Extraction and identification by high resolution mass spectrometry of bioactive substances in different extracts obtained from pomegranate peel.

This work proposes a method to separate proteins and polyphenols in a food byproduct with high bioactive properties and demonstrate by high performance liquid chromatography tandem mass spectrometry its efficiency. Bioactive substances were extracted using high intensity focused ultrasounds. Resulting extract (SR) was submitted to a step for the purification of proteins and to obtain a protein isolate (PI). Both extracts (SR and PI) were digested using two different enzymes (alcalase and thermolysin). Antioxidant, hypocholesterolemic, and antihypertensive properties of hydrolysates were explored. High antioxidant capacity, mainly due to the presence of polyphenols, was observed in SR and its hydrolysates. Hydrolysates obtained from PI using the alcalase enzyme showed simultaneously a high capacity to inhibit cholesterol esterase and to reduce micellar cholesterol solubility. Hydrolysate obtained from PI using the thermolysin enzyme showed a high antihypertensive capacity. Peptides and polyphenols in hydrolysates were identified by RP-HPLC-ESI-Q-TOF. Hydrolysates obtained from PI showed a high amount of peptides and a negligible amount of polyphenols while polyphenols were mainly present in hydrolysates from SR.

A capillary micellar electrokinetic chromatography method for the stereoselective quantitation of bioallethrin in biotic and abiotic samples.

A capillary micellar electrokinetic chromatography (MEKC) method was developed enabling the stereoselective separation of the insecticide bioallethrin. The use of sodium deoxycholate bile salt and acetyl-ß-cyclodextrin (acetyl-ß-CD) made possible the separation of bioallethrin stereoisomers with a high enantioresolution (7.4) in a short analysis time (6.5min). The analytical characteristics of the developed method were evaluated in terms of linearity, accuracy, precision, and limits of detection (LOD) and quantitation (LOQ) showing a good performance for the quantitation of bioallethrin stereoisomers with LODs of 0.2 and 0.3mg/L. The developed method was applied to the stereoselective analysis of a commercial bioallethrin pediculicide formulation and to evaluate the toxicity of bioallethrin stereoisomers on the growth of the unicellular freshwater green alga Pseudokirchneriella subcapitata and on the germination of the higher plant Sorghum bicolor (non-target organisms). The analysis of the commercial pediculicide showed a good agreement between the contents determined for the two stereoisomers and those labelled in the commercial samples. Different toxic responses and biodegradation profiles were found for each stereoisomer in ecotoxicity assays. The mixture of S/R stereoisomers of bioallethrin resulted more toxic than S-bioallethrin for green algae, with EC50 values of 1.10±0.06 for the mixture and of 1.73±0.05mg/L for the pure S-biallethrin (esbiol). Germination of plants seeds was also affected.