Discovery and Mechanistic Investigation of Piperazinone Phenylalanine Derivatives with Terminal Indole or Benzene Ring as Novel HIV-1 Capsid Modulators

HIV-1 capsid (CA) performs multiple roles in the viral life cycle and is a promising target for antiviral development. In this work, we describe the design, synthesis, assessment of antiviral activity, and mechanistic investigation of 20 piperazinone phenylalanine derivatives with a terminal indole or benzene ring. Among them, F-2-7f exhibited moderate anti-HIV-1 activity with an EC50 value of 5.89 mu M, which was slightly weaker than the lead compound PF74 (EC50 = 0.75 mu M). Interestingly, several compounds showed a preference for HIV-2 inhibitory activity, represented by 7f with an HIV-2 EC50 value of 4.52 mu M and nearly 5-fold increased potency over anti-HIV-1 (EC50 = 21.81 mu M), equivalent to PF74 (EC50 = 4.16 mu M). Furthermore, F-2-7f preferred to bind to the CA hexamer rather than to the monomer, similar to PF74, according to surface plasmon resonance results. Molecular dynamics simulation indicated that F-2-7f and PF74 bound at the same site. Additionally, we computationally analyzed the ADMET properties for 7f and F-2-7f. Based on this analysis, 7f and F-2-7f were predicted to have improved drug-like properties and metabolic stability over PF74, and no toxicities were predicted based on the chemotype of 7f and F-2-7f. Finally, the experimental metabolic stability results of F-2-7f in human liver microsomes and human plasma moderately correlated with our computational prediction. Our findings show that F-2-7f is a promising small molecule targeting the HIV-1 CA protein with considerable development potential.

Automated summary

In this study, a series of piperazinone phenylalanine derivatives with a terminal indole or benzene ring were designed and synthesized. The antiviral activity and mechanism of action were assessed. F-2-7f exhibited moderate antiviral activity against HIV-1 and showed a preference for inhibiting HIV-2. Molecular dynamics simulation revealed that F-2-7f bound to the HIV-1 CA protein. Computational analysis predicted improved drug-like properties and metabolic stability for F-2-7f.