The Cylindrospermopsin Alkaloids Literature review

The Cylindrospermopsin Alkaloids - Literature review Example This review is initially focused on isolation of these natural products then moving on to environmental concerns regarding cylindrospermopsin alkaloids contamination before finally describing methods used in their synthesis (Murphy and Thomas, 2001) Figure one. The cylindrospermopsin alkaloids of cylindrospermopsin (1), 7-deoxy-cylindrospermopsin (2) and 7-epi-cylindrospermopsin (3). II. Isolation and Characterization Cylindrospermopsin (1), was extracted in 1992 from the cyanobacterium Cylindrospermopsis raciborskii and characterized by Moore and co-workers. The characterisation was done using a combination of NMR and mass spectroscopy. (Ohtani, Moore and Runnegar, 1992) In 1999 during routine purification of cylindrospermopsin using HPLC 7-deoxy-cylindrospermopsin (2) was discovered and characterised (Norris, et al., 1999). It was also believed that the newly discovered cylindrospermopsin derivative could exist in the form of two tautomers. The conclusion was drawn from the fact th at the vinylic proton of the uracil ring was not detected using 1H NMR technique (Figure two). However, the presence of the uracil group in (4) was proven by investigating the absorbance maximum (?max) that was observed for every sample of 7-deoxy-cylindrospermopsin (2). It was obvious that the natural material existed as a mixture of compounds but it was not possible to estimate the quantity of (2) (Looper, et al., 2005). Figure two. Proposed tautomeric forms of 7-deoxy-cylindrospermopsin (2). Discovered in 2000, 7-epi-cylindrospermopsin (3) initially was found to be synthesised by Aphanizomenon ovalisporum (Banker, et al., 2000). Taking into account the unusual tautomer enol existence of the uracil D ring, estimation of the relative stereochemistry of cylindrospermopsin (1) was made. The uracil D ring was intramolecularly hydrogen attached to a nitrogen terminus of the guanidine group as described in structure 6. The produced configuration was in correlation with the NMR evidence which led the research group to the structure 7 as the most likely description of cylindrospermopsin (1) (Figure three) (Heintzelman, et al., 2001). The correct stricture for cylindrospermopsin (1) and its epimer, 7-epi-cylindrospermopsin (2), were deduced by thinking about these alkaloids as uracil tautomers (Figure one). Figure three. Proposed structures of cylindrospermopsin (1) and 7-epi-cylindrospermopsin (3). III. Occurrence and Production of Cylindrospermopsin After the first isolation of cylindrospermopsin (1) from C. raciborskii in 1992 a number of cyanobacteria species have been found to produce cylindrospermopsin alkaloids in various quantities. These alkaloids were found in Asia, North and South America, Europe, South Pacific and Middle East. However, the leader is Australia. Most cyanobacterial species can be found on that continent. Therefore the concentration of cylindrospermopsin in that country is the highest. In connection with that, the outbreak of hepatoenteritis on Palm Island Australia is worth mentioning. The disease affected one hundred and forty eight people the majority of which were children (Prociv, 2004). It is presumed that treatment of algal blooms with copper sulfate caused the lysis of the cyanobacterial cells with further release of the toxins into the drinking water. The toxin was also found in Poland (Kokocinski, et al., 2009), however, the cyanobacteria responsible for its synthesis was not reported. There are cases where it was possible to isolate the toxin without detecting