Identification of Maple Anthocyanin and Its Antiproliferative Activity against LLC, T47D and C3H10T1/2 Cells

Background: The genus Acer contains around 200 species, with more than 400 garden varieties. There is considerable diversity in these species and garden varieties, and each can be characterized by morphology and chemical composition. The red appearance of Acer leaves is due to anthocyanin compounds, including cyanidin glycosides, delphinidin glycosides, and galloylated anthocyanins. Few studies have investigated the diversity of anthocyanin compounds in garden varieties, and no studies have examined the pharmacological effects of these compounds.

Objective: The purpose of this study was to identify the anthocyanins of Acer palmatum cv. 'Chishio', a garden variety of A. palmatum and evaluate their antiproliferative and antioxidant activities.

Methods: A methanol extract of fresh leaves was partitioned with ethyl acetate. The extract was purified by column chromatography and compounds were subsequently identified by 1H and 13C NMR and ESI-HRMS. Antiproliferative activity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt (MTS) colorimetric assay. The antioxidant assay was evaluated by scavenging activity using the stable radical DPPH.

Results: The anthocyanins cyanidin-3-O-(6''-O-α-rhamnopyranosyl-β- glucopyranoside), cyanidin-3-O-βglucopyranoside, cyanidin-3-O-[2''-O-(galloyl)-6''-O-(rhamnosyl)-β-glucoside], and cyanidin-3-O-[2''-O-(galloyl)-βglucopyranoside] were isolated from A. palmatum cv. 'Chishio'. All four anthocyanin compounds showed antiproliferative activity against LLC and T47D cells, and galloylated anthocyanin showed antiproliferative activity against C3H10T1/2 cells. All four anthocyanins inhibited the activity of DPPH radicals in a dose-dependent manner.

Conclusion: Maple anthocyanins could be a new cancer therapeutic agent or prophylactic medicine.

Keywords: Acer; Anthocyanin; Antioxidant activity; Antiproliferative activity; Galloylated anthocyanin; Garden varieties.