192879-72-4Relevant academic research and scientific papers
2'-Substituted 5-phenylterbenzimidazoles as topoisomerase I poisons
Rangarajan, Meera,Kim, Jung Sun,Jin, Song,Sim, Sai-Peng,Liu, Angela,Pilch, Daniel S.,Liu, Leroy F.,Lavoie, Edmond J.
, p. 1371 - 1382 (2007/10/03)
5-Phenylterbenzimidazole (1) is active as a topoisomerase I poison (topo I) and is cytotoxic to human tumor cells. No cross-resistance was observed for 1 when it was evaluated against the camptothecin-resistant cell line, CPT-K5. Derivatives of 1 substituted at the 2'-position, however, did exhibit cross-resistance to this cell line. The basis for the resistance of this cell line towards CPT is that it possesses a mutant form of topo I. These results suggest that substituents at the 2'-position may be in proximity to the wild-type enzyme. Therefore, we hypothesized that terbenzimidazoles with 2'-substituents could be capable of interacting with the enzyme and thereby influence activity within this class of topo I poisons. 5-Phenylterbenzimidazoles with a hydroxy, hydroxymethyl, mercapto, amino, N-benzoylaminomethyl, chloro, and trifluoromethyl group at the 2'-position were synthesized. In addition, several 2'-ethyl-5-phenylterbenzimidazoles were prepared containing either a methoxy, hydroxy, amino, or N-acetylamino group at the 2-position of the ethyl side-chain. These 2'-substituted 5-phenylterbenzimidazoles were evaluated as topo I poisons and for cytotoxic activity. The presence of a strong electron-withdrawing group at the 2'-position, such as a chloro or trifluoromethyl group, did enhance both topo I poisoning activity and cytotoxicity. Studies on the relative DNA binding affinity of 1 to its 2'-amino and 2'-trifluoromethyl derivatives did exhibit a correlation with their relative differences in biological activity. Copyright (C) 2000 Elsevier Science Ltd.
Terbenzimidazoles: Influence of 2''-, 4-, and 5-substituents on cytotoxicity and relative potency as topoisomerase I poisons
Kim, Jung Sun,Yu, Chiang,Liu, Angela,Liu, Leroy F.,LaVoie, Edmond J.
, p. 2818 - 2824 (2007/10/03)
Terbenzimidazoles poison the nuclear enzyme topoisomerase I and possess significant cytotoxic activity against several human tumor cell lines. The relative pharmacological activity of 4,5- and 5,6-benzoterbenzimidazoles was compared to that of 5-phenylterbenzimidazole (3). 5,6-Benzoterbenzimidazole is inactive as a topoisomerase I poison and did not exhibit significant cytotoxic activity. In contrast, 4,5-benzoterbenzimidazole retained activity as a topoisomerase I poison but exhibited weak cytotoxic activity relative to 3. While 5-(1-naphthyl)-terbenzimidazole is less potent than 3 as a topoisomerase I poison and cytotoxic agent, 5-(2-naphthyl)terbenzimidazole has comparable activity to 3. The presence of a p-methoxy or p-chloro substituent on the phenyl moiety did not dramatically alter the pharmacological activity of 3. Several analogs of 3 were synthesized wherein the 2''-substituent varied from methyl, ethyl, propyl, isopropyl, phenyl to p-methoxyphenyl. Evaluation of the intrinsic activity of these analogs as topoisomerase I poisons indicates that topoisomerase I poisoning was not diminished by the presence of a methyl, ethyl, propyl, and isopropyl substituent at the 2''-position. Among the various 2''-substituted analogs evaluated, only in the case of 2''-(p-methoxyphenyl)-5-phenylterbenzimidazole was a significant decrease in cytotoxicity observed.
