Enantioselective total synthesis of cyathin A3

The cyathins are a unique group of diterpenoids produced by the bird’s nest fungi Cyathus helenae, C. africanus, and C. earlei. Several of the cyathins show strong antibiotic activity. More recently, several fungal metabolites with structures closely related to those of the cyathins have been found to be potent inducers of nerve growth factor (NGF) synthesis. The structural complexity and the exciting biological activity of the cyathane family of diterpenes have prompted our efforts to develop an efficient and general synthetic approach.To date, there have been seven total syntheses and six partial syntheses of cyathins. Most of these syntheses target allocyathin B2, which does not contain the common 6-7 trans ring fusion or the hydroxyl group within the seven member ring. Modifications of these routes to provide targets with these features have not been demonstrated and may be challenging. We have developed a concise asymmetric synthesis of cyathin A3, based on the enantioselective Diels-Alder reaction of quinone (106) and diene (105). Because the transformations of cyathin A3 into other cyathins are well documented, this synthesis provides a general approach to the cyathane diterpene family. In Section 2.2, the enantioselective Diels-Alder reaction of quinone 106 and diene 105 is presented. This reaction is effectively catalyzed by a carefully prepared Mikami catalyst. It was carried out on a preparative scale to give the chiral building block 108. The absolute configuration of the Diels-Alder adduct 108 was determined by NMR and X-ray analysis.In Sections 2.3-5, the enantioselective total synthesis of (-)-cyathin A3 is described. This approach features the successful oxymercuration ring opening, a newly developed in situ configuration inversion, a much improved intramolecular aldol reaction and a radical cyclization. Now envisioned in our laboratory is the development of a new access to cyathin A4, which is surmised to be possible via the intermediate prepared in this synthesis

Poly[μ-(1,3-dihy­droxy­propan-2-olato)-potassium]

The asymmetric unit of the title compound, [K(C3H7O3)]n or K[H2gl]n, common name potassium glycerolate, contains half the K+ cation and half of the glycerolate anion. The other half of the anion is generated through a mirror plane passing through the K atom, and a C, an H and an O atom of the glycerolate ligand. The K+ ion is coordinated by the O atoms of the OH groups, leading to a six-membered chelate ring that adopts a very distorted boat conformation. The negatively charged O atom of the glycerolate anion, [H2gl−], is found in the flagpole position and forms an ionic bond with the K+ ion. The O atoms of the hydroxo groups are coordinated to two K+ ions, whereas the negatively charged O atom is bonded to one K+ ion. The K+ ion is coordinated by three other symmetry-related monodentate H2gl− ligands, so that each H2gl− ligand is bonded to two K+ ions, and the potassium has a seven-coordinate environment. The H2gl− ligands are connected via a strong O—H⋯O hydrogen bond and, together with the K⋯O inter­connections, form polymeric sheets which propagate in the directions of the a and b axes

Wild Mustard Seed's "Suicidal Germination" after Smoke water priming: A promising tool for weed management

Non-Peer ReviewedFire is a natural disturbance which plays a key role in maintaining ecosystem functioning of Fescue Prairies. Smoke produced during the burning of plant material have shown promotive action on seed germination in plant species including arable weeds and crops in both fire-prone habitats and fire-free habitats around the World. To date, few beneficial chemicals have been characterized from plant-derived smoke water solutions such as Karrikin (KAR1), Cyanohydrin, Hydroquinine etc. These isolated chemicals have demonstrated a positive effect in breaking seed dormancy followed by stimulated seed germination and seedling growth in species and growth condition specific manner. Seed related smoke-induced physiological mechanisms includes activation of enzymes, phytochrome-mediated, other phytohormone interaction and improved rate of germination and seedling vigour. Recent study showed that alfalfa-derived smoke does not contain KAR1. But it showed a promotive and a light requirement substitution action on germination of selected fire responsive fescue prairie forbs, indicating that a different chemical compound is active in alfalfa-derived smoke. The present study was conducted to investigate (1) light-substitution ability of different smoke; (2) the wild mustard seed priming effect with alfalfa smoke water; and (3) the efficacy of using non-polar resin in fractionating active compounds in alfalfa smoke water. In experiments smoke-responsive wild mustard (Sinapis arvensis L.) and lettuce (Lactuca sativa L. cv. Salad Bowl) seeds were used during dark germination as rapid bioassay species under laboratory conditions. Smoke water solutions were produced by smoldering alfalfa hay and six savannah fire ephemerals. Alfalfa smoke water serial dilutions (1/1000v/v, 1/100v/v, 1/10v/v and 1/1v/v) and HPLC grade distilled water (control) were used as the seed priming treatments in further experiments. Lettuce seed plates were incubated in 24 h fully darkness at alternate 25/15  °C for 01 day. Wild mustard seeds were primed for 24 h in darkness followed by 7 d drying at 20 °C in darkness before adding distilled water. Seeds were incubated at constant 20 °C under 16 h light/8 h darkness or 24 h darkness for 10 days. A non-polar resin (FPX-66) was used to isolate the active chemical compound in alfalfa smoke water. Three fractions were tested with Lettuce bioassay and 1D 1H NMR spectra analysis. At 25/15 °C, Salad bowl bioassay significantly (P<0.001) responses to smoke water solutions irrespective of the smoke types except Eragrostis curvula and Hilliardiella spp. Dilutions, 1/1 v/v and 1/10 v/v have a negative effect on lettuce seed dark germination. In wild mustard seeds, except 1/100 v/v dilution, all other alfalfa smoke water dilutions have maintained a significant seed germination capacity (P<0.001) and pattern over the time showing a suicidal dark germination. Resin fractions significantly (P<0.05) increase lettuce seed dark germination compared to control. 1D 1H NMR spectra for 100% aqueous fraction showed a proton pattern closer to the standard KAR1, indicating the efficacy of non-polar resin in isolating active compounds. Thus, it can be concluded that higher smoke responsiveness of wild mustard seeds is an economically importan

