Physical and Chemical Stability of Formulations Loaded with Taxifolin Tetra-octanoate.

Chemically stable ester derivatives of taxifolin have become a focus of interest for their role in the satisfactory effects on human health. Accordingly, the aim of this study was to evaluate the physical and chemical stability of different formulations containing 0.02% taxifolin tetra-octanoate, which was proved to possess higher inhibitory effect on tyrosinase activity compared with taxifolin in a cell-free system. In the studies of physical stability, a Brookfield viscometer was used to determine rheological behavior of formulations containing taxifolin tetra-octanoate, and a portable pH meter was used to determine pH change. Moreover, chemical stability was determined by HPLC with UV detection. Formulations were evaluated for 12 weeks stored at 25 and 40°C. Results showed that storage time had no significant influence on viscosity of the formulations containing taxifolin tetra-octanoate, and pH value was relatively stable, which was within the limits of normal skin pH range. In the chemical stability studies, taxifolin tetra-octanoate in the essence formulation was most unstable at 40°C with about 81% degradation in 12 weeks of storage, however, the percentage of remaining taxifolin tetra-octanoate in cream formulation stored for 12 weeks at 25°C was the highest, about 93%. The results in this study may contribute to the development of more stable formulations containing taxifolin tetra-octanoate.

First total syntheses and antimicrobial evaluation of penicimonoterpene, a marine-derived monoterpenoid, and its various derivatives.

The first total synthesis of marine-derived penicimonoterpene (±)-1 has been achieved in four steps from 6-methylhept-5-en-2-one using a Reformatsky reaction as the key step to construct the basic carbon skeleton. A total of 24 new derivatives of 1 have also been designed and synthesized. Their structures were characterized by analysis of their 1H NMR, 13C NMR and HRESIMS data. Some of them showed significant antibacterial activity against Aeromonas hydrophila, Escherichia coli, Micrococcus luteus, Staphylococcus aureus, Vibrio anguillarum, V. harveyi and/or V. parahaemolyticus, and some showed activity against plant-pathogenic fungi (Alternaria brassicae, Colletotrichum gloeosporioides and/or Fusarium graminearum). Some of the derivatives exhibited antimicrobial MIC values ranging from 0.25 to 4 µg/mL, which were stronger than those of the positive control. Notably, Compounds 3b and 10 showed extremely high selectively against plant-pathogenic fungus F. graminearum (MIC 0.25 µg/mL) and pathogenic bacteria E. coli (MIC 1 µg/mL), implying their potential as antimicrobial agents. SAR analysis of 1 and its derivatives indicated that modification of the carbon-carbon double bond at C-6/7, of groups on the allylic methylene unit and of the carbonyl group at C-1, effectively enhanced the antimicrobial activity.

Effects of newly synthesized DCP-LA-phospholipids on protein kinase C and protein phosphatases.

BACKGROUND/AIMS: The linoleic acid derivative DCP-LA selectively activates PKCε and inhibits protein phosphatase 1 (PP1). In the present study, we have newly synthesized phosphatidyl-ethanolamine, -serine, -choline, and -inositol containing DCP-LA at the α and ß position (diDCP-LA-PE, -PS, PC, and -PI, respectively), and examined the effects of these compounds on activities of PKC isozymes and protein phosphatases. METHODS: Activities of PKC isozymes PKCα, -ßΙ, -ßΙΙ, -γ, -δ, -ε-, ι, and -ζ and protein phosphatases PP1, PP2A, and protein tyrosine phosphatase 1B (PTP1B) were assayed under the cell-free conditions. RESULTS: All the compounds activated PKC, with the different potential, but only PKCγ inhibition was obtained with diDCP-LA-PC. Of compounds diDCP-LA-PE alone significantly activated PKCι and -ζ. diDCP-LA-PE and diDCP-LA-PI suppressed PP1 activity, but otherwise diDCP-LA-PI enhanced PP2A activity. diDCP-LA-PE, diDCP-LA-PS, and diDCP-LA-PI strongly reduced PTP1B activity, while diDCP-LA-PC enhanced the activity. CONCLUSION: All the newly synthesized DCP-LA-phospholipids serve as a PKC activator and of them diDCP-LA-PE alone has the potential to activate the atypical PKC isozymes PKCι and -ζ. diDCP-LA-PE and diDCP-LA-PI serve as an inhibitor for PP1 and PTP1B, diDCP-LA-PS as a PTP1B inhibitor, diDCP-LA-PI as a PP2A enhancer, and diDCP-LA-PC as a PTP1B enhancer.

