Antioxidant, antiproliferative, genotoxic and cytoprotective effects of the methanolic extract of Padina tetrastromatica on human breast adenocarcinoma and embryonic fibroblast cell lines

Figures & data

Table 1. Median inhibitory concentration (IC₅₀) values of the methanolic extract of Padina tetrastromatica in free radical scavenging assays.

	P. tetrastromatica	Quercetin	Rutin	Catechin
TPC (mg GAE/g)	97.5 ± 1.51	980.8 ± 1.98	437.6 ± 2.05	–
TFC (mg/g dried weight)	69.2 ± 1.30	–	–	56.7 ± 1.36
IC50 of DPPH radical scavenging activity (µg/ml)	45.57 ± 1.63	21.67 ± 2.89	23.33 ± 2.89	–
IC50 of superoxide anion scavenging activity (µg/ml)	101.33 ± 1.24	260.00 ± 0	223.33 ± 2.89	–
IC50 of nitric oxide scavenging activity (µg/ml)	116.04 ± 1.59	20.00 ± 0	20.00 ± 0	–
IC50 of hydroxyl radical scavenging activity (µg/ml)	36.58 ± 2.13	20.00 ± 0	101.67 ± 2.89	–

Note: Each value is expressed as mean ± SD (n = 3).

Quercetin and rutin were used as positive controls for all scavenging assays and for the determination of total phenolic content (TPC), whereas catechin was used as a positive control for the determination of total flavonoid content (TFC). GAE = gallic acid equivalents; DPPH = 1,1-diphenyl-2-picrylhydrazyl.

Figure 1. Percentage of inhibition of MCF-7 cells versus different concentrations of the methanolic extract of Padina tetrastromatica. MCF-7 cells were treated with various concentrations of the extract (100, 200, 300, 400 and 500 µg/ml) or 0.1% dimethyl sulfoxide (DMSO; vehicle control) for 48 h. Cell viability of MCF-7 cells was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

Figure 2. Comet tail length of the extract-treated 3T3-L1 and MCF-7 cells relative to hydrogen peroxide (H₂O₂)-treated and untreated negative controls. 3T3-L1 and MCF-7 cells were treated with various concentrations of the extract (5, 10, 15, 20 and 25 µg/ml) or 0.2 µg/ml of doxorubicin, as the positive control. Untreated cells and cells treated with 100 mM of H₂O₂ served as negative controls. Data are shown as mean ± SD. *p < 0.05, **p < 0.01.

Figure 3. Percentage of DNA damage in extract-treated 3T3-L1 and MCF-7 cells relative to hydrogen peroxide (H₂O₂)-treated and untreated negative controls. 3T3-L1 and MCF-7 cells were treated with various concentrations of the extract (5, 10, 15, 20 and 25 µg/ml) or 0.2 µg/ml of doxorubicin, as the positive control. Untreated cells and cells treated with 100 mM of H₂O₂ served as negative controls. Data are shown as mean ± SD. *p < 0.05, **p < 0.01.

Figure 4. Percentage of DNA protection in extract-treated 3T3-L1 and MCF-7 cells relative to hydrogen peroxide (H₂O₂)-treated and untreated negative controls. 3T3-L1 and MCF-7 cells were treated with various concentrations of the extract (5, 10, 15, 20 and 25 µg/ml) or 0.2 µg/ml of doxorubicin, as the positive control. Untreated cells and cells treated with 100 mM of H₂O₂ served as negative controls. Data are shown as mean ± SD. *p < 0.05, **p < 0.01.