The Study Of Diketopiperazines From Marine Bacterium Pseudomonas Putida And Its Biological Activity

Marine environment is known to harbor unique properties, such as high pressure, high salinity, low nutrient, low temperature (partial high temperature) and little light. These speical conditions allow the organisms that live in marine to evolve specially metabolic pathways. Therefore, the secondary metabolites of marine biology own novel structures and activity diversities with useful pharmaceutical properties. In order to isolate natural compounds with unique structure and pronounced biological activities from marine microorganism, the marine bacterium272isolated from the sponge tissues was investigated in this work.Marine bacterium272was identified as Pseudomonas putida by compensive analysis using colonial morphology, scanning electron microscope (SEM) and16S rDNA sequence analysis. A large scale fermentation of P.putida was performed and the crude organic solvent extract was subjected to silica gel column, the fractions were analysed by TLC and DAD-HPLC, the Fr.c-1and Fr.d-1contained various of diketopiperazines. In this study the separation procedure was guided by chemical (TLC, DAD-HPLC�'�1H NMR) analysis, aimed to get different diketopiperazines.The Fr.c-1and Fr.d-1were examined by using TL、silica gel column、ODS column and HPLC to yield21compounds.1HNMR、13CNMR、APT、1H-1H COSY、HMQC、HMBC、 NOESY�'�X-ray were utilized to identified their stuctures, including Cyclo (4R-L-Hydroxypro-L-Phe)(1),Cyclo (4R-D-Hydroxypro-L-Phe),(2), Cyclo (D-Pro-L-Leu)(3), Cyclo (L-Pro-D-Leu)(4), Cyclo (D-Pro-D-Ile)(5), Cyclo (L-Pro-L-Ala)(6), Cyclo (Val-Ala)(7), Cyclo (Leu-Ala)(8), Cyclo (Leu-Gly)(9), Cyclo (Ile-Gly)(10), Cyclo (Val-Gly)(11), Cyclo (Phe-Gly)(12), Cyclo (Tyr-Gly)(13), Cyclo (Tyr-Ala)(14), Cyclo (Tyr-Val)(15), Cyclo (Phe-Ser)(16), Cyclo (Phe-Ala)(17), Cyclo (Tyr-9-Cl-Arg)(18-1), Cyclo (D-Tyr-D-Pro)(18-2), Cyclo(Tyr-Try)(19), Cyclo (Ala-Try)(20). Note that the compound18-1is a novel one and the compound18-2is the derivative of the compound18-1.We selected some of these isolated and identfiied compounds to examine if these compounds had the cytotoxic activity, anti-diatom activity, quorum sensing inhibitory activity and a-glucosidase inhibitory activity. Our resluts showed that the compounds8and17displayed the cytotoxic activity against Hela cell. At the concentration of50μg/mL, the compounds8and17exhibited the53.55%and58.60%inhibitory rates, respectively. Furthermore, we found that the compounds17and20had the significant anti-diatom activity with the inhibitory rates of50%and85%at the concentration of50μg/mL, respectively. Diatom is one of the main marine organisms that form early biofilm for antifouling. Because the biofouling cause huge economic loss in overall development and utilization of maine resource and military use, it must be have important scientific and economic value to screen the natural compounds with inhibiting the activity of diatom from marine microorgiansms.