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 1 H‐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 1 H‐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 (IC 50 43.0 and 56.6 μg/mL, respectively) and MV3 human melanoma cells (IC 50 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.