δ-Aminolaevulinic acid and amino acid neurotransmitters

Summary The effects of the porphyrin precursor -aminolaevulinic acid (ALA) on -aminobutyric acid (GABA) and L-glutamate transmitter systems was investigated in rat brain. It was found that ALA inhibited GABA and glutamate uptake and stimulated basal efflux of the amino acids in purified nerve endings. These effects were evident only at relatively high concentrations of ALA (at least 100 M). Such concentrations probably do not occur in the nervous systems of patients suffering from acute porphyria. In addition, it was found that ALA inhibited the stimulated release of GABA from nerve endings probably by acting as an agonist at GABA autoreceptors. This effect was found at very low concentrations of ALA (1 M). It is therefore likely that the neuropsychiatric manifestations of the acute porphyric attack are attributable, to some extent, to reduced GABA release at central synapses.     

Endogenous abscisic acid and 2-trans-abscisic acid in alternate bearing ‘Wilking’ mandarin trees

The relationship of abscisic acid (ABA) and 2-trans-abscisic acid (t-ABA) to alternate bearing has been examined in Wilking mandarin (Citrus reticulata Blanco) trees. Leaves, stems and buds of trees loaded with fruit (on trees) had 4.3, 6.0 and 2.2 fold higher ABA levels than the corresponding organs from off trees. Leaves had higher ABA levels than stems and buds in both on and off trees. t-ABA was non-detectable in Wilking leaf, stem and bud tissue. Amounts of t-ABA not exceeding 40% of the ABA content, were found in Shamouti and Valencia orange buds and in Wilking fruit peel.The elevated levels of ABA in on tree organs may reflect a stress imposed by the fruit overload.     

2′-(E)-O-p-coumaroylgalactaric acid and 2′-(E)-O-feruloylgalactaric acid in citrus

2′-(E)-O-p-Coumaroyl- and 2′-(E)-O-feruloylgalactaric acids, hitherto unknown in nature, have been isolated and identified from orange peel.     

Quantitative analysis and comparative decarboxylation of aminomalonic acid, β-carboxyaspartic acid,and γ-carboxyglutamic acid

Methods for quantitative analysis of the carboxylated amino acids, aminomalonic acid, β-carboxyaspartic acid, and γ-carboxyglutamic acid, are presented. These substances are acid labile and thus can be measured only after alkaline hydrolysis of proteins and peptides. Half-times for decarboxylation in 1 m HCl at 100°C are: aminomalonic acid (1.2 min); β-carboxyaspartic acid (1.7 min); and γ-carboxyglutamic acid (8.6 min). This property is useful for unequivocal identification in complex hydrolysates.     

Effects of capric acid on rumen methanogenesis and biohydrogenation of linoleic and α-linolenic acid

Capric acid (C10:0), a medium chain fatty acid, was evaluated for its anti-methanogenic activity and its potential to modify the rumen biohydrogenation of linoleic (C18:2n-6) and α-linolenic acids (C18:3n-3). A standard dairy concentrate (0.5 g), supplemented with sunflower oil (10 mg) and linseed oil (10 mg) and increasing doses of capric acid (0, 10, 20 and 30 mg), was incubated with mixed rumen contents and buffer (1 : 4 v/v) for 24 h. The methane inhibitory effect of capric acid was more pronounced at the highest (30 mg) dose compared to the medium (20 mg) (-85% v. -34%), whereas the lower dose (10 mg) did not reduce rumen methanogenesis. A 23% decrease in total short-chain fatty acid (SCFA) production was observed, accompanied by shifts towards increased butyrate at 20 mg and increased propionate at 30 mg of capric acid (P < 0.001). Capric acid linearly decreased the extent of biohydrogenation of C18:2n-6 and C18:3n-3, by up to 60% and 86%, respectively. This reduction was partially due to a lower extent of lipolysis when capric acid was supplemented. Capric acid at 20 and 30 mg completely inhibited the production of C18:0 (P < 0.001), resulting in an accumulation of biohydrogenation intermediates, mainly C18:1t10 + t11 and C18:2t11c15. In contrast to effects on rumen fermentation (methane production and proportions of SCFA), 30 mg of capric acid did not induce major changes in rumen biohydrogenation as compared to the medium (20 mg) dose. This study revealed the dual action of capric acid, being inhibitory to both methane production and biohydrogenation of C18:2n-6 and C18:3n-3.     

