Photoprotective and antioxidant properties of scytonemin isolated from Antarctic cyanobacterium Nostoc commune Vaucher ex Bornet & Flahault and its potential as sunscreen ingredient / Dajana Ručová, Mária Vilková, Simona Sovová, Zuzana Vargová, Zuzana Kostecká, Richard Frenák, Deepti Routray, Martin Bačkor KE304