Aspects Of Biosynthesis Research Articles

Occurrence of taraxerol and taraxasterol in medicinal plants.

Indian soil germinates thousands of medicinal drugs that are cultivated with a purpose to obtain a novel drug. As it is a well-established fact that the structural analogs with greater pharmacological activity and fewer side-effects may be generated by the molecular modification of the functional groups of such lead compounds. This review throws light on two natural triterpenes - Taraxerol and Taraxasterol which have many important pharmacological actions including anti-cancer activity, their chemistry, biosynthesis aspects, and possible use of these compounds as drugs in treatment of cancer. A silent crisis persists in cancer treatment in developing countries, and it is intensifying every year. Although at least 50-60% of cancer victims can benefit from radiotherapy that destroys cancerous tumors, but search for the paramount therapy which will prove to be inexpensive with minimal side effects still persists. Various treatment modalities have been prescribed, along with conventional and non-conventional medicine but due to their adverse effects and dissatisfaction among users, these treatments are not satisfactory enough to give relief to patients. Hence, this review sparks the occurrence of Taraxerol (VI) and Taraxasterol (VII) in nature, so that the natural godowns may be harvested to obtain these potent compounds for novel drug development as well as discusses limitations of these lead compounds progressing clinical trials.

Cell wall O-glycoproteins and N-glycoproteins: aspects of biosynthesis and function.

Cell wall O-glycoproteins and N-glycoproteins are two types of glycomolecules whose glycans are structurally complex. They are both assembled and modified within the endomembrane system, i.e., the endoplasmic reticulum (ER) and the Golgi apparatus, before their transport to their final locations within or outside the cell. In contrast to extensins (EXTs), the O-glycan chains of arabinogalactan proteins (AGPs) are highly heterogeneous consisting mostly of (i) a short oligo-arabinoside chain of three to four residues, and (ii) a larger β-1,3-linked galactan backbone with β-1,6-linked side chains containing galactose, arabinose and, often, fucose, rhamnose, or glucuronic acid. The fine structure of arabinogalactan chains varies between, and within plant species, and is important for the functional activities of the glycoproteins. With regards to N-glycans, ER-synthesizing events are highly conserved in all eukaryotes studied so far since they are essential for efficient protein folding. In contrast, evolutionary adaptation of N-glycan processing in the Golgi apparatus has given rise to a variety of organism-specific complex structures. Therefore, plant complex-type N-glycans contain specific glyco-epitopes such as core β,2-xylose, core α1,3-fucose residues, and Lewisa substitutions on the terminal position of the antenna. Like O-glycans, N-glycans of proteins are essential for their stability and function. Mutants affected in the glycan metabolic pathways have provided valuable information on the role of N-/O-glycoproteins in the control of growth, morphogenesis and adaptation to biotic and abiotic stresses. With regards to O-glycoproteins, only EXTs and AGPs are considered herein. The biosynthesis of these glycoproteins and functional aspects are presented and discussed in this review.

Flavonoids in Selected Primula Spp.: Bridging Micromorphology with Chemodiversity

A combined study was carried out on the micromorphology and chemistry of glandular trichomes with focus on Primula vialii and P. vulgaris, respectively. Epifluorescence microscopy was applied to study the auto-fluorescent properties of flavonoids and their localization in glandular trichomes. Both species differed in the morphology of the glandular trichomes and in the exudate flavonoid composition. Leaf glands from P. vialii and from some species of subgen. Primula exhibited uniform glandular fluorescence, but notable differentiation was observed within a single leaf of P. vulgaris. Our observations indicate that exudate flavonoids are not transported from the tissue to the glandular hairs. Conversely, only the newly isolated glycoside 1 (kaempferol 3-O-(2"'-rhamnosyl)-robinobioside) was obtained from leaf tissue of P. vialii after removal of the exudate. Its structure was confirmed by NMR and mass spectrometry. This glycoside was not detected in tissue extracts of P. vulgaris after similar treatment. The observed chemical diversity is discussed, with focus on possible correlation with glandular structures and tissue differentiation in Primula, and also against other studied species. Aspects of biosynthesis in relation to tissue-specific flavonoid diversification are shortly addressed.

