Biochemometrics-Based Identification of Gallic Acid and Gallic Acid Galloylglucosides From Kalanchoe fedtschenkoi With Cytotoxic Effects on Cultured Melanoma Cells.

Abstract

Introduction: Kalanchoe Adans. (Crassulaceae) is a genus of widespread succulent plants extensively studied for their biological activities. Plants of the genus are considered a potential source of antitumor agents.

Objective: This study aimed to investigate the effect of an aqueous extract and fractions of leaves of Kalanchoe fedtschenkoi R. Hamet & H. Perrier on the proliferation of melanoma cell lines employing an NMR-based biochemometric approach complemented with HPLC-DAD and UHPLC-MS/MS analyses.

Material and methods: The n-butanol fraction (KFBuOH) from K. fedtschenkoi aqueous leaf extract, which decreased B16F10 murine melanoma cells viability by 65% at 100 μg/mL, was fractionated with RP-18 SPE and Sephadex LH-20 column chromatography. The fractions were analyzed by ¹H-NMR spectroscopy and submitted to MTT cytotoxicity assays against cultured melanoma cells. Orthogonal projection to latent structures discriminant analysis (OPLS-DA) was used to correlate their ¹H-NMR profile and cytotoxic activity.

Results: This strategy enabled the identification of gallic acid (1) and two gallic acid glucosides-gallic acid 4-O-(6'-O-galloyl)-glucopyranoside) (2) and gallic acid 3-O-(6'-O-galloyl)-glucopyranoside) (3)-as putative bioactive substances, which was further corroborated by subsequent assays with enriched fractions and a gallic acid standard. The fractions enriched in gallic acid (KFA) and gallic acid galloylglucosides (KFB) evidenced selective cytotoxicity towards B16F10 cells (IC₅₀ 43.0 and 56.6 μg/mL, respectively) and MV3 human melanoma cells (IC₅₀ 93.6 and 66.1 μg/mL, respectively).

Conclusion: These results suggest a potential therapeutic use for K. fedtschenkoi in melanoma treatment. This is the first study to evidence a potential antitumor activity for gallic acid galloylglucosides.