A gram-scale synthesis of very-long chain polyunsaturated fatty acids (VLC-PUFAs).

This manuscript describes our third generation, gram-scale synthesis of very long chain-polyunsaturated fatty acids (VLC-PUFAs), a unique and increasingly important class of lipids. Critical to this work and what makes it different from our previous approach to this family was the avoidance of oxidation sequences. Central to accomplishing this involved the use of a Negishi coupling reaction between the acid chloride derived from DHA and a saturated alkyl zinc reaction. Overall, the general approach required 6 synthetic transformations from DHA and was accomplished with an overall yield of 40%.

Verification of the versatility of the in vitro enzymatic reaction giving (+)-cis-12-Oxo-phytodienoic acid.

Jasmonic acid (JA) is a plant hormone involved in the defense response against insects and fungi. JA is synthesized from α-linolenic acid (LA) by the octadecanoid pathway in plants. 12-oxo-Phytodienoic acid (OPDA) is one of the biosynthetic intermediates in this pathway. The reported stereo selective total synthesis of cis-(+)-OPDA is not very efficient due to the many steps involved in the reaction as well as the use of water sensitive reactions. Therefore, we developed an enzymatic method for the synthesis of OPDA using acetone powder of flax seed and allene oxide cyclase (PpAOC2) from Physcomitrella patens. From this method, natural cis-(+)-OPDA can be synthesized in the high yield of approximately 40%. In this study, we investigated the substrate specificity of the enzymatic synthesis of other OPDA analogs with successions to afford OPDA amino acid conjugates, dinor-OPDA (dn-OPDA), and OPDA monoglyceride, and it was suggested that the biosynthetic pathway of arabidopsides could occur via MGDG.

Total Synthesis and Anti-Inflammatory Bioactivity of (-)-Majusculoic Acid and Its Derivatives.

The first total synthesis of marine natural product, (-)-majusculoic acid (1) and its seven analogs (9-15), was accomplished in three to ten steps with a yield of 3% to 28%. The strategy featured the application of the conformational controlled establishment of the trans-cyclopropane and stereochemical controlled bromo-olefination or olefination by Horner-Wadsworth-Emmons (HWE) reaction. The potential anti-inflammatory activity of the eight compounds (1 and 9-15) was evaluated by determining the nitric oxide (NO) production in the lipopolysaccharide (LPS)-induced mouse macrophages RAW264.7. (-)-Majusculoic acid (1), methyl majusculoate (9), and (1R,2R)-2-((3E,5Z)-6-bromonona-3,5-dien-1-yl)cyclopropane-1-carboxylic acid (12) showed significant effect with inhibition rates of 33.68%, 35.75%, and 43.01%, respectively. Moreover, they did not show cytotoxicity against RAW264.7 cells, indicating that they might be potential anti-inflammatory agents.

Synthesis, in vitro and in silico anti-bacterial analysis of piperine and piperic ester analogues.

A set of 12 analogues of piperine was designed, replacing the amide functional group of the molecule with different aliphatic and aromatic ester functional groups. Molecular docking studies of these molecules with FDA-approved target proteins for anti-bacterial drugs were done. The binding energy of the proteins and the ligands were low and the analogues were found to be drug-like based on the ADME results; hence, the molecules were synthesized. The synthesized compounds were tested for their anti-bacterial property against six bacterial species via Agar well-diffusion method. Acinetobacter baumannii, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus epidermidis were the strains tested. The overall susceptibility is higher in gram-positive. The analogues showed better activity than piperine. The analogues, propyl piperic ester (P3) and 2-fluorophenyl piperic ester (P9) and 4-fluorophenyl piperic ester (P10) showed comparatively bigger inhibition zones for all the strains.

Synthesis and discovery of ω-3 polyunsaturated fatty acid- alkanolamine (PUFA-AA) derivatives as anti-inflammatory agents targeting Nur77.

