Activity of Matricaria chamomilla essential oil against anisakiasis.

The increase in diagnosed cases of anisakiasis and the virtual absence of effective treatments have prompted the search for new active compounds against Anisakis L(3) larvae. The biocidal efficacy against different pathogens shown by various essential oils (EO) led us to study the Matricaria chamomilla EO and two of its main components (chamazulene and α-bisabolol) against the L(3) larvae of Anisakis type I. The activity of M. chamomilla EO, chamazulene and α-bisabolol was established by in vitro and in vivo experiments. The EO (125µg/ml) caused the death of all nematodes, which showed cuticle changes and intestinal wall rupture. In the in vivo assays, only 2.2%±1.8 of infected rats treated with M. chamomilla EO showed gastric wall lesions in comparison to 93.3%±3.9 of control. Chamazulene was ineffective, while α-bisabolol showed a high activity to that of the EO in vitro tests but proved less active in vivo. These findings suggest that the larvicidal activity may result from the synergistic action of different compounds of M. chamomilla EO. Neither of the tested products induces irritative damage in the intestinal tissues. In conclusion, M. chamomilla EO is a good candidate for further investigation as a biocidal agent against Anisakis type I.

CO2-fixing enzymes and phosphoenolpyruvate metabolism in the fish parasite Hysterothylacium aduncum (Ascaridoidea, Anisakidae).

CO2 stimulates the development of many of the intestinal helminths that are able to fix CO2 by means of phosphoenolpyruvate carboxykinase (PEPCK), such as Hysterothylacium aduncum. We determined the activity of CO2-fixing enzymes such as PEPCK and phosphoenolpyruvate carboxylase (PEPC), although no significant activity was detected for pyruvate carboxylase or carboxylating-malic enzyme. The former act on phosphoenolpyruvate (PEP) to yield oxalacetate. In the helminths studied, PEP has a vital role in glucidic metabolism. Consequently, we determined the activity of other enzymes involved in the crossroad of PEP, such as pyruvate kinase (PK), lactate dehydrogenase and malate dehydrogenase. All enzymes detected showed significant variations in activity during the in vitro development of the parasite from the third larval stage to mature adult. Fixing of CO2 by PEPCK decreased during development (from 228 to 115 nmol min(-1) mg(-1) protein), while that by PEPC increased (from 19 to 46 nmol min(-1) mg(-1) protein). This enzyme, which is rare in animals, could play a part in detecting levels of free phosphate, releasing it from PEP when required for processes such as glycogenolysis, glycolysis and adenosine 5'-triphosphate (ATP) synthesis. PK, which showed increasing activity during development up to immature adult (from 56 to 82 nmol min(-1) mg(-1) protein), could act in combination with PEPC to obtain energy in the cytosol (in the form of ATP) and in the mitochondria (possible destination of the pyruvate formed), compensating for the decrease in activity of PEPCK.