Chemical Composition and Cytotoxicity of Kalanchoe pinnata Leaves Extracts prepared using Accelerated System Extraction (ASE)

Abstract

Kalanchoe pinnata (Crassulaceae) is a medicinal plant distributed in several areas of the World. Their leaves have been used, in folk medicine, for anxiety and sleep disorders among other proposes. Chemically, this plant is composed by organic acids, flavonoids, bufadienolides, triterpenoids and some ubiquitous compounds. In this study, the fresh leaves of K. pinnata were extracted in an accelerated solvent extraction (ASE) system using H2O (cold and hot) as well as with EtOH:H2O 1:1. The obtained crude extracts were analyzed by HPLC-UV-MS. As a result, were identified organic acids and flavonoids, these being quercetin-3- O-α-L-arabinopyranosyl-(1→2)-α-L-rhamnopyranoside, kaempferol-3- O-α-L-arabinopiranosyl-(1→2)-α-L-rhamnopyranoside, quercitrin, and trans- p-coumaryl glutaric acid the main compounds in the studied extracts. Obtained results revealed the predominance of flavonoids in extracts prepared using hot H2O (70 26 α 2.19%) or EtOH:H2O 1:1 (74.65 α 5.39%) while a reduction in the amount of these compounds was observed in the extracts prepared using cold H2O (54.41 α 2.93%). Additionally, crude extracts from leaves of K. pinnata extracted with hot H2O and EtOH:H2O 1:1 showed in vitro cytotoxicity on five tested cancer cell lines: murine melanoma (B16F10), human melanoma (A2058), human cervical carcinoma (HeLa), human leukemia (HL-60), and human glioblastoma (U87-MG), with IC50 values in the range of 10.6 α 2.5-91.3 α 7.2 μg/mL. On the other hand, the extract prepared using cold H2O displayed reduced potential. These crude extracts were also tested against human foreskin fibroblasts (non-tumorigenic cells) showing IC50 values ranging from 79.5 to 90.2 μg/mL. In conclusion, our results showed the impact that different extraction methods have on the chemical composition and pharmacological activity, which are notable for the anticancer activity associated to flavonoids.