2, 5, 6-Tribromo-l-methylgramine, an Antifouling Substance from the Marine Bryozoan <i>Zoobotryon pellucidum</i>

Abstract

In our screening for antifouling substances using laboratory-reared larvae of the barnacle Balanus amphitrite, the crude extract of the marine bryozoan Zoobotryon pellucidum exhibited promising activity . Bioassay-guided isolation led to the isolation of 2 ,5,6-tribromo-1-methylgramine as an effective inhibitor. I ts inhibitory activity was 6 times as strong as that of bis-(n-butyltin)oxide (TBTO) , while its toxicity to cyprid larvae was one-tenth that of TBTO . This substance also inhibited settlement of the blue mussel Mytilus edulis.

A settlement inhibition assay with cyprid larvae of the barnacle Balanus amphitrite

“…Settlement inhibition assays using barnacle cyprids similar to that described above, have been employed in the routine screening of synthetic and natural antifouling compounds [14,15,16]. The test is relatively simple and provides an assessment of the impact of a toxicant on one of the key life-stages of an ecologically important shore species that occurs world wide.…”

Anti-Biofouling Defence Mechanism of Basibionts (A Chemical Warfare) - A Critical Review

“…In response to this, a variety of chemical compounds are secreted by benthic invertebrates like soft corals, sea cucumbers, sponges to prevent surface fouling [22]. Some of these compounds prevent settlement much more effectively than organotin compounds and at the same time are far less toxic [23]. Chemical-based settlement inhibition against bacteria and other bio-foulers has been reported in sponges [24][25][26][27][28][29][30], Ascidians [24,31,32] and Cnidarians [30,[33][34][35][36] and Bryozoans [23,37].…”

Potent Attachment-inhibiting and -promoting Substances for the Blue Mussel,Mytilus edulis galloprovincialis, from Two Species ofEucalyptus

“…However, the activity cannot be solely assigned to the metal-chelating ability, because most of the 1,3-diketones such as 5 and 6, which have no hydrophobic side chains, can also act as metal-chelating agents. Complete absence of activity in the cases of acetyl acetone (5) and dipivaloylmethane (6) indicate that both the I ,3-diketone moiety and long chains on both sides of the fi-diketone are essential for this activity.…”

“…TBG was found to be active at a concentration of 0.037 IlmoI/cm2 (unit 1360), being the most active repellent known to date. 6 ) Grandinol (2), a germination inhibitor 7) present in E. grandis, also showed attachment-repelling activity at a concentration of 6.3llmolicm2 (unit 8), but was inactive at a concentration of 1.0 Ilmolicm2. It is noteworthy that grandinol, which is a monomeric phloroglucinol, was far less active than the dimeric phloroglucinol derivative, sideroxylonal A. Sideroxylonals can exist in four stereoisomeric forms.…”