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de Souza IMM, Novaes RD, Gonçalves RV, Fialho FLB, Carvalho DT, de Souza TB, Dias DF, Lavorato SN, Souza RLM, Marques MJ, Castro AP. In vitro and in silico evaluation of the schistosomicidal activity of eugenol derivatives using biochemical, molecular, and morphological tools. J Venom Anim Toxins Incl Trop Dis 2022; 28:e20210108. [PMID: 35854812 PMCID: PMC9258719 DOI: 10.1590/1678-9199-jvatitd-2021-0108] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 05/20/2022] [Indexed: 11/22/2022] Open
Abstract
Background Eugenol shows both antibacterial and antiparasitic activities, suggesting
that it might be evaluated as an option for the treatment of
praziquantel-resistant schistosome. Methods The in vitro activities of three eugenol derivatives (FB1,
FB4 and FB9) on adult worms from Schistosoma mansoni were
examined by fluorescence and scanning electron microscopy to analyze effects
on the excretory system and integument damage, respectively. Biochemical
tests with verapamil (a calcium channel antagonist) and ouabain (a
Na+/K+-ATPase pump inhibitor) were used to
characterize eugenol derivative interactions with calcium channels and the
Na+/K+-ATPase, while in silico
analysis identified potential Na+/K+-ATPase binding
sites. Results The compounds showed effective doses (ED50) of 0.324 mM (FB1),
0.167 mM (FB4), and 0.340 mM (FB9). In addition, FB4 (0.322 mM), which
showed the lowest ED50, ED90 and ED100 (p
< 0.05), caused the most damage to the excretory system and integument,
according to both fluorescence and scanning electron microscopy analysis.
The death of adult worms was delayed by ouabain treatment plus FB1 (192
versus 72 hours) and FB9 (192 versus
168 hours), but the response to FB4 was the same in the presence or absence
of ouabain. Besides, no changes were noted when all of the eugenol
derivatives were combined with verapamil. Moreover, FB1 and FB9 inhibited
Na+/K+-ATPase activity according to in
silico analysis but FB4 did not show a time-dependent
relationship and may act on targets other than the parasite Na+/K+-ATPase.
Conclusion Eugenol derivatives, mainly FB4 when compared to FB1 and FB9, seem to act
more effectively on the integument of adult S. mansoni
worms.
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Affiliation(s)
| | - Romulo Dias Novaes
- Institute of Biomedical Sciences, Federal University of Alfenas (Unifal), Alfenas, MG, Brazil
| | | | | | - Diogo Teixeira Carvalho
- School of Pharmaceutical Sciences, Federal University of Alfenas (Unifal), Alfenas, MG, Brazil
| | | | | | - Stefânia Neiva Lavorato
- Center of Biological Sciences and Health, Federal University of Western Bahia (Ufob), Barreiras, BA, Brazil
| | | | - Marcos José Marques
- Institute of Biomedical Sciences, Federal University of Alfenas (Unifal), Alfenas, MG, Brazil
| | - Aline Pereira Castro
- Institute of Biomedical Sciences, Federal University of Alfenas (Unifal), Alfenas, MG, Brazil.,Department of Pharmacy, University Center of Lavras (Unilavras), Lavras, MG, Brazil
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Lazarević J, Jevremović S, Kostić I, Vuleta A, Manitašević Jovanović S, Kostić M, Šešlija Jovanović D. Assessment of Sex-Specific Toxicity and Physiological Responses to Thymol in a Common Bean Pest Acanthoscelides obtectus Say. Front Physiol 2022; 13:842314. [PMID: 35250641 PMCID: PMC8892178 DOI: 10.3389/fphys.2022.842314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 01/25/2022] [Indexed: 11/13/2022] Open
Abstract
Acanthoscelides obtectus Say (Coleoptera: Chrysomelidae: Bruchinae), is one of the most important pests of the common bean Phaseolus vulgaris L. Without appropriate management it may cause significant seed loss in storages. In search for means of environmentally safe and effective protection of beans we assessed biological activity of thymol, an oxygenated monoterpene present in essential oils of many aromatic plants. We studied contact toxicity of thymol on bean seeds and its effects on adult longevity and emergence in F1 generation. Furthermore, we determined acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CAT), mixed-function oxidase (MFO), carboxylesterases (CarE) and glutathione S-transferase (GST) activities in response to 24 h exposure of beetles to sublethal and lethal thymol concentrations. Our results showed that thymol decreased adult survival, longevity and percentage of adult emergence. Higher median lethal concentration (LC50) was recorded in females indicating their higher tolerance comparing to males. Overall, activities of SOD, CAT and CarE increased at sublethal and MFO increased at both sublethal and lethal thymol concentrations. On the other hand, GST and AChE activities decreased along with the increase in thymol concentrations from sublethal (1/5 of LC50, 1/2 of LC50) to lethal (LC50). Enzyme responses to the presence of thymol on bean seed were sex-specific. In the control group females had lower CarE and higher SOD, CAT and GST activity than males. In treatment groups, females had much higher CAT activity and much lower CarE activity than males. Our results contribute to deeper understanding of physiological mechanisms underlying thymol toxicity and tolerance which should be taken into account in future formulation of a thymol-based insecticide.
