Evaluation of the radical scavenging activity of some representative isoprenoid and aromatic cytokinin ribosides (N⁶-substituted adenosines) by in vitro chemical assays

Abstract

Cytokinins are naturally occurring adenine derivatives whose physiological role is that of growth regulators in plants and that show also many other activities either in plants and in mammalian cells. In plants, they can be found mainly as free bases ((N 6substituted adenines, CKs), but also as the corresponding N 9ribosides (N 6 -substituted adenosines, CKRs). In mammalian cells, CKRs are, in general, more active than CKs. In order to evaluate the intrinsic in vitro antioxidant capacity of some significant CKRs, their scavenging activity against synthetic radicals that are at the basis of well-established antioxidant assays (ORAC, TEAC, DPPH) has been evaluated. The results of the in vitro scavenging activity of biologically relevant radicals such as hydroxyl (HO ), superoxide (O 2 .-) and lipid peroxides (R-OO . ) are reported and discussed.

Synthesis, DFT Study, and In Vitro Evaluation of Antioxidant Properties and Cytotoxic and Cytoprotective Effects of New Hydrazones on SH-SY5Y Neuroblastoma Cell Lines

“…The scavenging activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay is attributed to the hydrogen-donating ability of antioxidants with a following decrease in the absorbance at 517 nm. The most probable mechanisms of the DPPH·assay are based on hydrogen atom abstraction (HAT) [ 24 ], single electron transfer (SET) [ 25 ], or mixed mode [ 26 ]. The following reaction schemes are related to these mechanisms: DPPH (violet at 515 nm) + ArOH → DPPHH (colorless) + ArO·HAT DPPH (violet at 515 nm) + ArOH → DPPH− (colorless) + ArO·+ SET as suggested in [ 27 ].…”

“…The scavenging activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay is attributed to the hydrogen-donating ability of antioxidants with a following decrease in the absorbance at 517 nm. The most probable mechanisms of the DPPH•assay are based on hydrogen atom abstraction (HAT) [24], single electron transfer (SET) [25], or mixed mode [26] as suggested in [27]. This allowed us to apply this method in order to evaluate the possible radical scavenging effects of the newly synthesized pyrrole-based hydrazones.…”