In this work, three series of ω-3 polyunsaturated fatty acid-alkanolamine derivatives (PUFA-AAs) were synthesized, characterized and their anti-inflammatory activity in vivo was evaluated. Compounds 4a, 4f, and 4k exhibited marked anti-inflammatory activity in LPS-stimulated RAW 264.7 cells. The most promising compound 4k dose-dependently suppressed the cytokines with IC50 values in the low micromolar range. Further, 4k exhibited potential in vitro Nur77-binding affinity (Kd = 6.99 × 10-6 M) which is consistent with the result of docking studies. Next, the anti-inflammatory mechanism of 4k was found to be through NF-κB signal pathway in a Nur77-dependent manner. Moreover, we also observed 4k significantly inhibited LPS-induced expression of cytokines (IL-6, TNF-α, and IL-1ß) through suppressing NF-κB activation and attenuated LPS-induced inflammation in mouse acute lung injury (ALI) model. In conclusion, the study strongly suggests that the PUFA-AA derivatives can be particularly as new Nur77 mediators for further treatment in inflammatory diseases.

New synthetic analogues of natural 5Z,9Z-dienoic acids: Stereoselective synthesis and study of the anticancer activity.

A stereoselective method was developed for the synthesis of synthetic analogues of natural 5Z,9Z-dienoic acids by esterification of aliphatic and aromatic alcohols and carboxylic acids with (5Z,9Z)-1,14-tetradeca-5,9-dienedioic acid and (5Z,9Z)-1,14-tetradeca-5,9-dienediol, synthesized by Ti-catalyzed homo-cyclomagnesiation of the tetrahydropyran ether of hepta-5,6-dien-1-ol with Grignard reagents. In order to establish the effect of molecular structure on the antitumor activity, the obtained 5Z,9Z-dienoic acids were tested for the inhibitory activity against human topoisomerase I, the cytotoxic activity in vitro against several cancer and normal cell lines (Jurkat, HL-60, K562, U937, fibroblasts), the effect on the cell cycle, and apoptosis-inducing ability using flow cytofluorometry. In addition, the effect of the synthesized acids on the cancer cell production of some phosphorylated and unphosphorylated proteins responsible for proliferation and apoptosis was studied by a new multiplex assay technology, MAGPIX.

Total Synthesis of Kalimantacin A.

The kalimantacins make up a family of hybrid polyketide-nonribosomal peptide-derived natural products that display potent and selective antibiotic activity against multidrug resistant strains of Staphylococcus aureus. Herein, we report the first total synthesis of kalimantacin A, in which three fragments are prepared and then united via Sonogashira and amide couplings. The enantioselective synthetic approach is convergent, unlocking routes to further kalimantacins and analogues for structure-activity relationship studies and clinical evaluation.

The First Total Synthesis of the Lipid Mediator PD2n-3 DPA.

The resolution of inflammation is governed by the active biosynthesis of specialized pro-resolving mediators using ω-6 and ω-3 polyunsaturated fatty acids as substrates. These mediators act as resolution agonists and display several interesting bioactivities. PD2n-3 DPA is an oxygenated polyunsaturated fatty acid biosynthesized from n-3 docosapentaenoic acid belonging to the specialized pro-resolving lipid mediator family named protectins. The protectins exhibit anti-inflammatory properties and pro-resolving bioactivities. These endogenously produced compounds are of interest as leads in resolution pharmacology and drug development. Herein, together with its NMR, MS, and UV data, a stereoselective total synthesis of PD2n-3 DPA is presented.

A New E-Series Resolvin: RvE4 Stereochemistry and Function in Efferocytosis of Inflammation-Resolution.

The resolution of the acute inflammatory response is governed by phagocytes actively clearing apoptotic cells and pathogens. Biosynthesis of the specialized pro-resolving mediators (SPMs) is pivotal in the resolution of inflammation via their roles in innate immune cells. Resolvin E4 (RvE4: 5S,15S-dihydroxy-eicosapentaenoic acid) is a newly uncovered member of the E-series resolvins biosynthesized from eicosapentaenoic acid (EPA) recently elucidated in physiologic hypoxia. This new resolvin was termed RvE4 given its ability to increase efferocytosis of apoptotic cells by macrophages. Herein, we report on the total organic synthesis of RvE4 confirming its unique structure, complete stereochemistry assignment and function. This synthetic RvE4 matched the physical properties of biogenic RvE4 material, i.e. ultra-violet (UV) absorbance, chromatographic behavior, and tandem mass spectrometry (MS2) fragmentation, as well as bioactivity. We confirmed RvE4 potent responses with human M2 macrophage efferocytosis of human apoptotic neutrophils and senescent red blood cells. Together, these results provide direct evidence for the assignment of the complete stereochemistry of RvE4 as 5S,15S-dihydroxy-6E,8Z,11Z,13E,17Z-eicosapentaenoic acid and its bioactions in human phagocyte response.

