Cytotoxicity Evaluation and Dereplication of Flavonoids-Guided by Antioxidant Activity and Total Phenolics Content from Ephedrantus amazonicus Leaves

Abstract

Plants synthesize secondary metabolites as a means of survival and competition. These metabolites are a potential source of natural antioxidants that may promote activity, favoring the control of cellular damage caused by oxidative stress. The Annonaceae family occurs in tropical and subtropical regions worldwide. The medicinal benefits of plants from this family are caused by secondary metabolites present in these species. Thus, this study aimed to determine the total phenolic content, evaluate the antioxidant potential, and in vitro cytotoxicity of the leaf ethanolic extract from Ephedrantus amazonicus R. E. Fries. The phenolic content and antioxidant activity were evaluated by the Folin-Ciocalteu and DPPH methods, respectively. The assays were adapted for 96-well microplates, with absorbance reading at λ = 630 and 517 nm, respectively, using a UV-Vis spectrophotometer. The in vitro cytotoxicity assay was performed using fibroblasts (L929 cell line). The MS/MS analyses were performed through direct infusion using a LCQ Fleet mass spectrometer equipped with APCI font and ion trap analyzer, in the positive and negative mode. A molecular network was created using the online workflow on the GNPS website (http://gnps.ucsd.edu). The phenolic content at 400μg was 25.24 ± 0.98μg.GAE/g, while the antioxidant activity showed an EC₅₀ of 13.37±2.63 μg.mL^-1. Dereplication led to the annotation of three flavonoids that may contribute to the observed antioxidant activity. The extract showed low cytotoxicity at the highest tested concentration (> 500μM). The results demonstrate that the extract from Ephedrantus amazonicus R.E. Fries leaves is a promising source of natural antioxidants.

Keywords:
Antioxidant; natural; cytotoxic activity; Ephedranthus amazonicus

HIGHLIGHTS

The phenolic content shows a positive correlation with antioxidant activity;

The leaf ethanolic extract from Ephedranthus amazonicus has antioxidant activity;

The leaf ethanolic extract from Ephedranthus amazonicus didn’t show cytotoxic activity against L929 (fibroblast) cell lines.

GRAPHICAL ABSTRACT