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Kang MS, Park JH, Lee HS. Acaricidal potential of active components derived from Alpinia galanga rhizome oils and their derivatives against Haemaphysalis longicornis (Acari: Ixodidae). EXPERIMENTAL & APPLIED ACAROLOGY 2022; 86:313-326. [PMID: 35024988 DOI: 10.1007/s10493-022-00685-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
Acaricidal activities and acetylcholinesterase (AChE) inhibitory activities were evaluated of active constituents of the essential oil extracted from Alpinia galanga rhizomes cultivated from India and their derivatives against Haemaphysalis longicornis nymphs. In addition, the effect was investigated of active components of A. galanga oil on egg laying of adult females of H. longicornis and egg hatchability. Of the volatile components identified in A. galanga oil, ethyl cinnamate, ethyl methoxycinnamate, and methyl cinnamate at 0.32 mg/cm2 resulted in 100% mortality, respectively, indicating that the acaricidal activity of the A. galanga oil against H. longicornis nymphs could be attributed to these compounds. To evaluate the structure-activity relationship between cinnamate derivatives and their acaricidal activities, allyl cinnamate, benzyl cinnamate, isopropyl cinnamate, isobutyl cinnamate, and isoamyl cinnamate were selected. Among cinnamate derivatives tested, allyl cinnamate exhibited the most potent toxicity (LC50 = 0.055 mg/cm2) against H. longicornis nymphs. The allyl cinnamate was also tested for AChE activity in vivo in H. longicornis nymphs and was found to affect the AChE activity. Allyl cinnamate at 10-50 mg/mL inhibited egg laying of adult females of H. longicornis by 10-43%. Egg hatching was suppressed completely by treatment with allyl cinnamate at 50 mg/mL, whereas allyl cinnamate was minimally toxic against non-target earthworms, Eisenia fetida. These results suggest that allyl cinnamate can be used as an active ingredient for the development of eco-friendly tick acaricides against H. longicornis, a vector for Sever fever with thrombocytopenia syndrome (SFTS) virus.
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Affiliation(s)
- Min-Seung Kang
- Department of Bioenvironmental Chemistry, College of Agriculture and Life Sciences, Jeonbuk National University, Chonju, 54896, South Korea
| | - Jun-Hwan Park
- Department of Bioenvironmental Chemistry, College of Agriculture and Life Sciences, Jeonbuk National University, Chonju, 54896, South Korea.
| | - Hoi-Seon Lee
- Biomedical Research Team, HS Biotech and Holdings (HSBH) for Medical Research, Basel, Switzerland.
