Cyanobacteria are ubiquitous in nature as they efficiently tolerate various
extreme climatic conditions for survival, such as increasing effects of solar radiation,
salinity, temperature, etc. Cyanobacteria are important sources of secondary
metabolites, which enable them to withstand these harsh environmental conditions.
Small-molecular-weight secondary compounds are primarily implied in the defense
mechanisms in case of biotic and abiotic stresses. Various beneficiary secondary
compounds are extracted from cyanobacteria, such as UV-screening pigments
(mycosporine-like amino acids, scytonemin, carotenoids, etc.), phytohormones,
cyanotoxins and antioxidants. Bioactivity-directed isolation techniques are used to
identify these molecules from complicated matrices in pharmacognosy (discovery of
biologically active compounds from natural sources). NMR spectroscopy has appeared
as a specific major analytical technique applied in metabolomics. The easy sample
preparation, the expertise to evaluate metabolite quantity, the notable investigational
reliability, and the innately non-destructive quality of NMR spectroscopy have made it
the first-line option for significant scientific metabolic analyses. Unlike some mass
spectrometry methods, NMR is not discriminatory, depending on the metabolites'
precursors or their ionization potential. Screening of metabolites needs maximum
sensitivity, and it is a process with a broad scope. In this chapter, we have discussed the
usage of NMR spectroscopy in the identification of photoprotective compounds and its
advantages and disadvantages for metabolomic studies. We have also explored several
new NMR techniques that have recently become available in order to fortify its
advantages and overcome its inherent limitations in metabolomics applications.
Keywords: Cyanobacteria, Metabolomics, Nuclear Magnetic Resonance Spectroscopy, Secondary Metabolites, Scytonemin, Ultraviolet Radiation.