M. Ann D. N. Perera

Platform biochemicals for a biorenewable chemical industry

The chemical industry is currently reliant on a historically inexpensive, petroleum-based carbon feedstock that generates a small collection of platform chemicals from which highly efficient chemical conversions lead to the manufacture of a large variety of chemical products. Recently, a number of factors have coalesced to provide the impetus to explore alternative renewable sources of carbon. Here we discuss the potential impact on the chemical industry of shifting from non-renewable carbon sources to renewable carbon sources. This change to the manufacture of chemicals from biological carbon sources will provide an opportunity for the biological research community to contribute fundamental knowledge concerning carbon metabolism and its regulation. We discuss whether fundamental biological research into metabolic processes at a holistic level, made possible by completed genome sequences and integrated with detailed structural understanding of biocatalysts, can change the chemical industry from being dependent on fossil-carbon feedstocks to using biorenewable feedstocks. We illustrate this potential by discussing the prospect of building a platform technology based upon a concept of combinatorial biosynthesis, which would explore the enzymological flexibilities of polyketide biosynthesis.

Developmental Changes in the Metabolic Network of Snapdragon Flowers

Evolutionary and reproductive success of angiosperms, the most diverse group of land plants, relies on visual and olfactory cues for pollinator attraction. Previous work has focused on elucidating the developmental regulation of pathways leading to the formation of pollinator-attracting secondary metabolites such as scent compounds and flower pigments. However, to date little is known about how flowers control their entire metabolic network to achieve the highly regulated production of metabolites attracting pollinators. Integrative analysis of transcripts and metabolites in snapdragon sepals and petals over flower development performed in this study revealed a profound developmental remodeling of gene expression and metabolite profiles in petals, but not in sepals. Genes up-regulated during petal development were enriched in functions related to secondary metabolism, fatty acid catabolism, and amino acid transport, whereas down-regulated genes were enriched in processes involved in cell growth, cell wall formation, and fatty acid biosynthesis. The levels of transcripts and metabolites in pathways leading to scent formation were coordinately up-regulated during petal development, implying transcriptional induction of metabolic pathways preceding scent formation. Developmental gene expression patterns in the pathways involved in scent production were different from those of glycolysis and the pentose phosphate pathway, highlighting distinct developmental regulation of secondary metabolism and primary metabolic pathways feeding into it.

Quantitative analysis of short-chain acyl-coenzymeAs in plant tissues by LC–MS–MS electrospray ionization method

Because acyl-CoAs play major roles in numerous anabolic and catabolic pathways, the quantitative determination of these metabolites in biological tissues is paramount to understanding the regulation of these metabolic processes. Here, we report a method for the analysis of a collection of short-chain acyl-CoAs (<6 carbon chain length) from plant extracts. Identification of each individual acyl-CoA was conducted by monitoring specific mass-fragmentation ions that are derived from common chemical moieties of all Coenzyme A (CoA) derivatives, namely the adenosine triphosphate nucleotide, pantothenate and acylated cysteamine. This method is robust and quick, enabling the quantitative analysis of up to 12 different acyl-CoAs in plant metabolite extracts with minimal post-extraction processing, using a 30min chromatographic run-time.

Identification and characterization of wheat drought-responsive MYB transcription factors involved in the regulation of cuticle biosynthesis

Highlight We uncovered significant structural and compositional differences between leaf cuticles of drought-tolerant and drought-sensitive wheat cultivars. Specific MYB factors drive cuticular responses to drought and may underlie genotypes with contrasting drought tolerance.

Biological origins of normal-chain hydrocarbons: a pathway model based on cuticular wax analyses of maize silks.

Long-chain normal hydrocarbons (e.g. alkanes, alkenes and dienes) are rare biological molecules and their biosynthetic origins are obscure. Detailed analyses of the surface lipids that accumulate on maize silks have revealed that these hydrocarbons constitute a large portion (>90%) of the cuticular waxes that coat this organ, which contrasts with the situation on maize seedling leaves, where the cuticular waxes are primary alcohols and aldehydes. The normal hydrocarbons that occur on silks are part of a homologous series of alkanes, alkenes and dienes of odd-number carbon atoms, ranging between 19 and 33 in number. The alkenes and dienes consist of a homologous series, each of which has double bonds situated at defined positions of the alkyl chains: alkenes have double bonds situated at the sixth, ninth or 12th positions, and dienes have double bonds situated at the sixth and ninth, or ninth and twelfth positions. Finding a homologous series of unsaturated aldehydes and fatty acids suggests that these alkenes and dienes are biosynthesized by a series of parallel pathways of fatty-acid elongation and desaturation reactions, which are followed by sequential reduction and decarbonylation. In addition, the silk cuticular waxes contain metabolically related unsaturated long-chain methylketones, which probably arise via a decarboxylation mechanism. Finally, metabolite profiling analyses of the cuticular waxes of two maize inbred lines (B73 and Mo17), and their genetic hybrids, have provided insights into the genetic control network of these biosynthetic pathways, and that the genetic regulation of these pathways display best-parent heterotic effects.