Poly[μ-2,3-dihydroxy­propan-1-olato-sodium]

The Na+ cation in the title compound, [Na(C3H7O3)]n or Na[H2gl], is coordinated by five O atoms leading to a distorted trigonal-bipyramidal geometry. The negatively charged O atom of the glycerolate anion is in an equatorial position, and the O atom of the hydroxo group, attached to the secondary C atom, occupies an axial position completing a five-membered non-planar chelate ring; this defines the asymmetric unit. The Na+ cation is coordinated by three other symmetry-related monodentate H2gl− ligands, so that each H2gl− ligand is bonded to four Na+ ions. The H2gl− ligands are connected via strong O—H⋯O hydrogen bonds and these, together with the Na⋯O inter­connections, are responsible for the formation of polymeric sheets which propagate in the directions of the b and c axes

Increased hypolipidemic benefits of cis-9, trans-11 conjugated linoleic acid in combination with trans-11 vaccenic acid in a rodent model of the metabolic syndrome, the JCR:LA-cp rat

<p>Abstract</p> <p>Background</p> <p>Conjugated linoleic acid (<it>cis</it>-9, <it>trans</it>-11 CLA) and <it>trans</it>-11 vaccenic acid (VA) are found naturally in ruminant-derived foods. CLA has been shown to have numerous potential health related effects and has been extensively investigated. More recently, we have shown that VA has lipid-lowering properties associated with reduced hepatic lipidogenesis and chylomicron secretion in the JCR:LA<it>-cp </it>rat. The aim of this study was to evaluate potential additional hypolipidemic effects of purified forms of CLA and VA in an animal model of the metabolic syndrome (the JCR:LA-<it>cp </it>rat).</p> <p>Methods</p> <p>Twenty four obese JCR:LA-<it>cp </it>rats were randomized and assigned to one of three nutritionally adequate iso-caloric diets containing 1% w/w cholesterol and 15% w/w fat for 16 wk: 1) control diet (CD), 2) 1.0% w/w <it>cis</it>-9, <it>trans</it>-11 CLA (CLA), 3) 1.0% w/w VA and 1% w/w <it>cis</it>-9, <it>trans</it>-11 CLA (VA+CLA). Lean rats were fed the CD to represent normolipidemic conditions.</p> <p>Results</p> <p>Fasting plasma triglyceride (TG), total cholesterol and LDL-cholesterol concentrations were reduced in obese rats fed either the CLA diet or the VA+CLA diet as compared to the obese control group (p < 0.05, p < 0.001; p < 0.001, p < 0.01; p < 0.01, p < 0.001, respectively). The VA+CLA diet reduced plasma TG and LDL-cholesterol to the level of the normolipidemic lean rats and further decreased nonesterified fatty acids compared to the CLA diet alone. Interestingly, rats fed the VA+CLA diet had a higher food intake but lower body weight than the CLA fed group (P < 0.05). Liver weight and TG content were lower in rats fed either CLA (p < 0.05) or VA+CLA diets (p < 0.001) compared to obese control, consistent with a decreased relative protein abundance of hepatic acetyl-CoA carboxylase in both treatment groups (P < 0.01). The activity of citrate synthase was increased in liver and adipose tissue of rats fed, CLA and VA+CLA diets (p < 0.001) compared to obese control, suggesting increased mitochondrial fatty acid oxidative capacity.</p> <p>Conclusion</p> <p>We demonstrate that the hypolipidemic effects of chronic <it>cis</it>-9, <it>trans</it>-11 CLA supplementation on circulating dyslipidemia and hepatic steatosis are enhanced by the addition of VA in the JCR:LA-<it>cp </it>rat.</p