Relationship between transport and metabolism of α-naphthaleneacetic acid, β-naphthaleneacetic acid and α-decalylacetic acid in segments of Coleus

Summary Transportand metabolism of -naphthaleneacetic acid -naphthaleneacetic acid, and -decalylacetic acid, all labelled with ¹⁴C in the carboxyl, group, were studied. Only -naphthaleneacetic acid is transported in a polar way. Most of the radioactivity in the tissue is in a low molecular form, either free or as immobilization products. The immobilization of -naphthaleneacetic acid is similar to that of -naphthaleneacetic acid. Immobilization of -decalylacetic acid is typically different. Bioassays showed -naphthaleneacetic acid as the sole biologically active component. It is concluded that stereo requirements necessary for biological activity are also required for polar auxin transport. It is further concluded that the observed specificity of the transport system is not related to the formation of immobilization products.     

Virtual target screening reveals rosmarinic acid and salvianolic acid A inhibiting metallo- and serine-β-lactamases

Rosmarinic acid (RA), a polyphenolic phytochemical, has broad-spectrum biological and pharmacological activity. A virtual target screening method termed IFPTarget combined with enzyme inhibition assays led to the identification of the clinically relevant metallo-β-lactamase (MBL) VIM-2 as one of unexploited targets of RA. The enzyme kinetic studies indicated that RA is a fully reversible, substrate-competitive VIM-2 inhibitor. The isothermal titration calorimetry (ITC) analyses revealed that the initial binding of RA to VIM-2 is mainly due to enthalpy contribution. Further inhibition assays with RA related compounds revealed that salvianolic acid A, a derivative of RA, manifests potent inhibition to VIM-2, more interestingly, which shows inhibitory activity against the NDM-1, another clinically relevant MBL subtype, and the serine-β-lactamase TEM-1 that is structurally and mechanistically distinct from the VIM-2 and NDM-1.     

Eicosapentaenoic acid and docosahexaenoic acid reduce interleukin-1β-mediated cartilage degradation

Introduction  

In inflammatory joint disease, such as osteoarthritis (OA), there is an increased level of proinflammatory cytokines, such as interleukin (IL)-1β. These cytokines stimulate the production of matrix metalloproteinases (MMPs), which leads to the degradation of the cartilage extracellular matrix and the loss of key structural components such as sulphated glycosaminoglycan (sGAG) and collagen II. The aim of this study was to examine the therapeutic potential of n-3 polyunsaturated fatty acids (PUFAs) in an in vitro model of cartilage inflammation.     

(−)-Allo-pertusaric acid and (−)-dihydropertusaric acid from the lichen Pertusaria albescens

The structures of two γ-lactone carboxylic acids from the lichen Pertusaria albescens, (−)-allo-pertusaric acid and (−)dihydropertusaric acid, have been elucidated by spectroscopic and chemical methods. From P. ophthalmiza, taraxerone and a mixture of long chain aliphatic alcohols and fatty acids have been isolated.     

One-pot synthesis of bioactive cyclopentenones from α-linolenic acid and docosahexaenoic acid

Oxidation products of the poly-unsaturated fatty acids (PUFAs) arachidonic acid, α-linolenic acid and docosahexaenoic acid are bioactive in plants and animals as shown for the cyclopentenones prostaglandin 15d-PGJ₂ and PGA₂, cis-(+)-12-oxophytodienoic acid (12-OPDA), and 14-A-4 neuroprostane. In this study an inexpensive and simple enzymatic multi-step one-pot synthesis is presented for 12-OPDA, which is derived from α-linolenic acid, and the analogous docosahexaenoic acid (DHA)-derived cyclopentenone [(4Z,7Z,10Z)-12-[[-(1S,5S)-4-oxo-5-(2Z)-pent-2-en-1yl]-cyclopent-2-en-1yl] dodeca-4,7,10-trienoic acid, OCPD]. The three enzymes utilized in this multi-step cascade were crude soybean lipoxygenase or a recombinant lipoxygenase, allene oxide synthase and allene oxide cyclase from Arabidopsis thaliana. The DHA-derived 12-OPDA analog OCPD is predicted to have medicinal potential and signaling properties in planta. With OCPD in hand, it is shown that this compound interacts with chloroplast cyclophilin 20-3 and can be metabolized by 12-oxophytodienoic acid reductase (OPR3) which is an enzyme relevant for substrate bioactivity modulation in planta.     

Immunocytochemical demonstration ofγ-amino butyric acid and glutamic acid decarboxylase in R7 photoreceptors and C2 centrifugal fibres in the blowfly visual system

Summary Neurons within the compound eye of the flyCalliphora erythrocephala, suspected of containing gamma-aminobutyric acid were revealed immunocytochemically, using antibodies directed against gamma-aminobutyric acid (GABA) and glutamic acid decarboxylase (GAD). The GABA content within putative GABAergic neurons was increased by high affinity uptake of GABA and selective blocking of GABA metabolism with Gabaculine. Only neuronal populations which were labelled with the GABA as well as the GAD antibodies were presumed to be GABAergic. The first optic neuropil (lamina) exhibited two distinct GA-BAergic fibre populations amongst a larger population comprised of fourteen cell classes. One fibre population was formed by the axons of the photopic photoreceptors R7 which pass through the lamina and terminate in the second optic neuropil (the medulla). The identity of R7 was established from longitudinal and transverse sections of the retina where R7 can be unequivocally distinguished from the six scotopic photoreceptors R1-6 and the other photopic receptor, R8.The other fibre population matched the profiles in the lamina of terminals of efferent C2 neurons. These neurons project distally from beneath the medulla out to the lamina ganglionaris where each retinotopic unit (cartridge) contains a characteristic hook-like terminal arbor distally. We propose from these data that the photoreceptors R7 and the efferent C2 neurons use GABA as a neurotransmitter.     