Human blood mononuclear cell in vitro cytokine response before and after two different strenuous exercise bouts in the presence of bloodroot and Echinacea extracts.

The purpose of this multidisciplinary investigation was to characterize cytokine production by human blood mononuclear cells after 2 contrasting exercise bouts (a maximal graded oxygen consumption [VO(2)max] test and 90 min of cycling at 85% of ventilatory threshold [VT]) when stimulated in vitro with extracts from bloodroot (Sanguinaria canadensis), coneflower (Echinacea tennesseensis), or solvent vehicle controls. Blood was sampled pre- and post-exercise. Production of TNF, IL-1beta, and IL-10 were measured at 24, 48, and 72 h, respectively. In the VO(2)max test there was a main effect of exercise such that exercise increased cytokine synthesis and a main effect of stimulant such that bloodroot extracts significantly increased cytokine production compared to other stimulants or controls. In the 90-min bout, there was a main effect of exercise for TNF and IL-1beta (but not IL-10) such that exercise decreased cytokine synthesis and a main effect of stimulant such that bloodroot extracts significantly increased cytokine production compared to other stimulants or controls, with exercisexstimulant interactions for both IL-1beta and IL-10. A similar though weaker effect was seen with Echinacea extracts; subsequent biochemical analyses suggested this was related to alkamide decay during 3 years undisturbed storage at ultralow (-80 degrees C) temperature. In this study, the VO(2)max test was associated with enhanced cytokine production whereas the 90-min cycling at 85% VT was associated with suppressed cytokine production. Bloodroot extracts were able to increase cytokine production in both contexts. Herbal extracts purported to offset exercise-associated effects on immune activity warrant continued investigation.

A Role for GIBBERELLIN 2-OXIDASE6 and Gibberellins in Regulating Nectar Production

The regulation of nectar production is dependent on hormonal signaling. For example, Arabidopsis PIN6, which encodes an auxin efflux transporter family protein, was identified as a nectary-enriched gene whose expression level was positively correlated to total nectar production (Bender et al., 2013). Furthermore, jasmonic acid (JA) levels peak in Brassica flowers just prior to anthesis and promote nectar secretion (Radhika et al., 2010). While auxin and JA have been demonstrated to play roles in the regulation of nectar production, it is unclear about the impacts other phytohormones have on this process.

Rhodium amine complexes tethered on silica-supported gold–palladium bimetal catalysts. Arene hydrogenation

Abstract Arene hydrogenation activities of catalysts prepared by tethering Rh(COD)[H2NCH2CH2NHCH2CH2CH2Si(OCH3)3](X) on the silica support of the bimetal catalyst Au:Pd–SiO2 were studied under the mild conditions of 40°C and 1 atm H2 pressure. The most active catalyst PF6–Rh(N–N)/Au:Pd–SiO2, with the weakly coordinating PF6− anion, remains highly active for toluene hydrogenation through at least three catalytic cycles involving 2900 mol H2/mol Rh turnovers over a 19-h period. As compared with the activity of the Pd-supported catalyst PF6–Rh(N–N)/Pd–SiO2, the catalysts with added Au are less active only by a factor of two. But the activity depends strongly on the Pd and Rh complex loadings. Although the detailed functioning of these TCSM catalysts (tethered complex on a supported metal) is not known, a mechanism that is consistent with the results involves dissociative adsorption of H2 on the supported Pd. The hydrogen spills over onto the silica surface where the Rh complex uses it to hydrogenate the arene substrate.

Phytochemical and Immunomodulatory Properties of an Echinacea laevigata (Asteraceae) Tincture

BACKGROUND Echinacea preparations are consumed for the prevention or treatment of upper respiratory infections. OBJECTIVE The objective of this study was to provide the first data regarding the in vitro immunomodulatory properties of the American federally endangered species Echinacea laevigata (Asteraceae). METHODS Human peripheral blood mononuclear cells were cultured with root tinctures from E. laevigata, E. angustifolia, E. pallida, and E. purpurea. Cytokine production (tumor necrosis factor [TNF], interleukin [IL]-2, IL-10) and mononuclear cell proliferation were measured. High-performance liquid chromatography was used to assay levels of known bioactive compounds from all extracts tested to statistically determine whether there were relationships between extract phytochemical content and observed immune effects. RESULTS E. laevigata extract was most similar to E. pallida extract and able to augment IL-10 and mononuclear cell proliferation, but not TNF or IL-2. Echinacoside, a caffeic acid derivative, correlated most strongly with results. CONCLUSIONS This species may deserve continued investigation in both experimental and therapeutic contexts.