Multivalent Benzoboroxole Functionalized Polymers as gp120 Glycan Targeted Microbicide Entry Inhibitors

摘要

Microbicides are women-controlled prophylactics for sexually transmitted infections. The most important class of microbicides target HIV-1 and contain antiviral agents formulated for topical vaginal delivery. Identification of new viral entry inhibitors that target the HIV-1 envelope is important because they can inactivate HIV-1 in the vaginal lumen before virions can come in contact with CD4+ cells in the vaginal mucosa. Carbohydrate binding agents (CBAs) demonstrate the ability to act as entry inhibitors due to their ability to bind to glycans and prevent gp120 binding to CD4+ cells. However, as proteins they present significant challenges in regards to economical production and formulation for resource poor environments. We have synthesized water soluble polymer CBAs that contain multiple benzoboroxole moieties. A benzoboroxole-functionalized-monomer was synthesized and incorporated into linear oligomers with 2-hydroxypropylmethacrylamide (HPMAm) at different feed ratios using free radical polymerization. The benzoboroxole small molecule analog demonstrated weak affinity for HIV-1BaL gp120 by SPR; however, the 25 mol% functionalized benzoboroxole oligomer demonstrated a ten-fold decrease in the KD for gp120 suggesting an increased avidity for the multivalent polymer construct. High molecular weight polymers functionalized with 25, 50 and 75 mol% benzoboroxole were synthesized and tested for their ability to neutralize HIV-1 entry for two HIV-1 clades and both R5 and X4 co-receptor tropism. All three polymers demonstrated activity against all viral strains tested with EC50's that decrease from 15000 nM (1500 μg mL-1 ) for the 25 mol% functionalized polymers to 11 nM (1 μg mL-1) for the 75 mol% benzoboroxole-functionalized-polymers. These polymers exhibited minimal cytotoxicity after 24 hr exposure to a human vaginal cell line.