Identification of phenolic compounds by HPLC-ESI-MS/MS and antioxidant activity from Chilean propolis.

Propolis is a complex hive product produced by honey bees, Apis mellifera. Its composition and biological activities depend on the vegetation where hives are placed. Propolis is often used as a food supplement. The aim of this research is to determine the antioxidant properties in vitro and the phenolic composition of six propolis collected from the region of Santiago of Chile. We obtained the ethanolic extracts dry and wax free (EEPs) and studied their antioxidant properties by FRAP, ORAC-FL, ORAC-PGR and DPPH radical methods. The total phenols were quantified by a spectrophotometric method and 30 phenolic compounds were identified by HPLC-ESI-MS/MS analysis. Curacaví EEP has the highest relative abundance of caffeic acid phenylethyl ester (CAPE) while Buin EEP has the highest relative abundance of caffeic acid benzyl ester and quercetin. Both have the highest antioxidant activity in vitro in all methods used. Our research shows, for the first time, a comparative analysis of the antioxidant activity and phenolic composition of six Chilean propolis. Pinobanksin is the only phenol present in the six samples of propolis so it may be a good candidate for the standardization of propolis ethanolic extracts in the region of Santiago.

Extraction of arsenic as the diethyl dithiophosphate complex with supercritical fluid and quantitation by cathodic stripping voltammetry.

The separation of arsenic based on in situ chelation with ammonium diethyl dithiophosphate (ADDTP) has been carried out using methanol-modified supercritical CO(2). Aliquots of extract were added to an electroanalytical cell and arsenic was determined by square wave cathodic stripping voltammetry (SWCSV) at a hanging mercury drop electrode (HMDE). Quantitative extractions of As(DDTP)(3) were achieved when the experiments were carried out at a pressure of 2500psi, a temperature of 90 degrees C, 2.0mL of methanol, 20.0min of static extraction and 5.0min of dynamic extraction in the presence of 18mg of ADDTP. Analysis of arsenic was made using 150mgL(-1) of Cu(II) in 1M HCl solution as supporting electrolyte in the presence of ADDTP as ligand. Preconcentration was carried out by deposition at a potential of -0.50V and the intermetallic compound Cu(x)As(y) was reduced at a potential of -0.77 to -0.82V, depending on ligand concentration. The results showed that the presence of ligand plays an important role, increasing the method's sensitivity and preventing the oxidation of As(III). The calibration graph of the As(DDTP)(3) solution was linear from 0.8 to 12.5mugL(-1) of arsenic (LOD 0.5mugL(-1), R=0.9992, t(acc)=60s). The method was validated using carrot pulp spiked with arsenic solution. This method was applied to the determination of arsenic in samples of carrots, beets and irrigation water. Arsenic in beets was: skin 4.10+/-0.18mgkg(-1); pulp 3.83+/-0.19mgkg(-1) and juice 0.71+/-0.09mgL(-1); arsenic in carrots was: skin 2.15+/-0.09mgkg(-1); pulp 0.59+/-0.11mgkg(-1) and juice 0.71+/-0.03mgL(-1). Arsenic in water were: Chiu-Chiu 0.08mgL(-1), Inacaliri 1.12mgL(-1), and Salado river 0.17+/-0.07mgL(-1).