Competitive, irreversible thioredoxin-1 (Trx-1) inhibitor (Ki = 31 μM) that attenuates expression of HIF-1α, VEGF and iNOS (IC50 values are 7.2, ~10 and 18.1 μM respectively). Exhibits antitumor activity; directly inhibits tubulin polymerization in vitro and decreases tumor microvessel density in vivo.