Leaf Anatomical-Histophytochemical Study and Evaluation of the Cytotoxicity of Ottonia frutescens Trel (Piperaceae)

Abstract

To investigate the leaf histochemistry and micromorphology of Ottonia frutescens Schltdl Trel (Piperaceae), the antioxidant potential, and in vitro cytotoxic bioactivity of the leaf extract of this species against human leukemia and colorectal cells. Leaf micromorphology and histoanatomy were detailed and recorded by optical and transmission and scanning electron microscopy. The histochemical results reveal classes of secondary phytometabolites such as alkaloids, anthraquinones, coumarins, polyphenols, and saponins. Cardiotonics, flavonoids, and triterpenes compounds were not detected. All concentrations of leaf extracts showed a significant dose-dependent and time-dependent apoptotic effect with more than 90% apoptosis of U937 cells and about 60% apoptosis of COLO-205 cells in 24 h of culture under 200 μg/mL of leaf extract. In addition, the phenolic compounds present in the fractions of the sample contribute to its strong antioxidant capacity. Ottonia frutescens exhibit anatomical and histochemical characteristics similar to other Piperaceae, and for the first time, provides a new source for secondary metabolite classes that exhibit high antioxidant potential and cytotoxic bioactivity, reduce cell viability and induce apoptosis in U937 leukemic cells and COLO-205 colorectal cells.