Synthesis and In Silico Molecular Docking Studies on Substituted Piperic Acid Derivatives as Inhibitors of Bacterial DNA Gyrase.

BACKGROUND: Piperine or piperic acid was isolated from fruits of Piper nigrum and had been reported as pharmacological valuable bioactive constituents. Keeping in view, a series of piperic acid-based N heterocyclic's derivatives were synthesized and evaluated for antibacterial activity. All these prepared ligands were docked to study the molecular interactions and binding affinities against the protein PDB ID: 5 CDP. OBJECTIVE: To meet the real need of newer antibacterials, we designed and synthesized scaffolds with good antibacterial activity. The obtained antibacterials have been validated in terms of ligand-protein interaction and thus prove to build up as good drug candidates. METHODS: Antibacterial activity of the compounds were carried out against bacterial strains; three Grampositive and three Gram-negative bacterial strains using agar well diffusion method. In silico molecular docking studies were carried out using Glide (grid-based ligand docking) program incorporated in the Schrödinger molecular modeling package by Maestro 11.0. RESULTS: Compounds BC 28, BC 32, and BC 33 exhibits antibacterial activity along with Glide docking score of -8.580, -9.753 kcal/mol, and -8.813 kcal/mol, respectively. Docking studies explained hydrogen bonding, pi-pi, and hydrophobic interactions with amino acid residues which explain the binding affinity of the most docked ligand with protein. CONCLUSION: In the present study, substituted piperic acid was synthesized and evaluated as antibacterial compared with standard drug ciprofloxacin and results interpret that having nitrogen as heteroatom in the heterocyclic nucleus found to be more potent than the standard drug ciprofloxacin. On comparing, substitution with electron-donating groups generates excellent antibacterial potential against the bacterial strains. It was also proved that having substitution with electron-donating groups on meta and para position with triazoline ring system exhibits greater potential while compounds which have a meta- electron-donating substituent showed lesser activity with thiazole nucleus. In addition, structure-based activities of the prepared analogs were discussed under Structure-Activity Relationship (SAR) section.

Synthesis and antimicrobial evaluation of piperic acid amides and their lower homologues.

Seven piperic acid amides along with their lower homologs (12) were synthesized using HATU-DIPEA coupling reagent. All the synthesized derivatives were evaluated for their antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, and vancomycin-resistant P. aeruginosa. They were found to be more active on P. aeruginosa than on S. aureus. However, they did not exhibit potent activity on Vancomycin resistant P. aeruginosa. Among the tested compounds, methylenedioxycinnamic acid amide of anthranilic acid (MDCA-AA, 2a) was found to be most active against S. aureus with MIC of 3.125 µg/ml. The PAS and INH amides of piperic acid were screened against Mycobacterium tuberculosis H37Ra strain. They were found to be most active among all the tested compounds but were found to be less active than the standard drug, isoniazid.

Simultaneous targeted and untargeted UHPLC-ESI-MS/MS method with data-independent acquisition for quantification and profiling of (oxidized) fatty acids released upon platelet activation by thrombin.

