Activity of Thymus vulgaris essential oil against Anisakis larvae

Re-evaluation of certain aspects of the EFSA Scientific Opinion of April 2010 on risk assessment of parasites in fishery products, based on new scientific data. Part 1: ToRs1-3

Surveillance data published since 2010, although limited, showed that there is no evidence of zoonotic parasite infection in market quality Atlantic salmon, marine rainbow trout, gilthead seabream, turbot, meagre, Atlantic halibut, common carp and European catfish. No studies were found for greater amberjack, brown trout, African catfish, European eel and pikeperch. Anisakis pegreffii, A. simplex (s. s.) and Cryptocotyle lingua were found in European seabass, Atlantic bluefin tuna and/or cod, and Pseudamphistomum truncatum and Paracoenogonimus ovatus in tench, produced in open offshore cages or flow-through ponds or tanks. It is almost certain that fish produced in closed recirculating aquaculture systems (RAS) or flow-through facilities with filtered water intake and exclusively fed heat-treated feed are free of zoonotic parasites. Since the last EFSA opinion, the UV-press and artificial digestion methods have been developed into ISO standards to detect parasites in fish, while new UV-scanning, optical, molecular and OMICs technologies and methodologies have been developed for the detection, visualisation, isolation and/or identification of zoonotic parasites in fish. Freezing and heating continue to be the most efficient methods to kill parasites in fishery products. High-pressure processing may be suitable for some specific products. Pulsed electric field is a promising technology although further development is needed. Ultrasound treatments were not effective. Traditional dry salting of anchovies successfully inactivated Anisakis. Studies on other traditional processes - air-drying and double salting (brine salting plus dry salting) - suggest that anisakids are successfully inactivated, but more data covering these and other parasites in more fish species and products is required to determine if these processes are always effective. Marinade combinations with anchovies have not effectively inactivated anisakids. Natural products, essential oils and plant extracts, may kill parasites but safety and organoleptic data are lacking. Advanced processing techniques for intelligent gutting and trimming are being developed to remove parasites from fish.

Effect of Selected Entomopathogenic Fungal Species on Embryonic Development of Ascaris suum (Nematoda)

The aim of the study was to evaluate the potential of using five selected species of entomopathogenic fungi (Beauveria bassiana, B. brongniartii, Conidiobolus coronatus, Isaria fumosorosea, and Metarhizium robertsii) in the bioregulation of the dispersive stages of the parasitic nematode-Ascaris suum. Experimental cultures of each of the selected entomopathogenic fungi, as well as a control culture without fungi, were incubated with A. suum eggs at 26 °C for 28 days. Development of the A. suum eggs was observed using a light microscope on the 7th, 14th, 21st, and 28th days of incubation. The API-ZYM® test was used to determine, semiquantitatively, the activity of 19 hydrolytic enzymes from the entomopathogenic fungi. The cytotoxicity of the fungi was determined using tetrazole salt MTT. It was found that none of the five tested strains of entomopathogenic fungi showed an ovicidal effect, and none of them colonized the A. suum egg shells. However, ovistatic activity was observed mainly until the 14th day of incubation by I. fumosorosea, M. robertsii, and B. bassiana. In the MTT test, M. robertsii showed moderate cytotoxicity, while the other species showed low cytotoxicity. Among the strains tested, I. fumosorosea showed the highest spectrum of hydrolase production (13 out of 19 enzymes gave a positive reaction from 3 to 5; 20-40 nM or more). The absence of morphological changes in the A. suum egg shells suggests that the antagonistic effect of the studied entomopathogenic fungi may be due to their cytotoxicity, associated with the production of secondary metabolites-toxins (M. robertsii) and enzymatic activity (I. fumosorosea).

Thyme Extract Alleviates High-Fat Diet-Induced Obesity and Gut Dysfunction

Prolonged intake of a high-fat diet (HFD) disturbs the composition of gut microbiota, contributing to the development of metabolic diseases, notably obesity and increased intestinal permeability. Thyme (Thymus vulgaris L.), an aromatic plant, is known for its several therapeutic properties. In this study, we explored the potential of thyme extract (TLE) to mitigate HFD-induced metabolic derangements and improve the gut environment. Eight-week-old C57BL/6 mice were administered 50 or 100 mg/kg TLE for eight weeks. Administration of 100 mg/kg TLE resulted in decreased weight gain and body fat percentage, alongside the regulation of serum biomarkers linked to obesity induced by a HFD. Moreover, TLE enhanced intestinal barrier function by increasing the expression of tight junction proteins and ameliorated colon shortening. TLE also altered the levels of various metabolites. Especially, when compared with a HFD, it was confirmed that 2-hydroxypalmitic acid and 3-indoleacrylic acid returned to normal levels after TLE treatment. Additionally, we investigated the correlation between fecal metabolites and metabolic parameters; deoxycholic acid displayed a positive correlation with most parameters, except for colon length. In contrast, hypoxanthine was negatively correlated with most parameters. These results suggest a promising role for thyme in ameliorating obesity and related gut conditions associated with a HFD.

