Three-dimensional structure-activity analysis of a series of porphyrin derivatives with anti-HIV-1 activity targeted to the V3 loop of the gp120 envelope glycoprotein of the human immunodeficiency virus type 1

Using comparative molecular field analysis (CoMFA), a 3D-QSAR model was developed for 21 porphyrin derivatives which have anti-HIV-1 activity and bind to the V3 loop of the envelope glycoprotein gp120 of the human immunodeficiency virus type 1. A significant PLS cross-validated r2cv (0.590) was obtained, indicating that the model could be used as a predictive tool for further design of porphyrin analogs. The model revealed at least three important sites for favorable electrostatic interactions and indicated favorable and unfavorable steric interaction sites. It was found that the occurrence of at least three positively charged and several hydrophobic amino acid residues is highly conserved at fixed positions of gp120 V3 loop sequences. This may support the validity of the proposed model and the hypothesis that porphyrins containing anionic and hydrophobic groups may interact with some of the highly conserved positively charged and hydrophobic sites, respectively, of the V3 loop. These interactions may induce conformational changes in the gp120 envelope glycoprotein leading to inhibition of virus entry into cells and of syncytium formation (cell-to-cell fusion) and thus to inhibition of virus replication.