Calothrix cyanobacteria

In 1999, Rickards et al. reported the isolation of calothrixins A (377) and B (378) from photoautrophic cultures of Calothrix cyanobacteria (345). These two, novel, pentacyclic carbazole alkaloids contain a quinolino[4,3-fc]carbazole-l,4-quinone framework. Calothrixins A and B inhibit the growth of a chloroquin-resistant strain of the malaria parasite P. falciparum and human HeLa cancer cells (345). 

The main framework is made up of five key modules for chemical library editing, enumeration, conversion, visualization, and analysis. The operations of these functionalities are accomplished by the various applications at the resource layer. For the purpose of illustration, the compound calothrixin B, a secondary metabolite isolated from the Calothrix cyanobacteria (11-13), is used as the scaffold molecule with the variable functional groups Rw] attached (Fig. 18.1). The calothrixins are redox-active natural products which display potent antimalarial and anticancer properties and thus there is interest in probing the physical as well as biological profiles of their derivatives (14). In this exercise, six functional groups have been selected as the building blocks (Table 18.1). 

Rickards, R. W., Rothschild, J. M., Willis, A. C., de Chazal, N. M., Kirk, J., Kirk, K., Sal-iba, K. J., Smith, G. D. (1999) Calothrixins A and B, novel pentacyclic metabolites from Calothrix Cyanobacteria with potent activity against malaria parasites and human cancer cells. Tetrahedron Lett 55, 13513-13520. 

Photic zone I Cyanobacteria E Endosymbiont/ diatom Calothrix rhizosoleniae Janson et al., 1999a,b Foster and Zehr, 2006... 

Most heterocystous cyanobacteria dominate brackish and freshwater environments where they occur in the plankton and the benthos as free-Hving cells and are seldom found in the open ocean. Few report Richelia and Calothrix as free-living (Gomez et al., 2005 White et al., 2007), thus both are the exception and have made their successful transition to the open ocean as symbionts. 

Reports on the anti-influenza virus effects of extracts from marine algae from all over the world have been found in the literature [115]. These results show that the blue-green algae (cyanobacterium) are able to produce compounds with anti-influenza activity that may be of potential clinical interest. For example, aqueous and methanolic extracts of cultured cyanobacteria of several genera. Microcystis, Nodularia, Oscillatoria, Scytonema, Lyngbya and Calothrix were evaluated for their in vitro antiviral activity against the influenza A virus in Madin Darby kidney cells [116,117]. The further analysis of methanolic extracts of cultured strains of genus Microcystis revealed a remarkable antiviral... 

Calothrix is a genus of cyanobacteria that produces what is known as the black zone, a line of black, tarlike blobs, in the high intertidal zone. Each globule is a colony of cyanobacterial cells. These colonies can endure extended periods without water because they are contained in gel-like sheaths that keep them moist. Calothrix also grows like a crust on rocks and on other types of algae in many intertidal regions. 

Fig. 4.8. Characteristic cyanobacteria 1 — Chroococcus, 2 — Aphanothece, 3 — Chamaeaiphon, 4 — Oscillatoria, 5 — Spirulina, 6 — Lyngbya, 7 — Anabaena, 8 — Cylindrospermum, 9 — Calothrix, 10 — Tolypothrix, 11 — Richelia inside a cell of the diatom Rhizosolenia (modified from ref. [13])...

The aggregation of cells and filaments often yields macroscopic colonies which lie on lake sediments, float freely in the water, rest on soil or form blackish clusters on rock faces. Colonies of Calothrix (Fig. 4.8) often form a conspicuous zone on rocks in the upper inter-tidal zone, in some areas associated with other cyanobacteria which actively bore into the rock. 

Weckesser, J., Hofmann, K., Jurgens, U.J., Whitton, B.A. and Raffelsberger, B. (1988) Isolation and chemical analysis of sheath from the filamentous cyanobacteria Calothrix parietina and C. scopulorum. Journal of General Microbiology 134, 529-634. 

About 30 brominated derivatives have been identified in marine cyanobacteria. In each of these cases, bromine atoms are fixed on a benzene nucleus, a bis-indolic system, or on a linear chain, but always in the vinylic position. The two simplest compounds are lanosol and 3,5-dibromo-p-hydroxybenzylic alcohol, both isolated from the species Calothrix brevissima (Pedersen and Da Silva, 1973). 

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