Asymmetric allylic alkylation of acyclic allylic ethers with organolithium reagents.

A highly efficient, regio- and enantioselective Cu(I)/phosphoramidite-catalyzed asymmetric allylic alkylation of allyl ethers with organolithium reagents is reported (see scheme). The use of organolithium reagents is essential for this catalytic C-C bond formation due to their compatibility with different Lewis acids. The versatility of allylic ethers under the copper-catalyzed reaction conditions with organolithium reagents is demonstrated in the shortest synthesis of (S)-Arundic acid.

A piperidine chiron for the Veratrum alkaloids.

A Veratrum piperidine chiron was prepared over 11 steps (7.9% yield) from (-)-citronellal. Three methods for the installation of the propargylic side chain onto a cyclic enamide are presented.

Replacement of hydrochloride in metformin hydrochloride with caprylic acid to investigate its effects on MCF-7 and MDA-MB-231 breast cancer cell lines.

AIMS: Metformin hydrochloride is a highly hydrophilic molecule with low permeability. In the present study, to develop an effective drug to treat the metastatic breast cancer, metformin caprylic acid was synthesized using metformin hydrochloride as a permeable agent. MAIN METHODS: The cytotoxic effects of various concentrations of metformin caprylic acid and metformin hydrochloride (0 to 20 mM) on MCF-7 and MDA-MB-231 breast cancer cells and MCF-10A human mammary epithelial cell line were assessed by the MTT assay. Furthermore, Annexin V, PI staining, and cell flow cytometry assays were performed to evaluate the apoptotic effects. The invasion and migration ability of these cells were evaluated following treatment with equal concentration (3 mM) of the two compounds. KEY FINDINGS: The treatment of tested cell lines with an equal concentration of two chemicals decreased cell viability in a time and dose-dependent manner, where in all cases, metformin caprylic acid caused significantly more apoptosis and invasion inhibition than that of metformin hydrochloride (*p < 0.05). Chemical structures of both compounds were confirmed by FTIR and 1H NMR, 13C NMR. Both chemicals inhibited the migration of MCF-7 and MCF-10A cells, but had no effect on MDA-MB-231 migration. All data are expressed as mean ± SD (n = 3). SIGNIFICANCE: It seems that in an equal concentration, the similarity of the hydrophobic tail of caprylic acid to the cell membrane improves its entrance, while decreasing the drug excretion.

Synthesis of new 8(S)-HETE analogs and their biological evaluation as activators of the PPAR nuclear receptors.

Structural modifications around 8-HETE (8-hydroxyeicosatetraenoic acid), a natural agonist of the PPAR (peroxisome proliferator-activated receptor) nuclear receptors have led previously to the identification of a promising analog, the quinoline S 70655. Series of novel quinoline or benzoquinoline derivatives were designed through the modification of this lead. Variations of the nature of the aromatic core and of the side chains were carried out. The SAR studies indicated the high sensitivity of the upper acid chain to modifications as well as the strong effect of the length and size of the lipophilic side chain. They afforded several new promising PPARalpha/gamma dual agonists with a high PPARalpha activity in vitro.

Rapid synthesis of flavor compound 4-ethyloctanoic acid under microwave irradiation.

Rapid synthesis of 4-ethyloctanoic acid by means of microwave irradiation is described. Diethyl malonate reacted with 2-ethyl-1-bromohexane in the presence of sodium ethoxide to give diethyl (2-ethylhexyl)malonate (1b). 1b was saponified in the solution of ethanol and potassium hydroxide and then acidified to form (2-ethylhexyl)propanedioic acid (1c), and 1c was heated and decarboxylized to give 4-ethyloctanoic acid (1d). The influence of reaction temperature and reaction time on the yield of 1b and the effect of reaction time on the yield of 1c and 1d were investigated in order to optimize the synthetic conditions. The relative optimal conditions for the synthesis of 1b were a mole ratio of sodium to diethyl malonate to 2-ethylhexyl bromide of 0.1:0.11:0.11, a reaction temperature of 80-85 °C, and a reaction time of 2-2.5 h. The yield of 1b was about 79%. 1b was saponified for 30 min and then acidified to form 1c, and the yield of 1c was 96%. 1c was heated for 16 min at 180°C to give 1d, and the yield of 1d was about 90%. The overall yield of 1d is 70% under microwave irradiation. The reaction time was reduced greatly. In order to compare the result of microwave irradiation with that of an oil bath, the reactions were also performed in an oil bath. The structures of intermediates, product and by-product were confirmed by HRMS, (1)H NMR, (13)C-NMR and IR.

