Nabil el Jaber-Vazdekis

Significance of long chain polyunsaturated fatty acids in human health

In the last decades, the development of new technologies applied to lipidomics has revitalized the analysis of lipid profile alterations and the understanding of the underlying molecular mechanisms of lipid metabolism, together with their involvement in the occurrence of human disease. Of particular interest is the study of omega-3 and omega-6 long chain polyunsaturated fatty acids (LC-PUFAs), notably EPA (eicosapentaenoic acid, 20:5n-3), DHA (docosahexaenoic acid, 22:6n-3), and ARA (arachidonic acid, 20:4n-6), and their transformation into bioactive lipid mediators. In this sense, new families of PUFA-derived lipid mediators, including resolvins derived from EPA and DHA, and protectins and maresins derived from DHA, are being increasingly investigated because of their active role in the “return to homeostasis” process and resolution of inflammation. Recent findings reviewed in the present study highlight that the omega-6 fatty acid ARA appears increased, and omega-3 EPA and DHA decreased in most cancer tissues compared to normal ones, and that increments in omega-3 LC-PUFAs consumption and an omega-6/omega-3 ratio of 2–4:1, are associated with a reduced risk of breast, prostate, colon and renal cancers. Along with their lipid-lowering properties, omega-3 LC-PUFAs also exert cardioprotective functions, such as reducing platelet aggregation and inflammation, and controlling the presence of DHA in our body, especially in our liver and brain, which is crucial for optimal brain functionality. Considering that DHA is the principal omega-3 FA in cortical gray matter, the importance of DHA intake and its derived lipid mediators have been recently reported in patients with major depressive and bipolar disorders, Alzheimer disease, Parkinson’s disease, and amyotrophic lateral sclerosis. The present study reviews the relationships between major diseases occurring today in the Western world and LC-PUFAs. More specifically this review focuses on the dietary omega-3 LC-PUFAs and the omega-6/omega-3 balance, in a wide range of inflammation disorders, including autoimmune diseases. This review suggests that the current recommendations of consumption and/or supplementation of omega-3 FAs are specific to particular groups of age and physiological status, and still need more fine tuning for overall human health and well being.

Effects of Elicitors on Tropane Alkaloids and Gene Expression in Atropa baetica Transgenic Hairy Roots

Elicitation of transgenic Atropa baetica overexpressing the h6h gene with salicylic acid (SA), acetylsalicylic acid (ASA),or methyl jasmonate (MeJ) was conducted to boost tropane alkaloid yields. Scopolamine (1) amounts increased after treatment with ASA and MeJ, but not with SA. The highest enhancement of 1 was achieved with MeJ followed by ASA dissolved in EtOH. Transcriptomic analyses showed a direct relationship between content of 1 and gene expressions;the engineered h6h gene and other biosynthetic genes were stimulated. ASA dissolved in EtOH showed a high h6h gene expression, increasing 25-fold and 5-fold compared to controls; tr-I also displayed a 5-fold increase. The controls to which EtOH was added showed a 5-fold increase in h6h gene expression and 125-fold for pmt, demonstrating that EtOH also functioned as an enhancer of 1. MeJ was the best elicitor, displaying a 25-fold increase in h6h expression level, not affecting the expression of the other three genes analyzed, and it appears to possibly stimulate the phenylpropanoids branch of the tropane alkaloid pathway.

Cloning, characterization and analysis of expression profiles of a cDNA encoding a hyoscyamine 6β-hydroxylase (H6H) from Atropa baetica Willk

A new cDNA encoding hyoscyamine 6beta-hydroxylase (H6H, EC 1.14.11.11), a bifunctional enzyme catalyzing the last two steps in the biosynthesis of scopolamine, was isolated from Atropa baetica roots (GenBank accession no. EF442802). The full cDNA sequence showed an ORF of 1035bp, coding for a protein with 344 amino acid residues. Sequence analyses at the nucleotide level showed that this ORF shares high identity with other H6H from different plant species, such as Anisodus tanguticus and Hyoscyamus niger with 90% identity, and an almost total identity with A. belladonna (98%). Tissue expression analyses showed that the gene transcript was tissue dependent, appearing exclusively in roots, thus being the only biosynthetic site for the production of scopolamine. Furthermore, Southern hybridization experiments revealed that this gene was not part of a multigene family as appears in low copy number. Phylogenetic tree analysis indicated that A. baetica H6H had a very close relationship with A. belladonna and to a lesser extent with H. niger.

