Evaluation of the antioxidant, genotoxic and cytotoxic activity of organic fractions from leaves and roots of Piper patulum Bertol. from Guatemala

Abstract

Piper patulum Bertol., is a native Mesoamerican species. Previous studies have demonstrated that its leaves have antioxidant activity and the essential oil has shown cytotoxic activity against brine shrimp (Artemia salina) at a concentration of 0.5 mg/mL. The aim of this research was to demonstrate the antioxidant, cytotoxic and genotoxic activity of fractions of the vegetal material. Fractions were obtained by separate sequential extraction of leaves and roots. Phytochemicals were evaluated to determine the qualitative composition, suggesting a possible pattern to continue the study of cytotoxic activity. Qualitative antioxidant activity was evaluated by TLC based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) test, and quantitative DPPH and total phenolics by spectrophotometry. Cytotoxic activity against A. salina was evaluated macrometrically, and towards cancer cell lines [U251 (glioma), MCF-7 (mammary) and NCI-H460 (lung)] by micrometric sulforhodamine B assay, estimating the Total Growth Inhibition (TGI). Genotoxicity was tested by the Allium cepa assay. The dichloromethane fraction from the roots showed the best antioxidant activity (IC50 of 0.61 ± 0.04 mg/mL) and the greatest concentration of total phenolics (848.42 ± 9.89 µg of gallic acid equivalents/mL). Cytotoxic activity was determined against A. salina and neoplastic cell lines. For A. salina, the highest activity was observed in the methanol (DL50 0.26 ± 0.02 mg/mL) and dichloromethane (DL50 0.29 ± 0.02 mg/mL) organic fractions from the roots. In cytotoxic assays against cancer cell lines, the best TGI were obtained in the dichloromethane (U251: 68.9 µg/mL, MCF-7: 23.5 µg/mL, NCI-H460: 74.4 µg/mL) and ethyl acetate leaf fractions (U251: 53.8 µg/mL, MCF-7: 42.0 µg/mL, NCI-H460: 71.6 µg/mL), and the dichloromethane root fraction (U251: 94.2 µg/mL, MCF-7: 31.0µg/mL, NCI-H460: 88.6 µg/mL). By means of the A. cepa assay, no genotoxic activity was demonstrated. The dichloromethane fraction of the leaf from P. patulum shows interesting cytotoxic activity, which deserves further investigation of a responsible molecule by bioguided fractionation.