Cell experiment:

For these assays worms of different developmental stages are incubated in liquid with and without Fluensulfone for up to 24 h, and paralysis is scored. 400 μL of M9 phosphate buffer with either Fluensulfone (100 μM, 200 μM or 1 mM) or vehicle (0.5% acetone) is put into each well of a 24 well plate (5 replicates for each Fluensulfone concentration). 5 μL suspension of age synchronised C. elegans (L1, L2/3, L4 or one day old adult) is added to each well. Each well contains approximately 50 to100 worms. The number of worms not moving at 1, 2, 3, 4, 5, 6 and 24 h is determined. The experiment is conducted on two separate occasions with five replicates[1].

Animal experiment:

Groups of 10 female specific pathogen-free CD-1 mice each are treated with untreated diet, diet containing 1200 mg/kg Fluensulfone (high dose in carcinogenicity study), or 1305 mg/kg of isoniazid as a positive control substance for 3 or 7 days, respectively. Two and 14 h before sacrifice, the animals are injected ip with 100 μL of a 10 mg/mL aqueous bromodeoxyuridine (BrdU)-solution. Sacrifice by exsanguination under deep irreversible pentobarbital narcosis is performed early in the morning to assure that the animals are exposed to the test item until shortly before sacrifice[2].

Fluensulfone is identified as a new nematicide for chemical control of plant parasitic nematodes.

Plant parasitic nematodes can infest crops and present a threat to food security. Currently available chemical controls such as methyl bromide, organophosphates as well as carbamates have an unacceptable toxicity level to non-target organisms and are being withdrawn.

In vitro: Previous study showed that the model genetic organism Caenorhabditis elegans was susceptible to the treatment of fluensulfone. While the required dose was higher than that which had nematicidal activity against Meloidogyne spp. In addition, the profile of effects on motility, egg-hatching and survival was similar to that reported for plant parasitic nematodes.C. elegans therefore provided a tractable paradigm to analyze the effects of fluensulfone on nematode behaviour. Moreover, it was also found that fluensulfone had pleiotropic actions and inhibited development, egg-laying, egg-hatching, feeding and locomotion [1].

In vivo: In mice, but not in rats, fluensulfone at high doses has shown an increased incidence of lung adenomas. Moreover, fluensulfone was not genotoxic. In addition, the administration of fluensulfone to mice resulted in an early increase in Clara cell proliferation [2].

Clinical trial: Up to now, fluensulfone is still in the preclinical development stage.

References:
[1] Kearn J,Ludlow E,Dillon J,O'Connor V,Holden-Dye L.  Fluensulfone is a nematicide with a mode of action distinct from anticholinesterases and macrocyclic lactones. Pestic Biochem Physiol.2014 Feb;109:44-57.
[2] Strupp C,Banas DA,Cohen SM,Gordon EB,Jaeger M,Weber K.  Relationship of metabolism and cell proliferation to the mode of action of fluensulfone-induced mouse lung tumors: analysis of their human relevance using the IPCS framework. Toxicol Sci.2012 Jul;128(1):284-94.