Antitumor Agents. 3. Synthesis and Biological Activity of 4β-Alkyl Derivatives Containing Hydroxy, Amino, and Amido Groups of 4′-O-Demethyl-4-desoxypodophyllotoxin as Antitumor Agents

A series of 4β-alkyl (7–10), 4β-aminoalkyl (12a–y), and 4β-amidoalkyl derivatives (14a–g) of 4′-O-demethyl-4-desoxypodophyllotoxin have been synthesized, and their cytotoxicity, inhibition of DNA topoisomerase II (Topo II), and tubulin polymerization were evaluated. All derivatives of 12a–y and 14a–g did not inhibit tubulin polymerization. Many compounds exhibited cytotoxicity and inhibition of Topo II. In particular, 12o, 12s, 12t, and 12u strongly inhibited Topo II (IC₅₀ (µM) 32.5, 60.9, 58.8, and 33.6, respectively) and were strong cytotoxicity against P388 cells (IC₅₀ (M) 1.0, 4.1, 3.3, and 3.0 × 10⁻⁹, respectively), compared with VP-16 (IC₅₀ (µM) 59.2, IC₅₀ (M) 1 × 10⁻⁸, respectively). These compounds were nearly equal to or superior to VP-16 in antitumor activity in vivo (L1210, P388, and Lewis lung) and were more cytotoxic against various human cell lines in vitro than VP-16.