Stereoselective synthesis of chaulmoogric acid and related fatty acid from 2-(±)-cyclopentenecarboxylic acid by Bacillus subtilis (ATCC 7059)

2-(±)-Cyclopentenecarboxylic acid added to the culture medium is incorporated into two new fatty acids by the growing cells of Bacillus subtilis (ATCC 7059). The new fatty acids, amounting to 24% of the total cellular fatty acids, are identified as hydrocarpic [11-(2′-cyclopentenyl)-hendecanoic] and chaulmoogric [13-(2′-cyclopentenyl)-tridecanoic] by gas-liquid chromatography and mass spectrometry. These C₁₆ and C₁₈ fatty acids are optically active, levorotatory, with the specific rotation of ?50.4° as mixture, thus the optical purity of approximately 80%. This indicates that the optical rotation of these bacterial fatty acids are opposite with that of the fatty acids from plant oils.     

What makes the bioactive lipids phosphatidic acid and lysophosphatidic acid so special?

Phosphatidic acid and lysophosphatidic acid are minor but important anionic bioactive lipids involved in a number of key cellular processes, yet these molecules have a simple phosphate headgroup. To find out what is so special about these lipids, we determined the ionization behavior of phosphatidic acid (PA) and lysophosphatidic acid (LPA) in extended (flat) mixed lipid bilayers using magic angle spinning 31P NMR. Our data show two surprising results. First, despite identical phosphomonoester headgroups, LPA carries more negative charge than PA when present in a phosphatidylcholine bilayer. Dehydroxy-LPA [1-oleoyl-3-(phosphoryl)propanediol] behaves in a manner identical to that of PA, indicating that the difference in negative charge between LPA and PA is caused by the hydroxyl on the glycerol backbone of LPA and its interaction with the phosphomonoester headgroup. Second, deprotonation of phosphatidic acid and lysophosphatidic acid was found to be strongly stimulated by the inclusion of phosphatidylethanolamine in the bilayer, indicating that lipid headgroup charge depends on local lipid composition and will vary between the different subcellular locations of (L)PA. Our findings can be understood in terms of a hydrogen bond formed within the phosphomonoester headgroup of (L)PA and its destabilization by competing intra- or intermolecular hydrogen bonds. We propose that this hydrogen bonding property of (L)PA is involved in the various cellular functions of these lipids.     

Production of ω-hydroxyundec-9-enoic acid and n-heptanoic acid from ricinoleic acid by recombinant Escherichia coli-based biocatalyst

ω-Hydroxyundec-9-enoic acid and n-heptanoic acid are valuable building blocks for the production of flavors and antifungal agents as well as bioplastics such as polyamides and polyesters. However, a biosynthetic process to allow high productivity and product yield has not been reported. In the present study, we engineered an Escherichia coli-based biocatalytic process to efficiently produce ω-hydroxyundec-9-enoic acid and n-heptanoic acid from a renewable fatty acid (i.e., ricinoleic acid). Expression systems for catalytic enzymes (i.e., an alcohol dehydrogenase of Micrococcus luteus, a Baeyer–Villiger monooxygenase of Pseudomonas putida KT2440, an esterase of Pseudomonas fluorescens SIK WI) and biotransformation conditions were investigated. Biotransformation during stationary growth phase of recombinant E. coli in a bioreactor allowed to produce ω-hydroxyundec-9-enoic acid and n-heptanoic acid at a rate of 3.2 mM/h resulting in a final product concentration of ca. 20 mM. The total amount of ω-hydroxyundec-9-enoic acid and n-heptanoic acid produced reached 6.5 g/L (4.0 g/L of ω-hydroxyundec-9-enoic acid and 2.5 g/L of n-heptanoic acid). These results indicate that the high value carboxylic acids ω-hydroxyundec-9-enoic acid and n-heptanoic acid can be produced from a renewable fatty acid via whole-cell biotransformation.     

