Phytochemical evaluation and biological activity of three plant extracts from Cumana, Venezuela

Kalanchoe pinnata, Lantana camara L., and Melia azedarach L. are common plants in Cumana, Venezuela, and are traditionally used by locals to treat infections. This research aimed to evaluate the phytochemical profile and antibacterial and cytotoxic activities of the ethanolic leaf extracts from these plants. Specimens were collected and identified. Using qualitative colorimetric and precipitation tests, the profile of secondary metabolites in the ethanolic extract of the leaves of each plant was determined. These metabolites were confirmed by FT-IR and UV-visible spectroscopies. Antimicrobial and cytotoxic activities were evaluated using the disk diffusion method and the Artemia salina model, respectively. All three extracts contain coumarins and polyphenols. K. pinnata and Lantana camara L. contain unsaturated sterols, but alkaloids and saponins were only detected in L. camara. None of the extracts exhibited antibacterial activity at the concentrations tested. However, according to the Clarkson Toxicity Index, all extracts showed medium toxic activity (LC50: 100–500 µg mL-1) against A. salina nauplii, with LC50 values of 245.20, 261.27, and 151.40 µg∙mL⁻¹ for K. pinnata, L. camara, and M. azedarach, respectively. These results demonstrate that the plants studied are a potential source of polar chemical compounds with useful biological activity.