Photostabilization of phycocyanin from Spirulina platensis modified by formaldehyde

Phycocyanin exists in abundance, but due to its instability, the utilization of this pigment is still very limited. Here, the phycocyanin (PC) was modified using formaldehyde crosslinks yielding phycocyanin-formaldehyde (PC-F). The modified structure was visualized by UV–vis spectrophotometer and Fourier-Transform Infra-Red Spectroscopy. The modification was carried out by incubation PC with formaldehyde. The modified PC-F was exposure to many sources of lights to evaluate its photostability. The modification of phycocyanin by formaldehyde crosslink can increase significantly photostability upon yellow light irradiation, but poor photostability upon white light, UV-A and UV-B irradiation. [Display omitted] Spirulina platensis contain variety of pigments, such as chlorophylls, carotenoids, and phycocyanin. Phycocyanin (PC) exists in abundance, but due to its instability, the utilization of this pigment is still very limited. In this study, the PC was modified using formaldehyde crosslinks yielding phycocyanin-formaldehyde (PC-F), and its photostability was evaluated. The PC-F formation was designated by the distinctive alterations of the maximum absorption to 611 nm, which was 10 nm blue-shifted than those of the PC. Additionally, the sharp peaks of FTIR spectra at 1636 nm for CO and at 1019 nm for COC, suggesting the interaction of phycocyanin with formaldehyde. The PC-F showed stabilization improvement up to 1.53-folds after 300 mins of yellow light exposure than those of PC. Contrary to yellow light irradiation, a severe decrease of PC-F absorbance was observed reach to 4.9-folds under UV-B irradiation. The poor stability of PC-F upon white light and UV-A irradiation were indicated by the decline of PC-F absorbance up to 1.72 and 1.80, respectively. Moreover, the present study suggests that the modification of phycocyanin by formaldehyde crosslink can increase photostability upon yellow light irradiation.