In this study, a combined targeted/untargeted UHPLC-ESI-QTOF-MS/MS method for the targeted quantitative analysis of the primary platelet lipid mediators thromboxane B2 (TXB2), 12S-hydroxy-5Z,8E,10E-heptadecatrienoic acid (HHT) and its oxidation product 12-keto-5Z,8E,10E-heptadecatrienoic acid (KHT) was developed, which allowed simultaneous untargeted profiling for the detection of other lipid biomarkers such as other oxylipins and fatty acids (FAs) in platelet releasates. A general procedure for the synthesis of keto-analogs from hydroxylated polyunsaturated FAs (PUFAs) using Dess-Martin periodinane oxidation reagent was proposed for the preparation of KHT standard. MS detection was performed in data independent acquisition (DIA) mode with sequential window acquisition of all theoretical fragment ion mass spectra (SWATH) in the range of 50-500 Da with variable window sizes. The LC-MS/MS assay was validated for the targeted analytes and applied for analysis of supernatants derived from resting platelets and from platelets treated with thrombin. The targeted analytes KHT, HHT and TXB2 were found at highly elevated levels in the activated platelet releasates. On average, 13 ±â€¯7, 15 ±â€¯9, and 0.6 ±â€¯0.2 attomols per platelet were released upon thrombin-activation. Furthermore, the simultaneous untargeted profiling (n = 8 in each group) revealed that these oxylipins are released with a pool of other (significantly upregulated) oxidized (12-HETE, 12-HEPE) and non-oxidized PUFAs. All these compounds can be considered additional biomarkers of platelet activation complementing the primary platelet activation marker thromboxane B2. The other lipids may support platelet activation or trigger other biological actions with some potential implications in thromboinflammation.

Co-functionalization with phosphate and carboxylate on polydiacetylene for colorimetric detection of calcium ions in serum.

In this study, co-functionalization with phosphate and carboxylate on polydiacetylene (PDA) was proposed to detect calcium ions in serum, inspired by biologically abundant phosphate-calcium ion and carboxylate-calcium ion binding. The cooperative interaction of calcium ions with phosphate and carboxylate in PDA induced the change of electronic properties in the backbone without aggregation of liposomes, accompanied by blue-to-purple color transition. The cooperative effect through the introduction of mixed ligands facilitated the selective detection of calcium ions over magnesium ions, which was a source of major interference in many calcium ion probes, and in the presence of major serum metal ions. The sensor system exhibited highly sensitive detection of calcium ions with an estimated limit of detection of 0.97 µM. In addition, the detection method was employed to determine the concentration of calcium ions in various serums.

Enantioselective Halolactonizations Using Amino-Acid-Derived Phthalazine Catalysts.

Amino-acid-derived phthalazine catalysts have been designed and synthesized for enantioselective halolactonization of prochiral dienoic acids. The scope of the reaction is evidenced by 17 examples of spiro α-exo-methylene-halolactones with up to 99.8% enantiomeric excess. The resulting enantio-enriched spiro halolactone products are found to exhibit potent antitumor effects. In addition, both antipodes of products with equally excellent enantioselevity could be obtained since a pair of enantiomeric catalysts is guaranteed.

Nutrient-Based Chemical Library as a Source of Energy Metabolism Modulators.

Covalent conjugates of multiple nutrients often exhibit greater biological activities than each individual nutrient and more predictable safety profiles than completely unnatural chemical entities. Here, we report the construction and application of a focused chemical library of 308 covalent conjugates of a variety of small-molecule nutrients. Screening of the library with a reporter gene of sterol regulatory element-binding protein (SREBP), a master regulator of mammalian lipogenesis, led to the discovery of a conjugate of docosahexaenoic acid (DHA), glucosamine, and amino acids as an inhibitor of SREBP (molecule 1, DHG). Mechanistic analyses indicate that molecule 1 impairs the SREBP activity by inhibiting glucose transporters and thereby activating AMP-activated protein kinase (AMPK). Oral administration of molecule 1 suppressed the intestinal absorption of glucose in mice. These results suggest that such synthetic libraries of nutrient conjugates serve as a source of novel chemical tools and pharmaceutical seeds that modulate energy metabolism.

Synthetic manipulations of polyunsaturated fatty acids as a convenient strategy for the synthesis of bioactive compounds.

Stereoselective synthesis of Z-configured double bonds is central in organic synthesis due to the presence of such motifs in polyunsaturated fatty acids and many natural products. Traditionally, reductions of internal alkynes or Wittig, Ando or Still-Gennari reactions, are often used for preparing such compounds. The substrate scope is limited for both the Ando and the Still-Gennari reactions, while the Wittig reaction often gives low Z-selectivity for the synthesis of polyunsaturated Z-configured methylene interrupted (skipped) double bonds. Reductions of internal alkynes are challenging due to diminished Z-selectivity, poor catalyst reproducibility and over-reductions. An alternative and highly attractive approach is to employ naturally occurring and commercially available polyunsaturated fatty acids as starting materials. The main advantage of this strategy is the conservation of the multiple Z-configured double bonds present in the starting material, allowing a precise incorporation of the desired double bonds into the final product. In particular, arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid have been used for the stereoselective synthesis of polyunsaturated fatty acids, their derivatives and other polyunsaturated natural products. Herein, such efforts are reviewed.

