Mycosporine-2-glycine

Mycosporine-like amino acids (MAAs) are a group of water-soluble low-molecular-weight secondary metabolites, which are well-documented UV-screening molecules and antioxidants. We have recently demonstrated that a rare MAA, mycosporine-2-glycine (M2G), efficiently inhibited the formation of advanced glycation end-products (AGEs). Because AGEs contribute significantly to the aging process, including the pathogenesis and progression of age-related diseases, the present study further evaluated anti-inflammatory effects of M2G using an in vitro model of RAW 264.7 macrophages. We measured the inflammatory signaling molecule nitric oxide (NO) under inflammatory stimulation by lipopolysaccharide (LPS), revealing that M2G diminished LPS-induced NO production. M2G inhibited NO production approximately 2-3-fold more potently than other MAAs, including shinorine, porphyra-334, and palythine. Transcriptional analyses revealed that M2G significantly suppressed iNOS and COX-2 expression. Therefore, M2G inhibits the production of inflammatory mediators by suppressing the NF-κB pathway. Furthermore, under H2O2-induced oxidative stress, M2G down-regulated Sod1, Cat, and Nrf2 expression. Our findings clearly demonstrate anti-inflammatory and antioxidant effects of M2G in LPS-stimulated RAW 264.7 macrophages. Structure-activity relationships of biologically active MAAs are also discussed.

Mycosporine-2-glycine (M2G), isolated from the halotolerant cyanobacterium Aphanothece halophytica, was purified and characterized in order to determine its utility as a cosmetic and pharmaceutical ingredient. M2G efficiently inhibited protein crosslinking. The inhibitory activity of M2G was significantly greater than that of the well-known Maillard reaction inhibitor aminoguanidine. In addition, M2G and other known mycosporine-like amino acids inhibited bacterial collagenase activity. To the best of our knowledge, this is the first report describing that M2G specifically inhibits the formation of advanced glycation end-products (AGEs), which play a critical role in ageing process and age-related diseases. These observations indicate that M2G may have potential therapeutic applications by suppressing the formation of AGEs and inhibiting excess collagenase activity. Significance and impact of the study: Mycosporine-like amino acids (MAAs) are known as multifunctional natural compounds. The MAA mycosporine-2-glycine (M2G), isolated from the halotolerant cyanobacterium Aphanothece halophytica, has potential therapeutic applications for the prevention of skin ageing. Purified M2G was endotoxin-free. M2G had greater inhibitory activity of protein cross-linking compared with well-known inhibitor, aminoguanidine and hindered bacterial collagenase activity. The mechanisms for these inhibitory activities of M2G are discussed in this study.

A halotolerant cyanobacterium Aphanothece halophytica thrives in extreme salinity with accumulation of a potent osmoprotectant glycine betaine. Recently, this cyanobacterium was shown to accumulate sunscreen molecule mycosporine-2-glycine significantly at high salinity. In this study, we investigated effects of nitrate and amino acid provision on the accumulation of glycine betaine and mycosporine-2-glycine. With elevated nitrate concentrations at high salinity, intracellular levels of both metabolites were enhanced. Six-fold high nitrate concentration increased the relative amounts of glycine betaine and mycosporine-2-glycine to be 1.5 and 2.0 folds compared with control condition : Increased levels were time- and dose-dependent manner. Exogenous supply of glycine/serine at high salinity resulted in the similar trends as observed in excess nitrate experiment. Intracellular level of glycine betaine increased ~1.6 folds with glycine/serine supplementation. These supplementations also caused the increased level of mycosporine-2-glycine, namely 1.4 and 2 folds by glycine and serine, respectively. The transcription of glycine betaine and mycosporine-2-glycine biosynthetic genes was strongly induced under high-nitrate-salt condition. These results suggest the dependence of glycine betaine and mycosporine-2-glycine productions on substrate availability, and the effect of nitrate was possibly associated with stimulation of osmoprotectant increment in this extremophile.