Probing Mercaptobenzamides as HIV Inactivators via Nucleocapsid Protein 7

Human immunodeficiency virus type 1 (HIV-1) nucleocapsid protein 7 (NCp7), a zinc finger protein, plays critical roles in viral replication and maturation and represents an attractive target for drug development. However, development of drug-like molecules that inhibit NCp7 has been a significant challenge. In this report, a series of novel 2-mercaptobenzamide prodrugs have been investigated for anti-HIV activity in the context of NCp7 inactivation. The molecules are synthesized from the corresponding thiosalicylic acids, and they are all crystalline solids and stable at room temperature. Derivatives with a range of amide side chains and aromatic substituents were synthesized and screened for anti-HIV activity. Wide ranges of antiviral activity were observed, with IC50 values ranging from 1 to 100 μM depending on subtle changes to the substituents on the aromatic ring and the sidechain. Results from these structure-activity relationships were fit to a probable mode of intracellular activation and interaction with NCp7 to explain variations in antiviral activity. Our strategy to make a series of mercaptobenzamide prodrugs represents a general new direction to make libraries that can be screened for anti-HIV activity.