Phenolic Compounds in Fractionated Blackcurrant Leaf Extracts in Relation to the Biological Activity of the Extracts

Abstract

The aim of this study was to determine the relationship between antioxidant and anticancer properties of extracts from blackcurrant (Ribes nigrum L.) leaves and their fractions and chemical contents. Dried ethanolic extract was divided into three fractions using solid phase extraction: aqueous (F1), 40% MeOH (F2), and 70% MeOH (F3). Both the extract and the fractions were analyzed in terms of antiradical activity (DPPH^• and ABTS^+•), total phenolic compounds, and total flavonoids. The antitumor potential of the fractions was evaluated in vitro on human colorectal (HCT 116) and prostate (PC-3) cancer cells. Phenolics were identified using HPLC-QTOF-MS, and twelve compounds were quantified by HPLC-DAD. Finally, principal component analysis was carried out to assess the relationship between the tested factors. The results confirmed that blackcurrant leaves are a rich source of phenolics with high antioxidant activity and anticancer properties. It was demonstrated that the F2 fraction had the highest content of phenolics and the highest antiradical activity. Additionally, only this fraction showed cytotoxic activity against HCT 116 cells. It was confirmed that both the blackcurrant leaf extract and its fractions are a promising source of condensed active compounds and can be used as natural functional food additives.

Keywords: Ribes nigrum L.; anticancer activity; antiradical activity; blackcurrant leaf; phenolic compounds.

Figure 1

Anticancer properties of the ethanol extract from blackcurrant leaves and its subfractions expressed as IC₅₀ (μg/mL). The values are expressed as the mean ± SD (n = 3). According to the one-way ANOVA LSD test, means with a p-value lower than 0.05 were considered statistically different. Values marked by * mean cytotoxic activity. E—ethanol extract; F1—water fraction, F2—40% methanol/water fraction; and F3—70% methanol/water fraction.

Figure 2

Chromatogram of the blackcurrant leaf ethanol extract (λ = 330 nm). The peaks are numbered as described in Table 2 and Table 3.

Figure 3

Analysis of the main components (PCA) of selected phenolic compounds examined in the blackcurrant leaf extract: (A) projection of variables on the plane of factors; (B) projection of cases: E—ethanol extract, F1—water fraction, F2—40% methanol/water fraction, and F3—70% methanol/water fraction.