Synthesis of novel 3-amino and 29-hydroxamic acid derivatives of glycyrrhetinic acid as selective 11β-hydroxysteroid dehydrogenase 2 inhibitors

Glycyrrhetinic acid, the metabolite of the natural product glycyrrhizin, is a well known nonselective inhibitor of 11β-hydroxysteroid dehydrogenase (11β-HSD) type 1 and type 2. Whereas inhibition of 11β-HSD1 is currently under consideration for treatment of metabolic diseases, such as obesity and diabetes, 11β-HSD2 inhibitors may find therapeutic applications in chronic inflammatory diseases and certain forms of cancer. So far, no selective 11β-HSD2 inhibitor has been developed and neither animal studies nor clinical trials have been reported based on 11β-HSD2 inhibition. Starting from the lead compound glycyrrhetinic acid, novel triterpene type derivatives were synthesized and analyzed for their biological activity against overexpressed human 11β-HSD1 and 11β-HSD2 in cell lysates. Several hydroxamic acid derivatives showed high selectivity for 11β-HSD2. The most potent and selective compound is active against human 11β-HSD2 in the low nanomolar range with a 350-fold selectivity over human 11β-HSD1.     

Dietary linoleic acid has no effect on arachidonic acid,but increases n-6 eicosadienoic acid,and lowers dihomo-γ-linolenic and eicosapentaenoic acid in plasma of adult men

High intakes of linoleic acid (LA,18:2n-6) have raised concern due to possible increase in arachidonic acid (ARA, 20:4n-6) synthesis, and inhibition of alpha linolenic acid (ALA, 18:3n-3) desaturation to eicosapentaenoic (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). In healthy men, 10.5% energy compared to 3.8% energy LA with 1% energy ALA increased plasma phospholipid LA and 20:2n-6, the elongation product of LA, and decreased EPA, with no change in ARA. However, LA was inversely related to ARA at both 10.5% energy and 3.8% energy LA, (r=?0.761, r=?0.817, p<0.001, respectively). A two-fold variability in ARA among individuals was not explained by the dietary LA, ARA, ALA, or fish intake. Our results confirm LA requirements for ARA synthesis is low, <3.8% energy, and they suggest current LA intakes saturate Δ-6 desaturation and adversely affect n-3 fatty acid metabolism. Factors other than n-6 fatty acid intake are important modifiers of plasma ARA.     

Structure–activity relationship investigation of tertiary amine derivatives of cinnamic acid as acetylcholinesterase and butyrylcholinesterase inhibitors: compared with that of phenylpropionic acid,sorbic acid and hexanoic acid

In the present investigation, 48 new tertiary amine derivatives of cinnamic acid, phenylpropionic acid, sorbic acid and hexanoic acid (4d–6g, 10d–12g, 16d–18g and 22d–24g) were designed, synthesized and evaluated for the effect on AChE and BChE in vitro. The results revealed that the alteration of aminoalkyl types and substituted positions markedly influences the effects in inhibiting AChE. Almost of all cinnamic acid derivatives had the most potent inhibitory activity than that of other acid derivatives with the same aminoalkyl side chain. Unsaturated bond and benzene ring in cinnamic acid scaffold seems important for the inhibitory activity against AChE. Among them, compound 6g revealed the most potent AChE inhibitory activity (IC₅₀ value: 3.64?µmol/L) and highest selectivity over BChE (ratio: 28.6). Enzyme kinetic study showed that it present a mixed-type inhibition against AChE. The molecular docking study suggested that it can bind with the catalytic site and peripheral site of AChE.     

Human β2-glycoprotein I: molecular analysis of DNA and amino acid polymorphism

In this study, we describe a two-allelic RsaI restriction fragment length polymorphism identified by Southern blot analysis and by allele-specific polymerase chain reaction amplification for the human ₂-glycoprotein I (₂-I; apolipoprotein H=APOH) gene. This polymorphism, which segregates in a co-dominant fashion, leads to a valine-leucine amino acid exchange at amino acid position 247. The allele frequency has been established in 34 unrelated parents of the Centre d'Etude du Polymorphisme Humain family panel and was found to be 0.76 for valine and 0.23 for leucine. The Val-Leu polymorphism described in this study does not correlate with the four isoelectric focusing alleles previously described, indicating that other variants are responsible for this polymorphism.     

Biotechnological production and applications of the ω-3 polyunsaturated fatty acid docosahexaenoic acid

Docosahexaenoic acid (DHA) is a polyunsaturated fatty acid composed of 22 carbon atoms and six double bonds. Because the first double bond, as counted from the methyl terminus, is at position three, DHA belongs to the so-called -3 group. In recent years, DHA has attracted much attention because of its beneficial effect on human health. At present, fish oil is the major source of DHA, but alternatively it may be produced by use of microorganisms. Marine microorganisms may contain large quantities of DHA and are considered a potential source of this important fatty acid. Some of these organisms can be grown heterotrophically on organic substrates without light. These processes can be well controlled and DHA with constant quality can be produced all year round. This paper reviews recent advances in the biotechnological production of DHA by marine microorganisms.