Dibucaine inhibits ketoprofen photodegradation via a mechanism different from that of antioxidants

Exploring the emulsification potential of chitosan modified with phenolic acids: Emulsifying properties, functional activities, and application in curcumin encapsulation

This study successfully grafted caffeic acid and 3,4-dihydroxybenzoic acid into chitosan through a coupling reaction, yielding grafting ratio of 8.93 % for caffeic acid grafted chitosan (CA-GC) and 9.15 % for 3,4-dihydroxybenzoic acid grafted chitosan (DHB-GC) at an optimal concentration of 4 mmol phenolic acids. The characterization of modified chitosans through ultraviolet visible spectrometer (UV-vis), Fourier transform infrared spectrometer (FTIR), proton nuclear magnetic resonance (1H NMR), and x-ray photoelectron spectrometer (XPS) confirmed the successful grafting of phenolic acids. In the subsequent step of emulsion preparation, confocal laser scanning microscope images confirmed the formation of O/W (oil-in-water) emulsions. The phenolic acid-grafted chitosans exhibited better emulsification properties compared to native chitosan, such as reduced droplet size, more uniform emulsion droplet distribution, increased ζ-potential, and enhanced emulsifying activity and stability. Moreover, the modified chitosans demonstrated increased antioxidant activities (evidenced by DPPH and β-carotene assays) and displayed greater antimicrobial effects against E. coli and S. aureus. Its efficacy in curcumin encapsulation was also notable, with improved encapsulation efficiency, sustained release rates, and enhanced storage and photostability. These findings hint at the potential of modified chitosans as an effective emulsifier.

Photodegradation of Anti-Inflammatory Drugs: Stability Tests and Lipid Nanocarriers for Their Photoprotection

The present paper provides an updated overview of the methodologies applied in photodegradation studies of non-steroidal anti-inflammatory drugs. Photostability tests, performed according to international standards, have clearly demonstrated the photolability of many drugs belonging to this class, observed during the preparation of commercial forms, administration or when dispersed in the environment. The photodegradation profile of these drugs is usually monitored by spectrophotometric or chromatographic techniques and in many studies the analytical data are processed by chemometric procedures. The application of multivariate analysis in the resolution of often-complex data sets makes it possible to estimate the pure spectra of the species involved in the degradation process and their concentration profiles. Given the wide use of these drugs, several pharmaceutical formulations have been investigated to improve their photostability in solution or gel, as well as the pharmacokinetic profile. The use of lipid nanocarriers as liposomes, niosomes or solid lipid nanoparticles has demonstrated to both minimize photodegradation and improve the controlled release of the entrapped drugs.

LC-MS/MS-based metabolomic analysis of caffeine-degrading fungus Aspergillus sydowii during tea fermentation

Natural microorganisms involved in solid-state fermentation (SSF) of Pu-erh tea have a significant impact on its chemical components. Aspergillus sydowii is a fungus with a high caffeine-degrading capacity. In this work, A. sydowii was inoculated into sun-dried green tea leaves for SSF. Metabolomic analysis was carried out by using UPLC-QTOF-MS method, and caffeine and related demethylated products were determined by HPLC. The results showed that A. sydowii had a significant (P < 0.05) impact on amino acids, carbohydrates, flavonoids, and caffeine metabolism. Moreover, A. sydowii could promote the production of ketoprofen, baclofen, and tolbutamide. Along with caffeine degradation, theophylline, 3-methylxanthine, 1,7-dimethylxanthine, 1-methylxanthine, and 7-methylxanthine were increased significantly (P < 0.05) during inoculated fermentation, which showed that demethylation was the main pathway of caffeine degradation in A. sydowii secondary metabolism. The absolute quantification analysis showed that caffeine could be demethylated and converted to theophylline and 3-methylxanthine. Particularly, about 93.24% of degraded caffeine was converted to theophylline, 27.92 mg/g of theophylline was produced after fermentation. PRACTICAL APPLICATION: Aspergillus sydowii could cause caffeine degradation in Pu-erh tea solid-state fermentation and produce theophylline through the demethylation route. Using a starter strain to ferment tea leaves offers a more controllable, reproducible, and highly productive alternative for the biosynthesis of theophylline.

Chitosan/hyaluronan/edaravone membranes for anti-inflammatory wound dressing: In vitro and in vivo evaluation studies

A novel wound healing material composed of chitosan (Ch) and hyaluronan (HA) boosted with edaravone (Ed) as an anti-inflammatory drug was developed. The fabricated membranes were verified using FT-IR, and the thermal properties were estimated employing TGA instrument. Moreover, Physical characterizations of the prepared membranes demonstrated a decrease in the membrane wettability, whereas an increase in membrane roughness was monitored due to the effect of edaravone supplementation. A comparative study of free-radical scavenging activity of edaravone itself was carried out by two in vitro approaches: uninhibited/inhibited hyaluronan degradation and decolorization of ABTS methods in normal and simulated inflammation condition (acidic condition). Accordingly, the scavenging activity of edaravone was significantly diminished to OH and peroxy-/alkoxy-type radicals in acidic conditions in compared to the neutral reactions. The biochemical studies evidenced the haemocompatibility of the examined membranes. The consequence of membranes composed of Ch/HA/Ed on the wound healing of the rat's skin was studied, and the macroscopic and microscopic investigations revealed remarkable healing at 21^st day post-surgery compared with injuries treated with cotton gauze as a negative control in addition to Ch/HA membrane without edaravone. For these reasons, the Ch/HA/Ed membrane could be implemented as wound dressing material.