Editorial: Structural Aspects of Biosynthesis themed issue

Editorial: Structural Aspects of Biosynthesis themed issue

Galactofuranose in eukaryotes: aspects of biosynthesis and functional impact

Galactofuranose (Galf) is the five-membered ring form of galactose. It is widely distributed among several branches of the eukaryotic kingdom. This review highlights recent advances in our understanding of the biosynthesis and function of Galf-containing glycoconjugates in fungal Aspergillus spp. and the protozoan trypanosomatid parasites. We give an overview of the biosynthetic pathways leading to the production of glycolipids, glycoproteins and polysaccharides containing Galf in these species and their biological relevance. Remarkably, modification of the cell surface caused by Galf absence often results in morphological abnormalities and an impaired cell wall function in these organisms. Galf-deficient mutants are generally hypersensitive to drugs, exhibit a constitutive osmotic stress phenotype and/or have an attenuated virulence. Since Galf has never been found in mammals and higher plants, Galf-biosynthetic pathways have raised much interest as targets for drug development to combat microbial infections.

New aspects of biosynthesis and metabolism of N-acyldopamines in rat tissues

Possible biosynthetic pathways of N-acyldopamines in rat tissues were compared. It was shown that an insignificant amount of the conjugation products was formed during the incubation of arachidonic acid and dopamine, whereas the substitution of tyrosine for dopamine resulted in the productive biosynthesis of N-arachidonoyldopamine. The biosynthesis presumably involves several closely conjugated enzymatic stages, and free fatty acids rather than their CoA esters served as the starting substrates. The decarboxylation stage probably precedes the stage of catechol system formation, because N-acetyltyramine (a probable intermediate) was easily oxidized by monophenol monooxygenase to N-acyldopamine, whereas N-acyltyrosine is hydrolyzed under these conditions. Biosynthesis of N-acyldopamines in a cell-free medium was accompanied by their methylation. The possibility of oxidative metabolism of N-acyldopamines, which could serve as co-substrates or inhibitors of different oxidoreductases, was shown for the first time.

5-Deoxynevadensin, a Novel Flavone in Sunflower and Aspects of Biosynthesis during Trichome Development

Fluorescent microscopy of sunflower glandular trichomes from anther appendages showed a strong autofluorescence, caused by flavonoids. Chemical analysis with NMR and HRMS lead to the identification of 7-hydroxy-6,8,4′-trimethoxyflavone, a novel 5-deoxyflavone, exclusively found in capitate glandular trichomes. 5-Deoxy flavones are rarely found in Asteraceae and this is the first report for the genus Helianthus. Semiquantitative RT-PCR showed the presence of transcripts for phenylalanine ammonia lyase (PAL) and chalcone synthase (CHS) in all biosynthetically active trichome stages. PAL and CHS are key steps in flavonoid biosynthesis indicating that flavonoid production occurs directly within the trichomes. This offers the possibility for examination of 5-deoxyflavone biosynthesis within Asteraceae.

Diatom/Copepod Interactions in Plankton: The Indirect Chemical Defense of Unicellular Algae

Numerous coexisting species can be observed in the open oceans. This includes the complex community of the plankton, which comprises all free floating organisms in the sea. Traditionally, nutrient limitation, competition, predation, and abiotic factors have been assumed to shape the community structure in this environment. Only in recent years has the idea arisen that chemical signals and chemical defense can influence species interactions in the plankton as well. Key players at the base of the marine food web are diatoms (unicellular algae with silicified cell walls) and their main predators, the herbivorous copepods. It was assumed that diatoms represent a generally good food source for the grazers but recent work indicates that some species use chemical defenses. Secondary metabolites, released by these algae immediately after wounding, are targeted not against the predators themselves but rather at interfering with their reproductive success. This strategy allows diatoms to reduce the grazer population, thereby influencing the marine food web. This review addresses the chemical ecology of the defensive oxylipins formed by diatoms and the question of how these metabolites can act in such a dilute environment. Aspects of biosynthesis, bioassays, and the possible implications of such a chemical defense for the plankton community structure are also discussed.

Harrewijn P., van Oosten A.M., Piron P.G.M. Natural terpenoids as messengers. A multidisciplinary study of their production, biological functions and practical applications.

