Multiple Roles of Photosynthetic and Sunscreen Pigments in Cyanobacteria Focusing on the Oxidative Stress

Abstract

Cyanobacteria have two types of sunscreen pigments, scytonemin and mycosporine-like amino acids (MAAs). These secondary metabolites are thought to play multiple roles against several environmental stresses such as UV radiation and desiccation. Not only the large molar absorption coefficients of these sunscreen pigments, but also their antioxidative properties may be necessary for the protection of biological molecules against the oxidative damages induced by UV radiation. The antioxidant activity and vitrification property of these pigments are thought to be requisite for the desiccation and rehydration processes in anhydrobiotes. In this review, the multiple roles of photosynthetic pigments and sunscreen pigments on stress resistance, especially from the viewpoint of their structures, biosynthetic pathway, and in vitro studies of their antioxidant activity, will be discussed.

Characterization of the chemical diversity of glycosylated mycosporine-like amino acids in the terrestrial cyanobacterium Nostoc commune

“…The glycosylated MAAs in N. commune are thought to be localized in the extracellular matrix to allow interaction with other constituents in its complex architecture [2,32,33]. These compounds have multiple functions including roles as UV sunscreens and radical scavengers to protect the cells in terrestrial environments [15].…”

“…Thus, these secondary metabolites are thought to play multiple roles against environmental stresses such as UV radiation and desiccation through their photoprotective and antioxidative properties [15,20].…”

“…In addition to extreme desiccation tolerance, N. commune colonies are exposed to direct solar radiation and can tolerate UV radiation stress [13,14]. The desiccated N. commune has extreme longevity [3,4]; antioxidants protect biomolecules from oxidation and are thought to be involved in the mechanisms of anhydrobiosis in N. commune [15]. N. commune has two types of UV-absorbing pigments which are scytonemin and mycosporine-like amino acids (MAAs) [14,16].…”

Cyanobacterial metabolites as a source of sunscreens and moisturizers: a comparison with current synthetic compounds

“…The precise mechanism of scytonemin biosynthesis is still ambiguous, however, recent studies indicated that biosynthesis of this pigment in cyanobacteria is a highly conserved process (Rastogi et al, 2015). Wada et al (2013) proposed a pathway for scytonemin synthesis in cyanobacteria in which enzymes ScyA, B and C are assumed to catalyse the synthesis of scytonemin monomers, while ScyC, D and F are assumed to catalyse the dimerization of the subunits (Fig. 5).…”

Characterization of extracellular matrix components from the desiccation-tolerant cyanobacterium <i>Nostoc commune</i>

“…We have studied the desiccation tolerance in N. commune in physiological and biochemical terms (Matsui et al, 2011(Matsui et al, , 2012Morsy et al, 2008;Nazifi et al, 2013Nazifi et al, , 2015Sakamoto et al, 2009Sakamoto et al, , 2011Tamaru et al, 2005;Yoshida and Sakamoto, 2009;Wada et al, 2013Wada et al, , 2015.…”