Vaccenic acid suppresses intestinal inflammation by increasing anandamide and related N-acylethanolamines in the JCR:LA-cp rat

Vaccenic acid (VA), the predominant ruminantderived trans fat in the food chain, ameliorates hyperlipidemia, yet mechanisms remain elusive. We investigated whether VA could influence tissue endocannabinoids (ECs) by altering the availability of their biosynthetic precursor, arachidonic acid (AA), in membrane phospholipids (PLs). JCR:LA-cp rats were assigned to a control diet with or without VA (1% w/w), cis-9, trans-11 conjugated linoleic acid (CLA) (1% w/w) or VA+CLA (1% + 0.5% w/w) for 8 weeks. VA reduced the EC, 2-arachidonoylglycerol (2-AG), in the liver and visceral adipose tissue (VAT) relative to control diet (P 0.05). Interestingly, VA increased jejunal concentrations of anandamide and those of the noncannabinoid signaling molecules, oleoylethanolamide and palmitoylethanolamide, relative to control diet (P < 0.05). This was consistent with a lower jejunal protein abundance (but not activity) of their degrading enzyme, fatty acid amide hydrolase, as well as the mRNA expression of TNFα and interleukin 1β (P < 0.05). The ability of VA to reduce 2-AG in the liver and VAT provides a potential mechanistic explanation to alleviate ectopic lipid accumulation. The opposing regulation of ECs and other noncannabinoid lipid signaling molecules by VA suggests an activation of benefit via the EC system in the intestine

Optimal cooperation modes and information strategies under asymmetric sustainable investment efficiency

Currently, sustainability is of widespread concern among consumers and branders, compelling an increasing number of suppliers to invest in sustainable practices. This paper establishes a supply chain model comprising a supplier with private investment efficiency and a brander. By employing signaling and reverse selection theories, the equilibrium strategies of the supplier and the brander are explored. Additionally, the impact of investment efficiency and the probability of H-type on the brander’s information strategy and optimal cooperation mode are analyzed. Our analyses reveal that concealing private information may not be beneficial to the supplier under the quotation mode. Moreover, when the probability of H-type is low, the supplier prefers to signal its exact type to the brander. Under the bidding mode, the brander may benefit more from not obtaining the exact supplier type. When the efficiency difference is higher and the probability of H-type is smaller, the brander indicates a preference for the quotation mode and is more willing to await a signal from the supplier. Furthermore, different information structures yield different optimal cooperation modes for the brander

Water-modification of micro- and nano-adsorbents: A strategy for enhancing biodiesel refining efficiency

In this study, we compared nanometer-scale (nm) silica (SiO2) and alumina (Al2O3) with conventional micrometer-scale (μm) adsorbents (SiO2 and Al2O3) to determine their utility in refining crude fatty acid methyl esters (FAME). Unlike their μm counterparts, hydrated SiO2 and Al2O3 nm-adsorbents did not retain water after utilization in FAME refining. However, hydrated adsorbents significantly improved performance of μm-scale SiO2 and Al2O3 adsorbents for FAME refining. Structurally, the μm-adsorbents are porous multi-layered structures, with FAME adhering to the surface or entrained between layers. Meanwhile, nm-adsorbents were aggregated. As such, FAME loss associated with nm-SiO2 adsorbent was 50.5 % higher than μm-SiO2 adsorbent. In addition, the electrical charge density of the adsorbents influenced their performance in FAME refining. Finally, conventional separation methods (e.g., gravitational setting) were impractical for separating spent nm-adsorbents from FAME; although, the use of an electrostatic field enhanced the removal of nm-adsorbents from solution. Altogether, this study examines the application of nm-adsorbents, compared to μm-adsorbents, and highlights potential increased efficiency in refining biodiesel, such as potentially reducing the need for extensive wet washing processes. Although new separation technologies may be required in recovering spent nm-adsorbents, their application could enhance the sustainability and cost efficiency of biodiesel production