Plants produce a large number of natural organic compounds devoted to their protection from biotic and abiotic stresses, such as environmental hazards, UV exposure and pathogenic attack. These phytochemicals, which are produced besides the primary biosynthetic and metabolic routes, contribute to plant's color, aroma and flavor and, therefore, impart specific sensory characteristics to edible plants and food of plant origin. In addition, it has been evidenced that these "non-nutritive" compounds play an important role in the protection of human health, when their dietary intake is significant. The identification and quantification of secondary metabolites in plants and agro-food matrices is a challenging task, continuously requesting the development of more robust, efficient and sensitive instrumental analytical techniques. This communication discusses fundamental and practical aspects of the chromatographic and capillary electrodiven separation techniques used in our laboratory for studying the main classes of secondary metabolites occurring in medicinal and edible plants and in food of plant origin. The two liquid-phase separation techniques cited above might display complementary capability in separating secondary metabolites, as it is discussed for the analysis of phenolic compounds, performed by reversed phase high performance liquid chromatography (RP -HPLC) and capillary zone electrophoresis (CZE). The different selectivity exhibited by RP-HPLC and CZE has been ascribed to the concomitant presence of hydrophilic, hydrophobic and ionogenic groups displayed by most of these compounds, which is expected to influence to different extents the separation mechanisms operating in CZE and in RP-HPLC for molecules bearing multifunctional moieties. The communication discusses the results of our recent studies carried out to investigate a variety of factors that influence electrophoretic and chromatographic behavior of plant secondary metabolites, mainly phenolic compounds. In particular, we have investigated the dependence of the retention behavior of a variety of biomolecules in RP-HPLC on the experimental parameters, such as flow rate, column length and internal diameter, dwell volume, column temperature, isocratic and gradient elution mode, variation of the organic solvent concentration in gradient elution mode (gradient shape and duration). The influence of the considered parameters on the chromatographic behavior of the selected compounds has been evaluated in the framework of solvophobic theory, using a chromatographic modeling software that allows the development of RP-HPLC methods according to a Quality by Design (QbD) criteria, with the result of decreasing the number of experiments requested for method development and increasing flexibility in routine operations. Also discussed is the practical application of either CZE or RP-HPLC to the study of secondary metabolites occurring in plants and in agro-food matrices during the transformation of raw ingredients into food and in the production of foods that have a potentially positive effect on health and disease prevention beyond basic nutrition.
Potential and Practical Use of Chromatographic and Capillary Elctrodriven Separation Techniques for the Study of Plant Secondary Metabolites
Danilo Corradini
2017
Abstract
Plants produce a large number of natural organic compounds devoted to their protection from biotic and abiotic stresses, such as environmental hazards, UV exposure and pathogenic attack. These phytochemicals, which are produced besides the primary biosynthetic and metabolic routes, contribute to plant's color, aroma and flavor and, therefore, impart specific sensory characteristics to edible plants and food of plant origin. In addition, it has been evidenced that these "non-nutritive" compounds play an important role in the protection of human health, when their dietary intake is significant. The identification and quantification of secondary metabolites in plants and agro-food matrices is a challenging task, continuously requesting the development of more robust, efficient and sensitive instrumental analytical techniques. This communication discusses fundamental and practical aspects of the chromatographic and capillary electrodiven separation techniques used in our laboratory for studying the main classes of secondary metabolites occurring in medicinal and edible plants and in food of plant origin. The two liquid-phase separation techniques cited above might display complementary capability in separating secondary metabolites, as it is discussed for the analysis of phenolic compounds, performed by reversed phase high performance liquid chromatography (RP -HPLC) and capillary zone electrophoresis (CZE). The different selectivity exhibited by RP-HPLC and CZE has been ascribed to the concomitant presence of hydrophilic, hydrophobic and ionogenic groups displayed by most of these compounds, which is expected to influence to different extents the separation mechanisms operating in CZE and in RP-HPLC for molecules bearing multifunctional moieties. The communication discusses the results of our recent studies carried out to investigate a variety of factors that influence electrophoretic and chromatographic behavior of plant secondary metabolites, mainly phenolic compounds. In particular, we have investigated the dependence of the retention behavior of a variety of biomolecules in RP-HPLC on the experimental parameters, such as flow rate, column length and internal diameter, dwell volume, column temperature, isocratic and gradient elution mode, variation of the organic solvent concentration in gradient elution mode (gradient shape and duration). The influence of the considered parameters on the chromatographic behavior of the selected compounds has been evaluated in the framework of solvophobic theory, using a chromatographic modeling software that allows the development of RP-HPLC methods according to a Quality by Design (QbD) criteria, with the result of decreasing the number of experiments requested for method development and increasing flexibility in routine operations. Also discussed is the practical application of either CZE or RP-HPLC to the study of secondary metabolites occurring in plants and in agro-food matrices during the transformation of raw ingredients into food and in the production of foods that have a potentially positive effect on health and disease prevention beyond basic nutrition.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
