Estudo fitoquímico e avaliação das atividades antioxidante e anticolinesterásica de Tabernaemontana catharinensis

Abstract

Tabernaemontana catharinensis A.D.C. is a small tree of the Apocynaceae family currently found in Brazil, Argentina, Uruguay, Paraguay and Bolivia. The genus Tabernaemontana has evoke interest due the important biologic activity of their extracts, particularly, antimicrobial, anti-tumoral, antioxidant, anti-cholinesterasic and anti-inflammatory activities, most of which have been associated to indolic alkaloids. Although several biological activities of T. catharinensis extracts have been reported, few substances with both antioxidant and anticholinesterasic activities have been identified. The association of these properties may represent an alternative for the studies involving the control of neurodegenerative disorders as Alzheimer disease. In this context, the present work aimed to analyze the alkaloid content of the ethanolic extract of T. catharinensis and its fractions, as well as to evaluate their antioxidant and anticholinesterasic activities. The analyses of the ethanolic extract of T. catharinensis by mass spectrometry allowed identifying the presence of the alkaloids 16-epi-affinine, coronaridine-hydroxyindolenine, voachalotine, voacristine-hydroxyindolenine, and 12- methoxy-n-methyl-voachalotine, as well as an alkaloid with m/z 385.21 which spectrum suggest a derivative of voacristine or voacangine. The extract and its alkaloid rich fractions showed antioxidant activity, especially those that contain the alkaloid m/z385.21 or 16-epi-affinine with DPPH scavenging activity (IC50) between 37.18 and 74.69 μg/ml. Moreover, the extract and its fractions exhibited anticholinesterasic activity, particularly the fractions characterized by the presence of 12-methoxy-nmethyl- voachalotine, with IC50 = 2.1 e 2.5 μg/ml. Fractions with 16-epi-affinine combined good antioxidant (IC50= 65.59 to 74.69 μg/ml) and anticholinesterasic (IC50= 7.7 to 8.3 μg/ml) activities, representing an option for further studies aimed at treating neurodegenerative diseases.