Biological activity of the freshwater alga Spirogyra sp. from the Algerian desert

Algae species in Algeria have adapted to a wide range of environmental niches, from the Mediterranean coastline to the arid region of the Sahara Desert. Despite this ecological diversity, the taxonomic composition and biotechnological potential of these organisms remain poorly characterised. To date, only a limited number of studies have investigated the bioactive properties of algae from the Sahara region of Algeria. The present study aimed to evaluate the antioxidant, antimicrobial, and anticancer properties of Spirogyra sp. from the Béni Abbès oasis in Béchar Province, Algerian Sahara. Taxonomic identification was conducted through molecular analyses of the 18S rRNA, 23S rRNA, and rbcL loci, which showed distinctiveness of the alga within the Spirogyra genus. The crude algal extract was fractionated using flash chromatography and analysed with LC-MS/MS. Among the eleven collected fractions, F5 exhibited the most significant antioxidant and antibacterial activities, attributed primarily to the presence of gallotannins – a class of phenolic compounds known for their diverse biological activities. Fractions F2, F8, and F9 demonstrated pronounced cytotoxic effects against a panel of human cancer cell lines, but also affected normal human dermal fibroblasts (HDFa). In contrast, fractions F3 and F10 selectively reduced cancer cells viability without compromising the viability of HDFa. These findings underscore the potential of Spirogyra sp. from the Algerian Sahara as a promising source of natural antioxidant, antibacterial, and anticancer agents. • Spirogyra from oasis in Algerian Sahara differs genetically from other algae of this genus. • Spirogyra produces metabolites of antioxidant, antibacterial and cytotoxic activities. • Among the detected metabolites gallotannins and monolinolenin were identified. • Molecular networking supports the process of metabolite identification.