Non-hydrolytic synthesis of caprylate capped cobalt ferrite nanoparticles and their application against Erwinia carotovora and Stenotrophomonas maltophilia.

Magnetic cobalt Ferrite nanoparticles capped with caprylate groups, CH3(CH2)6CO2-, have been synthesized using a novel non-hydrolytic coprecipitation method under inert conditions. Particle diameter was characterized using dynamic light scattering (DLS) and transmission electron microscopy (TEM). The spinel ferrite crystal phase was verified using X-ray diffraction (XRD), and the presence of the capping agent was confirmed using Fourier Transform Infrared spectroscopy (FTIR). Bactericidal effects of the particles were tested against broth cultures of Erwinia carotovora and Stenotrophomonas maltophilia. The final particles had an average diameter of 3.81 nm and readily responded to a neodymium magnet. The particles did have a significant effect on the OD600 of both broth cultures.

In vivo imaging of mesenchymal-epithelial transition factor (c-Met) expression using an optical imaging system.

Mesenchymal-epithelial transition factor (c-Met) is a receptor tyrosine kinase that has been shown to be overexpressed and mutated in a variety of malignancies, such as glioma. We have recently found that an (125)I-radiolabeled Gly-Gly-Gly (GGG)- or 8-aminooctanoic acid (AOC)-containing c-Met binding peptide (cMBP) specifically targets c-Met receptor in vivo and in vitro. In this report, cyanine dye 5.5 (Cy5.5)-conjugated GGG- or AOC-containing cMBPs were evaluated in human cancer cell xenografts in order to investigate the possibility of c-Met receptor targeting using an optical imaging system. The receptor binding affinity of Cy5.5-conjugated peptides was tested in 96-well plates coated with a c-Met/Fc chimeric protein. Optical imaging studies were performed in U87MG and Ramos bearing athymic mice. The binding affinities of Cy5.5-conjugated GGG- or AOC-containing cMBPs were determined to be 0.318 and 0.342 microM, respectively. Confocal images show that Cy5.5-conjugated peptides bound mainly to the cell surface and that peptide binding was clearly inhibited by free cMBP. Subcutaneous U87MG tumors were clearly visualized with each of the two fluorescent probes. Of the two, cMBP-AOC-Cy5.5 displayed higher tumor uptake and tumor-to-normal tissue ratios at 10 min to 24 h postinjection in the U87MG tumor model. For the in vivo blocking study, cMBP-AOC-Cy5.5 (4 nmol) was co-injected with cold cMBP (0.13 micromol) into the U87MG xenograft mice. Image-based tumoral uptake decreased up to approximately 35%. These results suggest that Cy5.5-conjugated cMBP could potentially be used to detect c-Met-positive cancers in vivo. However, additional modifications to this optical imaging agent are needed to further improve its efficacy.

Intramolecular Prins cyclisations for the stereoselective synthesis of bicyclic tetrahydropyrans.

Methyl (4E,7R)-7-hydroxyoctanoate was prepared in 71% yield from ethyl (R)-3-hydroxybutanoate and on reaction with a series of aldehydes in the presence of TMSOTf gave bicyclic oxygen heterocycles in good yields and with the creation of three new stereogenic centres in a single pot.

Synthesis and in vitro evaluation of a library of modified endomorphin 1 peptides.

