Interaction of Retinoic Acid Radical Cation with Lysozyme and Antioxidants: Laser Flash Photolysis Study in Microemulsion

Abstract

All-trans retinoic acid (ATRA) plays essential roles in the normal biological processes and the treatment of cancer and skin diseases. Considering its photosensitive property, many studies have been focused on the photochemistry of ATRA. In this study, we investigated the transient phenomena in the laser flash photolysis (LFP) of ATRA in microemulsion to further understand the photochemistry of ATRA. Results show that 355 nm LFP of ATRA in both acidic and alkaline conditions leads to the generation of retinoic acid cation radicals (ATRA(•+)) via biphotonic processes. The employment of microemulsion system allows us to investigate the reaction of hydrophobic ATRA(•+) with molecules of different polarity. Therefore, we studied the reaction activity of ATRA(•+) to many hydrophobic and hydrophilic molecules. Results show that ATRA(•+) can efficiently interact with lysozyme, tyrosine, tryptophan and many antioxidants, such as curcumin (Cur), vitamin C (VC) and gallic acid (GA). The apparent rate constants of these reactions were measured and compared. These findings suggest that ATRA(•+) is a reactive transient product which may pose damage to lysozyme, and antioxidants, such as Cur, VC and GA, may inactivate ATRA(•+) by efficient quenching reactions.

Generation of spin in single cholesterol molecules on gold

“…It may be speculated that the extracted electron stems from the endocyclic double bond, similar to the case of retinoic acid. 37,38 At the low temperature of the experiment the cationic state may be stabilized by a concomitant change of the molecular geometry. A closely related mechanism has been reported from charged metal atoms on insulators.…”

Scavenging of Retinoid Cation Radicals by Urate, Trolox, and α-, β-, γ-, and δ-Tocopherols

“…Furthermore, it has been also demonstrated that α-tocopherol can reduce, and thereby recycle, the semi-oxidized forms of other antioxidants, including cation radicals of two forms of vitamin A: retinol and retinoic acid [11,12,13]. Retinoid cation radicals can be formed as a result of the interaction of retinoids with hydroxyl radicals, peroxyl radicals, such as trichloromethylperoxyl radical, or the photoionization of retinoids by exposure to ultraviolet light [12,13,14,15,16].…”

“…It has been demonstrated that cation radicals of retinol and retinoic acid can damage important biomolecules, such as certain amino acids and proteins [12,13]. It has been also shown that α-tocopherol has the potential to act as an antioxidant, protecting the amino acids from oxidation by the retinol cation radical.…”

“…In methanol, the bimolecular rate constant of the interaction of retinol cation radical with α-tocopherol, 2.5 × 10 9 M −1 ·s −1 , is two orders of magnitude greater than it is with arginine [13]. However, in oil-in-water microemulsions, the apparent bimolecular rate constants of the interaction of the retinoic acid cation radical with α-tocopherol are 26, 47, and 69-fold smaller than those for its interactions with tryptophan, lysozyme, and tyrosine, respectively [12]. This indicates that the cation radicals of different retinoids can exhibit varied reactivities toward α-tocopherol.…”

Antioxidant activities of anastatin A & B derivatives and compound 38c's protective effect in a mouse model of CCl4-induced acute liver injury

“…36 Hence, the antioxidant capacities of compounds 38c and 40c were studied using DPPH and ABTS, assays rst. In fact, VC and GA have been used as a standard antioxidant in the performed experiments, 37,38 According to the data obtained from the present study, it was found that compounds 38c and 40c showed good scavenging activity against DPPH and ABTS free radicals, and suggested that both of compounds 38c and 40c had good antioxidant activity. Testing compound inhibition cell proliferation method is a common method to indicate the toxicity of a compound.…”