Anisakicidal Effects of R (+) Limonene: An Alternative to Freezing Treatment in the Industrial Anchovy Marinating Process

Anisakiasis is a fish-borne zoonotic disease caused by the ingestion of raw/undercooked fishes or cephalopods parasitized by members of the genus Anisakis. Freezing ensures the inactivation of viable Anisakis larvae; however, since it affects the organoleptic properties of food, essential oils and their compounds were proposed as an alternative. In this study, fresh anchovy fillets were experimentally parasitized with L3 Anisakis larvae to test the anisakicidal efficacy of R (+) limonene (LMN) in marinated fishery products. The anisakicidal effectiveness and organoleptic influence of several LMN concentrations (0.5%, 1%, and 5%) were tested during the marinating process (MS) and storage in sunflower seed oil (SO) of marinated anchovy fillets. Double treatment (DT) with 1% LMN was also performed both during marination and subsequent storage in oil. MS treatment resulted only in a reduction in larvae viability after 48 h, while a complete inactivation was observed in SO after 8, 10, and 20 days of treatment with 5%, 1%, and 0.5% LMN, respectively. DT was the most effective with complete larval inactivation after 7 days. Only 5% LMN influenced the sensory characteristics of the fillets, resulting, however, in a pleasant lemon-like odor and taste. Considering the results obtained, LMN might be a suitable natural alternative to manage Anisakis risk in the fishery industry.

Ovicidal effect of essential oils of Lippia alba, Lippia sidoides and Lippia gracilis on the acanthocephalan Neoechinorhynchus buttnerae (Eoacanthocephala: Neoechinorhynchidae)

Acanthocephalosis in tambaqui Colossoma macropomum culture is a limiting factor for the production of the species, being the most recurrent, which makes it necessary to develop strategies to control parasitosis even in the early stages of parasite development. This study aimed to elucidate the morphological characteristics of eggs of the acanthocephalan Neoechinorhynchus buttnerae and the ovicidal effect of the essential oils of Lippia alba, Lippia sidoides, and Lippia gracilis. The parasites were collected from hosts naturally infected with N. buttnerae, and the eggs obtained from the female 'parasites' abdominal cavity were added to 12-well plates containing the essential oils at different dilutions. After the eggs (N = 300) were separated and measured (length and width) with the aid of an optical microscope coupled to a digital program, the viability of the treated eggs was monitored 24 h after treatments, L. gracilis essential oil was 100% effective at the highest concentration, whereas L. sidoides essential oil showed over 50% efficacy at 2 mg/ml, reaching 100% efficacy at all higher concentrations. Lippia. alba essential oil did not show satisfactory efficacy in preventing N. buttnerae egg hatching.

Can orange essential oil reduce the severity of parasitic infection in sheep?

In this study, a three-step experiment was conducted to evaluate the effectiveness of orange essential oil (OEO) to reduce the severity of parasitic infection in lambs naturally infected with gastrointestinal parasites. In the first and second stages of the experiment, the lambs were distributed in groups (n = 10): without treatment (control), treated with levamisole (7.5 mg/kg), and treated either with 200, 300 or 400 mg/kg OEO in the first stage and with two doses of 300 or 350 mg/kg each of OEO with a six-hour interval in the second stage. In the third stage of the experiment, 20 lambs were distributed into control and treated groups (two doses of 350 mg/kg OEO) and slaughtered for determining the parasite count in the abomasum and small intestine. Evaluations were performed on D0, D3, D7, D10, and D14 by determining the egg count per gram of feces (EPG), and the percentage of EPG reduction was calculated in comparison to D0. Coproculture was performed on days D0 and D14 of the first and second stages of the study. In the first stage, the EPG increased by 20.90 and 100.99% and decreased by 5.54% on D14 in the groups treated with 200, 300, or 400 mg/kg OEO, respectively. At the second stage, the EPG of the OEO groups decreased by more than 96% on D3, but on D14 was decreased by 0.82% and 77.07% in the 2 × 300 and 2 × 350 mg/kg groups, respectively. Haemonchus sp. was the highest percentage of collected larvae in all coproculture tests, ranging from 90 to 100%. In the third stage, there was no difference (P > 0.05) in the mean number of parasites between the OEO groups and the control. Although the decrease in EPG of more than 96% on D3 did not persist in the other evaluations, and immature forms and adult parasites were collected at slaughter, the EPG reduction of 77.07% on D14 with the dose of 700 mg/kg (OEO2 × 350) suggests that OEO can help to reduce the severity of parasitic infection and, consequently, to diminish pastures contamination, when used together with other methods to control gastrointestinal parasites in sheep.

