Dimeric cyanobacterial cyclopent-4-ene-1,3-dione as selective inhibitor of Gram-positive bacteria growth: Bio-production approach and preparative isolation by HPCCC

Cyanobacteria as Valuable Tool in Biotechnology

Cyanobacteria constitute an interesting group of photosynthetic microorganisms due to their morphological and genetic diversity that is related to their extremely long evolution process, which created the need for them to adapt to immensely heterogeneous environmental conditions. Cyanobacteria grow in salt and fresh waters as well as on the surface of soils and rocks. The diverse cell structure is characterized by the fact that they occur in many morphological forms, from small single cells through to larger ones as well as branches, threads, or spirals. Taking into account the presence of cyanobacteria in virtually all possible conditions and places on Earth, cyanobacteria represent an unexplored potential that is worth investigating. This review presents the possibilities of using algae in chosen areas of biotechnology: e.g., as biocatalysts or in industries such as the pharmaceutical industry. It covers the characteristics of secondary metabolites along with their division and the potential of using them as sources of effective drugs for many diseases. It presents an overview of the possibilities of using cyanobacteria in biotransformation processes. These processes are of great importance in the case of, for example, the neutralization of municipal, industrial, or chemical waste, the amount of which is constantly growing every year, and they are also an easier and cheaper path to obtain chemical compounds.

Nostotrebin 6 Related Cyclopentenediones and δ-Lactones with Broad Activity Spectrum Isolated from the Cultivation Medium of the Cyanobacterium Nostoc sp. CBT1153

Cyanobacteria are an interesting source of biologically active natural products, especially chemically diverse and potent protease inhibitors. On our search for inhibitors of the trypanosomal cysteine protease rhodesain, we identified the homodimeric cyclopentenedione (CPD) nostotrebin 6 (1) and new related monomeric, dimeric, and higher oligomeric compounds as the active substances in the medium extract of Nostoc sp. CBT1153. The oligomeric compounds are composed of two core monomeric structures, a trisubstituted CPD or a trisubstituted unsaturated δ-lactone. Nostotrebin 6 thus far has been the only known cyanobacterial CPD. It has been found to be active in a broad variety of assays, indicating that it might be a pan-assay interference compound (PAIN). Thus, we compared the antibacterial and cytotoxic activities as well as the rhodesain inhibition of selected compounds. Because a compound with a δ-lactone instead of a CPD core structure was equally active as nostotrebin 6, the bioactivities of these compounds seem to be based on the phenolic substructures rather than the CPD moiety. While the dimers were roughly equally potent, the monomer displayed slightly weaker activity, suggesting that the compounds show unspecific activity depending upon the number of free phenolic hydroxy groups per molecule.