Abstract
Prolonged exposure to harmful ultraviolet radiation (UVR) can induce many chronic or acute skin disorders in humans. To protect themselves, many people have started to apply cosmetic products containing UV-screening chemicals alone or together with physical sunblocks, mainly based on titanium–dioxide (TiO2) or zinc-oxide (ZnO2). However, it has now been shown that the use of chemical and physical sunblocks is not safe for long-term application, so searches for the novel, natural UV-screening compounds derived from plants or bacteria are gaining attention. Certain photosynthetic organisms such as algae and cyanobacteria have evolved to cope with exposure to UVR by producing mycosporine-like amino acids (MAAs). These are promising substitutes for chemical sunscreens containing commercially available sunblock filters. The use of biopolymers such as chitosan for joining MAAs together or with MAA-Np (nanoparticles) conjugates will provide stability to MAAs similar to the mixing of chemical and physical sunscreens. This review critically describes UV-induced skin damage, problems associated with the use of chemical and physical sunscreens, cyanobacteria as a source of MAAs, the abundance of MAAs and their biotechnological applications. We also narrate the effectiveness and application of MAAs and MAA conjugates on skin cell lines.
Highlights
Over recent decades, due to the depletion of the stratospheric ozone layer and by increasing anthropogenic pollution, the levels of UV radiation are increasing gradually over the Earth’s surface
There is, an urgent need to identify natural and effective sunscreen materials such as mycosporine-like amino acids (MAAs) that have the potential to protect against UV-induced damage and can enhance the efficacy of natural sunscreens by forming conjugates with nanoparticles or biopolymers. In response to this need, this review critically summarizes UV-induced skin damage, the use of and problems associated with chemical, physical or inorganic sunscreens, the abundance and properties of MAAs, and the efficacy of MAAs to protect against UV-induced skin damage
Aqueous extracts of Gracilariopsis longissima and Hydropuntia cornea induced both tumor necrosis factor-α (TNF-α) and IL-6 production in macrophages of cell line RAW264.7. These results demonstrate the anti-inflammatory properties of MAAs, palythine, asterina-330, shinorine, porphyra-334, and palythinol, which are present in cell extracts of H. cornea and G. longissima [123]
Summary
Due to the depletion of the stratospheric ozone layer and by increasing anthropogenic pollution, the levels of UV radiation are increasing gradually over the Earth’s surface. A declining ozone column leads to an increase in the intensity of UV-B reaching the Earth’s surface, and the wavelength composition is proportionally shifted towards shorter wavelengths, which are more dangerous [1,5] Such increases in UV-B radiation are most pronounced in the Antarctic, but similar trends have been recorded at other latitudes [5,6]. Continuous exposure to UV radiation can lead to structural and functional changes in the skin epidermis It can cause degradation of collagen fibers, lesions and pigmentation, and further promote photo-aging and cancer [10,11]. This study may provide new insights into our understanding of how MAAs may be a better and safer alternative than the use of cytotoxic sunblocks
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