Comprehensive Evaluation on the Use of Thymus vulgaris Essential Oil as Natural Additive against Different Serotypes of Salmonella enterica

Essential oils were proposed as natural additives to ensure food safety and quality in a more sustainable approach. The chemical composition of Thymus vulgaris essential oil (TV-EO) collected from Morocco, its antioxidant and antimicrobial activity against different serotypes of Salmonella enterica subsp. enterica was investigated. A mathematical model was implemented to predict the Salmonella behavior when exposed to TV-EO. In situ antimicrobial activity and sensory influence were tested in minced poultry meat experimentally contaminated with Salmonella and treated with TV-EO. Hydrodistillation was used to extract TV-EO, and gas chromatography-mass spectrometry (GC-MS) analysis found thymol as the most representative compound. Results of the antioxidant activity showed an IC50 of 0.29 ± 0.04 mg/mL, EC50 of 0.74 ± 0.08 mg/mL, and RC50 of 0.59 ± 0.06 mg/mL. All the Salmonella strains were susceptible to TV-EO with performing results for the disc diffusion method (inhibition diameters ranged between 24 ± 0.4 mm and 32 ± 0.6 mm), determination of minimum inhibitory concentration (MIC; 0.5%) and minimum bactericidal concentration (MBC; 1%), sublethal-injured cells (7.99 ± 0.08%), in situ activity (growth inhibition after 3 days), and meat sensory preservation (up to 1 week). The implemented mathematical model well fitted the Salmonella growth curve. TV-EO with significant antioxidant and antibacterial activities was suitable to ensure food safety and quality consistent with the new sustainable trends in the food field.

Chemical composition, antioxidant capacity and antibacterial action of five Moroccan essential oils against Listeria monocytogenes and different serotypes of Salmonella enterica

Essential oils (EOs) obtained from aromatic plants are rich in natural components with interesting antimicrobial effects. The aim of this study was to evaluate the chemical composition of EOs extracted from Origanum majorana (OM-EO), Mentha suaveolens (MS-EO), Rosmarinus officinalis (RO-EO), Salvia officinalis (SO-EO) and Mentha pulegium (MP-EO). Their antioxidant properties and antibacterial activity against Listeria monocytogenes and different serotypes of Salmonella enterica subsp. enterica were also studied. The EOs were extracted from plants by hydro-distillation and their chemical composition was determined by GC-MS. Terpinen-4-ol, 1,8-Cineole, Camphor, Limonene and Cinerone were the main chemical components found in OM-EO, RO-EO, SO-EO, MP-EO and MS-EO, respectively. To the best of our knowledge, Limonene and Cinerone were reported, for the first time, as the major components of MP-EO and MS-EO. Moreover, our results showed that MS-EO had the best antioxidant activity with an IC₅₀ of 0.78 ± 0.05 mg/mL, EC₅₀ of 1.53 ± 0.07 mg/mL, and RC₅₀ of 0.98 ± 0.04 mg/mL, and the higher antibacterial activity using microdilution broth method with MIC of 0.5% for Salmonella and 0.25% for L. monocytogenes, while OM-EO had the best antibacterial activity using disc diffusion method (inhibition diameters ranged between 15.3 ± 0.3 mm and 18.5 ± 0.3 mm for Salmonella and between 20.1 ± 0.2 mm and 25.4 ± 0.4 mm for L. monocytogenes). However, OM-EO and MS-EO present the higher percentage of sub-lethally injured cells against S. enterica (5.50 ± 0.11%) and L. monocytogenes (5.23 ± 0.07%), respectively. From this study, we can conclude that the investigated EOs are rich in components with interesting antibacterial activity and they could be applied in food preparations as natural preservatives to extend the shelf life of food products and to inhibit the growth of food-borne pathogens.

