Effects of Growth Conditions on Phenolic Composition and Antioxidant Activity in the Medicinal Plant Ageratina petiolaris (Asteraceae)

Abstract

Secondary metabolites, in addition to playing an essential role in the adaptation of plants to the environment and phytochemical responses in recovery processes to stress conditions, are the base material of the healing effect of medicinal plants. In this study, the effect of growth conditions and localities of origin of Ageratina petiolaris on phenolic compounds content and antioxidant activity was evaluated; the plant is used for medicinal purposes in Oaxaca, Mexico. Samples of stem and young leaves were collected from plants growing naturally (in situ) in two locations in Oaxaca and from propagules collected in situ; plants were grown ex situ to obtain a set of equivalent samples to the first sampling (in situ). In both sets of samples, total polyphenol and flavonoid contents and antioxidant activity were evaluated by spectrometry, and later the phenolic acids and flavonoids were also identified and quantified by high-performance liquid chromatography with diode-array detection (HPLC-DAD). The growth conditions of A. petiolaris significantly influenced its phenolic composition and antioxidant activity, where samples collected in situ had a higher phenolic compounds content than did plants grown ex situ. Five phenolic acids and five flavonoids were identified, eight of which had not been reported in A. petiolaris: caffeic acid, ρ-coumaric acid, robinin, rutin, luteolin-7-glucoside, apigenin-7-glucoside, rosmarinic acid and kaempferol, in terms of HPLC-DAD analysis.