Relationship Between Parameters of Development and Functional Compounds of Yacon Leaves

Abstract Yacon is a tuberous root from the Andean region being increasingly grown across the world due to the low caloric values of their roots and the functional properties of extractions of its leaves. However, there is still a gap in the knowledge of how the plant develops, and if physical and chemical changes are noticed regarding maturity. The subject of this work was to investigate the dynamics of a group of parameters and to establish correlations across them. To achieve this goal, leaves collected from three different parts of the plant in three months were assessed regarding size (plant height and leaf area), color and the presence of sesquiterpene lactones. Different methods of extraction were also studied and the total phenolic content was analyzed. The analysis of the results revealed different patterns in the quantity, size and leaf distribution according to the age of the plant. From three different methods of extraction studied, decoction seems to be the most appropriate one to obtain phenolic compounds with greater yield and safety. Besides, the greenness of yacon leaves showed a linear correlation to the total phenolic content, being a simple and promising estimator of the corresponding bioactive group. Sesquiterpene lactones were identified in all extracts, indicating the ease of their extractability even in simple procedures of tea-making.

A comparative approach of methylparaben photocatalytic degradation assisted by UV-C, UV-A and Vis radiations.

Due to the widespread use of methylparaben (MEP) and its high chemical stability, it can be found in wastewater treatment plants and can act as an endocrine disrupting compound. In this study, the photocatalytic degradation and mineralization of MEP solutions were evaluated under UV-A, UV-C and Vis radiations in the presence of the photocatalyst TiO2. In this sense, the effects of the catalyst load, pH and MEP initial concentration were studied. Remarkably higher reaction rates and total photodegradation were achieved in systems assisted by UV-C radiation. The complete degradation was achieved after 60 min of reaction using the MEP concentration of 30 mg L-1 at pH 9 and 500 mg L-1 TiO2. The experimental data apparently followed a Langmuir-Hinshelwood kinetic model, which could predict 88-98% of the reaction behavior. For the best photodegradation condition, the model predicted an apparent reaction rate constant (kapp) equal to 0.0505 min-1 and an initial reaction rate of 1.5641 mg (L min)-1. Mineralization analyses showed high removal for MEP and derived compounds from the initial solution when using UV-C after 90 min of reaction. The lower toxicity was also confirmed by in vivo tests using MEP solutions previously treated by photocatalysis.