Singh, VidyaPathak, JainendraPandey, AbhaAhmed, HaseenRajneeshKumar, DeepakSinha, Rajeshwar P.2025-01-272025-01-2720222546299https://dl.bhu.ac.in/ir/handle/123456789/13590Mycosporine-like amino acids (MAAs) are valuable secondary metabolite with notable photoprotective potential. The present study investigateS the im???ts of ?h?t?syntheti? ??tive r?di?ti?n (??R) and ultraviolet radiation (UVR) on various physiological processes in the cyanobacterium Fischerella sp. strain HKAR-13. Cell viability was reduced by 36 and 65% after 72h of ex??sure to ??R+UV-? (PA) and ??R+UV-?+UV-B (PAB) radiations respectively. Significant decline in Chl a content was observed during PA and PAB exposure after 36h. Carotenoid content increased significantly after 48h of exposure, thereafter began to decline. Cultures exposed to PAB showed maximum detrimental effect on protein synthesis. In PAB and PA, the levels of intracellular reactive oxygen species (ROS) increased significantly. Fluorescence microscopic images of cyanobacteria revealed generation of ROS in UVR as indicated by increase in green fluorescence. Besides, Fischerella sp. strain HKAR-13 was also tested for the ?resen?e of M??s and their induction under UVR. UV-Vis spectrophotometry and high-?erf?rm?n?e liquid ?hr?m?t?gr??hy ?n?lyses revealed the ?resen?e of a MAA having absorption maxima ?max 334 nm and retention time of 1.5 min. Maximum induction of MAA was found in samples exposed to PAB followed by PA. Based on electrospray ionization-mass s?e?tr?s???y (m/z: 333+1), fourier transform infrared and nuclear magnetic res?n?n?e s?e?tr?s???y, the MAA was identified as shinorine. Shinorine was found to be highly stable under some abiotic stress factors such as UV-B, temperature and H2O2. It also showed efficient antioxidant activity in a dose-dependent manner as depicted by in vitro antioxidant assays. � 2022 SAABAntioxidantsCyanobacteriaMycosporine-like amino ??idsReactive oxygen speciesShin?rineUltraviolet radiationArticlehttps://doi.org/10.1016/j.sajb.2022.01.004