With all of life's diversity, however, there is a ubiquitous presence of carbon, oxygen, and hydrogen.
This article has been cited by other articles in PMC. Abstract Brown algae represent a major component of littoral and sublittoral zones in temperate and subtropical ecosystems. An essential adaptive feature of this independent eukaryotic lineage is the ability to couple oxidative reactions resulting from exposure to sunlight and air with the halogenations of various substrates, thereby addressing various biotic and abiotic stresses i.
Whereas marine organisms mainly make use of bromine to increase the biological activity of secondary metabolites, some orders of brown algae such as Laminariales have also developed a striking capability to accumulate and to use iodine in physiological adaptations to stress. We review selected aspects of the halogenated metabolism of macrophytic brown algae in the light of the most recent results, which point toward novel functions for iodide accumulation in kelps and the importance of bromination in cell wall modifications and adhesion properties of brown algal propagules.
The importance of halogen speciation processes ranges from microbiology to biogeochemistry, through enzymology, cellular biology and ecotoxicology. Introduction Most organisms seem to have the ability to produce organohalogens, and the reported chemodiversity of this class of compounds 3, in has jumped fold in the last 30 years [ 1 ].
Marine halocarbon producers encompass an extensive phyletic range, and sessile life forms algae and invertebrates use a rich repertoire of diffusible and mucus-bound molecules, many of which are halogenated, for communication in the largest sense.
Biogenic halogen chemistry is thought to have arisen in prokaryotes in response to the emergence of photosynthesis, the oxygen enrichment of the atmosphere by cyanobacteria in archean times some three billion years agoand in response to the cellular generation of toxic reactive oxygen species ROS originating from one i.
The call for efficient reducing biochemistries involved chlorine, bromine and iodine available in seawater, and the development of corresponding enzymatic machineries with haloperoxidases. Oxidative H2O2 detoxication strategies, e. Therefore, it is likely that the halogen chemistry of marine algae reflects an episode of their polyphyletic evolutionary history.
On one hand, the latter has involved a primary endosymbiosis the engulfing of a prokaryotic cyanobacterium by a heterotrophic host cellwhich lead to the emergence of the Plantae, the green lineage green algae and land plants and its sister group the red algae.
On the other hand, chromophytic algae evolved by an additional process termed secondary endosymbiosis [ 3 ] which includes the endosymbiotic uptake of a eukaryotic alga, presumably an ancestor of modern red algae.
Brown algae belong to the Stramenopile lineage, with marine representatives including the unicellular diatoms. While phylogenomic studies have recently validated the various lineages, the evolutionary relationships between the lineages remain partly unresolved [ 4 ].
Regarding halogen chemistry, iodination is more frequent and chlorination is less frequent in brown algae metabolites than in the red and green lineages.
In this review, we describe the specificity of the evolution of the halogen metabolism in brown algae, pointing towards the emergence of strict specificity for the oxidation of iodide in the most evolved orders of Phaeophyceae, such as the Laminariales, and, consequently, the emergence of novel physiological adaptations with their ecological and atmospheric significance.
Halogenated Metabolites of Brown Algae More than 1, metabolites have been reported in the Phaeophyceae in [ 6 ], out of about 3, from the three macroalgal lineages and of a total of about 15, marine molecules [ 7 ].
However, in contrast to red algae, i the number of novel structures in brown algae decreases every year [ 8 ], ii surprisingly few brown algal metabolites are halogenated, yet as end products or as potential intermediates, they are involved in a wide range of primary and secondary functions, some of which are not completely established and iii no specific pharmacological use has been found for brown algal halogenated metabolites.
We will consider the various classes of halogenated metabolites found in brown algae with considerations of their biosynthetic origin where applicable Table 1.
Table 1 Halogenated compounds from brown macrophytic algae reported in the literature.Organic compounds in the cell include carbohydrates, protein, lipids and nuclei acids. Some of these compounds are synthesised by the cell itself. Water is an inorganic compound which is composed of hydrogen and oxygen.
Adenosine triphosphate (ATP), a nucleotide composed of adenine, ribose, and three phosphate groups, is perhaps the most important of the so-called energy-rich compounds in a cell. Its concentration in the cell varies from to mg/mL of cell fluid. Introduction “Introduction to biological chemistry” is an integrated topic that combines the organic chemistry of atoms and molecules with the biological roles that molecules play in our everyday lives.
This organic chemistry course note focuses on the methods used to identify the structure of organic molecules, advanced principles of organic stereochemistry, organic reaction mechanisms, and methods used for the synthesis of organic compounds. Organic Chemistry With a Biological Emphasis i Tim Soderberg Table of Contents Volume I: Chapters Introduction Chapter 1: Introduction to organic structure and bonding I.
Biological activities importance of Tetrazole derivatives JALAL HASAN MOHAMMED INTRODUCTION Tetrazole are class of synthetic organic heterocyclic compounds consisting of five-member ring of four nitrogen and one carbon atom (plus hydrogen).