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Chiral cyclopalladated complexes derived from N,N-dimethyl-1-phenethylamine with bridging bis(diphenylphosphine)ferrocene ligand as inhibitors of the cathepsin B activity and as antitumoral agents.

Authors
  • Bincoletto, Cláudia
  • Tersariol, Ivarne L S
  • Oliveira, Carlos R
  • Dreher, Simone
  • Fausto, Daniela M
  • Soufen, Marco Antonio
  • Nascimento, Fábio D
  • Caires, Antonio C F
Type
Published Article
Journal
Bioorganic & Medicinal Chemistry
Publisher
Elsevier
Publication Date
Apr 15, 2005
Volume
13
Issue
8
Pages
3047–3055
Identifiers
PMID: 15781414
Source
Medline
License
Unknown

Abstract

Chiral cyclopalladated complexes derived from N,N-dimethyl-1-phenethylamine and the coordinating ligand 1,1'-bis(diphenylphosphine)ferrocene were synthesized and studied as Cathepsin B inhibitors and antitumoral agents against solid tumors. Our results revealed that the palladium compound [Pd2(C2,N-S(-)dmpa)2(mu-dppf)Cl2] (2) was able to inhibit Cathepsin B activity in a reversible fashion. This palladacycle compound binds to free cathepsin B (E) as well as to the enzyme-substrate complex (ES) with dissociation constants of KH=12+/-1 microM and alphaKH=2.4+/-0.3 microM, respectively. The application of this complex, in Walker tumor-bearing rats, resulted in 90% inhibition of the tumor growth. Subcutaneous inoculations of 10(6) tumoral cells produced solid tumors with a mass of 4.0+/-1.0 g in 12 days Walker tumor-bearing rats. However, when these animals were treated with one dose of the palladacycle compound (2.0 mg/kg), the tumoral mass was reduced to 0.3+/-0.1 g. On the other hand, the same complex (2) did not afford any protection to mice bearing the non-metastatic Ehrlich Ascites tumor treated with doses of 0.5, 5.0, and 30 mg/kg for a period of four, three and one day, respectively, beginning 72 h after tumor inoculation. Toxicological studies using mice treated with one high dose of the complex (2) (100 mg/kg) did not show any alterations in red and white blood cell morphology 14 days after the drug administration. Similar results were obtained with hepatic, kidney, and spleen tissues. The results presented in this work introduce the title cyclopalladated complexes as promising antitumoral drugs with reduced toxicity in experimental studies.

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