Bioactivity of two heteroleptic copper complexes based on pyridinedicarboxylic acid N-oxide and 2,2′-bipyridine which benefit from extensive hydrogen bonds and π-interactions are reported. Anti-cancer activities of 1 and 2 were evaluated by MTT assay against a panel of murine and human cancer cell lines. Moreover, the synergistic effects of 1 in combination with cisplatin, paclitaxel, and topotecan were investigated on HeLa cells. Cell death mechanism induced by 1 was also assessed using FITC-annexin V/PI staining. MTT results indicated that 1inhibited the proliferation of cancerous cells as compared with normal cells. Complex 2 also exerted selective toxicity towards both murine and human colon cancer cells. Moreover, the strongest synergistic effect was obtained from the combination of 1 with topotecan, and apoptosis was the main mechanism of cell death. Our results indicated that both complexes significantly inhibited the proliferation of cancerous cells. Furthermore, complex 1 can be a promising chemotherapeutic agent to be used in combination with other drugs for treatment of cervical cancer, although more studies are required to confirm this.

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