Isolation, Antiradical Activity, and Cytotoxicity of Flavonoids From Cunila angustifolia

TL;DR

This study identifies new flavonoids in a Brazilian plant and shows they have antioxidant and cancer cell inhibitory properties.

Contribution

The first report of acacetin and acacetin-7-O-rutinoside in Cunila angustifolia, along with their antiradical and cytotoxic effects.

Findings

The ethyl acetate fraction showed the highest phenolic content and strongest radical scavenging activity.

Acacetin-7-O-rutinoside had better antiradical activity than its aglycone form, suggesting glycosylation enhances this effect.

The crude extract and chloroform fraction showed selective cytotoxicity against breast and melanoma cancer cells.

Abstract

Cunila angustifolia (“vassourinha do campo”) is a plant species native to southern Brazil that is traditionally consumed as an herbal infusion. In the present study, the hydroethanolic extract of C. angustifolia leaves, its solvent‐partitioned fractions, and the flavonoids acacetin and acacetin‐7‐O‐rutinoside, reported herein for the first time in this species, were investigated for their antiradical and cytotoxic activities. Among the fractions, the ethyl acetate fraction exhibited the highest total phenolic content (633.7 mg GAE/g) and the strongest radical scavenging activity (EC50: 2.0 µg/mL). Comparative evaluation of the isolated flavonoids revealed that acacetin‐7‐O‐rutinoside displayed superior antiradical activity relative to its aglycone, suggesting that C‐7 glycosylation may enhance radical scavenging capacity. Cytotoxic assays demonstrated that the crude extract was most active against MCF‐7 breast cancer cells (IC50: 37.2 µg/mL), while the chloroform fraction showed selective inhibitory activity against SK‐Mel‐28 melanoma cells (IC50: 36.3 µg/mL). In contrast, the isolated flavonoids exhibited weak or selective cytotoxic effects, indicating that the biological activity of the extracts is likely attributable to synergistic interactions among multiple constituents. Overall, these findings expand the phytochemical knowledge of C. angustifolia and highlight its potential as a source of bioactive phenolic compounds.

Leaves of Cunila angustifolia were extracted and fractionated to isolate flavonoids and terpenoids. Chemical characterization led to the identification of acacetin and acacetin‐7‐O‐rutinoside. The ethyl acetate fraction exhibited pronounced antiradical activity, while selective cytotoxic effects were observed against human cancer cell lines, highlighting the biological potential of this species.

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