HPTLC Fingerprinting and Cytotoxicity of Secondary Metabolites of Equisetum Diffusum D. Don Extracts

Abstract

The aerial parts of Equisetum diffusum D.Don (Equisetaceae ED), a Vietnamese folk medicine used for hypertensive, anti-inflammatory, diuretic and hemostatic properties, were collected in Northern Vietnam. The secondary metabolites of the sequential n-hexane, ethyl acetate and methanol extracts were profiled by HPTLC with chromatographic conditions and derivatization reagents characteristic for flavonoids, polyphenols and terpenoids/steroids. All these metabolite classes were present in the methanol extract whereas the ethyl acetate extract comprised some polyphenols and flavonoids; no characteristic compound class could be identified in the n-hexane extract. HPLC allowed to determine the concentration of isoquercitroside, the major flavonoid of the methanol extract (1.60 ± 0.04 mg/g dry weight; n=3). In a preliminary assessment of Equisetum diffusum aerial parts safety, the cytotoxicity of these 3 ED extracts was investigated on the FHs 74 Int human intestinal epithelial cell line, a non-cancerous, non-transformed normal cell line. The ethyl acetate extract was shown to be the most toxic with an IC50 of 8.7 ± 2.3 µg/mL, followed by the n-hexane and methanol extracts, with an IC50 of 46.1 ± 3.6 µg/mL and 124.7 ± 23.0 µg/mL, respectively.