Effect of freezing on the metabolic status of L3 larvae of Anisakis simplex s. s

The fish-borne parasite, Anisakis simplex s. s., triggers a disease called anisakiasis, that is associated with a gastrointestinal infection. The Anisakis is also associated with allergic response which may lead to anaphylactic shock. The A. simplex s. s. L3 larvae may be freeze tolerant despite when the nematodes will be cooled rapidly to -20 °C according to the sanitary authorities of the USA and the EU. The aim of this work was to study the metabolic status of A. simplex s. s. L3 larvae when frozen in terms of viability, expression of genes involved in the nematodes' survival of freezing, as well content of carbohydrates which play a cryoprotective role in thermal stress and are the main source of energy. The levels of trehalose were significantly higher after slow freezing treatment (p < .0001), than the fast freezing (p < .002). The lower temperatures induce changes, especially in trehalose synthesis gene expression, genes responsible for oxidative metabolism, and chaperone proteins, but we cannot state clearly whether these changes occur during freezing, or because they are already prevalent during cold acclimation. The induction of mentioned genes seems to be a common trait of both cold- and dehydration tolerance.

Effectiveness of five flavored Tunisian olive oils on Anisakis larvae type 1: application of cinnamon and rosemary oil in industrial anchovy marinating process

BACKGROUND

Anisakidosis is caused by the ingestion of raw or undercooked fish or cephalopods containing viable Anisakis larvae. Several natural extracts, oils, essential oils, and their compounds have been tested against Anisakis. In this study the effectiveness of Tunisian olive oil with different spices or plants (cardamom, cinnamon, ginger, laurel, and rosemary) was tested against Anisakis larvae type 1.

RESULTS

For the in vitro test, larvae were submerged separately in the oils mentioned above and observed to check viability. Cinnamon oil was the most effective against parasites with lethal time (LT) scores being LT50  = 1.5 days and LT100  = 3 days, followed by rosemary. Laurel, cardamom, and ginger oils were less effective. For the ex vivo experiment, cinnamon, and rosemary oils were tested in anchovy fillets, previously artificially parasitized. Cinnamon was the most effective against parasites (dead after 4 days) as compared to rosemary (7 days).

CONCLUSION

The use of cinnamon and rosemary-flavored olive oil in the industrial marinating process can be considered as an efficient alternative to the freezing process required by European Regulation EC No 853/2004 to devitalize Anisakis. © 2019 Society of Chemical Industry.

Efficacy of Origanum syriacum Essential Oil against the Mosquito Vector Culex quinquefasciatus and the Gastrointestinal Parasite Anisakis simplex, with Insights on Acetylcholinesterase Inhibition

Developing effective and eco-friendly antiparasitic drugs and insecticides is an issue of high importance nowadays. In this study, we evaluated the anthelminthic and insecticidal potential of the leaf essential oil obtained from Origanum syriacum against the L3 larvae of the parasitic nematode Anisakis simplex and larvae and adults of the mosquito Culex quinquefasciatus. Tests on A. simplex were performed by standard larvicidal and penetration assays, while mosquito toxicity was assessed relying on larvicidal, tarsal contact, and fumigation tests. To shed light on the possible mode of action, we analyzed the oil impact as acetylcholinesterase (AChE) inhibitor. This oil was particularly active on L3 larvae of A. simplex, showing a LC₅₀ of 0.087 and 0.067 mg mL^-1 after 24 and 48 h treatment, respectively. O. syriacum essential oil was highly effective on both larvae and adults of C. quinquefasciatus, showing LC₅₀ values of 32.4 mg L^-1 and 28.1 µg cm^-2, respectively. Its main constituent, carvacrol, achieved larvicidal LC₅₀₍₉₀₎ of 29.5 and 39.2 mg L^-1, while contact toxicity assays on adults had an LC₅₀₍₉₀₎ of 25.5 and 35.8 µg cm^-2, respectively. In fumigation assays, the LC₅₀ was 12.1 µL L^-1 after 1 h and decreased to 1.3 µL L^-1 in 24 h of exposure. Similarly, the fumigation LC₅₀ of carvacrol was 8.2 µL L^-1 after 1 h of exposure, strongly decreasing to 0.8 µL L^-1 after 24 h of exposure. These results support the folk usage of Lebanese oregano as an antiparasitic agent, providing new insights about its utilization for developing new effective and eco-friendly nematocidal and insecticidal products.

