Filip Šibul

Influence of electron acceptors on the kinetics of metoprolol photocatalytic degradation in TiO2 suspension. A combined experimental and theoretical study

Metoprolol (MET) belongs to a group of frequently used β1-blockers, which often occur in waste waters. The objective of this work was to employ liquid chromatography (LC) and total organic carbon methods to study the photocatalytic degradation of MET in UV irradiated aqueous suspensions of TiO2 (Wackherrs “Oxyde de titane standard” and Degussa P25), in the presence of different electron acceptors such as molecular oxygen, hydrogen peroxide, potassium bromate, and ammonium persulfate. The degradation rates were found to be strongly influenced by the kind of electron acceptor and the type of catalyst. The optimal amount of hydrogen peroxide and potassium bromate was investigated as well. MET photocatalytic degradation was the fastest in the presence of O2 and potassium bromate with TiO2 Degussa P25, while mineralization was most efficient in the presence of molecular oxygen alone. In all investigated cases, degradation followed a pseudo-first order kinetics. Reaction intermediates of MET degradation in the presence of different electron acceptors with both catalysts were studied in detail and a number of them were indentified using LC-ESI-MS/MS. The interactions with MET of reactive radical species relevant to this study (O2˙−, ˙OH, BrO2˙, and SO4˙−) were theoretically investigated by means of density functional theory (DFT) computations.

Comparative study of biological activities and phytochemical composition of two rose hips and their preserves: Rosa canina L. and Rosa arvensis Huds.

The aim of this study was to compare phenolic profile, vitamin C content, antioxidant, anti-inflammatory and cytotoxic activity of rose hips and the preserves (purée and jam) of two Rosa species: renowned Rosa canina L. and unexplored Rosa arvensis Huds. The liquid chromatography-tandem mass spectrometry analysis of 45 phenolics resulted in quantification of 14 compounds, with quercitrin, gallic and protocatechuic acids as the most dominant. High antioxidant potential of R. canina and a moderate activity of R. arvensis extracts were determined through several assays. Purée of both species and methanol extract of air-dried R. canina hips showed some anti-inflammatory (cyclooxygenase-1 and 12-lipooxygense inhibition potency) activity. Purée of R. canina exerted cytotoxic activity only against the HeLa cell line among several others (HeLa, MCF7, HT-29 and MRC-5). The presented results support traditional use of rose hips and their fruit preserves as food with health and nutritional benefits.

The lignicolous fungus Trametes versicolor (L.) Lloyd (1920): a promising natural source of antiradical and AChE inhibitory agents

Abstract This study aimed to determine antiradical (DPPH• and •OH) and acetylcholinesterase (AChE) inhibitory activities along with chemical composition of autochtonous fungal species Trametes versicolor (Serbia). A total of 38 phenolic compounds with notable presence of phenolic acids were identified using HPLC/MS-MS. Its water extract exhibited the highest antiradical activity against •OH (3.21 μg/mL), among the rest due to the presence of gallic, p-coumaric and caffeic acids. At the concentration of 100 μg/mL, the same extract displayed a profound AChE inhibitory activity (60.53%) in liquid, compared to donepezil (89.05%), a drug in clinical practice used as positive control. The flavonoids baicalein and quercetin may be responsible compounds for the AChE inhibitory activity observed. These findings have demonstrated considerable potential of T. versicolor water extract as a natural source of antioxidant(s) and/or AChE inhibitor(s) to be eventually used as drug-like compounds or food supplements in the treatment of Alzheimer’s disease.

Advanced oxidation processes for the removal of [bmim][Sal] third generation ionic liquids: effect of water matrices and intermediates identification

Unique properties of ionic liquids make them green alternatives for conventional volatile organic compounds. Due to increased production and the high stability of these substances, they could be classified as persistent pollutants and could break through classical treatment systems into natural waters. A preliminary ionic liquid hydrolysis study demonstrated a pH dependent degradation profile with a significant decrease in hydrolysis efficiency as pH lowered from 10.0 to 2.8. In order to examine future prospects for ionic liquid removal, different advanced oxidation processes (TiO2 Degussa P25/H2O2, TiO2 Degussa P25, 7.2Fe/TiO2/H2O2, and H2O2) were studied for their applicability in the degradation of imidazolium-based ionic liquids in aqueous solution. These processes were conducted in the dark as well as in the presence of UVA and simulated sunlight (SS) radiation. Among the investigated dark processes, the 7.2Fe/TiO2/H2O2 system showed the highest efficiency, which can be attributed to a dark heterogeneous Fenton process. Otherwise, the most efficient among all the studied degradation processes was the UVA/TiO2 Degussa P25/H2O2 process. In order to make degradation processes more similar to that of the practical process SS radiation was used. Among studied processes, the 7.2Fe/TiO2/H2O2 system showed the greatest potential for the removal of ionic liquids. Also, it was observed that the impact of anions on the cation degradation efficiency was much more pronounced. Due to the possible fate of ionic liquids in the environment, for five different waters (pond, rain, tap, river, and condensate) degradations in the dark and under simulated sunlight were studied. For all processes, and all water types in the presence of SS radiation a remarkable positive effect of naturally dissolved organic matter on the degradation efficiency was observed. Also, in all experiments, the anion was less stable than the cation. The major photodegradation products identified using liquid chromatography-mass spectrometry (HPLC-MS/MS) techniques were hydroxylated compounds.

Anti-hydroxyl radical activity, redox potential and anti-AChE activity of Amanita strobiliformis polysaccharide extract

Abstract This study outlines antioxidant and anti-AChE activities of the polysaccharide (PSH) extract from the mushroom species Amanita strobiliformis. Both the presence of α and ß glucans within the aforementioned extract was recorded. PSH extract displayed a profound scavenging activity of OH radicals (IC50 value, 11.86 ± 0.59 μg/mL) and high potential for reduction of Fe3+ ions (174.11 ± 8.70 mg eq. AA/g d.w.) being almost 48- and 5-fold more effective than mannitol and butylated hydroxytoluene used as a positive control, respectively. Compared with galanthamine (0.001 μg), the same extract exhibited a moderate anti-AChE activity (10 μg) in solid. Since purified PSH extract exhibited higher bioactivity (IC50 value 7.27 ± 0.31 μg/mL, 197.68 ± 9.47 mg eq. AA/g d.w. and 0.1 μg, respectively), it can be predominantly ascribed to the polysaccharide compounds. A. strobiliformis PSH extract may be considered as a promising resource of potent bioactive polysaccharides of natural origin successfully addressing both oxidative stress and lack of acetylcholine.

The polysaccharide extracts from the fungi Coprinus comatus and Coprinellus truncorum do exhibit AChE inhibitory activity

Abstract The polysaccharide (PSH) extracts from the edible mushroom species Coprinus comatus and Coprinellus truncorum were screened in liquid for their acetylcholinesterase inhibitory (AChE) activity. Both extracts were found to display inhibition of the aforementioned enzyme reaching similar IC50 values of 0.62 ± 0.07 and 0.61 ± 0.03 mg/mL, respectively. According to the means of FTIR spectroscopy, these PSH extracts mostly contained β-glucans. However, the presence of some proteins and polyphenolics as minor ingredients were also detected. Compared with existing literature data for anti-AChE activity of the sugar samples, the findings within this study may be treated as a profound bioactivity. Consequently, this study puts some light on the possible use of the screened macrofungi in the palliative treatment of Alzheimer’s disease.