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Enhancing a search for traditional medicinal plants with anthelmintic action by using wild type and stress reporter Caenorhabditis elegans strains as screening tools

Kumarasingha R, Palombo EA, Bhave M, Yeo TC, Lim DS, Tu CL, et al.

Int J Parasitol, 2014 Apr;44(5):291-8.
PMID: 24583111 DOI: 10.1016/j.ijpara.2014.01.008

Traditional healers in Sarawak, Malaysia, use plants such as Picria fel-terrae, Linariantha bicolor and Lansium domesticum to treat gastrointestinal infections. This study aimed to test whether their nematocidal activities could be confirmed in vitro using highly standardised Caenorhabditis elegans models. We applied eight different ethanol solubilised plant extracts and two commercial anthelmintic drugs to larval and adult stages of C. elegans in vitro. Seven C. elegans strains were evaluated, one wild type and six strains with GFP-tagged stress response pathways to help characterise and compare the pathways affected by plant extracts. Our in vitro screen confirmed that both of the commercial anthelmintic drugs and five of the eight traditionally used plant extracts had significant nematocidal activity against both larval and adult C. elegans. The most effective extracts were from P. fel-terrae. The plant extracts triggered different stress response pathways from the commercial anthelmintic drugs. This study showed that using traditional knowledge of plant medicinal properties in combination with a C. elegans in vitro screen provided a rapid and economical test with a high hit rate compared with the random screening of plants for nematocidal activities. The use of transgenic C. elegans strains may allow this approach to be refined further to investigate the mode of action of active extracts.
Fulltext Anthelmintic activity of selected ethno-medicinal plant extracts on parasitic stages of Haemonchus contortus

Kumarasingha R, Preston S, Yeo TC, Lim DS, Tu CL, Palombo EA, et al.

Parasit Vectors, 2016;9(1):187.
PMID: 27036205 DOI: 10.1186/s13071-016-1458-9

Parasitic roundworms (nematodes) cause substantial morbidity and mortality in livestock animals globally, and considerable productivity losses to farmers. The control of these nematodes has relied largely on the use of a limited number of anthelmintics. However, resistance to many of these these anthelmintics is now widespread, and, therefore, there is a need to find new drugs to ensure sustained and effective treatment and control into the future.
Fulltext Transcriptional alterations in Caenorhabditis elegans following exposure to an anthelmintic fraction of the plant Picria fel-terrae Lour

Kumarasingha R, Young ND, Yeo TC, Lim DSL, Tu CL, Palombo EA, et al.

Parasit Vectors, 2019 Apr 25;12(1):181.
PMID: 31023350 DOI: 10.1186/s13071-019-3429-4

BACKGROUND: Natural compounds from plants are known to provide a source of anthelmintic molecules. In previous studies, we have shown that plant extracts from the plant Picria fel-terrae Lour. and particular fractions thereof have activity against the free-living nematode Caenorhabditis elegans, causing quite pronounced stress responses in this nematode. We have also shown that a fraction, designated Pf-fraction 5, derived from this plant has a substantial adverse effect on this worm; however, nothing is known about the molecular processes affected in the worm. In the present study, we explored this aspect.
RESULTS: Key biological processes linked to upregulated genes (n = 214) included 'response to endoplasmic reticulum stress' and 'lipid metabolism', and processes representing downregulated genes (n = 357) included 'DNA-conformation change' and 'cellular lipid metabolism'.
CONCLUSIONS: Exposure of C. elegans to Pf-fraction 5 induces significant changes in the transcriptome. Gene ontology analysis suggests that Pf-fraction 5 induces endoplasmic reticulum and mitochondrial stress, and the changes in gene expression are either a direct or indirect consequence of this. Further work is required to assess specific responses to sub-fractions of Pf-fraction 5 in time-course experiments in C. elegans, to define the chemical(s) with potent anthelmintic properties, to attempt to unravel their mode(s) of action and to assess their selectivity against nematodes.
Fulltext Metabolic profiling and in vitro assessment of anthelmintic fractions of Picria fel-terrae Lour

Kumarasingha R, Karpe AV, Preston S, Yeo TC, Lim DSL, Tu CL, et al.

Int J Parasitol Drugs Drug Resist, 2016 12;6(3):171-178.
PMID: 27639945 DOI: 10.1016/j.ijpddr.2016.08.002

Anthelmintic resistance is widespread in gastrointestinal nematode populations, such that there is a consistent need to search for new anthelmintics. However, the cost of screening for new compounds is high and has a very low success rate. Using the knowledge of traditional healers from Borneo Rainforests (Sarawak, Malaysia), we have previously shown that some traditional medicinal plants are a rich source of potential new anthelmintic drug candidates. In this study, Picria fel-terrae Lour. plant extract, which has previously shown promising anthelmintic activities, was fractionated via the use of a solid phase extraction cartridge and each isolated fraction was then tested on free-living nematode Caenorhabditis elegans and the parasitic nematode Haemonchus contortus. We found that a single fraction was enriched for nematocidal activity, killing ≥90% of C. elegans adults and inhibiting the motility of exsheathed L3 of H. contortus, while having minimal cytotoxic activity in mammalian cell culture. Metabolic profiling and chemometric analysis of the effective fraction indicated medium chained fatty acids and phenolic acids were highly represented.