Harrewijn P., van Oosten A.M., Piron P.G.M. Natural terpenoids as messengers. A multidisciplinary study of their production, biological functions and practical applications.

Mechanistic aspects of biosynthesis of 12-oxo-10,15(Z)-phytodienoic acid and related oxylipins: effect of pH on cyclization of the oxides of allene (18:3 and 18:2).

Mechanistic aspects of biosynthesis of 12-oxo-10,15(Z)-phytodienoic acid and related oxylipins: effect of pH on cyclization of the oxides of allene (18:3 and 18:2).

An Introduction to the Biosynthesis of Chemicals Used in Plant-Microbe Communication.

Plants accumulate a diverse array of natural products, which can serve either to defend the plant against various microbes in its environment or to attract various microbes, both beneficial and pathogenic. Plants must also attract pollinators, repel or poison herbivores, compete with other plant species, and protect themselves from environmental dangers such as high light intensities. Some compounds have been implicated in playing a role in multiple interactions. Although the structures vary immensely in size and complexity, most are derived from a limited number of core biosynthetic pathways. This review briefly summarizes the biosynthetic origins of phenylpropanoid (including simple phenolics, flavonoids, anthocyanins and isoflavonoids), polyacetate, terpenoid, and alkaloid classes of metabolites. Compounds reported to be important in plant-microbe, plant-animal, and plant-plant interactions will be given as examples of each of these classes. Other aspects of biosynthesis also will be discussed, including the timing or location of biosynthesis, the potential for genetic manipulation of these pathways, and various questions regarding the biosynthesis of these compounds.

Infraspecific Variation and Alkaloids of Papaver Species

Many species of PAPAVER exist as chemical races and, in order to illustrate this fact, examples have been chosen from the sections Miltantha and Oxytona. Future work on the alkaloids of PAPAVER species, including the possibility of novel compounds, aspects of biosynthesis and plant cell culture, are briefly discussed.

Immobilised plant cells: General aspects

AbstractThe immobilisation of plant cells grown in suspension cultures by entrapment in various gels is described. The viability and biosynthetic capacity of such immobilised cells have been investigated. Model studies covering different aspects of biosynthesis, i.e. biotransformation, synthesis from added precursors and synthesis de novo from a simple carbon source, are described. In some model studies it has been observed that the immobilised cells can produce higher amounts of secondary products than freely suspended cells under the same conditions. Furthermore the permeabilisation of plant cells for continuous release of formed products with subsequent immobilisation is also discussed.

Carotenoids—Aspects of Biosynthesis and Enzymology

Carotenoids—Aspects of Biosynthesis and Enzymology

Lantibiotics: A Candidate for Future Generation of Antibiotics

Emergence of multi-resistant pathogens has urged the exploration of antibiotic repertoires. The long reliability on the glycopeptide antibiotic vancomycin against fatal diseases caused by Gram-positive bacteria is also in wrecked to insist on finding more promising alternative antibiotics. The peptide antibiotic nisin is effective against vancomycin resistant bacteria. Nisin is the first lantibiotic that was discovered before penicillin and has been widely used as a safe alternative for chemical reagents in food preservation in around 50 countries for over 40 years without natural resistance development. Therefore, lantibiotics are one of the most promising alternative candidate for future antibiotics that maintain their antibacterial efficacy by many modes of action. Till now, more than 60 lantibiotics have been isolated, identified and characterized. We explained various aspects of biosynthesis, grouping, mutagenesis, activities and modes of action of lantibiotics in this review. DOI: http://dx.doi.org/10.3329/sjm.v1i1.9096 Stamford Journal of Microbiology, Vol.1(1), July 2011, p.1-12

Aspects of Synthesis and Order in Growth

This book, a collection of papers delivered at a recent symposium of the Society for the Study of Development and Growth held at Dartmouth, does not present the subject in the classical pediatric manner. Rather, it is a consideration of the problems of growth and differentiation first at the molecular level and later from the standpoints of enzyme function, genetic action, and the more fundamental aspects of biosynthesis and growth determinants. The biologist and the botanist have been quick to take up the newer tools of immunochemistry, tracer techniques and enzyme chemistry in an attempt to further elucidate the problems of growth and development at the cellular level.