TITLE:
Photochemical Reactions of Microcystin-LR Following Irradiation with UV Light
AUTHORS:
Yoshihiro Mizukami
KEYWORDS:
Microcystin-LR, UV Irradiation, UV Spectra, DFT Calculations, Photochemical Reactions
JOURNAL NAME:
Open Journal of Physical Chemistry,
Vol.6 No.4,
October
25,
2016
ABSTRACT: Photochemical
reactions of microcystin-LR, a toxic compound produced by some blue green
algae, were investigated. Ultraviolet absorption of microcystin-LR was
assessed. Time-dependent density functional theory (TDDFT) calculations
indicated that absorption peak at 238 nm was mainly due to excitation of
electrons from the linear chain structure Adda of
microcystin-LR. Irradiation of microcystin-LR with UV light resulted in the
reduction of the 238 nm absorption peak and the appearance of a new peak at 300
nm. Density functional theory (DFT) and TDDFT calculations with a model molecule
suggested that this 300 nm peak was due to tricyclo-Adda microcystin-LR,
an intermediate in photochemical reactions of microcystin-LR. Analysis of the
rate of this photochemical reaction showed that it was a first order reaction.