Endomorphin 1 (Endo-1=Tyr-Pro-Trp-Phe-NH(2)), an endogenous opioid with high affinity and selectivity for mu-opioid receptors, mediates acute and neuropathic pain in rodents. To overcome metabolic instability and poor membrane permeability, the N- and C-termini of Endo-1 were modified by lipoamino acids (Laa) and/or sugars, and 2',6'-dimethyltyrosine (Dmt) replacement of Tyr. Analogues were assessed for mu-opioid receptor affinity, inhibition of cAMP accumulation, enzymatic stability, and permeability across Caco-2 cell monolayers. C-terminus modification decreased receptor affinity, while N-terminus C8-Laa improved stability and permeability with slight change in receptor affinity. Dmt provided a promising lead compound: [C8Laa-Dmt[1]]-Endo-1 is nine times more stable (t(1/2)=43.5min), >8-fold more permeable in Caco-2 cell monolayers, and exhibits 140-fold greater mu-opioid receptor affinity (K(imu)=0.08nM).

Synthesis of FF8181-A.

Both enantiomers of FF8181-A were synthesized through optical resolution from the known Diels-Alder reaction product in 15 steps. The absolute configuration of the natural product was determined to be 1S,5S,5aS,9aS,9bS.

Structural modification of the P2' position of 2,7-dialkyl-substituted 5(S)-amino-4(S)-hydroxy-8-phenyl-octanecarboxamides: the discovery of aliskiren, a potent nonpeptide human renin inhibitor active after once daily dosing in marmosets.

Due to its function in the rate limiting initial step of the renin-angiotensin system, renin is a particularly promising target for drugs designed to control hypertension, a growing risk to health worldwide. Despite vast efforts over more than two decades, no orally efficacious renin inhibitor had reached the market. As a result of a structure-based topological design approach, we have identified a novel class of small-molecule inhibitors with good oral blood-pressure lowering effects in primates. Further lead optimization aimed for improvement of in vivo potency and duration of action, mainly by P2' modifications at the hydroxyethylene transition-state isostere. These efforts resulted in the discovery of aliskiren (46, CGP060536B, SPP100), a highly potent, selective inhibitor of renin, demonstrating excellent efficacy in sodium-depleted marmosets after oral administration, with sustained duration of action in reducing dose-dependently mean arterial blood pressure. Aliskiren has recently received regulatory approval by the U.S. Food and Drug Administration for the treatment of hypertension.

Novel 2,7-dialkyl-substituted 5(S)-amino-4(S)-hydroxy-8-phenyl-octanecarboxamide transition state peptidomimetics are potent and orally active inhibitors of human renin.

The action of renin is the rate-limiting step of the renin-angiotensin system (RAS), a key regulator of blood pressure. Effective renin inhibitors directly block the RAS entirely at source and, thus, may provide a vital weapon for hypertension therapy. Our efforts toward identifying novel small-molecule peptidomimetic renin inhibitors have resulted in the design of transition-state isosteres such as 1 bearing an all-carbon 8-phenyl-octanecarboxamide framework. Optimization of the extended P3 portion of 1 and extensive P2' modifications provided analogues with improved in vitro potencies in the presence of plasma. X-ray resolution of rh-renin/38a in the course of SAR work surprisingly unveiled the exploitation of a previously unexplored pocket (S3sp) important for strong binding affinities. Several inhibitors demonstrated oral efficacy in sodium-depleted marmosets. The most potent, 38a, induced dose-dependently a pronounced reduction in mean arterial blood pressure, paralleled by complete blockade of active plasma renin, up to 8 h post-dose. Oral bioavailability of 38a was 16% in marmosets.

Efficient synthesis of (+/-)-4-methyloctanoic acid, aggregation pheromone of rhinoceros beetles of the genus Oryctes (Coleoptera: Dynastidae, Scarabaeidae).

(+/-)-4-Methyloctanoic acid and its ethyl ester are aggregation pheromones of many rhinoceros beetles of the genus Oryctes and are investigated for the control of these pests by olfactory trapping. A simple, economical, and high-yield (>50%) synthesis of (+/-)-4-methyloctanoic acid and its ethyl ester is presented starting from n-hexanal. The key step in this sequence is an orthoester Claisen rearrangement for the elongation of the carbon chain by two.

Site-Specific Radiofluorination of Biomolecules with 8-[(18)F]-Fluorooctanoic Acid Catalyzed by Lipoic Acid Ligase.

