Optimization of extraction conditions for secondary biomolecules from various plant species

Extraction of plant secondary metabolites is an essential step in isolation of natural products. Non-optimized extraction conditions can lead to losses, degradation and modification of the biomolecules. In this paper, the influence of different solvent mixtures, solvent amounts, temperature, extraction time, and procedures for defatting on yield and profile of various classes of secondary metabolites was investigated. Rumex alpinus was used for the extraction of anthraquinones, Glycine max for isoflavonoids, Chaerophyllum bulbosum for flavonoids and phenolic acids, Anthriscus sylvestris for lignans and coumarins, alkaloids were extracted from Lupinus albus and sesquiterpene lactones from Artemisia absinthium. Extraction efficiency was evaluated by use of LC-DAD-ESI-MS/MS. The compromise extraction solvent for all of the examined compounds is 80 % methanol, mixed in ratio 13 : 1 with plant material. Maceration should last for six hours, repeated four times with fresh solvent. Defatting of the extracts does not lead to significant losses of the compounds of interest. It is acceptable to use extraction and evaporation temperature of 60ºC, while the extracts should be stored in the dark, on -20ºC. [Projekat Ministarstva nauke Republike Srbije, br. 172058

Removal of alprazolam from aqueous solutions by heterogeneous photocatalysis: Influencing factors, intermediates, and products

Efficiency of heterogeneous photocatalytic degradation of aiprazolam was investigated. The structural and morphological properties of ZnO were investigated in detail. It was found that ZnO has wurtzite structure with crystallite size about 41 nm, specific surface area about 6.5 m(2)/g, and intraparticle system of pores (maximum pore width about 160 nm). The efficiency of aiprazolam photocatalytic degradation was examined as a function of the type of irradiation (UVA, visible, and simulated solar irradiation) and photocatalyst (ZnO, TiO2 Degussa P25), photocatalyst loading, pH, and the presence of hydroxyl radical, and positive hole scavengers. By examining the effect of types of irradiation and catalysts, it was found that the UVA/ZnO system is the most efficient for alprazolam removal. The optimum catalyst loading was 2.0 mg/mL for TiO2 Degussa P25, while in presence of ZnO degradation rate increases in whole investigated range. In the case of ZnO, the pH 7 was selected as an optimal condition, while in aqueous suspension of TiO2 Degussa P25, degradation rate increases in whole investigated pH range (3.4-8.8), but increasing is not as pronounced as in case of ZnO. Also, it was found that ZnO photocatalysis takes place only via hydroxyl radicals, while using TiO2 Degussa P25 positive holes play significant role, too. The results of total organic carbon and ionic chromatography analysis showed that after 60 min of irradiation using both catalysts aiprazolam was completely mineralized. Here, for the first time, reaction intermediates formed using both catalysts were studied in detail, whereby the main intermediates were hydroxyl derivates. ZnO showed high stability in photodegradation after three successive runs