STRUCTURE AND ACTIVITY OF NEW METABOLITES FROM MICROCYSTIS BLOOM MATERIALS COLLECTED IN ISRAEL

Four new natural products and six known natural products were isolated from the two cyanobacteria blooms identified as Microcystis spp. The cells were freeze-dried, extracted with 7:3 MeOH/H2O and separated by different chromatographic methods, including various Reversed phase columns, Sephadex LH-20 and HPLC chromatography. Sample IL-349 was collected from "Komem" river reservoir located in south Israel on August 24, 2005. A new natural product was isolated from its MeOH/H2O extract, 3-hydroxy-1,4-diphenylbutan-2-yl-acetate along with the known natural product, microginin SD755. Sample IL-348 was collected from the Bror-Hail water reservoir located in south Israel on August 24, 2005. Four new natural products were isolated from its MeOH/H2O extract: 3-hydroxy-1,4-diphenylbutan-2-yl-acetate, aeruginosin BH462A, aeruginosin BH462B and aeruginosin BH604, along with five known natural products: cyanopeptolin SS, cyanopeptolin S, (Ahp)OMe cyanopeptolin S, loliolide and isololiolide. All compounds were tested for their ability to inhibit the serine proteases: trypsin and thrombin. The structure elucidation and biological activity of the compounds will be presented.