Unexpected AChE inhibitory activity of (2E)α,ß-unsaturated fatty acids.

A small library of (E) α,ß-unsaturated fatty acids was prepared, and 20 different saturated and mono-unsaturated fatty acids differing in chain length were subjected to Ellman's assays to determine their ability to act as inhibitors for AChE or BChE. While the compounds were only very weak inhibitors of BChE, seven molecules were inhibitors of AChE holding IC50 = 4.3-12.8 M with three of them as significant inhibitors of this enzyme. The results have shown trans 2-mono-unsaturated fatty acids are better inhibitors for AChE than their saturated analogs. Furthermore, the screening results indicate that the chain length is crucial for obtaining an inhibitory efficacy. The best results were obtained for (2E) eicosenoic acid (14) showing inhibition constants Ki = 1.51 ±â€¯0.09 M and Ki' = 7.15 ±â€¯0.55 M. All tested compounds were mixed-type inhibitors with a dominating competitive part. Molecular modelling calculations indicate a different binding mode of active/inactive compounds for the enzymes AChE and BChE.

Sequential Alkene Isomerization and Ring-Closing Metathesis in Production of Macrocyclic Musks from Biomass.

We report successful utilization of sequential alkene isomerization and ring-closing metathesis of dec-9-enoic acid based dienes in synthesis of macrocyclic lactones that possess a strong scent of musk. This catalytic sequence was essential to trim the chain length of starting dienes to yield macrocycles of the right size. Dec-9-enoic acid is conveniently obtainable from oleic esters by Ru-catalysed ethenolysis.

Discovery of Hydrolysis-Resistant Isoindoline N-Acyl Amino Acid Analogues that Stimulate Mitochondrial Respiration.

N-Acyl amino acids directly bind mitochondria and function as endogenous uncouplers of UCP1-independent respiration. We found that administration of N-acyl amino acids to mice improves glucose homeostasis and increases energy expenditure, indicating that this pathway might be useful for treating obesity and associated disorders. We report the full account of the synthesis and mitochondrial uncoupling bioactivity of lipidated N-acyl amino acids and their unnatural analogues. Unsaturated fatty acid chains of medium length and neutral amino acid head groups are required for optimal uncoupling activity on mammalian cells. A class of unnatural N-acyl amino acid analogues, characterized by isoindoline-1-carboxylate head groups (37), were resistant to enzymatic degradation by PM20D1 and maintained uncoupling bioactivity in cells and in mice.

Stereocontrolled Synthesis of Resolvin D4.

The stereoselective synthesis of resolvin D4 (RvD4) was achieved using the Wittig reaction of the C1-C10 dienal with the known C11-C22 phosphonium salt. The ( S, E)-enantiomer ( S)-10, corresponding to the C1-C8 part, was synthesized in 95% ee by the asymmetric transfer hydrogenation reaction of the corresponding acetylenic ketone followed by Red-Al reduction. Sharpless epoxidation of this alcohol using Ti(O- i-Pr)4/l-(+)-DIPT as a catalyst produced anti epoxy alcohol with >99% ee as the sole product in 82% yield. A subsequent functional group manipulation, including removal of the PMB group, produced the alcohol, which upon Swern oxidation afforded anti 4-hydroxy-5-TBS-oxy enal via epoxide ring opening of the resulting aldehyde. The Horner-Wadsworth-Emmons reaction was used to add the C9-C10 enal part to this aldehyde, and the resulting dienal was subjected to the Wittig reaction with C11-C22 phosphonium salt to furnish the entire structure of RvD4. Conversion of the primary alcohol to the methyl ester and deprotection of the three TBS groups with TBAF afforded 5,17-dihydroxy-γ-lactone, which was hydrolyzed to RvD4. Additionally, anti-4,5-dihydroxydodecanoic acid, a model compound of RvD4, in CD3OD was observed to be stable at room temperature for several weeks, whereas 20% of the acid in CDCl3 was converted into the γ-lactone after 24 h at rt.