Tai Kyoung Kim

Selection of Extraction Solvent and Temperature Effect on Stability of the Algicidal Agent Prodigiosin

An organic solvent for extracting prodigiosin from culture broth was selected and a test to determine the long-term stability of prodigiosin was performed to develop prodigiosin as a biological control agent against Chattonella antiqua, a harmful alga that can cause red tides. Prodigiosin was extracted using nine solvents, and the extracts were analyzed by liquid chromatography-mass spectroscopy. Acetone was selected as the best organic solvent because of its high extraction efficiency and less processing time. Stability tests for prodigiosin were performed at various temperatures, and algicidal activity against C. antiqua was also tested. Ultimately, > 98% stability was sustained after 30 days at 4°C, whereas < 30% stability was maintained after 30 days at 37°C. Although prodigiosin was kept for 30 days in an optimum organic solvent, its stability was safely maintained and algicidal activity was sustained at 4°C. These results indicate that acetone is a very useful extraction and storage solvent for prodigiosin.

Total Syntheses of Lobaric Acid and Its Derivatives from the Antarctic Lichen Stereocaulon alpinum

The first total syntheses of the natural products lobaric acid (1) and its derivatives isolated from the Antarctic lichen Stereocaulon alpinum are reported in this study. Lobarin (3), with a pseudodepsidone structure, was synthesized first in 11 steps by utilizing an Ullmann aryl ether coupling reaction, and lobaric acid was synthesized in an additional three steps by a seven-membered lactonization reaction. Various derivatives were also obtained from the prepared lobaric acid, and the synthetic compounds exhibited significant PTP1B inhibitory activities.