Investigation of the chemistry and antiparasitic activity of metabolites from Tasmanian marine organisms
Creators: name: Narkowicz, Christian Karol
Publisher: name: University Of Tasmania
Year: 2023

description: More than 400 marine macroorganisms were collected from around the eastern and south eastern coasts of Tasmania. Organic extracts of these organisms were tested for activity against endo- and ecto-parasites of domestic animals. The incidence of high nematocidal activity was greatest for extracts of bryozoans (29%), a previously unrecognised source of nematocides. Ectoparasites were susceptible to about 10% of the extracts from each class of marine organism. The brown algae Sporochnus moorei and Perithalia caudata contained a nematocidal diprenylated phenol [3.8], LD99 50 jig/mi.-S. stylosus extract, lacking antiparasitic activity, contained a novel triprenylated phenol [3.13] and the related chromene [3.14]. A further triprenylated phenol [3.17] was detected. The brown alga Caulocystis cephalornithos contained 6-alkylsalicylic acids [3.19] - [3.23], known from other sources, which had nematocidal activity but could not account for the nematocidal activity of crude extracts. Labile precursors of the 6- alkylsalicylic acids were proposed as the major bioactive metabolites. The alga contained a unique profile of acetogenins which varied seasonally and between and within collection sites. The unreported enones [3.42] - [3.45] were present. Nematocidal and insecticidal activity of extracts from the red algae Jeannerettia lobata, Lophurella periclados and Polysiphonia nigrita was due to bromophenols. The most potent nematocide was 2,3,6-tribromo-4,5-dihydroxybenzyl alcohol [3.60], LD99 &lt;12.5 1.1g/ml. A Lissoclinum sp. ascidian contained varacin [4.1] and varacin A [4.2] which were lethal in the nematode assay via an indirect antibacterial action. The major pyridoacridines from the ascidian, shermilamine B [4.8], kuanoniarnine D [4.9] and stylesamine B [4.10] had modest nematocidal activity. Two novel pyridoacridines, proposed to be [4.11] and [4.12], were isolated from this ascidian. A Didemnum sp. ascidian contained three known [4.39] ‚ÄövÑvÆ [4.41] and one undescribed [4.42] aplysinopsins, not previously isolated from an ascidian, that were inactive in the antiparasitic assays. The extract of a Leptoclinides sp. ascidian had insecticidal and acaricidal activity. Glycosphingolipids [4.45], purines (including adenine) and nucleosides (including 2'-deoxyadenosine) present in the extract could not account for the antiparasitic activity. The bryozoan Amathia wilsoni contained the known amathamides A [5.1] and B [5.2] together with the closely related but not previously described (2S)-1-methyl-N[2-(2,4-dibromo-5-methoxyphenypethy1]-2-pyrrolidinecarboxamide [5.3]. Amathamide A had potent nematocidal activity (LD99 2.5 Kg/m1). Novel potent nematocides convolutamine H [5.5] and convolutindole A [5.6] were isolated from Amathia convoluta, with LD99 0.20 and 0.39 1.1g/m1 respectively. This bryozoan also contained a novel amathamide, proposed to exist as two amide rotamers [5.8a] and [5.8b], and a formamide of this amathamide [5.12]. A minor constituent was N-methyl-2[2,4-dibromo-5-methoxy]-ethanamine [5.10]. Nematocidal activity from a catenicellid bryozoan was associated with high levels of pavettine [5.73] and not with harman [5.70]. Homarine [5.79] from Ste ginoporella truncata lacked antiparasitic activity. A sponge contained the known nematocides, furodysin [6.2], furodysinin [6.3] and related metabolites [6.4] ‚ÄövÑvÆ [6.11], some of which are undescribed, as well as the putative precursor of these compounds, dehydrodendrolasin [6.1]. Halogenated furanosesquiterpenes were present as minor constituents.