Antioxidant and Antigenotoxic Activities of the Brazilian Pine Araucaria angustifolia (Bert.) O. Kuntze

Abstract

Polyphenols are natural products with recognized potential in drug discovery and development. We aimed to evaluate the polyphenolic profile of Araucaria angustifolia bracts, and their ability to scavenge reactive species. The antioxidant and antigenotoxic effects of A. angustifolia polyphenols in MRC5 human lung fibroblast cells were also explored. The total polyphenol extract of A. angustifolia was determined by the Folin-Ciocalteu reagent and the chemical composition was confirmed by HPLC. Reactive oxygen species' scavenging ability was investigated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method and superoxide dismutase- and catalase-like activities. The protective effect of the extract in MRC5 cells was carried out by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method and the determination of oxidative lipids, protein, and DNA (alkaline and enzymatic comet assay) damage. Total phenolic content of the A. angustifolia extract was 1586 ± 14.53 mg gallic acid equivalents/100 g of bracts. Catechin, epicatechin, quercetin, and apigenin were the major polyphenols. The extract was able to scavenge DPPH radicals and exhibited potent superoxide dismutase and catalase-like activities. Moreover, A. angustifolia extract significantly protected MRC5 cells against H₂O₂-induced mortality and oxidative damage to lipids, proteins, and DNA. Therefore, A. angustifolia has potential as a source of bioactive chemical compounds.

Keywords: Araucaria angustifolia; MRC5; antigenotoxicity; antioxidant; polyphenols.

Figure 1

Chromatograms (HPLC) for flavonoids (A) at 350 nm and tannins (B) at 280 nm of A. angustifolia aqueous extract.

Figure 2

Cell viability of human lung fibroblast cells (MRC5). MRC5 cells were treated for 1 h with Araucaria angustifolia extract (AAE) in FBS-free medium and subsequently administered H₂O₂ (900 µM) for 1 h. Data are mean ± SD values. * Different letters indicate significant difference according to analysis of variance (ANOVA) and Tukey’s post-hoc test (p ≤ 0.05).

Figure 3

(A) DNA damage index by the alkaline Comet assay in MRC5 cells after treatment with AAE and exposure to H₂O₂. * Different letters indicate significant differences by analysis of variance (ANOVA) and Tukey’s post-hoc test (p ≤ 0.05). (B) Frequency (%) of different classes of DNA damage in control and AAE-treated groups. The cells were assessed visually and received scores from 0 (no injury) to 4 (maximally damaged), according to the size and shape of the tail. Data are mean ± SD values.

Figure 4

(A) Content of DNA damage oxidative by the Comet assay modified. * Different letters indicate significant differences by analysis of variance (ANOVA) and Tukey’s post-hoc test (p ≤ 0.05). (B) Frequency (%) of different classes of DNA damage (Comet assay). Cells were evaluated visually and were given scores of 0 (no injury) to 4 (maximally damaged) according to the size and shape of the tail. Data are mean ± SD values.