An acetylated monoterpene and a sesquiterpene alcohol from Psiadia anchusifolia

Two compounds identified as 7,7-dimethyl-2-methylenebicyclo[3.1.1]heptan-6-ol acetate and 6,6,8,9-tetramethyltricyclo[3.3.3.0]undec-7-en-2-ol were isolated from the essential oil of the fresh leaves of Psiadia anchusifolia. Their structures were determined by extensive NMR studies (1H NMR, 13C NMR, DEPT, 1H-1H COSY, HSQC, HMBC) as well as by X-ray crystallographic analysis.     

Sesquiterpenes from pernettya furens

The novel sesquiterpene carboxylic acids, pernetic acid A-E, a new sesquiterpene alcohol pernetol, a new sesquiterpene aldehyde, pernetal, and pernetic acid A methyl ester, were isolated from the aerial parts of Pernettya furens. The structures were established by spectral and X-ray analysis. Pernetic acids D and E have a novel cis hydrindane skeleton presuming the oxidative modification from the cadalane skeleton.     

Alleviating monoterpene toxicity using a two-phase extractive fermentation for the bioproduction of jet fuel mixtures in Saccharomyces cerevisiae

Monoterpenes are a diverse class of compounds with applications as flavors and fragrances, pharmaceuticals and more recently, jet fuels. Engineering biosynthetic pathways for monoterpene production in microbial hosts has received increasing attention. However, monoterpenes are highly toxic to many microorganisms including Saccharomyces cerevisiae, a widely used industrial biocatalyst. In this work, the minimum inhibitory concentration (MIC) for S. cerevisiae was determined for five monoterpenes: β‐pinene, limonene, myrcene, γ‐terpinene, and terpinolene (1.52, 0.44, 2.12, 0.70, 0.53 mM, respectively). Given the low MIC for all compounds tested, a liquid two‐phase solvent extraction system to alleviate toxicity during fermentation was evaluated. Ten solvents were tested for biocompatibility, monoterpene distribution, phase separation, and price. The solvents dioctyl phthalate, dibutyl phthalate, isopropyl myristate, and farnesene showed greater than 100‐fold increase in the MIC compared to the monoterpenes in a solvent‐free system. In particular, the MIC for limonene in dibutyl phthalate showed a 702‐fold (308 mM, 42.1 g L^?1 of limonene) improvement while cell viability was maintained above 90%, demonstrating that extractive fermentation is a suitable tool for the reduction of monoterpene toxicity. Finally, we estimated that a limonane to farnesane ratio of 1:9 has physicochemical properties similar to traditional Jet‐A aviation fuel. Since farnesene is currently produced in S. cerevisiae, its use as a co‐product and extractant for microbial terpene‐based jet fuel production in a two‐phase system offers an attractive bioprocessing option. Biotechnol. Bioeng. 2012; 109: 2513–2522. © 2012 Wiley Periodicals, Inc.     

The relative effect of citral on mitotic microtubules in wheat roots and BY2 cells

The plant volatile monoterpene citral is a highly active compound with suggested allelopathic traits. Seed germination and seedling development are inhibited in the presence of citral, and it disrupts microtubules in both plant and animal cells in interphase. We addressed the following additional questions: can citral interfere with cell division; what is the relative effect of citral on mitotic microtubules compared to interphase cortical microtubules; what is its effect on newly formed cell plates; and how does it affect the association of microtubules with γ‐tubulin? In wheat seedlings, citral led to inhibition of root elongation, curvature of newly formed cell walls and deformation of microtubule arrays. Citral’s effect on microtubules was both dose‐ and time‐dependent, with mitotic microtubules appearing to be more sensitive to citral than cortical microtubules. Association of γ‐tubulin with microtubules was more sensitive to citral than were the microtubules themselves. To reveal the role of disrupted mitotic microtubules in dictating aberrations in cell plates in the presence of citral, we used tobacco BY2 cells expressing GFP‐Tua6. Citral disrupted mitotic microtubules, inhibited the cell cycle and increased the frequency of asymmetric cell plates in these cells. The time scale of citral’s effect in BY2 cells suggested a direct influence on cell plates during their formation. Taken together, we suggest that at lower concentrations, citral interferes with cell division by disrupting mitotic microtubules and cell plates, and at higher concentrations it inhibits cell elongation by disrupting cortical microtubules.     

