A Straightforward Procedure for the High-Yield Extraction of Tricin and Flavonoids from Ecuadorian Huperzia brevifolia (Lycopodiaceae)

Abstract

Rich natural sources of the flavone tricin (5,7,4′-trihydroxy-3′,5′-dimethoxyflavone; systematic IUPAC name: 5,7-dihydroxy-2-(4-hydroxy-3,5-dimethoxyphenyl)-4H-1-benzopyran-4-one) are actively sought since this compound is endowed with a broad spectrum of biological activities and its dietary supplementation has been considered as a colon cancer chemoprotectant and for the treatment of human intestinal polyps. This paper describes a straightforward procedure for the high-yield isolation of flavonoids and tricin from aerial parts of Huperzia brevifolia (Hook. & Grev.) Holub, which grows on the paramos of Southern Ecuador. Compared to existing procedures, this method requires limited organic solvent and no chromatographic separation. In brief, the selective separation of the metabolites expressed in H. brevifolia was achieved by exploiting their different chemical properties under basic or acidic conditions. The identity of isolated tricin was firmly established by 1D and 2D NMR spectra. The contents of the total flavonoid fraction (TFF) and tricin in dried aerial parts of H. brevifolia were determined to be 4.48% w/w (44.8 mg/g) and 3.89% w/w (38.9 mg/g), respectively, using HPLC-DAD analysis. On the other hand, unoptimized crystallization of TFF delivered pure tricin in a 0.66% (w/w) yield relative to TFF, which corresponded to 2.96% w/w (29.6 mg/g) of dried aerial parts. This concentration of tricin is thus one of the highest in any plant species and makes H. brevifolia a valuable source of the flavone for preclinical trials and dietary supplementation for colon health.