Abstract

Terrestrial cyanobacteria, Nostoc flagelliforme and Nostoc commune, are important natural resource for producing ultraviolet-absorbing mycosporine-like amino acids (MAAs), in addition to their edible value. MAAs can be used as sun-screening cosmetics, antioxidants and pharmaceuticals. Usually, water-soluble MAAs are extracted by pure or aqueous methanol after sample grinding. Development of new extraction technique without specific morphological destroyment will contribute to adequately exploit the commercial values of both edible cyanobacteria. The N-acetylcysteine solution has been preliminarily mentioned to cause the release of MAAs from N. flagelliforme via mere incubation with the sample. In this study, we explored the potential mechanism underlying this influence and further applied it to extract MAAs from various samples. It was revealed that N-acetylcysteine solutions primarily played a mild acid hydrolysis role in causing the dissociation and release of MAAs from the exopolysaccharide matrix of samples. N-acetylcysteine solutions also exerted similar physiological or morphological effects on the samples as other acidic solutions, and the morphological integrity of the treated samples was not destroyed. Finally, we found that those samples with good vitality could achieve high MAA harvests. In general, means of incubation with acidic solution serves as a simple and relatively nondestructive technique for MAA extraction from the edible terrestrial cyanobacteria.

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