperine inhibited HIV-1 envelope-mediated cell-cell fusion at low micromolar concentrations. To further improve the antiviral potency, more than 30 aloperine derivatives with a variety of N12-substitutions were synthesized. Among them, 12d with an N-(1-butyl)-4-trifluoromethoxy-benzamide side chain showed the most potent anti-HIV-1 activity with EC50 at 0.69 μM. Aloperine derivatives inhibited both X4 and R5 HIV-1 Env-mediated cell-cell fusions. In addition, both BMS-806, a compound representing a class of HIV-1 gp120-targeting small molecules in clinical trials, and resistant and sensitive HIV-1 Env-mediated cell-cell fusions were equally sensitive to aloperine derivatives. These results suggest that aloperine and its derivatives are a new class of anti-HIV-1 entry inhibitors.

Identification and synthesis of quinolizidines with anti-influenza A virus activity

Influenza A virus infection causes a contagious respiratory illness that poses a threat to human health. However, there are limited anti-influenza A therapeutics available, which is further compounded by the emergence of drug resistant viruses. In this study, Sophora quinolizidine alkaloids were identified as a new class of anti-influenza A virus agents. Among the tested Sophora alkaloids, dihydroaloperine exhibited the most potent activity with an EC50 of 11.2 μM. The potency of the quinolizidine alkaloids was improved by approximately 5-fold with chemical modifications on the aloperine molecule. These compounds were effective against an H1N1 influenza A virus that was resistant to the two antiflu drugs oseltamivir and amantadine. The identification of the quinolizidine alkaloids as effective and novel anti-influenza A agents may aid in the development of new therapeutics.

Inhibition of Human Immunodeficiency Virus Type 1 Entry by a Binding Domain of Porphyromonas gingivalis Gingipain

ABSTRACT Human immunodeficiency virus (HIV) transmission through saliva is extremely low. Several oral components, including secretory immunoglobulin A and secretory leukocyte protease inhibitor, are known as potential inhibitory agents of HIV oral transmission. Here we examined anti-HIV activity of oral bacterial components. We showed that recombinant protein HGP44 derived from Porphyromonas gingivalis, one of the primary infectious agents of periodontitis, was capable of inhibiting HIV type 1 (HIV-1) replication. HGP44 bound specifically to HIV-1 gp120 and blocked HIV-1 envelope-mediated membrane fusion. These findings suggest that HGP44 of P. gingivalis can inhibit HIV-1 infection by blocking HIV-1 entry.

Gnidimacrin, a Potent Anti-HIV Diterpene, Can Eliminate Latent HIV-1 Ex Vivo by Activation of Protein Kinase C β

HIV-1-latency-reversing agents, such as histone deacetylase inhibitors (HDACIs), were ineffective in reducing latent HIV-1 reservoirs ex vivo using CD4 cells from patients as a model. This deficiency poses a challenge to current pharmacological approaches for HIV-1 eradication. The results of this study indicated that gnidimacrin (GM) was able to markedly reduce the latent HIV-1 DNA level and the frequency of latently infected cells in an ex vivo model using patients peripheral blood mononuclear cells. GM induced approximately 10-fold more HIV-1 production than the HDACI SAHA or romidepsin, which may be responsible for the effectiveness of GM in reducing latent HIV-1 levels. GM achieved these effects at low picomolar concentrations by selective activation of protein kinase C βI and βII. Notably, GM was able to reduce the frequency of HIV-1 latently infected cells at concentrations without global T cell activation or stimulating inflammatory cytokine production. GM merits further development as a clinical trial candidate for latent HIV-1 eradication.

Inhibition of HIV-1 Entry by Inducing a Nonproductive Conformational Change in gp120

Conformational change in HIV-1 gp120 is a dynamic process essential for HIV-1 entry. It is not clear whether the dynamic nature of gp120 could be exploited to abort the viral entry machinery. Here we show that a small molecule entry inhibitor, IC9564, induces a conformational change in gp120 and locks the envelope into fusion incompetent conformation. Binding of IC9564 to HIV-1 envelope results in the exposure of CD4i epitopes that are ally concealed in gp120. As a result of the conformational effect, IC9564 significantly enhances the neutralizing activity of 17b that binds to an epitope overlapping chemokine receptor binding site. Unlike CD4, IC9564-induced conformational change in gp120 does not trigger a conformational change in gp41. In fact, IC9564 inhibits CD4 induced conformational changes in gp41. The binding site of IC9564 remains elusive due to the fact that mutations in both gp120 and gp41 could change IC9564 sensitivity. Nevertheless, a common effect of these mutations is that conformation of gp120 is changed to conceal conserved epitopes such as CD4i. In summary, IC9564 exploits the dynamic nature of HIV-1 gp120 by inducing a nonproductive conformational change in gp120 and prevents HIV-1 from entering the cells. from 2005 International Meeting of The Institute of Human Virology Baltimore, USA, 29 August – 2 September 2005