Formulation of a photoprotective cosmetic emulsion using extracts from the cyanobacteria Nostoc sphaericum

Introduction: Cyanobacteria are among the few organisms for which many evolutionary adaptations for photoprotection have evolved. Among them is synthesizing specific secondary metabolites that function as sunscreens and antioxidants. In our high Andean zone, specifically in bodies of water, it is widespread to observe colonies of gelatinous consistency of spherical or lobular shape, of bluish-green color; these are cyanobacteria type algae, one of them is Nostoc sphaericum, whose adaptation to the extreme conditions has allowed the biosynthesis of substances with potential photoprotective activity. Objective: The main aim of the present investigation was to formulate a photoprotective cosmetic emulsion using N. sphaericum extracts. Materials and methods: Samples of N. sphaericum were dried by lyophilization. Extraction was performed using different solvents by maceration. A preformulation study was carried out to choose the most stable emulsion with the best compatibility with the extract. Mansur’s spectrophotometric method measured the photoprotective activity to establish the SPF. Results: The solvent with the highest extraction percentage was ethanol 70°, achieving 2.6 %. The polawax formulation was the one that presented the best stability and compatibility with the 70° ethanolic extract at concentrations of 1.25 %, 2.5 %, and 5 %, maintaining its organoleptic and physicochemical characteristics for 7 days. The SPF calculated for the emulsions were 0.572, 0.651, and 1.096 at 1.25 %, 2.5 %, and 5 %, respectively. Conclusions: Photoprotective cosmetic emulsions were formulated using the 70° ethanolic extract of N. sphaericum with concentration-dependent SPFs similar to those of other species of cyanobacteria previously studied.