Abstract

Mycosporine-like amino acids (MAAs) are natural ultraviolet (UV)-absorbing compounds that are attracting attention in the industrial field includingcosmetics and pharmaceuticals. This book provides a wide range of descriptions ofMAAs, from fundamentals to applications. In order to discuss the properties of MAAs,an understanding of their chemical structures would be required. The purpose of thischapter is to understand the basic molecular structure of MAAs. In general, MAAshave structures in which amino acids are bound to the core structures of cyclohexenoneor cyclohexenimine. In addition to the basic structure, the resonance hybrid structuresof MAAs are also described here. Delocalization of electrons is considered to affect thestability and the absorption maximum wavelength of MAA molecules. We will alsodiscuss the environmental factors that can affect the structure of MAAs. Finally,databases of molecular structure information of MAAs will be described. 

Abstract

Accumulation of mycosporine-like amino acids (MAAs) has been reportedin a wide range of species in nature, including microalgae, macroalgae, cyanobacteria,phytoplankton, fungi, and some animals. This chapter describes the distribution ofMAAs with a focus on macroalgae and cyanobacteria. MAAs biosynthesized bymacroalgae have already been applied in cosmetic products, such as Helioguard 365and Helinori. Macroalgae tend to accumulate multiple types of MAAs, and the typesand accumulation levels are affected by changes in environmental factors. Regardingcyanobacteria, we focus on UV, salt, and osmotic stresses, temperature changes, anddrought stress as environmental factors, and describe the species in which theaccumulations of MAAs are induced by these stresses. UV-B irradiation is a commonenvironmental factor that can induce the accumulation of MAAs in cyanobacteria, butinduction by other abiotic stresses has been reported. These findings suggest thatMAAs act as a multifunctional molecule that responds to a variety of environmentalfactors, not just as a UV absorber.

Abstract

The biosynthetic mechanism of mycosporine-like amino acids (MAAs) hasbeen roughly elucidated. In 2010, the genes responsible for MAA biosynthesis wereidentified in cyanobacteria. In this chapter, first, we will describe the reactionmechanisms responsible for the biosynthetic pathways of MAAs, mainly based onresults from cyanobacteria. Next, as a regulatory mechanism for MAA biosynthesis,the response patterns of MAA accumulation in response to abiotic stresses, such as UVirradiation, salt, and osmotic pressure, will be explained. There are many points to beclarified regarding the detailed regulatory mechanisms, and further analyses areawaited in the future. Because MAAs have useful activities in addition to UVabsorption, they are substances that are expected to be used in cosmetics andpharmaceuticals. This chapter also includes discussions from the perspective of futureindustrial production.

Abstract

This chapter describes the basics of analytical and preparative methods formycosporine-like amino acids (MAAs). For samples whose molecular structures areknown, high-performance liquid chromatography is widely used as a simplequantitative or qualitative analytical method for MAAs. However, if the molecularstructures are unknown, they are often identified by combining several analyticalmethods, such as liquid chromatography-mass spectrometry and nuclear magneticresonance analysis. In MAA preparation, the first key factor is how efficiently MAAscan be obtained in the extraction process from biological samples. The second keyfactor is how efficiently high-purity MAAs can be obtained from the separationprocess. This chapter also discusses the production of MAAs from an industrialperspective.

Abstract

In this chapter, we focus on the UV absorption characteristics of MAAs anddescribe the application examples. UV rays that pass through the ozone layer and theatmosphere and reach the surface of the Earth consist of UV-A and UV-B. Becausethese rays are harmful to biomolecules, MAAs, which can efficiently absorb thesewavelength regions and detoxify their by-products, are promising natural organiccompounds such as sunscreens. Products containing MAAs extracted from red algaeare already on the market. With a focus on Helioguard 365 and HELINORI, thebiological effects of MAAs against UV irradiation will be described.

Abstract

 It is known that the generation of reactive oxygen species (ROS) caused byUV irradiation and oxidative reactions accelerate skin aging. Substances that suppressor eliminate the generation of ROS are called antioxidants. So far, variousmycosporine-like amino acids (MAAs) have been reported to have antioxidativeactivities. To prevent damage to the skin caused by ROS and maintain the homeostasisof the epidermis, skin cells have an endogenous antioxidant system consisting ofenzymatic reactions. Although many points are unclear about the regulatorymechanisms, it has been suggested that MAAs are involved in the regulation of genesencoding enzymes that are involved in this system. This chapter provides acomprehensive overview of the antioxidant activities of MAAs. 

Abstract

Inflammation is the defensive reaction system that occurs when the bodyreceives a harmful stimulus and tries to remove it. In general, the area where thereaction occurs has a fever, swelling, redness, and pain. The stimuli that causeinflammation are diverse but include UV irradiation and reactive oxygen species. Thischapter briefly describes the inflammatory response pathways caused by these stimuli.After that, it outlines the effects of mycosporine-like amino acids (MAAs) on theaccumulation, activity, and regulation of factors contained in the inflammatorypathway. Although research findings are accumulating, the molecular mechanisms arestill unknown. Details of the relationship between the molecular structures of MAAsand their functions in the inflammatory pathway await further study.

Abstract

Advanced glycation end products (AGEs) are formed by a series of chemicalreactions initiated by non-enzymatic glycation reactions. In this process, the reducingsugar binds to the free amino group of the protein. The formation of AGEs thataccompany the aging process is thought to be associated with various diseases such asdiabetes and Alzheimer's disease. A number of inhibitors derived from syntheticcompounds and natural products have been developed and evaluated to prevent theformation of AGEs. Compared to synthetic compounds, natural products areconsidered to be relatively safe for human consumption, so there is an increasingdemand for compounds derived from natural products. From this perspective, thischapter focuses on mycosporine-like amino acids as naturally occurring inhibitorsagainst AGEs formation. 

Abstract

Enzymes involved in the degradation of the extracellular matrix (ECM) aredeeply involved in skin aging. Compounds that suppress the degradation of collagenand elastin, constituents of the ECM, are of significant value to the cosmetics field. Sofar, more than 10 types of MAAs have been reported to inhibit the activity ofcollagenase, which belong to the family of matrix metalloproteinases. It has beensuggested that the metal-chelating activity of MAAs is involved in these mechanismsof action. However, MAAs have not been reported to have an inhibitory activity onelastase. This chapter briefly summarizes these observations.

Abstract

As mentioned in Chapters 8 and 9, the useful functions of MAAs, such asthe anti-glycative property and collagenase inhibitory activity, might be associated withtheir metal chelating activity. Although there are few reports on the metal-chelatingactivity of MAAs, a chelating model of MAAs and metal ions has recently beenproposed. This chapter briefly summarizes these observations.

Abstract

This chapter describes the research findings on the DNA protection, woundhealing, and anti-cancer effects of MAAs and their use in horticulture and as a rawmaterial for film-type UV-blocking materials. These applications are additional to theuse of MAAs as sunscreen agents and pharmaceuticals applied to humans.