RESUMO
In the present study, sodium azide (SA) toxicity and the anti-mutagenic effects of different algal extracts at 0.1% and 0.2% concentrations were studied on the mitotic index (MI), chromosomal and nuclear aberrations using Allium cepa L. root assay. Moreover, phytochemical screening of photosynthetic pigments, antioxidants compounds, total antioxidant, DPPH scavenging activity, polysaccharides, and phenolic contents were done for two red seaweeds (Laurencia obtusa (Hudson) Lamouroux and Polysiphonia morrowii Harvey) and for one brown seaweed (Dictyopteris delicatula Lamouroux). Treatment with 300 µg/ml sodium azide (SA) induced the highest number of aberrations in A. cepa root. A highly significant decrease in the MI appeared after treatment with SA, whereas its value increased following different algal extracts treatments. The highest anti-mutagenic inhibition activity of Dictyopteris delicatula added at 0.2% concentration was 72.96%, 69.84%, 56.89% and 43.59% with the algal polyphenol, polysaccharide, aqueous and methanol extract treatments, respectively. The different algal extracts minimized the genotoxicity and exhibited anti-mutagenic potential against SA in a dose-dependent manner. Phytochemical studies showed that Dictyopteris delicatula contained the highest total phenol, chlorophyll-a and carotenoid quantity. Moreover it exhibited the highest total antioxidant and DPPH scavenging activities. Total polysaccharides and the weight percentage of sulphated polysaccharides were relatively higher in Polysiphonia morrowii followed by Laurencia obtusa. Hydroquinone and bromophenol were detected only in the studied brown and red seaweeds, respectively. Polysiphonia morrowii and Laurencia obtusa contained the highest quantity of galactose, rhmnose and xylose, while Dictyopteris delicatula contained fucose and mannitol as main monosaccharide units. In conclusion, the studied seaweeds may be considered as rich sources of natural antioxidants. Meanwhile the investigated different algal extracts can minimize the genotoxicity in a dose-dependent manner and exhibit anti-mutagenic potential against the mutagenic substance sodium azide.
