| dc.description.abstract | Microcystis aeruginosa, a cyanbacteria, has been known rich in polypeptides nature products. In the past, our lab in NTU has been working on cultures of the toxic colones of this species and the structure identification of toxins isolated from these clones, and comparably less attentions on other natural products. This study continued the research of Yu, 2013 in recovering the bioactive micropeptin TY1042、TY1046 from the nontoxic fractions of M.TY-1, clone for Microcystin-LR production. Through the mass culture of this species in enriched medium, solvent extractions of the harvested cell masses, solvent partitions, fractionations of a flash column chromatography, and subsequent purifications of a high performance column chromatography (HPLC), we isolated five components. Four of them were identified by the comparisons of chramtographic data, 1D Nuclear Magnetic Resornance (NMR) spectra of previous studies as microcystin-LR, 3-demethylmicrocystin-LR, micropeptin TY1046, micropeptin TY1042 and the rest, micropeptin TY992, a new compound ever published. Structures of these compounds were further confirmed by 2D NMR, including HSQC, HMBC, and 1H-1H COSY where the advanced experiments were needed. We made some corrections on the micropeptin structures determined by Yu, 2013 and we also determined the stereochemistry of the chiral carbons of micropeptins by HPLC analysis of the chiral products from Marfey’s reaction of the mcropeptin hdrolysates through the collaboration with Tsao, 2015. These three micropeptins, namely TY992, TY1042, and TY1046 conatin different L-amino acid, leucine, tyrosine, p-hydroxy cyclohexenyl alanine (HcAla) respectively at the 5 position of their polypeptide chain. | en_US |