ABSTRACT
Eusynstyelamides A-C (1-3) were isolated from the Great Barrier Reef ascidian Eusynstyela latericius, together with the known metabolites homarine and trigonelline. The structures of 1-3, with relative configurations, were elucidated by interpretation of their spectroscopic data (NMR, MS, UV, IR, and CD). The NMR data of 1 were found to be virtually identical to that reported for eusynstyelamide (4), isolated from E. misakiensis, indicating that a revision of the structure of 4 is needed. Eusynstyelamides A-C exhibited inhibitory activity against neuronal nitric oxide synthase (nNOS), with IC(50) values of 41.7, 4.3, and 5.8 microM, respectively, whereas they were found to be nontoxic toward the three human tumor cell lines MCF-7 (breast), SF-268 (CNS), and H-460 (lung). Compounds 1 and 2 displayed mild inhibitory activity toward Staphylococcus aureus (IC(50) 5.6 and 6.5 mM, respectively) and mild inhibitory activity toward the C(4) plant regulatory enzyme pyruvate phosphate dikinase (PPDK) (IC(50) values of 19 and 20 mM, respectively).
Subject(s)
Indoles/isolation & purification , Indoles/pharmacology , Nitric Oxide Synthase Type I/antagonists & inhibitors , Urochordata/chemistry , Animals , Drug Screening Assays, Antitumor , Female , Humans , Indoles/chemistry , Inhibitory Concentration 50 , Molecular Structure , Nuclear Magnetic Resonance, Biomolecular , Pyruvate, Orthophosphate Dikinase/antagonists & inhibitors , Staphylococcus aureus/drug effectsABSTRACT
We describe two complementary strategies for preparing DNA-directed RNA interference (ddRNAi) constructs designed to express hpRNA. The first, oligonucleotide assembly (OA), uses a very simple annealing protocol to combine up to 20 short nucleotides. These are then cloned into appropriately designed restriction sites in expression vectors. OA can be used to prepare simple hairpin (hp)-expressing constructs, but we prefer to use the approach to generate longer constructs. The second strategy, long-range cloning (LRC), uses a novel adaptation of long-range PCR protocols. For LRC, entire vectors are amplified with primers that serve to introduce short sequences into plasmids at defined anchor sites during PCR. The LCR strategy has proven highly reliable in our hands for generating simple ddRNAi constructs. Moreover, LCR is likely to prove useful in many situations in which conventional cloning strategies might prove problematic. In combination, OA and LRC can greatly simplify the design and generation of many expression constructs, including constructs for ddRNAi.
