Ultra-high Performance Liquid Chromatography with Photodiode Array and Chemiluminescence Detection for the Determination of Polyphenolic Antioxidants in Erigeron acris L. Extracts

Chemiluminescence Detection in the Study of Free-Radical Reactions. Part 1

The present review, consisting of two parts, considers the application of the chemiluminescence detection method in evaluating free radical reactions in biological model systems. The first part presents a classification of experimental biological model systems. Evidence favoring the use of chemiluminescence detection in the study of free radical reactions, along with similar methods of registering electromagnetic radiation as electron paramagnetic resonance, spectrophotometry, detection of infrared radiation (IR spectrometry), and chemical methods for assessing the end products of free radical reactions, is shown. Chemiluminescence accompanying free radical reactions involving lipids has been the extensively studied reaction. These reactions are one of the key causes of cell death by either apoptosis (activation of the cytochrome c complex with cardiolipin) or ferroptosis (induced by free ferrous ions). The concept of chemiluminescence quantum yield is also discussed in this article. The second part, which is to be published in the next issue, analyzes the application of chemiluminescence detection using luminescent additives that are called activators, a.k.a. chemiluminescence enhancers, and enhance the emission through the triplet-singlet transfer of electron excitation energy from radical reaction products, followed by light emission with a high quantum yield.

Comparative analysis of phenolic compounds in four taxa of Erigeron acris s. l. (Asteraceae)

The aim of the present work was to investigate and compare the content of phenolic compounds in four taxa of Erigeron acris L. s. l.: E. acris (EAA), E. acris subsp. droebachiensis (O.F. Müll.) Arcang. (EAD), E. acris subsp. serotinus (Weihe) Greuter (EAS) and E. ×huelsenii Vatke (EH), a hybrid between E. acris and E. canadensis L. The total flavonoid content was determined by Christ-Müller method and the total phenolic acid content was determined by the method utilizing Arnov’s reagent. The method using ultra high performance liquid chromatography with photodiode array detection (UHPLC-PDA) was applied for the separation, identification and quantification of nine phenolic compounds (protocatechuic acid, chlorogenic acid, caffeic acid, 6′-O-caffeoylerigeroside, scutellarein-7-O-β-D-glucuronide, quercetin 3-O-glucoside, 4,5-dicaffeoylquinic acid, quercetin and luteolin) in the aerial parts of E. acris s. l. The chromatographic separation was carried out using a BEH C18 column packed with 1.7-μm particles and gradient elution with a mobile phase of water and methanol, both containing 0.02% (v/v) trifluoroacetic acid. The four investigated taxa of E. acris s. l. differed in the composition and the content of phenolic compounds. The main substances determined in the methanolic herbal extracts were: scutellarein-7-O-β-D-glucuronide (EAA, EAS, EAD and EH), 6′-O-caffeoylerigeroside (EAA, EAD and EH) and chlorogenic acid (EAS and EH). Moreover, the results indicated that five of the nine tested compounds were found in all investigated extracts from herbs of E. acris s. l. Two of them (6′-O-caffeoylerigeroside and scutellarein-7-O-β-D-glucuronide) could be selected as potential chemotaxonomic markers of the genus Erigeron L.