Identification of fromiamycalin and halaminol A from Australian marine sponge extracts with anthelmintic activity against haemonchus contortus
- Herath, Dilrukshi, Preston, Sarah, Jabbar, Abdul, Garcia-Bustos, Jose, Taki, Aya, Addison, Russell, Hayes, Sasha, Beattie, Karren, McGee, Sean, Martin, Sheree, Ekin, Merrick, Hooper, John, Chang, Bill, Hofmann, Andreas, Davis, Rohan, Gasser, Robin
- Authors: Herath, Dilrukshi , Preston, Sarah , Jabbar, Abdul , Garcia-Bustos, Jose , Taki, Aya , Addison, Russell , Hayes, Sasha , Beattie, Karren , McGee, Sean , Martin, Sheree , Ekin, Merrick , Hooper, John , Chang, Bill , Hofmann, Andreas , Davis, Rohan , Gasser, Robin
- Date: 2019
- Type: Text , Journal article
- Relation: Marine Drugs Vol. 17, no. 11 (Nov 2019), p. 14
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- Description: There is an urgent need to discover and develop new anthelmintics for the treatment of parasitic nematodes of veterinary importance to circumvent challenges linked to drug resistant parasites. Being one of the most diverse natural ecosystems, the marine environment represents a rich resource of novel chemical entities. This study investigated 2000 extracts from marine invertebrates, collected from Australian waters, for anthelmintic activity. Using a well-established in vitro bioassay, these extracts were screened for nematocidal activity against Haemonchus contortus - a socioeconomically important parasitic nematode of livestock animals. Extracts (designated Mu-1, Ha-1 and Ha-2) from two marine sponges (Monanchora unguiculata and Haliclona sp.) each significantly affected larvae of H. contortus. Individual extracts displayed a dose-dependent inhibition of both the motility of exsheathed third-stage larvae (xL3s) and the development of xL3s to fourth-stage larvae (L4s). Active fractions in each of the three extracts were identified using bioassay-guided fractionation. From the active fractions from Monanchora unguiculata, a known pentacyclic guanidine alkaloid, fromiamycalin (1), was purified. This alkaloid was shown to be a moderately potent inhibitor of L4 development (half-maximum inhibitory concentration (IC50) = 26.6 +/- 0.74 mu M) and L4 motility (IC50 = 39.4 +/- 4.83 mu M), although it had a relatively low potency at inhibiting of xL3 motility (IC50 >= 100 mu M). Investigation of the active fractions from the two Haliclona collections led to identification of a mixture of amino alcohol lipids, and, subsequently, a known natural product halaminol A (5). Anthelmintic profiling showed that 5 had limited potency at inhibiting larval development and motility. These data indicate that fromiamycalin, other related pentacyclic guanidine alkaloids and/or halaminols could have potential as anthelmintics following future medicinal chemistry efforts.
- Authors: Herath, Dilrukshi , Preston, Sarah , Jabbar, Abdul , Garcia-Bustos, Jose , Taki, Aya , Addison, Russell , Hayes, Sasha , Beattie, Karren , McGee, Sean , Martin, Sheree , Ekin, Merrick , Hooper, John , Chang, Bill , Hofmann, Andreas , Davis, Rohan , Gasser, Robin
- Date: 2019
- Type: Text , Journal article
- Relation: Marine Drugs Vol. 17, no. 11 (Nov 2019), p. 14
- Full Text:
- Reviewed:
- Description: There is an urgent need to discover and develop new anthelmintics for the treatment of parasitic nematodes of veterinary importance to circumvent challenges linked to drug resistant parasites. Being one of the most diverse natural ecosystems, the marine environment represents a rich resource of novel chemical entities. This study investigated 2000 extracts from marine invertebrates, collected from Australian waters, for anthelmintic activity. Using a well-established in vitro bioassay, these extracts were screened for nematocidal activity against Haemonchus contortus - a socioeconomically important parasitic nematode of livestock animals. Extracts (designated Mu-1, Ha-1 and Ha-2) from two marine sponges (Monanchora unguiculata and Haliclona sp.) each significantly affected larvae of H. contortus. Individual extracts displayed a dose-dependent inhibition of both the motility of exsheathed third-stage larvae (xL3s) and the development of xL3s to fourth-stage larvae (L4s). Active fractions in each of the three extracts were identified using bioassay-guided fractionation. From the active fractions from Monanchora unguiculata, a known pentacyclic guanidine alkaloid, fromiamycalin (1), was purified. This alkaloid was shown to be a moderately potent inhibitor of L4 development (half-maximum inhibitory concentration (IC50) = 26.6 +/- 0.74 mu M) and L4 motility (IC50 = 39.4 +/- 4.83 mu M), although it had a relatively low potency at inhibiting of xL3 motility (IC50 >= 100 mu M). Investigation of the active fractions from the two Haliclona collections led to identification of a mixture of amino alcohol lipids, and, subsequently, a known natural product halaminol A (5). Anthelmintic profiling showed that 5 had limited potency at inhibiting larval development and motility. These data indicate that fromiamycalin, other related pentacyclic guanidine alkaloids and/or halaminols could have potential as anthelmintics following future medicinal chemistry efforts.
1-Methyl-1 H-pyrazole-5-carboxamide derivatives exhibit unexpected acute mammalian toxicity
- Preston, Sarah, Garcia-Bustos, Jose, Hall, Liam, Martin, Sheree, Le, Thuy
- Authors: Preston, Sarah , Garcia-Bustos, Jose , Hall, Liam , Martin, Sheree , Le, Thuy
- Date: 2021
- Type: Text , Journal article
- Relation: Journal of Medicinal Chemistry Vol. 64, no. 1 (2021), p. 840-844
- Full Text: false
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- Description: A series of 1-methyl-1H-pyrazole-5-carboxamides were synthesized as potent inhibitors of the parasitic nematode of sheep, Haemonchus contortus. These compounds did not show overt cytotoxicity to a range of mammalian cell lines under standard in vitro culture conditions, had high selectivity indices, and were progressed to an acute toxicity study in a rodent model. Strikingly, acute toxicity was observed in mice. Experiments measuring cellular respiration showed a dose-dependent inhibition of mitochondrial respiration. Under these conditions, potent cytotoxicity was observed for these compounds in rat hepatocytes suggesting that the potent acute mammalian toxicity of this chemotype is most likely associated with respiratory inhibition. In contrast, parasite toxicity was not correlated to acute toxicity or cytotoxicity in respiring cells. This paper highlights the importance of identifying an appropriate in vitro predictor of in vivo toxicity early on in the drug discovery pipeline, in particular assessment for in vitro mitochondrial toxicity. © 2020 American Chemical Society. *Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “Sarah Preston” is provided in this record**
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