Polypyridyl-based Co(iii) complexes of vitamin B₆ Schiff base for photoactivated antibacterial therapy

Abstract

Polypyridyl-based Co(iii) complexes of the vitamin-B6 Schiff base presented 1O2-mediated visible light-activated antibacterial activity against S. aureus and E. coli, being non-toxic in the dark and toward human cells.

Green Light-Triggered Photocatalytic Anticancer Activity of Terpyridine-Based Ru(II) Photocatalysts

“…ROS are naturally formed as byproducts of cellular metabolism in various physiological processes in the human body. , However, increased ROS levels can cause oxidative stress or inflammation and damage cells and cellular components . Therefore, in photoactivated cancer therapy, controlled ROS generation has been used to selectively destroy cancer cells while sparing healthy ones .…”

“…Ru3 showed similar or better anticancer responses than some of the previously reported Ru­(II)-based phototherapeutic agents with similar structures in HeLa cells (Table ). ,,− For example, [Ru­(bpy)­(dppn)­(phpy)]­PF 6 gave an IC 50 value of 7 μM in HeLa cells, but in the dark . [Ru­(dppz-X 2 ) 3 ]­(PF 6 ) 2 (X = H and F) showed no toxicity in the dark, but upon light irradiation (light source: 9.27 J cm –2 ), it showed IC 50 values of ca.…”

“…Therefore, in photoactivated cancer therapy, controlled ROS generation has been used to selectively destroy cancer cells while sparing healthy ones . ROS are reported to damage cancer cells by primarily damaging their DNA, proteins, and cell membranes, ultimately triggering apoptosis or necrosis. − In photocatalytic cancer therapy, the photoresponsive metal complexes are reported to produce H 2 O 2 , OH • , and O 2 •– (as the byproducts of NADH oxidation) in addition to 1 O 2 (via a type II energy transfer pathway). − The encouraging photophysical properties, DFT calculation data, and enhanced light-triggered cytotoxicity indicated that Ru1 – Ru3 could have a notable ROS generation tendency. To examine the 1 O 2 production efficiency of Ru1 – Ru3 , 9,10-diphenyl anthracene (DPA) has been used.…”

“…Furthermore, the in-cell ROS generation by Ru3 was visualized by DCFDA assay in HeLa cells using fluorescence microscopy. − The nonfluorescent ROS marker 2′,7′-dichlorofluorescin diacetate (DCFH-DA) converts to highly green fluorescent 2′,7′-dichlorofluorescin (DCF) by the intracellular ROS. − As shown in Figure c, Ru3 generated significant ROS at its IC 50 concentrations only after light (white or green) exposure, being inactive under dark conditions, revealing that the remarkable phototoxicity of Ru3 is also due to its highly efficient in-cell ROS generation (in addition to NADH oxidation). A similar ROS-mediated anticancer mechanism was also observed with the other Ru­(II)-based photosensitizers like [Ru­(tpy)­( N,N )­(py)]­(PF 6 ) 2 (where, N,N = 2,2′-bipyridine, 6,6′-dimethyl-2,2′-bipyridine, benzo­[ i ]-dipyrido­[3,2-a:2′,3′-c]­phenazine, and 3,6-dimethylbenzo [ i ]­dipyrido [3,2-a:2′,3′-c]­phenazine) and chiral [Ru­(Ph 2 phen) 2 (κS,κN-(Ac-RGDH-NH 2 ))]­Cl 2 (where Ph 2 phen = 4,7-diphenyl-1,10-phenanthroline). − ,, …”

“…80,81 However, increased ROS levels can cause oxidative stress or inflammation and damage cells and cellular components. 80 Therefore, in photoactivated cancer therapy, controlled ROS generation has been used to selectively destroy cancer cells while sparing healthy ones. 81 ROS are reported to damage cancer cells by primarily damaging their DNA, proteins, and cell membranes, ultimately triggering apoptosis or necrosis.…”