Qualitative Identification of Secondary Metabolites and Determination of the Toxicity of Extracts Obtained from the Flower of Kalanchoe Pinnata

Abstract

Kalanchoe pinnata, also known as air leaf or life leaf, is a plant used in traditional medicine in different world regions. In Mexico, it is included in the Atlas de la Medicina Tradicional Mexicana with a wide variety of applications, such as antimicrobial, anti-inflammatory, anticancer, and antihistamine, among others. However, neither a secondary metabolite profile of the flower has been reported nor information on its possible toxicity. The latter is the purpose of this work. A phytochemical profile of extracts with solvents of different polarity (aqueous, methanol, ethanol, and ether) was carried out. In this profile, the structural compounds could be qualitatively determined by chemical reactions, and some changes in coloring or precipitation were observed. The acute toxicity test of the extracts was performed with an aquatic organism, Artemia sp, and a terrestrial organism Eisenia foetida, as well as the evaluation of the antioxidant capacity of the extracts in the organism of Eisenia foetida. The ABTS radical method and TROLOX were applied as synthetic antioxidants for the evaluation of the inhibition percentage. Most important secondary metabolites were qualitatively identified in the extracts of K. pinnata flowers. Mainly in the alcoholic extracts (methanol and ethanol) tannins, alkaloids, and flavonols were found. As mentioned above, they are reported to have toxicological effects. The toxicity and antioxidant activity tests confirm the preliminary results obtained in the identification of secondary metabolites. It is therefore concluded that the flower of Kalanchoe pinnata contains secondary metabolites that may be of great therapeutic interest.