Phytochemical screening and distribution of secondary metabolites across leaf position in pascuita (Euphorbia leucocephala Lotsy)

Pascuita (Euphorbia leucocephala Lotsy) is a plant with ornamental uses, which has not been explored in other areas such as phytochemistry. The objective of this study was to characterize the phytochemical profile of pascuita by evaluating the distribution of secondary metabolites in apical, intermediate, and basal leaves. Methanolic extracts (80 %) from dried leaves were analyzed using preliminary phytochemical tests and thin-layer chromatography (TLC). The content of total phenols, flavonoids, tannins, and terpenoids was quantified by spectrophotometry. Likewise, the main molecules among the phenolic compounds were detected and quantified by HPLC. Qualitative results confirmed the presence of phenolic compounds, flavonoids, tannins, and terpenoids, and the absence of alkaloids and saponins. Quantification revealed differences dependent on leaf position. Apical leaves showed the highest content of total phenols (1.46 mg GAE g⁻¹ DW) and flavonoids (0.309 mg QE g⁻¹ DW). Conversely, basal leaves showed the highest concentrations of tannins (0.280 mg g⁻¹ DW) and terpenoids (0.048 mg UAE g⁻¹ DW). HPLC exploration demonstrated the presence of catechin in high concentration (19.7 mg g⁻¹ DW), as well as other molecules from the phenolic compounds group. These findings contribute to the knowledge of the species and promote further research in the area.