Efficiency of Target Larvicides Is Conditioned by ABC-Mediated Transport in the Zoonotic Nematode Anisakis pegreffii

Anisakiasis is among the most significant emerging foodborne parasitoses contracted through consumption of thermally unprocessed seafood harboring infective Anisakis species larvae. The efficacy of the currently applied anthelminthic therapy in humans and in model organisms has not proven sufficient, so alternative solutions employing natural compounds combined with chemical inhibitors should be explored. By testing toxicity of the natural monoterpenes nerolidol and farnesol and the conventional anthelminthics abamectin and levamisole in the presence/absence of MK-571 and Valspodar, which inhibit the ABC transporter proteins multidrug resistance protein (MRP-like) and P-glycoprotein (P-gp), we determined the preliminary traits of Anisakis detoxifying mechanisms. We found that Anisakis P-gp and MRP-like transporters have a role in the efflux of the tested compounds, which could be useful in the design of novel anthelminthic strategies. As expected, transporter activation and efflux fluctuated over time; they were synchronously active very early postexposure, whereas the activity of one transporter dominated over the other in a time-dependent manner. MRP-like transporters dominated in the efflux of farnesol, and P-gp dominated in efflux of nerolidol, while both were active in effluxing levamisole. The highest toxicity was exerted by abamectin, a P-gp inhibitor per se, which also elicited the highest oxidative stress in treated Anisakis larvae. We suggest that β-tubulin, observed for the first time as a core element in Anisakis cuticle, might represent an important target for the tested compounds.

Use of Tunisian flavored olive oil as anisakicidal agent in industrial anchovy marinating process

BACKGROUND

Natural compounds are more frequently used against Anisakis, responsible for the important fish-borne disease anisakidosis. The aim of the study was to evaluate the effectiveness of enriched Tunisian olive oil with different spices (cumin, turmeric, clove, thyme, and lemon) against Anisakis larvae type 1.

RESULTS

In vitro experiment: larvae were submerged separately in the aforementioned oils and then examined to check viability. For each oil, LT50 and LT100 were calculated. Turmeric and cumin oils are the most effective against the parasites; followed by lemon, thyme and clove oils. For the in vivo experiment, turmeric and cumin oils were tested in anchovy fillets previously artificially parasitized with L3 larvae. Cumin was the most effective against parasites (dead after 5 days) compared with turmeric (8 days). For the two oils, the resulting odor was pleasant, as was the taste, while changes in color were much more evident in turmeric fillets.

CONCLUSION

All the flavored oils demonstrated a good nematodical action against Anisakis. Cumin oil was the most effective against encysted larvae. Turmeric oil showed the best activity in the in vitro experiment. The use of flavored oils in the marinating process could represent an efficient strategy to devitalize Anisakis. © 2017 Society of Chemical Industry.

Quality assessment of Zeus faber (Peter's fish) ovaries regularly commercialized for human consumption

In the last few years, the consumption of fish eggs has increased rapidly, finding widespread use also in mass catering. This increase has involved also those of the Peter's fish (Zeus faber). Females of this species, by their reproductive characteristics, have highly developed gonads in different periods of the year, making the raw material easy to find. The aim of the present study was to perform a quality assessment of Zeus faber ovaries regularly commercialized for human consumption. A total number of 34 samples, divided in fresh (11) and frozen (23), were processed for microbiological characterization, parasitological and histological evaluations. Fresh and frozen samples have significant (P<0.01) differences in total bacterial charge, with values of 4.75±0.5 Log CFU/g and 3.65±0.7 Log CFU/g respectively. The mean value of Enterobacteriaceae was 2.58±0.7 Log CFU/g in fresh products, while 52.17% (12) of frozen samples reported loads of <1 Log CFU/g. No Salmonella spp. and Listeria monocytogenes were found. Aeromonas spp. was detected in two frozen sample (with loads of 2.2 and <1 Log CFU/g) and in 5 fresh ovaries with value ranged from 1.70 to 3.48 Log CFU/g. Vibrio spp. was found in 4 (36.36%) and 3 (13.04%) of fresh and frozen samples respectively, with loads always <1 Log CFU/g. All 31 Vibrio strains isolated, were identified as Vibrio alginolyticus, and 61.29% (19) of them was positive for the ToxRS factor and 6.45% (2) for ToxR. The 47.06% (16) of total samples showed infestations by larvae of Anisakis Type 1 in the serous and inside the ovary. In this last case, histologically it was found to be free larvae. This study attested satisfactory hygiene conditions for Zeus faber ovaries currently marked for human consumption. The presence of potentially pathogenic strains of V. alginolyticus and Aeromonas spp., but above all the frequent infestation by Anisakis larvae, represent a potentially hazard for the consumer.