The lupane-type triterpene 30-oxo-calenduladiol is a CCR5 antagonist with anti-HIV-1 and anti-chemotactic activities

The existence of drug-resistant human immunodeficiency virus (HIV) viruses in patients receiving antiretroviral treatment urgently requires the characterization and development of new antiretroviral drugs designed to inhibit resistant viruses and to complement the existing antiretroviral strategies against AIDS. We assayed several natural or semi-synthetic lupane-type pentacyclic triterpenes in their ability to inhibit HIV-1 infection in permissive cells. We observed that the 30-oxo-calenduladiol triterpene, compound 1, specifically impaired R5-tropic HIV-1 envelope-mediated viral infection and cell fusion in permissive cells, without affecting X4-tropic virus. This lupane derivative competed for the binding of a specific anti-CCR5 monoclonal antibody or the natural CCL5 chemokine to the CCR5 viral coreceptor with high affinity. 30-Oxo-calenduladiol seems not to interact with the CD4 antigen, the main HIV receptor, or the CXCR4 viral coreceptor. Our results suggest that compound 1 is a specific CCR5 antagonist, because it binds to the CCR5 receptor without triggering cell signaling or receptor internalization, and inhibits RANTES (regulated on activation normal T cell expressed and secreted)-mediated CCR5 internalization, intracellular calcium mobilization, and cell chemotaxis. Furthermore, compound 1 appeared not to interact with β-chemokine receptors CCR1, CCR2b, CCR3, or CCR4. Thereby, the 30-oxo-calenduladiol-associated anti-HIV-1 activity against R5-tropic virus appears to rely on the selective occupancy of the CCR5 receptor to inhibit CCR5-mediated HIV-1 infection. Therefore, it is plausible that the chemical structure of 30-oxo-calenduladiol or other related dihydroxylated lupane-type triterpenes could represent a good model to develop more potent anti-HIV-1 molecules to inhibit viral infection by interfering with early fusion and entry steps in the HIV life cycle.

Multi-development–HPTLC Method for Quantitation of Hyoscyamine, Scopolamine and their Biosynthetic Precursors in Selected Solanaceae Plants Grown in Natural Conditions and as In Vitro Cultures

INTRODUCTION Hyoscyamine and scopolamine, anti-cholinergic agents widely used in medicine, are typically obtained from plants grown under natural conditions. Since field cultivation entails certain difficulties (changeable weather, pests, etc.), attempts have been made to develop a plant in vitro culture system as an alternative source for the production of these compounds. During experiments to locate the limiting steps in the biotechnological procedure, it is important to monitor not only the levels of the final products but also the changes in the concentration of their precursors. OBJECTIVE To develop a HPTLC method for the separation and quantitation of the main tropane alkaloids hyoscyamine and scopolamine, their respective direct precursors littorine and anisodamine, and cuscohygrine, a product of a parallel biosynthetic pathway that shares a common precursor (N-methyl-∆(1) -pyrrolium cation) with tropane alkaloids. METHODS Using alkaloid extracts from Atropa baetica hairy roots, different TLC chromatographic systems and developing procedures were investigated. RESULTS Full separation of all compounds was obtained on HPTLC Si60 F254 plates preconditioned with mobile phase vapours (chloroform:methanol:acetone:25% ammonia ratios of 75:15:10:1.8, v/v/v/v). The chromatograms were developed twice (at distances of 4.0 and 3.0 cm) in a Camag twin trough chamber and visualised with Dragendorffs reagent. Densitometric detection (λ = 190 and 520 nm) was used for quantitative analyses of the different plant samples. CONCLUSION This method can be recommended for quantitation of hyoscyamine, scopolamine, anisodamine, littorine and cuscohygrine in different plant material (field grown vs. in vitro cultures).

