(Metallo)porphyrins as potent phototoxic anti-cancer agents after irradiation with red light.

Novel photoactive (metallo)porphyrins were synthesised and characterised. When irradiated with light at a wavelength greater than 600 nm, these porphyrins act as photosensitisers and show high cytotoxicity towards two different human cancer cell lines with IC50 values down to 0.4 μM.

Vitamin B₁₂ as a carrier for targeted platinum delivery: in vitro cytotoxicity and mechanistic studies.

It is attractive to use vitamin B₁₂ as a carrier for targeted delivery of cytotoxic agents such as platinum complexes owing to the high demand for vitamin B₁₂ by fast proliferating cells. The basic {B₁₂-CN-Pt(II)} conjugates are recognized by intracellular enzymes and converted to coenzyme B₁₂ in an enzymatic adenosylation assay. The reductive adenosylation of {B₁₂-CN-Pt(II)} conjugates leads to the release of the Pt(II) complexes; thus, {B₁₂-CN-Pt(II)} conjugates can be considered as prodrugs.

Syntheses and characterization of vitamin B12-Pt(II) conjugates and their adenosylation in an enzymatic assay.

Aiming at the use of vitamin B12 as a drug delivery carrier for cytotoxic agents, we have reacted vitamin B12 with trans-[PtCl(NH3)2(H2O)]+, [PtCl3(NH3)](-) and [PtCl4](2-). These Pt(II) precursors coordinated directly to the Co(III)-bound cyanide, giving the conjugates [(Co)-CN-(trans-PtCl(NH3)2)]+ (5), [(Co)-CN-(trans-PtCl2(NH3))] (6), [(Co)-CN-(cis-PtCl2(NH3))] (7) and [(Co)-CN-(PtCl3)](-) (8) in good yields. Spectroscopic analyses for all compounds and X-ray structure elucidation for 5 and 7 confirmed their authenticity and the presence of the central "Co-CN-Pt" motif.