Thoms Carsten, Ebel Rainer, Proksch Peter
Institut für Pharmazeutische Biologie, Universität Düsseldorf, Universitätsstrasse 1, Geb. 26.23, D-40225, Düsseldorf, Germany.
J Chem Ecol. 2006 Jan;32(1):97-123. doi: 10.1007/s10886-006-9355-x. Epub 2006 Feb 26.
Sponges of the genus Aplysina accumulate brominated isoxazoline alkaloids in concentrations that sometimes exceed 10% of their dry weight. We previously reported a decrease in concentrations of these compounds and a concomitant increase in concentrations of the monocyclic nitrogenous compounds aeroplysinin-1 and dienone in Aplysina aerophoba following injury of the sponge tissue. Further investigations indicated a wound-induced enzymatic cleavage of the former compounds into the latter, and demonstrated that these reactions also occur in other Aplysina sponges. A recent study on Caribbean Aplysina species, however, introduced doubt regarding the presence of a wound-induced bioconversion in sponges of this genus. This discrepancy motivated us to reinvestigate carefully the fate of brominated alkaloids in A. aerophoba and in other Aplysina sponges following mechanical injury. As a result of this study we conclude that (1) tissue damage induces a bioconversion of isoxazoline alkaloids into aeroplysinin-1 and dienone in Aplysina sponges, (2) this reaction is likely catalyzed by enzymes, and (3) it may be ecologically relevant as the bioconversion products possibly protect the wounded sponge tissue from invasion of bacterial pathogens.
艾氏海绵属的海绵积累溴化异恶唑啉生物碱的浓度有时超过其干重的10%。我们之前报道过，在海绵组织受到损伤后，艾氏嗜气海绵中这些化合物的浓度降低，同时单环含氮化合物气单胞菌素-1和二烯酮的浓度增加。进一步的研究表明，前者的化合物会因伤口诱导而酶解为后者，并且证明这些反应也发生在其他艾氏海绵中。然而，最近一项关于加勒比海艾氏海绵物种的研究对该属海绵中是否存在伤口诱导的生物转化提出了疑问。这种差异促使我们仔细重新研究机械损伤后艾氏嗜气海绵和其他艾氏海绵中溴化生物碱的去向。作为这项研究的结果，我们得出以下结论：（1）组织损伤会诱导艾氏海绵中的异恶唑啉生物碱生物转化为气单胞菌素-1和二烯酮；（2）该反应可能由酶催化；（3）它可能具有生态相关性，因为生物转化产物可能保护受伤的海绵组织免受细菌病原体的入侵。