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4
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Qiao Y, Yu Z, Bai L, Li H, Zhang S, Liu J, Gao Z, Yang X. Chemical composition of essential oils from Thymus mongolicus, Cinnamomum verum, and Origanum vulgare and their acaricidal effects on Haemaphysalis longicornis (Acari: Ixodidae). ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 224:112672. [PMID: 34416637 DOI: 10.1016/j.ecoenv.2021.112672] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/27/2021] [Accepted: 08/15/2021] [Indexed: 06/13/2023]
Abstract
Chemical acaricides are mainly used in traditional tick control, which leads to the emergence of tick resistance and concurrently results in environmental pollution. In the present study, the chemical constituents of essential oils (EOs) from Thymus mongolicus, Cinnamomum verum, and Origanum vulgare was analyzed, and their potential application was evaluated to control the vector tick Haemaphysalis longicornis, which is widely distributed over vast areas of Eurasia, Australia, and New Zealand. Gas chromatography-mass spectrometry analysis revealed that the phenols thymol and carvacrol accounted for 34.66% and 75.72% of the EOs of T. mongolicus and O. vulgare, respectively, whereas trans-cinnamaldehyde (49.42%) was the main constituent of C. verum EO. Immersion tests showed that the EOs of C. verum and O. vulgare had significant acaricidal activity against larval H. longicornis, with the 50% lethal concentration (LC50) being 16.07 and 18.02 mg/mL, respectively, and the 95% lethal concentration (LC95) being 120.37 and 130.09 mg/mL, respectively. The EOs of O. vulgare and T. mongolicus showed significant acaricidal activity against unfed adult H. longicornis, with LC50 being 43.50 and 44.21 mg/mL, respectively, and LC95 being 113.66 and 137.99 mg/mL, respectively. The fumigant toxicity test showed significant acaricidal activity of the three EOs against both unfed and engorged nymphal and adult H. longicornis. Enzyme assays revealed that the EOs of both C. verum and O. vulgare significantly inhibited glutathione S-transferase activity (P < 0.05). In contrast, the activities of carboxylesterase and multifunction oxidases were significantly inhibited by EOs extracted from all three plants (P < 0.05). Taken together, these findings suggest that plant EOs may serve as an environment-friendly alternative for synthetic acaricides in future tick control.
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Affiliation(s)
- Ye Qiao
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Zhijun Yu
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Lingqian Bai
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Hao Li
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Songbo Zhang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Jingze Liu
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China
| | - Zhihua Gao
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
| | - Xiaolong Yang
- Hebei Key Laboratory of Animal Physiology, Biochemistry and Molecular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang 050024, China.
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Shang XF, Dai LX, Yang CJ, Guo X, Liu YQ, Miao XL, Zhang JY. A value-added application of eugenol as acaricidal agent: The mechanism of action and the safety evaluation. J Adv Res 2020; 34:149-158. [PMID: 35024187 PMCID: PMC8655235 DOI: 10.1016/j.jare.2020.12.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 11/27/2020] [Accepted: 12/18/2020] [Indexed: 12/21/2022] Open
Abstract
Introduction Eugenol is a major component of essential oils of several plants, it exhibits significant antiparasitic and acaricidal activities, yet its molecular targets remain unknown. Objectives We aimed to systematically investigate the mechanism of action and the potential targets of eugenol against P. cuniculi, and evaluate the safety for laying the theoretical foundation for clinical application as an acaricide. Methods Using RNA-Seq analysis, surface plasmon resonance analysis and RNA interference assay, the mode of action of eugenol against Psoroptes cuniculi was investigated. The effect on the mitochondrial membrane potential and complex I of PC12 cells and C6/36 cells was assayed to investigate the species specificity of eugenol in insects and mammals. Finally, a safety evaluation of eugenol in vivo was performed. Results Eugenol inhibited complex I activity of the mitochondrial respiratory chain in the oxidative phosphorylation pathway by binding to NADH dehydrogenase chain 2 and resulted in the death of mites. The inhibition rates were 37.89% for 50 μg/mL and 60.26% for 100 μg/mL, respectively. Further experiments indicated that the difference in the complex I sequence between insects and mammals led to the different affinity of eugenol to specific peptide, resulting in species specificity. Eugenol exhibited significant inhibitory effects against the mitochondrial membrane potential and complex I in Aedes albopictus C6/36 cells but was not active in rat PC12 cells. Insect cells were particularly sensitive to eugenol. In contrast to the known inhibitor rotenone, eugenol had better safety and did not result in Parkinson's disease or other diseases in rats. Conclusion This is the first report on acaricidal eugenol targeting complex I of the mitochondrial respiratory chain. This work lays the foundation for the development of eugenol as an environmentally alternative acaricidal agent.
