ABSTRACT
New 15-keto-prostaglandins (1-4) were isolated from the MeOH extract of the red alga, Gracilaria verrucosa. Their structures were determined to be prostaglandin B congeners (1-3) and a prostaglandin E congener (4) based on the NMR and MS data. Prostaglandins with a C-15 keto function are rare from natural sources. The presence of these metabolites in the alga is notable because 15-keto-prostaglandins (15-keto-PGs) are considered to be the metabolic products of regular prostaglandins in mammals. The occurrence of different prostaglandins in this alga might be due to the existence of different oxidative enzymes, as previously mentioned for oxygenated fatty acids of the red alga Gracilariopsis lemaneiformis. The antiinflammatory activity of these prostaglandins was examined by evaluating their inhibitory effects on nitric oxide production in lipopolysaccharide (LPS)-activated RAW264.7 murine macrophage cells. These prostaglandins showed weak activity on nitric oxide production.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/analysis , Anti-Inflammatory Agents, Non-Steroidal/chemistry , Drug Discovery , Gracilaria/chemistry , Prostaglandins/analysis , Prostaglandins/chemistry , Alprostadil/analogs & derivatives , Alprostadil/analysis , Alprostadil/chemistry , Alprostadil/isolation & purification , Alprostadil/pharmacology , Animals , Anti-Inflammatory Agents, Non-Steroidal/isolation & purification , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Cell Line, Transformed , Cell Survival/drug effects , Lipopolysaccharides/toxicity , Macrophage Activation/drug effects , Macrophages/drug effects , Macrophages/metabolism , Magnetic Resonance Spectroscopy , Mice , Molecular Structure , Nitric Oxide/metabolism , Plant Extracts/chemistry , Prostaglandins/isolation & purification , Prostaglandins/pharmacology , Prostaglandins B/analysis , Prostaglandins B/chemistry , Prostaglandins B/isolation & purification , Prostaglandins B/pharmacology , Spectrometry, Mass, Fast Atom BombardmentABSTRACT
3-(Dimethoxyphosphorylmethyl)cyclopent-2-enone was converted into (+/-)-prostaglandin B1 methyl ester in two steps involving regioselective alkylation at C(2) with methyl 7-iodoheptanoate and subsequent Horner-Wittig reaction with dimer of 2-hydroxyheptanal (42% overall yield). The use of (R)- and (S)-2-(tert-butyldimethylsilyloxy)heptanal for the Horner olefination reaction gave, after deprotection of the hydroxy group, the enantiopure forms of the title compound in 28% overall yield.
Subject(s)
Prostaglandins B/chemical synthesis , Esters/chemistry , Magnetic Resonance Spectroscopy , Prostaglandins B/chemistry , StereoisomerismABSTRACT
The 3D solution structure of wheat nonspecific lipid transfer protein (ns-LTP) complexed with prostaglandin B2, a lipid with both vinyl and hydroxylated groups, has been determined by 1H 2D NMR. The global fold of the protein is close to the previously published structures of wheat, maize, barley and rice ns-LTPs. The ligand is almost completely embedded in the hydrophobic core of the protein. Structure comparisons of free and bound wheat ns-LTP reveal that the binding of prostaglandin B2 hardly affects the global fold of the protein. The structural data on this unusual complex are discussed and compared with other known ns-LTP lipid-complexes.
Subject(s)
Carrier Proteins/chemistry , Carrier Proteins/metabolism , Prostaglandins B/metabolism , Triticum/chemistry , Binding Sites , Fatty Acids/metabolism , Ligands , Models, Molecular , Nuclear Magnetic Resonance, Biomolecular , Plant Proteins/chemistry , Plant Proteins/metabolism , Prostaglandins B/chemistry , Protein Binding , Protein Conformation , Protein Folding , SolutionsABSTRACT
A monomeric derivative and several oligomeric derivatives were synthesized from prostaglandin B2. Their lipid solubility was studied by measuring their octanol-water partition coefficients. With EPR spectroscopy, the oligomeric derivatives were shown to have g = 2 signal, indicating these compounds have intrinsic free radicals. Measuring the rate of adenochrome formation, it was shown that these derivatives could scavenge superoxide anions. Using a spin-trapping technique employing DMPO, we found that these oligomers could also scavenge hydroxyl radicals. The calcium chelating activity of these compounds were also studied. In an in vitro rat model, these compounds inhibited lipid peroxidation as measured by the production of thiobarbituric acid reacting substances. Other prostaglandin oligomeric derivatives synthesized from PGE1 were also studied, and their properties were compared with these new compounds. Results suggest that both the water solubility and the chelating activity for calcium ions may not be related to their protective effects in ischemic or traumatic injury.
Subject(s)
Alprostadil/analogs & derivatives , Antioxidants/chemistry , Prostaglandins, Synthetic/chemistry , Animals , Calcium/chemistry , Cell Membrane/drug effects , Chelating Agents/chemistry , Chemical Phenomena , Chemistry, Physical , Electron Spin Resonance Spectroscopy , Free Radical Scavengers , Hydroxylation , Lethal Dose 50 , Lipids , Mice , Nephelometry and Turbidimetry , Octanols , Prostaglandins/chemistry , Prostaglandins/toxicity , Prostaglandins B/chemistry , Solubility , Superoxides , WaterABSTRACT
Inhibition of human phospholipases A2 by cis-unsaturated fatty acids and their oxidative metabolites and/or polymers was studied using partially purified human phospholipases A2 and [1-14C]oleate labelled, autoclaved E. coli as substrate. As previously reported for other phospholipases A2, oleic and arachidonic acids inhibited human synovial fluid phospholipase A2 with IC50s of 15 and 30 microM respectively. Air oxidation of arachidonic acid or hydroxylation of oleic acid (12-hydroxy-oleate) substantially relieved that inhibition. Similarly, the enzymatically oxidatized metabolite of arachidonate, prostaglandin B1 (PGB1), did not inhibit enzymatic activity. However, prostaglandin Bx (PGBx), an oligomer (n = 6) of PGB1, was a potent inhibitor of Ca(++)-dependent, neutral-active phospholipase A2 activities. Enzymatic activity in acid extracts from human neutrophils, platelets, sperm, plasma, synovial fluid, endometrium, degenerative disc, and snake venom was inhibited by PGBx with IC50s ranging from 0.5-7.0 microM. Inhibition was independent of substrate phospholipid concentration over a 24-fold range (5-120 microM) and PGBx quenched the tryptophan fluorescence of snake venom phospholipase A2 in a dose-dependent manner. Agonist-induced (A23187) release of arachidonic acid from prelabelled human neutrophils and cultured human endothelial cells was also inhibited by PGBx with IC50s of 3 and 20 microM, respectively. These results illustrate that oxidative reactions of cis-unsaturated fatty acids relieve their natural inhibitory activity, and polymerization of an inactive fatty acid metabolite yields a potent inhibitor of in vitro and in situ phospholipase A2 activity.
