Recent Developments in the Field of Marine Natural Products with Emphasis on Biologically Active Compounds

Cyclic peptide marine metabolites and CuII

“…During her PhD she studied the influence of the stereochemistry and incorporated heterocycles on the Cu II table from L. patella and L. bistratum have attracted scientific interest for more than two decades, as they provide a wide range of cyclic peptides, based on unusual amino acids and with unusual structures and properties. [8][9][10][11][12][13][14][15][16]19 Ascidians harbor an obligate symbiont, Prochloron sp., which, it is thought, might produce the cyclic peptides. 20,21 Through photosynthesis, Prochloron is an extremely important nutrient for their hosts.…”

“…CO 2 hydration (carbonic anhydrase activity), 23,34,43,56,57,90,93,94 and phosphoester hydrolysis ( phosphatase activity) 88 have recently been proposed as possible biological functions, and this will be discussed in detail below. Due to the known cytotoxic, antibacterial, antineoplastic and antiviral activities of the metal-free cyclic pseudo-peptides, medicinal and pharmaceutical applications have been studied extensively 13,17,18,44,95,96 and still are a driving force for cyclic peptide chemistry. The cyclic pseudo-peptides' use as macrocyclic ligands in transition metal coordination chemistry has been another focus of Lissoclinum-derived cyclic peptides, and small side-chain (iso-propyl); right: bulky side-chain (tert-butyl).…”

“…It was suggested that a change between various conformations is important to prevent product inhibition in a putative catalytic cycle, and that this depends on the configuration of the macrocycle side-chains and the flexibility of the heterocycles (oxazoline vs. imidazole); this was confirmed by preliminary molecular dynamics and Monte-Carlo simulations. 57 Based on 13 Carbonic anhydrase kinetics are complicated by the fact that a gas is transformed to an ionisable compound, that the solubilities of the species involved in various equilibria strongly depend on solvent, temperature, pressure and pH value, and that all relevant species are colorless (see Scheme 6). Generally, carbonic anhydrase kinetics are measured by stopped-flow techniques, where the time dependence of the color change of a pH indicator is followed, using matched pairs of bases (to capture the protons released from H 2 CO 3 , see Scheme 6) and indicators.…”

Marine Natural Products and Their Potential Application in the Future

“…In the other researches, Kazilauskas et al isolated a new antibacterial alkaloid named N-metylat amide. However, this compound was later found to be too toxic for use [37]. Two new antimicrobial agents have been isolated from red alga, Laurencia elata and L. obtusa.…”

Marine products as a source of antiviral drug leads

“…Consequently, a large number of novel chemical structures have been discovered from aquatic animals, plants, and microbes [for reviews, see Scheuer, 1978Scheuer, -1983Okuda et al, 1982;Faulkner, 1984aFaulkner, ,b, 1986Faulkner, , 1987. Attention to pharmacologically active substances from marine flora and fauna was first drawn by Emerson and Taft (1945), and subsequently many marine products were found to have interesting pharmacological actions [for reviews, see Nigrelli et al, 1967;Burkholder and Sharma, 1969;Der Marderosian, 1969;Ruggieri, 1976;Grant and Mackie, 1977;Kaul, 1981;Rinehart et al, 1981~;Harnden and Planterose, 1985;Braekman and Daloze, 1986;Cardellina, 1986;Kaul and Daftari, 1986;Krebs, 1986;Okami, 1986;Munro et al, 1987;Kitagawa, 1988;Scheuer, 19891. Although marine natural products have never been intensely studied for their antiviral properties, available literature data clearly indicate that a number of secondary metabolites from aquatic organisms display in vitro antiviral activities in bioassay systems. The present review summarizes these results, with the objective of demonstrating that aquatic organisms can provide an array of leads with diverse chemical structures that may have potential for being developed into antiviral drugs.…”