New methodologies for site-specifically radiolabeling proteins with (18)F are required to generate high quality radiotracers for preclinical and clinical applications with positron emission tomography. Herein, we report an approach by which we use lipoic acid ligase (LplA) to conjugate [(18)F]-fluorooctanoic acid to an antibody fragment bearing the peptide substrate of LplA. The mild conditions of the reaction preserve antibody immunoreactivity, and the efficiency of LplA allows for >90% yield even with very small amounts of peptidic precursor (1-10 nmol). These features are advantageous compared to the current gold standard in the field. Moreover, the methodology introduces a new application for an important tool in chemical biology.

Discovery and preclinical development of a novel prodrug conjugate of mesalamine with eicosapentaenoic acid and caprylic acid for the treatment of inflammatory bowel diseases.

Mesalamine (5-ASA) is one of the drugs indicated as first line therapy in ulcerative colitis for induction and maintenance of remission. Sulfasalazine and formulations of 5-ASA (pH-dependent and controlled release formulations) were developed to minimize the systemic absorption and maximize the delivery of the mesalamine to colon. Although, its efficacy and safety is well documented there are approximately 30% nonresponders to 5-ASA therapy. This necessitates the need for novel therapeutic options to improve the efficacy and safety of the currently available 5-ASA therapy. CLX-103 is a novel, patented prodrug molecular conjugate of mesalamine, eicosapentaenoic acid and caprylic acid designed to offer incremental benefits over the currently approved 5-ASA formulations. Results of in vitro and in vivo studies showed that CLX-103, was stable in simulated gastric fluid, but undergoes enzymatic hydrolysis in the small/large intestines to release the active moiety. Our data also showed that the active moiety is retained in the targeted intestinal tissues (ileum and colon) over a longer period of time in relation to sulfasalazine. The in vitro data supports the observed in vivo plasma kinetics of 5-ASA characterized by longer Tmax, low Cmax after the oral administration of CLX-103. Efficacy study of CLX-103 in acute dextran sodium sulfate (DSS) mouse colitis model showed improved potency measured as Disease Activity Index (DAI) and histological scores in the colon as compared to sulfasalazine. These findings indicate that CLX-103 could offer a differentiated drug product which is more efficacious and safer than the currently approved 5-ASA formulations in the treatment of inflammatory bowel diseases.

Thromboxane receptor antagonism combined with thromboxane synthase inhibition. 5. Synthesis and evaluation of enantiomers of 8-[[(4-chlorophenyl)sulfonyl]amino]-4-(3-pyridinylalkyl)octanoic acid.

The enantiomers of 8-[[(4-chlorophenyl)sulfonyl]amino]-4-(3-pyridinylpropyl)octanoic acid (1) and its pyridinyl ether analog (2) were synthesized using the highly diastereoselective method of alkylation of acyloxazolidinone. These enantiomerically pure compounds were compared with the corresponding racemic compounds 1 and 2 for their in vitro activity. Compounds 1, 1R, and 1S and 2,2S, and 2R were equipotent as thromboxane receptor antagonists (TxRAs) and thromboxane synthase inhibitors (TxSIs) (IC50 = 2-30 nM). Upon oral administration to guinea pigs, the enantiomers inhibited the ex vivo U 46619-induced platelet aggregation with potency similar to that of the corresponding racemic compound. This indicates that the enantiomers have pharmacologic profile and bioavailability similar to that of the corresponding racemic compound.

Novel (2E,4E,6Z)-7-(2-alkoxy-3,5-dialkylbenzene)-3-methylocta-2,4,6-trienoic acid retinoid X receptor modulators are active in models of type 2 diabetes.

Previous data have shown that RXR-selective agonists (e.g., 3 and 4) are insulin sensitizers in rodent models of non-insulin-dependent diabetes mellitus (NIDDM). Unfortunately, they also produce dramatic increases in triglycerides and profound suppression of the thyroid hormone axis. Here we describe the design and synthesis of new RXR modulators that retain the insulin-sensitizing activity of RXR agonists but produce substantially reduced side effects. These molecules bind selectively and with high affinity to RXR and, unlike RXR agonists, do not activate RXR homodimers. To further evaluate the antidiabetic activity of these RXR modulators, we have designed a concise and systematic structure-activity relationship around the 2E,4E,6Z-7-aryl-3-methylocta-2,4,6-trienoic acid scaffold. Selected compounds have been evaluated using insulin-resistant rodents (db/db mice) to characterize effects on glucose homeostasis. Our studies demonstrate the effectiveness of RXR modulators in lowering plasma glucose in the db/db mouse model.