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Four lanthanide complexes with 8‐hydroxyquinoline‐2‐aldehyde‐2‐hydrazinopyridine (H‐L1), 8‐hydroxyquinoline‐2‐aldehyde‐2‐hydrazimidazole (H‐L2): [Sm(L1)2][Sm(L1)(NO3)3]·CHCl3·2CH3OH (1), [Gd(L1)2][Gd(L1)(NO3)3]·CHCl3·2CH3OH (2), [Sm(L2)(NO3)2]2·CH3OH (3), and [Eu(L2)(NO3)2]2·CH3OH (4) were synthesized and characterized. In vitro cytotoxicity evaluation showed that the ligands and four lanthanide complexes exhibited cytotoxicity to the five tested tumor cell lines. Among them, complex 1 showed the best antiproliferative activity against NCI‐H460 tumor cells. Mechanistic studies demonstrated that complex 1 arrested the cell cycle of NCI‐H460 cells in G1 phase and induced mitochondria‐mediated apoptosis, which resulted in the loss of mitochondrial membrane potential, enhanced intracellular Ca2+ levels and reactive oxygen species generation. In addition, complex 1 affected the expression levels of intracellular apoptosis‐related proteins and activated the caspase‐3/9 in NCI‐H460 cells. Therefore, complex 1 is a potential anticancer agent. [ABSTRACT FROM AUTHOR]

Six pyrazolopyrimidine Rh (III)/Pd(II) complexes were prepared and exhibited excellent cytotoxic activity, complex 5 and 6 induced cell cycle arrest, apoptosis and ER stress, suppressed cells proliferation in vivo. [Display omitted] • Six pyrazolopyrimidine Rh(III)/pd(II) complexes were synthesized and characterized. • Structure activity relationship (SAR) of the complexes was studied. • Complexes 1 – 6 exhibited excellent antitumor activity against various tumor cells. • Complexes 5 and 6 induced cell cycle arrest, apoptosis and ER stress. • Complex 5 and 6 inhibited the growth of T-24 in vivo. Six pyrazolopyrimidine rhodium(III) or palladium(II) complexes, [Rh(L1)(H 2 O)Cl 3 ] (1), [Rh(L2)(CH 3 OH)Cl 3 ] (2), [Rh(L3)(H 2 O)Cl 3 ] (3), [Rh 2 (L4)Cl 6 ]·CH 3 OH (4), [Rh(L5)(CH 3 CN)Cl 3 ]·0.5CH 3 CN (5), and [Pd(L5)Cl 2 ] (6), were synthesized and characterized. These complexes showed high cytotoxicity against six tested cancer cell lines. Most of the complexes showed higher cytotoxicity to T-24 cells in vitro than cisplatin. Mechanism studies indicated that complexes 5 and 6 induced G2/M phase cell cycle arrest through DNA damage, and induced apoptosis via endoplasmic reticulum stress response. In addition, complex 5 also induced cell apoptosis via mitochondrial dysfunction. Complexes 5 and 6 showed low in vivo toxicity and high tumor growth inhibitory activity in mouse tumor models. The inhibitory effect of rhodium complex 5 on tumor growth in vivo was more pronounced than that of palladium complex 6. [ABSTRACT FROM AUTHOR]