Two novel lanthanum (III) complexes containing 2-methylene–1,10-phenanthroline units bridged by aliphatic diamines were synthesized and characterized by elemental analysis, IR, NMR, thermal analysis and conductance measurements. They have been assayed for anticancer activity in vitro against HL-60 (human leukocytoma) cells, PC-3MIE8 (human prostate carcinoma) cells, BGC-823 (human stomach carcinoma) cells, MDA-MB-435 (human galactophore carcinoma) cells, Bel-7402 (human liver carcinoma) cells, and Hela (human cervix carcinoma) cells. The results show that the two complexes exhibit good cytotoxic activities against different cell lines in general, especially more effective than cisplatin against Bel-7402, BGC-823 and MDA-MB-435 cell lines. DNA-binding studies indicate that, besides the intercalation, the complexes bind to DNA by the other interaction(s), which might be responsible for the production of more compact DNA, coinciding with more A-like feature of DNA as suggested by CD spectra.

Two novel dinuclear palladium (II) complexes, {[Pd(en)Cl]2(bpse)}(NO3)2 (1) and {[Pd(en)Cl]2 (bpsu)}(NO3)2 (2), (where en is ethylenediamine; bpse is bis(3-methyl-4-pyridyl) selenide; bpsu is bis (3-methyl-4-pyridyl) sulfide) have been synthesized. The complexes have been characterized by elemental analysis, IR, 1H NMR, and 13C NMR. They have been assayed for antitumor activity in vitro against the mice leukemia L1210 and the human coloadenocarcinoma HCT8 cell lines. The results show that compound 1 has a lower I.D.50 value against the two cancer cell lines as compared to compound 2; the compounds also shows a lower I.D.50 value than cisplatin against the HCT8 cell line, but a higher I.D.50 value than cisplatin against the L1210 cell line. Binding studies indicate that compound 1 possibly interacts with DNA by a nonintercalative mode. Kinetics of binding of the two compounds to DNA are firstly studied using ethidium bromide as a fluorescence probe with stopped-flow spectrophotometer under pseudo-first-order condition. The stronger binding of two steps in the process of the compounds interacting with DNA are observed, and the kobs and Ea of binding of the two steps (where kobs is the observed pseudo-first-order rate constant, Ea is the observed energy of activation) are obtained.

Five new tetradentate ligands and their corresponding palladium complexes, [Pd(L)]Cl2 (L =N,N'-dimethyl-1,10-phenanthroline-2,9-dimathanamine, N,N'-diethyl-1,10-phenanthroline-2,9-dimathanamine, N,N'-dipropyl-1,10-phenanthroline-2,9-dimathanamine, N,N'-ditert-butyl-1,10-phenanthroline-2,9-dimathanamine, N,N'-dicyclohexyl-1,10-phenanthroline-2,9-dimathanamine) have been synthesized. The ligands and their complexes have been characterized by elemental analysis, IR, and 1H NMR. The complexes have been assayed for antitumor activity in vitro against the mouse leukemia L1210 and the mouse liver carcinoma Bel7402 cell lines. The results showed that the activities of these complexes are significantly dependent on the nature of the alkyl groups on the coordinated amine moieties, and three of these palladium complexes showed lower ID50 values against the two cell lines than cisplatin.

The DNA binding and interstrand cross-linking properties of the dinuclear platinum complex [{cis-Pt (NH3)2Cl}2bpsu] (NO3)2 (bpsu is 4,4'-dipyridyl sulfide) (II) and the mononuclear complex [cis-Pt (NH3)2Cl (4-methylpyridine)]NO3 (I) were compared with those of [{cis-Pt (NH3)2Cl}2H2N (CH2)4NH2](NO3)2 (III) in order to understand the mode of action of complexes I and II. Both compound I and compound II caused significantly different changes of conformation in poly(dG-dC)•poly(dG-dC) than compound III did. Studies of DNA binding, interstrand cross-linking and fluorescence assay suggest that compound I monofunctionally binds to DNA and compound II bifunctionally binds to DNA, that the dinuclear platinum complex II more efficiently interacts with DNA compared to its monomeric analog, and that platinum I and II complexes both interact with DNA in a non-intercalative mode. All the results indicate that the mode of action of the dinuclear complex II is different from that of the mononuclear complex I.

2.320 Å for Pd-Cl. In order to determine the donor strength of the aromatic pyridine ligands, the stability constants of binary complex ML2+ (M=[Pd (en) (H20) 2]2+; L=pyridine, 4-Me-pyridine, 4-OH-pyridine and 4-NH2-pyridine) were determined by potentiometric pH titration in aqueous solution (T=25℃, I=0.1mol 1-1 NaNO3). The results show that the stability constants of the binary complexes systematically increase with increasing pKa of the pyridines. The above four palladium complexes, [Pt (en)(pyridine) C1] NO3 and cis-diamminedichloro- platinum(II) (cis-DDP) were assayed for cytotoxicity in vitro against the human leukemia cell line HL-60, and compounds I, II, III and cis-DDP show significant cytotoxic activity against HL-60.