T. Nakanishi et al., Synthesis of derivatives of NK109, 7-OH benzo[c]phenanthridine alkaloid, and evaluation of their cytotoxicities and reduction-resistant properties, BIOORG MED, 10(20), 2000, pp. 2321-2323
The N-5-C-6 double bond of NK109 (an antitumor benzo[c]phenanthridine alkal
oid) is easily reduced under biological environment. To suppress the inacti
vation caused by reduction, we synthesized 5-, 6-, and 8-substituted NK109.
5-Substituted derivatives (4a-c) were reduced more easily than NK109. 6-Su
bstituted ones (10a-f) inhibited biological reduction, but showed weak cyto
toxic activity. 8-O-Substituted ones (13a-h), especially 8-O-hydroxyethyl N
K109 (13d), suppressed biological reduction and exhibited strong cytotoxic
activity. (C) 2000 Elsevier Science Ltd. All rights reserved.