Biotechnology for the production of plant natural products

Abstract This review deals with the application of recombinant DNA technology to investigate and tailor plant secondary metabolism as a tool for the control of the biosynthesis and accumulation of plant natural products. Firstly, it presents the different plant transformation technologies, followed by the description of the various strategies implemented for the genetic modification of metabolic pathways. Furthermore, a review of the modification of three metabolic pathways, i. e. tropane alkaloid, fatty acid and terpenoid biosynthetic routes has also been attempted. Finally, under future perspectives several views on how the technology might progress are outlined, as well as presenting the potential different approaches which might be devised in the future for the genetic engineering of metabolic networks.

Metabolic Engineering of Plant Cellular Metabolism: Methodologies, Advances, and Future Directions

Plant natural products are useful compounds, such as pigments, fragrances, pharmaceuticals used for the treatment of several human diseases. Development of plant manipulation techniques, such as particle bombardment, Agrobacterium-mediated transformation, vacuum infiltration, agrodrench, viral vector, protoplasts fusion and ultrasound, as well as recombinant DNA, and genetic technologies applied toward metabolic engineering of bioactive plant natural products are presented, together with different genetic engineering methods, such as overexpression of transgenes, multiple expression of transgenes, gene silencing, and transcription factors as powerful tools for the engineering of biosynthetic pathways. Future perspectives and the potential of different approaches are presented to highlight how a better understanding of secondary metabolite pathways represents a direct successful highway to genetic manipulation of desired metabolic pathways.

Importance of Polyunsaturated Fatty Acids from Marine Algae

Marine algae are non-vascular photoautotrophic organisms containing chlorophyll. They are the primary producers in marine food webs and responsible for the maintenance of life in many ecosystems. Algae are able to produce a wide range of active metabolites, many of which are of great importance to human health, such as the highly valued omega-3 eicosapentaenoic and docosahexaenoic acids (EPA and DHA). There is an increasing demand of these fatty acids, and new sources from algae are been investigated. As presented in this chapter, algae offer great potential and different biotechnological approaches have been developed for boosting fatty acid yields in microalgae. Many industrial exploitation examples exist and more will follow. Thus, in future decades with the scientific advances to come, marine algae will surely become an important, attractive, continuous, and sustainable omega-3 source, to thus satisfy the increasing world demand for these compounds.

Improvement of Polyunsaturated Fatty Acid Production in Echium acanthocarpum Transformed Hairy Root Cultures by Application of Different Abiotic Stress Conditions

Fatty acids are of great nutritional, therapeutic, and physiological importance, especially the polyunsaturated n-3 fatty acids, possessing larger carbon chains and abundant double bonds or their immediate precursors. A few higher plant species are able to accumulate these compounds, like those belonging to the Echium genus. Here, the novel E. acanthocarpum hairy root system, which is able to accumulate many fatty acids, including stearidonic and α-linolenic acids, was optimized for a better production. The application of abiotic stress resulted in larger yields of stearidonic and α-linolenic acids, 60 and 35%, respectively, with a decrease in linoleic acid, when grown in a nutrient medium consisting of B5 basal salts, sucrose or glucose, and, more importantly, at a temperature of 15°C. The application of osmotic stress employing sorbitol showed no positive influence on the fatty acid yields; furthermore, the combination of a lower culture temperature and glucose did not show a cumulative boosting effect on the yield, although this carbon source was similarly attractive. The abiotic stress also influenced the lipid profile of the cultures, significantly increasing the phosphatidylglycerol fraction but not the total lipid neither their biomass, proving the appropriateness of applying various abiotic stress in this culture to achieve larger yields.