Solid‐phase synthesis and screening of a library of C‐terminal arginine peptide aldehydes against Murray Valley encephalitis virus protease

Murray Valley encephalitis virus is a member of the flavivirus group, a large family of single‐stranded RNA viruses, which cause serious disease in all regions of the world. Unfortunately, no suitable antivirals are available, and there are commercial vaccines for only three flaviviruses. The solid‐phase synthesis of a library of 400 C‐terminal arginine peptide aldehydes and their screening against Murray Valley encephalitis virus protease are demonstrated. The library was utilised to elucidate several tripeptide sequences that can be used as inhibitors in further SAR studies. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.     

Effects of nitric oxide synthase-3 overexpression on post-translational modifications and cell survival in HepG2 cells

Hepatocarcinoma is the fifth most common neoplasm and the third cause of cancer-related death. The development of genetic- and/or molecular-based therapies is urgently required. The administration of high doses of nitric oxide (NO) promotes cell death in hepatocytes. NO contributes to cell signaling by inducing oxidative/nitrosative-dependent post-translational modifications. The aim of the present study was to investigate protein modifications and its relation with alteration of cell proliferation and death in hepatoma cells. Increased intracellular NO production was achieved by stable nitric oxide synthase-3 (NOS-3) overexpression in HepG2 cells. We assessed the pattern of nitration, nitrosylation and carbonylation of proteins by proteomic analysis. The results showed that NOS-3 cell overexpression increased oxidative stress, which affected proteins mainly involved in cell protein folding. Carbonylation also altered metabolism, as well as immune and antioxidant responses. The interaction of nitrosative and oxidative stress generated tyrosine nitration, which affected the tumor marker Serpin B3, ATP synthesis and cytoskeleton. All these effects were associated with a decrease in chaperone activity, a reduction in cell proliferation and an increased cell death. Our study showed that alteration of nitration, nitrosylation and carbonylation pattern of proteins by NO-dependent oxidative/nitrosative stress was related to a reduction of cell survival in a hepatoma cell line.     

Asymmetric Michael reaction of aldehydes with β-nitroalkenes catalyzed by pyrrolidine-camphor derived organocatalysts bearing hydrogen-bond donors

Several pyrrolidine-camphor derived organocatalysts were designed and synthesized. These organocatalysts were used for direct Michael reaction of aldehydes with nitroalkenes to give the desired γ-nitrocarbonyl compounds in high yields (up to 99%), high diastereoselectivities (syn:anti up to 92:8), and good to excellent enantioselectivities (up to 94% ee). Possible transition-state model was also proposed for this asymmetric transformation, which may involve hydrogen-bond interactions between the nucleophilic enamine formed in situ and the nitroalkenes.     

Catalase and antiquitin from <Emphasis Type="Italic">Euphorbia characias</Emphasis>: Two proteins involved in plant defense?

Here we report the cDNA nucleotide sequences of a calmodulin-binding catalase and an antiquitin from the latex of the Mediterranean shrub Euphorbia characias. Present findings suggest that catalase and antiquitin might represent additional nodes in the Euphorbia defense systems, and a multi-enzymatic interaction contributing to plant's protection against biotic and abiotic stresses is proposed to occur in E. characias laticifers.     

Molecular cloning and differential expression of an aldehyde dehydrogenase gene in rice leaves in response to infection by blast fungus

Aldehyde dehydrogenase (ALDH) superfamily is a group of enzymes metabolizing endogenous and exogenous aldehydes. Using differential display RT-PCR and cDNA library screening, a full-length aldehyde dehydrogenase cDNA (ALDH7B7) was isolated from rice leaves infected by incompatible race of blast fungus Magnaporthe grisea. The deduced amino acid sequence consists of 509 amino acid residues and shares 74∼81% identity with those of ALDH7Bs from other plants. ALDH7B7 expression was induced by blast fungus infection, ultraviolet, mechanical wound in rice leaves and was not detected in untreated rice organs. This gene has also been found to be inducible after exogenous phytohormones application, such as salicylic acid, methyl ester of jasmonic acid and abscisic acid. The function of ALDH7B7 in the interaction process between blast fungus and rice is discussed.     

Sesquiterpene lactones and other constituents from Matricaria chamomilla L.

An ethanolic extract of the aerial parts of Matricaria Chamomilla L. collected at Oued Tonga near El-Kala is eastern Argelia yielded two new substances named matricolone and chamolol, together with four known compounds. The structure of the new compounds were determined by chemical transformations and NMR spectroscopy with ¹H-¹H (COSY and ROESY), ¹H-¹³C (one bond and long range correlations) two dimensional experiments. The results obtained indicate the presence of sesquiterpene lactones of the eudesmanolide, germacranolide and guaianolide types. These products can be considered to be of great interest from a chemotaxonomical point of view for this wild-growing plant, because these types of lactones have not been found together in other Matricaria species.