Green drugs in the fight against Anisakis simplex-larvicidal activity and acetylcholinesterase inhibition of Origanum compactum essential oil

Anisakiasis is a fish-borne parasitic disease caused by the consumption of raw or undercooked fish, as well as cephalopods, contaminated by third instar larvae (L3) of species belonging to the genus Anisakis (Anisakidae). Origanum compactum is a small herbaceous aromatic plant endemic to Spain and Morocco. In Morocco, the plant is used under infusion to treat heart diseases and intestinal pains or as preservative for foodstuffs. This is the first time that the O. compactum essential oil is tested against the parasitic nematode Anisakis simplex. The phytochemical analysis by GC-MS revealed carvacrol (50.3%) and thymol (14.8%) as the major oil constituents. The essential oil and its major constituents carvacrol and thymol were tested against A. simplex L3 larvae isolated from blue whiting fish (Micromesistius poutassou). A. simplex mortality (%) after 24 and 48 h of treatment at 1 μl/ml was 100%, with a low LD₅₀ compared with other essential oils and extracts, and the penetration in the agar assay was also reduced, if compared with control wells. The oil, as well as its major constituents, demonstrated a dose-dependent larvicidal activity. Inhibition of the enzyme acetylcholinesterase through a colorimetric assay in 96-well plates was used to elucidate the pharmacological mechanism as this enzyme plays a key role in nematodes neuromuscular function. Interestingly, O. compactum essential oil, carvacrol and thymol inhibited the enzyme, confirming that this could be one of the mechanisms involved in the anthelmintic activity. To the best of our knowledge, this is the first time that O. compactum essential oil is reported as a larvicidal agent against A. simplex L3 larvae.

Evaluation of different Mediterranean essential oils as prophylactic agents in anisakidosis

CONTEXT

Anisakis Dujardin 1845 (Anisakidae) nematodes can cause gastrointestinal and allergic diseases when humans eat raw or undercooked seafood containing larvae. There is currently no drug available in the market against this parasitic disease, and the study of plant-derived molecules could be useful in the discovery of effective compounds.

OBJECTIVE

This research assesses the biocidal activity of a range of essential oils (EOs) from some Mediterranean plants against larvae found in the musculature of fresh fish.

MATERIALS AND METHODS

EOs composition was analyzed by gas chromatography-mass spectroscopy. All the EOs were diluted at 5% v/v in olive oil to cover the fish with the solutions for 24 h. The larvae that abandoned the muscle and the larvae obtained from the artificial digestion of the fish were collected. Controls were carried out in parallel. Furthermore, Wistar rats were infected with the live larvae collected from the in vitro trials in order to find any larvae that may have penetrated the gastrointestinal wall.

RESULTS

Between 60.8% and 87.6% of parasites treated with EOs abandoned the fish muscle, and the highest in vitro mortality rate was achieved with oregano EO (53.9%). Rats previously treated with oregano, cumin and Spanish lavender EOs showed no detectable lesions in the digestive tract due to the infection with larvae.

CONCLUSIONS

Oregano (Origanum vulgare L. Lamiaceae), cumin (Cuminum cyminum L. Apiaceae) and Spanish lavender (Lavender stoechas L. Lamiaceae) EOs could be used as promising ingredients in the development of products for the control of anisakiasis.

Modelling studies determing the mode of action of anthelmintics inhibiting in vitro trehalose-6-phosphate phosphatase (TPP) of Anisakis simplex s.l

The trehalose-6-phosphate phosphatase (TPP) enzyme is involved in the synthesis of trehalose, the main sugar in the energy metabolism of nematodes. TPP is a member of the HAD-like hydrolase superfamily and shows a robust and specific phosphatase activity for the substrate trehalose-6-phosphate. The presence of conserved active sites of TPP in closely related nematodes and its absence in humans makes it a promising target for antiparasitic drugs. In the present study, homology modeling, molecular docking and MD simulation techniques were used to explore the structure and dynamics of TPP. In the active site, a magnesium ion is stabilized by 3 coordinate bonds formed by D₁₈₉, D₁₉₁ and D₄₀₀. The key amino acids involved in ligand binding by the enzyme are C₁₉₈, Y₂₀₁,T₃₅₇, D₁₉₁ and Y₁₉₇. This study relied on docking to select potential inhibitors of TPP which were tested in vitro for sensitivity to anthelmintic drugs such as levamisole and ivermectin targeting Anisakis simplex. The higher toxicity of LEV than IVM was demonstrated after 96 h, 30% of larvae were motile in cultures with 100 μg/ml of LEV and 1000 μg/ml of IVM. We identified drug combination of LEV-IVM against in vitro A. simplex as agonistic effect (CI = 1.1). Levamisole appeared to be a more effective drug which inhibited enzyme activity after 48 h and expression of mRNA after 96 h at a concentration of 10 μg/ml. This preliminary study predicted the structure of TPP, and the results of an in vitro experiment involving A. simplex will contribute to the development of effective inhibitors with potential antiparasitic activity in the future.

