HPLC-ElCD: an useful tool for the pursuit of novel analytical strategies for the detection of antioxidant secondary metabolites

Abstract

As células estão continuamente expostas a uma série de fatores que exercem estresse oxidativo o qual gera várias patologias que estão relacionadas a fatores de senescência tais como doenças coronárias, artrites reumática, e câncer. Para combater esse efeito, os organismos vivos desenvolveram uma rede complexa de antioxidantes que agem contra essas espécies radicalares nocivas à vida. Com o intuito de fazer uma bioprospecção de espécies vegetais da Mata Atlântica e Cerrados brasileiros estabelecemos uma metodologia para detetar compostos com atividade antioxidante. A combinação de CLAE a um detetor eletroquímico permitiu a detecção de micromoléculas antioxidantes nos extratos brutos das folhas de Chimmarhis turbinata (DC). Foi possível detectar e identificar nas matrizes naturais os compostos responsáveis após comparação com padrões isolados da mesma espécie.Living cells are continuously exposed to a variety of challenges that exert oxidative stress and are directly related with senescence and the onset of various pathological conditions such as coronary heart disease, rheumatoid arthritis and cancer. Nevertheless, living organisms have developed a complex antioxidant network to counteract reactive species that are detrimental to life. With the aim of bio-prospecting plant species from the Brazilian Cerrado and Atlantic Forest, we have established a methodology to detect secondary antioxidant metabolites in crude extracts and fractions obtained from plant species. Combining HPLC with an electrochemical detector allowed us to detect micromolecules that showed antioxidant activities in Chimarrhis turbinata (DC) leaf extracts. Comparison with purified flavonoid standards led us to identify the compounds in their natural matrices giving valuable information on their antioxidant capacity.Keywords: antioxidant, HPLC-ElCD, reactive-oxygen-species, flavonoids IntroductionOxygen-derived free radicals such as the superoxide anion radical and hydroxyl radical are thought to be linked to the onset of various pathological conditions such as coronary heart disease, rheumatoid arthritis and cancer. [1][2][3] Living cells, including those of man, animals and plants, are continuously exposed to a variety of challenges that exert oxidative stress. These could stem from endogenous sources through normal physiological processes such as mitochondrial respiration. Alternatively, they could result from exogenous sources such as exposure to pollutants and ionizing irradiation. 4,5 Oxidative stress arises in a biological system after an increased exposure to oxidants, a decrease in the antioxidant capacity of the system, or both. This is often associated with the generation of reactive oxygen species (ROS), including free radicals, which are strongly implicated in the pathophysiology of diseases. [6][7][8] Cells are equipped with several defense systems, which act through a variety of mechanisms. 9 These can be categorized into protection via enzymatic activities and protection through low-molar mass antioxidants (LMMAs) . 10 The LMMA fa...

Differential metabolic and biological profiles of Lychnophora ericoides mart. (Asteraceae) from different localities in the Brazilian "campos rupestres"

“…Electrochemical studies can provide evidence on the mechanisms of biological electron-transfer processes, 23,24 and one obvious application is in electroanalytical studies of antioxidants. A linear correlation has been reported between the antioxidant activity of fruit and vegetables and the total electrochemical responses obtained by HPLC-ECD, 25 i.e., the sum of all peak areas in a given HPLC-ECD chromatogram is proportional to the total amount and total concentration of electroactive compounds present in the analyte (extract).…”

“…In the antioxidant assay using the DPPH radical scavenging system, extracts from specimens collected at Ibiraci and Pirenópolis showed the highest activity (no significant statistical difference between them), while extracts from São João Batista do Glória and Delfinópolis (not statistically different from each other) exhibited the lowest antioxidant activity (Table 1). The results mean that lower concentrations of extracts from Ibiraci and Pirenópolis plants are need to inhibit the same concentration of DPPH radical.Electrochemical studies can provide evidence on the mechanisms of biological electron-transfer processes, 23,24 and one obvious application is in electroanalytical studies of antioxidants. A linear correlation has been reported between the antioxidant activity of fruit and vegetables and the total electrochemical responses obtained by HPLC-ECD, 25 i.e., the sum of all peak areas in a given HPLC-ECD chromatogram is proportional to the total amount and total concentration of electroactive compounds present in the analyte (extract).…”

Iridoids from the aerial parts of Verbena littoralis (Verbenaceae)

“…DPPH solution (2 mL) in MeOH (1 mL) served as control. The evaluation of the reduced form of DPPH generated in situ was performed measuring the decrease in the current (I) on the electrochemical cell of the E1CD (Castro-Gamboa et al, 2003). The areas obtained in each chromatogram were normalized and compared with the one obtained for the blank.…”

Anthocyanin Monitoring in Four Red Grape Skin Extract Varieties Using RP‐HPLC‐ED

“…Chromatographic methods, with different detectors (Villiers et al 2004;Castro-Gamboa et al 2003;Costa et al 1998), are used for the determination of anthocyanins in grapes and wines. Because anthocyanins are compounds that can absorb UV and visible light, HPLC with UV-visible detection has been the most used (Villiers et al 2004).…”