Synthesis of acylated derivatives of alginate oligosaccharides and evaluation of their potential antibacterial activities against Staphylococcus aureus.

Alginate oligosaccharides (AOS) are crucial carbohydrate-based biomaterial used in the synthesis of potential drugs and biological agents, but their antibacterial activities are not significant. In this study, AOS acylated derivatives were synthesized by grafting maleic anhydride (MA) onto AOS at varying ratios. Additionally, their inhibitory effects against Staphylococcus aureus were thoroughly investigated. Characterization of the AOS acylated derivatives (AOS-MA-x, where x = 1, 5, 10, and 20) was conducted using Fourier-transformed infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, and X-ray diffraction, which confirmed the successful synthesis of these derivatives. The bacteriostatic activity of the AOS-MA derivatives was assessed using growth curves and plate coating method, demonstrating significant antibacterial effects against S. aureus, as compared with AOS. Among these derivatives, AOS-MA-20 exhibited the most potent bacteriostatic activity and was selected for further investigation of its inhibitory mechanism. Scanning electron microscopy analysis revealed that treatment with AOS-MA-20 led to the lysis and rupture of S. aureus cells, expelling their intracellular contents. Moreover, AOS-MA-20 disrupted the integrity of cell wall and cell membrane, impacted ATPase activity, and inhibited the formation of biofilm to some extent, ultimately resulting in bacterial death. These findings lay a foundational framework for the development of environmentally friendly antimicrobial agents.

Advances in the preparation, characterization, and biological functions of chitosan oligosaccharide derivatives: A review.

Chitosan oligosaccharide (COS), which represent the positively charged basic amino oligosaccharide in nature, is the deacetylated and degraded products of chitin. COS has become the focus of intensive scientific investigation, with a growing body of practical and clinical studies highlighting its remarkable health-enhancing benefits. These effects encompass a wide range of properties, including antibacterial, antioxidant, anti-inflammatory, and anti-tumor activities. With the rapid advancements in chemical modification technology for oligosaccharides, many COS derivatives have been synthesized and investigated. These newly developed derivatives possess more stable chemical structures, improved biological activities, and find applications across a broader spectrum of fields. Given the recent interest in the chemical modification of COS, this comprehensive review seeks to consolidate knowledge regarding the preparation methods for COS derivatives, alongside discussions on their structural characterization. Additionally, various biological activities of COS derivatives have been discussed in detail. Lastly, the potential applications of COS derivatives in biomedicine have been reviewed and presented.

Efficacy of metoprolol plus atorvastatin for carotid atherosclerosis and its influence on carotid intima-media thickness and homocysteine level.

OBJECTIVE: To analyze the effects of metoprolol (MET) plus atorvastatin (ATO) on carotid intima-media thickness (IMT) and homocysteine (Hcy) level in carotid atherosclerosis (CAS) patients. METHODS: In this retrospective study, 90 patients with CAS admitted to the Hangzhou Ninth People's Hospital between January 2019 and July 2021 were enrolled, including 40 cases (control group, the Con) treated with MET and 50 cases treated with the combination therapy of MET plus ATO (Research group, the Res). The efficacy and related influencing factors were observed and compared. The clinical effects (IMT, plaque score), Hcy level, inflammatory cytokines (ICs; matrix metalloproteinase-9 [MMP-9], high-sensitivity C-reactive protein [hs-CRP]), blood lipid indices (low-/high- density lipoprotein cholesterol [LDL-C/HDL-C], total cholesterol [TC], triglyceride [TG]) and coagulation markers (thrombin time [TT], prothrombin time [PT], activated partial thromboplastin time [APTT], fibrinogen [FIB]) of the two groups were observed and compared. RESULTS: The results identified a statistically higher overall response rate in the Res group. Age, coronary heart disease, cerebral infarction and plaque score were confirmed to be closely related to the efficacy of CAS. In addition, statistically lower post-treatment IMT, plaque score, MMP-9, hs-CRP, LDL-C, TG, TC and FIB while higher PT, TT and APTT were determined in the Res group compared with the pre-treatment values and the Con group. CONCLUSIONS: MET plus ATO can significantly improve efficacy, reduce IMT and plaque score of patients with CAS, as well as improve inflammatory factors, blood lipid indices and coagulation markers, for which it deserves clinical promotion.

Role of primary reaction initiated by 254 nm UV light in the degradation of p-nitrophenol attacked by hydroxyl radicals.

The degradation kinetics of p-nitrophenol (p-NP) exposed to 254/185 nm UV light were studied in two modes, i.e., 254 nm UV light intensity enhanced mode and normal mode. It was observed that the extra 254 nm UV light source accelerated the degradation process both in the presence and the absence of oxygen. Considering that hydroxyl radical (*OH) is the dominant factor that causes the degradation of p-NP, the enhanced degradation that occurred in the presence of the extra light source was attributed to the synergistic effect between *OH attack and the primary reactions initiated by 254 nm UV light. The synergistic effect has been confirmed by 266 nm laser flash photolysis (LFP) experiments. It is demonstrated that the phenoxy radical generated from the photoionization of p-NP is capable of reacting with *OH. On the basis of these results, it should be noted that UV light could cause more severe damage to p-NP attacked by *OH in aqueous solution.

Study on the mechanism of photo-degradation of p-nitrophenol exposed to 254 nm UV light.

The degradation mechanism of p-nitrophenol (p-NP) exposed to 254 nm UV light was studied in the presence and the absence of oxygen respectively via both steady-state photolysis and time-resolved laser flash photolysis (LFP) experiments. It has been confirmed that p-NP can be photo-ionized to produce its radical cation (p-NP(+)) and hydrated electron (e(aq)(-)) with a quantum yield of 0.52. In neutral solution p-NP(+) will be quickly deprotonated to form its phenoxyl radical (p-NP) which will react with oxygen to promote the breakage of benzene ring of p-NP. The degradation efficiency of p-NP exposed to 254 nm UV is as low as commonly reported. However, oxygen could improve the photo-degradation efficiency, which is due to the reaction of oxygen with p-NP. The reaction between oxygen and p-NP has been experimentally confirmed both in LFP and in pulse radiolysis.