Thymus vulgaris L. extract has antimicrobial and anti-inflammatory effects in the absence of cytotoxicity and genotoxicity

OBJECTIVES

This study evaluated the biological effects of the T. vulgaris L. extract., such as antimicrobial activity on planktonic cultures and mono- and polymicrobial biofilms, cytotoxicity, anti-inflammatory activity and genotoxicity.

METHODS

Monomicrobial biofilms of Candida albicans, Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans and Pseudomonas aeruginosa and polymicrobial biofilms composed by C. albicans with each bacterium were formed for 48h and exposed for 5min to the plant extract. Murine macrophages (RAW 264.7), human gingival fibroblasts (FMM-1), human breast carcinoma cells (MCF-7) and cervical carcinoma cells (HeLa) were also exposed to the plant extract for 5min and the cell viability were analyzed by MTT, neutral red (NR) and crystal violet (CV) assays. Interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) produced by RAW 264.7 was quantified by ELISA, after 24h exposure to the plant extract, both in the absence and presence of lipopolysaccharide (LPS) from Escherichia coli. Genotoxicity of the plant extract was evaluated by micronucleus formation (MN) in 1000 cells. The results were analyzed by T-Test or ANOVA and Tukey's Test (P≤0.05).

RESULTS

All biofilms showed significant reductions in CFU/mL (colony-forming units per milliliter). Cell viability was above 50% for all cell lines. Anti-inflammatory effect on the synthesis of IL-1β and TNF-α was observed. The MN was similar or lower than the control group in all cells.

CONCLUSIONS

T. vulgaris L. extract was effective against all biofilms, promoted high cell viability, anti-inflammatory effect and presented no genotoxicity.

Activity of Tagetes minuta Linnaeus (Asteraceae) essential oil against L3 Anisakis larvae type 1

OBJECTIVE

To evaluate in vitro effects of Tagetes minuta L. essential oil (TEO) on L3 Anisakis larvae type 1.

METHODS

In order to evaluate the potential use of Tagetes minuta essential oil against L3 Anisakis larvae three different media were tested: 1) a saline solution (SS); 2) an industrial marinating solution (MS); 3) sunflower seeds oil (SO). For each media and concentrations of TEO (0.1%, 0.5%, 1.0% and 5.0% v/v), 20 parasites were introduced into plastic Petri dishes (diameter 90 mm) and maintained at room temperature. As controls, larvae were maintained without TEO under identical experimental conditions in SS, MS and SO. A total of 900 larvae were tested. The normalized mean viability, LT100, LT50 and the percentage of inactivation at 24 h were calculated.

RESULTS

In vitro tests revealed a complete inactivation of parasites in saline solution after 2 h with 5% and 1% of TEO. In marinating solution, a complete inactivation of parasites was observed after 4 h at all concentrations used. A slower activity for all TEO concentration was reported in SO.

CONCLUSIONS

The results obtained, showing a strong activity against Anisakis larvae, confirm TEO as a larvicidal agent in the treatment of human anisakidosis and in the industrial marinating process.

Chemical Composition and Anti-inflammatory Activity of Algerian Thymus vulgaris Essential Oil

This work aims to elucidate the chemical composition of two essential oil (EO) samples obtained from the leaves of Thymus vulgaris L. ( Lamiaceae) collected in two regions of Northwestern Algeria (Tlemcen and Mostaganem) and to assess their in vivo acute toxicity and anti-inflammatory activity. Sixty-six compounds could be identified by means of simultaneous GC-FID and GC-MS, accounting for 99.3% of total thyme oil of Mostaganem (EO.TM) and 99.0% of Tlemcen (EO.TT). In both samples, thymol was the major component, amounting to 59.5% (EO.TM) and 67.3% (EO.TT) of the total oil. EO.TT proved to be acutely toxic to mice at a dose of 4500 mg/kg p.o., whereas EO.TM did not show signs of acute toxicity, even at the highest dose tested (5000 mg/kg p.o.). Both EO samples were proven to possess anti-inflammatory activities, significantly reducing carrageenan-induced paw edema in mice (after 6 hours at a dose of 400 mg/kg p.o) at 58.4% for EO.TT and 50.4% for EO.TM, respectively. In conclusion, it could be demonstrated that EOs of T. vulgaris exhibit a considerable in vivo anti-inflammatory activity at non-toxic doses.

