Antioxidant Activity and Inhibition of Liver Cancer Cells' Growth of Extracts from 14 Marine Macroalgae Species of the Mediterranean Sea

Macroalgae exhibit beneficial bioactivities for human health. Thus, the aim of the present study was to examine the antioxidant and anticancer potential of 14 macroalgae species' extracts, namely, Gigartina pistillata, Gigartina teedei, Gracilaria gracilis, Gracilaria sp., Gracilaria bursa pastoris, Colpomenia sinuosa, Cystoseira amentacea, Cystoseira barbata, Cystoseira compressa, Sargassum vulgare, Padina pavonica, Codium fragile, Ulva intestinalis, and Ulva rigida, from the Aegean Sea, Greece. The antioxidant activity was assessed using DPPH, ABTS(center dot+), (OH)-O-center dot, and O-2(center dot-) radicals' scavenging assays, reducing power (RP), and protection from ROO center dot-induced DNA plasmid damage assays. Moreover, macroalgae extracts' total polyphenol contents (TPCs) were assessed. Extracts' inhibition against liver HepG2 cancer cell growth was assessed using the XTT assay. The results showed that G. teedei extract's IC50 was the lowest in DPPH (0.31 +/- 0.006 mg/mL), ABTS(center dot+) (0.02 +/- 0.001 mg/mL), (OH)-O-center dot (0.10 +/- 0.007 mg/mL), O-2(center dot-) (0.05 +/- 0.003 mg/mL), and DNA plasmid breakage (0.038 +/- 0.002 mg/mL) and exhibited the highest RP (RP0.5AU 0.24 +/- 0.019 mg/mL) and TPC (12.53 +/- 0.88 mg GAE/g dw). There was also a significant correlation between antioxidant activity and TPC. P. pavonica (IC50 0.93 +/- 0.006 mg/mL) exhibited the highest inhibition against HepG2 cell growth. Conclusively, some of the tested extracts exhibited significant chemopreventive properties, and so they may be used for food products.