Divalent anion catalyzed photodegradation of riboflavin: A kinetic study

Vaid, Faiyaz H.M.; Gul, Wajiha; Faiyaz, Ambreen; Anwar, Zubair; Ejaz, Muhammad Ahsan; Zahid, Saima; Ahmad, Iqbal

doi:10.1016/j.jphotochem.2018.10.048

Cited by 10 publications

(10 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is hypothesized that the ester bonds of the side chains are at least partially hydrolyzed. The remaining scaffold of the former PS might then undergo a cyclization comparable to cyclodehydroriboflavin CDRF–similar to the photoaddition of riboflavin [ 32 , 41 ]. It has been described elsewhere that both carbonate and phosphate facilitate such processes [ 41 ].…”

Section: Discussionmentioning

confidence: 99%

“…The remaining scaffold of the former PS might then undergo a cyclization comparable to cyclodehydroriboflavin CDRF–similar to the photoaddition of riboflavin [ 32 , 41 ]. It has been described elsewhere that both carbonate and phosphate facilitate such processes [ 41 ]. However, carbonate promotes the cyclisation more than phosphate, which is also supported by the data shown in this publication.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Interplay of phosphate and carbonate ions with flavin photosensitizers in photodynamic inactivation of bacteria

et al. 2021

View full text Add to dashboard Cite

Photodynamic inactivation (PDI) of pathogenic bacteria is a promising technology in different applications. Thereby, a photosensitizer (PS) absorbs visible light and transfers the energy to oxygen yielding reactive oxygen species (ROS). The produced ROS are then capable of killing microorganisms via oxidative damage of cellular constituents. Among other PS, some flavins are capable of producing ROS and cationic flavins are already successfully applied in PDI. When PDI is used for example on tap water, PS like flavins will encounter various ions and other small organic molecules which might hamper the efficacy of PDI. Thus, the impact of carbonate and phosphate ions on PDI using two different cationic flavins (FLASH-02a, FLASH-06a) was investigated using Staphylococcus aureus and Pseudomonas aeruginosa as model organisms. Both were inactivated in vitro at a low light exposure of 0.72 J cm-2. Upon irradiation, FLASH-02a reacts to single substances in the presence of carbonate or phosphate, whereas the photochemical reaction for FLASH-06a was more unspecific. DPBF-assays indicated that carbonate and phosphate ions decreased the generation of singlet oxygen of both flavins. Both microorganisms could be easily inactivated by at least one PS with up to 6 log10 steps of cell counts in low ion concentrations. Using the constant radiation exposure of 0.72 J cm-2, the inactivation efficacy decreased somewhat at medium ion concentrations but reached almost zero for high ion concentrations. Depending on the application of PDI, the presence of carbonate and phosphate ions is unavoidable. Only upon light irradiation such ions may attack the PS molecule and reduce the efficacy of PDI. Our results indicate concentrations for carbonate and phosphate, in which PDI can still lead to efficient reduction of bacterial cells when using flavin based PS.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Interplay of phosphate and carbonate ions with flavin photosensitizers in photodynamic inactivation of bacteria

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Several studies on RF photochemistry were reported that RF (vitamin B 2 ) can be reversibly reduced by hydrogen atoms by UV or visible light exposures [27–29]. In this study, RF-sensitized photocrosslinking system was applied to HA/Tyr hydrogel.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, when SPS was added, the viscosity of the HA solution was much lower than the addition of RF only. This result was due to divalent anions, such as sulfate and phosphate groups, which were known to catalyze the ROS generation in RF system [29]. Also, riboflavin phosphate, a water-soluble form of RF, was used as photoinitiator in this study.…”

Section: Discussionmentioning

confidence: 99%

Effect of photoinitiator on chain degradation of hyaluronic acid

Hong

Park

2019

Biomater Res

View full text Add to dashboard Cite

ObjectivesPhotocrosslinking systems of polymers have been widely studied using UV or visible light irradiation. However, the photodegradation behavior derived from light irradiation was rarely reported, comparing with the photocrosslinking. In this study, the tyramine-modified hyaluronic acid (HA/Tyr) hydrogel was prepared using riboflavin (RF) as a photoinitiator, and the degradation behavior of HA by the reactive oxygen species (ROS) generated in photochemical process was investigated.Materials and methodsThe HA/Tyr conjugate was synthesized by EDC/NHS chemistry to introduce phenol group. Degree of substitution (DS, %) of phenol group to HA molecule was about 25%. The structural change of HA/Tyr was measured by proton nuclear magnetic resonance (1H-NMR) and attenuated total reflectance infrared spectroscopy (ATR-FTIR), and the rheological properties of photocrosslinked HA/Tyr hydrogel were investigated by rheometer.ResultsThe HA/Tyr solution with 25% substitution formed a stable hydrogel via visible light irradiation in the presence of RF photoinitiator. Rheological data of HA/Tyr solution showed that the storage modulus (G’) was increased with increasing HA concentration. Additionally, it was found that RF initiated by visible light irradiation induced the degradation of HA molecular chain, and consequently reduced the viscosity of HA/Tyr solutions.ConclusionThe results indicate that RF-based photoinitiator system caused the degradation of HA molecule by ROS generated in photochemical process as well as the crosslinking of HA/Tyr.

show abstract

“…21 The values of F of CMF are higher than those of RF photolysis in presence of divalent anions. 72 LC The peak for b-KA was not found using positive ionization mode which could probably appear in negative ionization mode of MS. Extracted ion chromatograms of all the mentioned compounds along with their high resolution masses (Fig. 1-5) are given in ESI.…”

Section: Quantum Yields Of Photolysismentioning

confidence: 96%