Evaluation of the Antibacterial Activity of Bergamot Essential Oils on Different Listeria Monocytogenes Strains

Essential oils are aromatic and volatile substances extracted from plants and characterized by antimicrobial activity. The aim of the present study was to evaluate the antibacterial activity (agar disc-diffusion method) of seven different bergamot essential oils (BEOs) on eight Listeria monocytogenes strains. Minimal inhibitory concentration (MIC) of most efficient BEOs was estimated. Extremely variable results for agar disc-diffusion method for L. monocytogenes strains were reported. One of the tested microorganisms resulted insensible to all the BEOs; 3 strains showed an inhibition from weak to null and the remaining 4 a variable susceptibility. Among the BEOs tested, one showed a strong activity against four pathogenic strains. Four BEOs revealed weak, moderate or null activity in all the 7 sensitive strains, while for two oils only a weak or no activity was reported. MIC values were 0.625 μL/mL for the most efficient BEO, 2.5 and 5 μL/mL for the other samples that showed moderate inhibition. Experiment results are significantly related to the strains tested (P<0.01), rather than the BEO employed (P>0.01). In conclusion, we can consider BEO as a natural technological hurdle for Listeria monocytogenes in combination with other preservation strategies. Finally, this study underlines the necessity to evaluate the antimicrobial activity of EOs on a significant strains number of the same bacteria.

Selective nematocidal effects of essential oils from two cultivated Artemisia absinthium populations

Essential oils (EOs) obtained from two crops and populations of thujone-free cultivated Artemisia absinthium were tested against two nematode models, the mammalian parasite Trichinella spiralis, and the plant parasitic root knot nematode Meloidogyne javanica. The EOs were characterized by the presence of (Z)-epoxyocimene and chrysanthenol as major components and showed time and population dependent quantitative and qualitative variations in composition. The EOs showed a strong ex vivo activity against the L1 larvae of the nematode Trichinella spiralis with a reduction of infectivity between 72 and 100% at a dose range of 0.5-1 mg/ml in absence of cytotoxicity against mammalian cells. Moreover, the in vivo activity of the EO against T. spiralis showed a 66% reduction of intestinal adults. However, these oils were not effective against M. javanica.

Activity of R(+) Limonene Against Anisakis Larvae

The aim of this work is to evaluate the activity of R(+) limonene of against Anisakidae larvae. Its effectiveness was tested in vitro. The results obtained showed a significant activity of the compound against Anisakis larvae, suggesting further investigation on its potential use in the industrial marinating process. In this regard, the use of R(+) limonene in seafood products could be interesting, also due the sensory attributes resulting from its use and its relatively safe status.

Natural products: Perspectives in the pharmacological treatment of gastrointestinal anisakiasis

OBJECTIVE

To evaluate the activity of different natural products against L3 larvae of Anisakis type I.

METHODS

Information on investigations into the activity of natural products against the L3 larvae of Anisakis simplex was collected from scientific journals, books, theses and reports via a library and electronic search (using Pubmed, Scopus, Medline, Web of Science and ScienceDirect). The search terms included: natural products, medicinal plants, essential oils, terpenic derivatives, Anisakis, antinematodal activity.

RESULTS

In the literature reviewed numerous papers were found concerning the in vitro and in vivo activity against Anisakis type I of various natural products (plant extracts, essential oils and their major components). Analysis of the results showed that in vitro tests the Melaleuca alternifolia essential oil and the ar-turmerone isolated from Curcuma longa displayed the greatest activity. In vivo, the most active compound was perillaldehyde, the main component of Perilla frutescens essential oil.

CONCLUSIONS

This study shows that some natural products exhibited promising antianisakis properties.

Effect of allyl isothiocyanate against Anisakis larvae during the anchovy marinating process

Allyl isothiocyanate (AITC), is a natural compound found in plants belonging to the family Cruciferae and has strong antimicrobial activity and a biocidal activity against plants parasites. Anisakidosis is a zoonotic disease caused by the ingestion of larval nematodes in raw, almost raw, and marinated and/or salted seafood dishes. The aim of this work was to evaluate the effect of AITC against Anisakis larvae and to study its potential use during the marinating process. The effects of AITC against Anisakis larvae were tested in three experiment: in vitro with three liquid media, in semisolid media with a homogenate of anchovy muscle, and in a simulation of two kinds of anchovy fillets marinating processes. For all tests, the concentrations of AITC were 0, 0.01, 0.05, and 0.1%. Significant activity of AITC against Anisakis larvae was observed in liquid media, whereas in the semisolid media, AITC was effective only at higher concentrations. In anchovy fillets, prior treatment in phosphate buffer solution (1.5% NaCl, pH 6.8) with 0.1% AITC and then marination under standard conditions resulted in a high level of larval inactivation. AITC is a good candidate for further investigation as a biocidal agent against Anisakis larvae during the industrial marinating process.