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Affiliation(s)
- Xiao-Fei Shang
- Key Laboratory of New Animal Drug Project, Gansu Province, Key Laboratory of Veterinary Pharmaceutical Development of Ministry of Agriculture, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, PR China.,School of Pharmacy, Lanzhou University, Lanzhou 730000, P.R. China
| | - Li-Xia Dai
- Key Laboratory of New Animal Drug Project, Gansu Province, Key Laboratory of Veterinary Pharmaceutical Development of Ministry of Agriculture, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, PR China
| | - Chen-Jie Yang
- School of Pharmacy, Lanzhou University, Lanzhou 730000, P.R. China
| | - Xiao Guo
- Tibetan Medicine Research Center, Qinghai University, Xining 810016, P.R. China
| | - Ying-Qian Liu
- School of Pharmacy, Lanzhou University, Lanzhou 730000, P.R. China
| | - Xiao-Lou Miao
- Key Laboratory of New Animal Drug Project, Gansu Province, Key Laboratory of Veterinary Pharmaceutical Development of Ministry of Agriculture, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, PR China
| | - Ji-Yu Zhang
- Key Laboratory of New Animal Drug Project, Gansu Province, Key Laboratory of Veterinary Pharmaceutical Development of Ministry of Agriculture, Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, Lanzhou 730050, PR China
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Ruwizhi N, Aderibigbe BA. Cinnamic Acid Derivatives and Their Biological Efficacy. Int J Mol Sci 2020; 21:ijms21165712. [PMID: 32784935 PMCID: PMC7460980 DOI: 10.3390/ijms21165712] [Citation(s) in RCA: 160] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/30/2020] [Accepted: 05/06/2020] [Indexed: 12/17/2022] Open
Abstract
The role played by cinnamic acid derivatives in treating cancer, bacterial infections, diabetes and neurological disorders, among many, has been reported. Cinnamic acid is obtained from cinnamon bark. Its structure is composed of a benzene ring, an alkene double bond and an acrylic acid functional group making it possible to modify the aforementioned functionalities with a variety of compounds resulting in bioactive agents with enhanced efficacy. The nature of the substituents incorporated into cinnamic acid has been found to play a huge role in either enhancing or decreasing the biological efficacy of the synthesized cinnamic acid derivatives. Some of the derivatives have been reported to be more effective when compared to the standard drugs used to treat chronic or infectious diseases in vitro, thus making them very promising therapeutic agents. Compound 20 displayed potent anti-TB activity, compound 27 exhibited significant antibacterial activity on S. aureus strain of bacteria and compounds with potent antimalarial activity are 35a, 35g, 35i, 36i, and 36b. Furthermore, compounds 43d, 44o, 55g–55p, 59e, 59g displayed potent anticancer activity and compounds 86f–h were active against both hAChE and hBuChE. This review will expound on the recent advances on cinnamic acid derivatives and their biological efficacy.
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7
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Fang F, Li M, Jiang Z, Lu X, Guillot J, Si H. Comparing acaricidal and ovicidal activity of five terpenes from essential oils against Psoroptes cuniculi. Parasitol Res 2020; 119:4219-4223. [PMID: 32725319 DOI: 10.1007/s00436-020-06823-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 07/19/2020] [Indexed: 10/23/2022]
Abstract
Essential oils and their components represent an appealing alternative strategy against parasitic mites. The chemical complexity and variability of essential oils limit their use and additional work is required to analyze the efficacy and application rate of essential oils' individual components. In the present study, the activity of five terpenes (terpinen-4-ol, citral, linalool, eugenol, and geraniol) was evaluated against Psoroptes cuniculi motile stages and eggs collected from naturally infected rabbits. Eugenol presented the best acaricidal efficacy with a median lethal concentration (LC50) value of less than 0.1% at 24 h, followed by geraniol (0.33%), linalool (0.38%), citral (0.46%), and terpinen-4-ol (0.66%). Geraniol and eugenol were able to kill all mites within 5 min at 1% concentration. The effective concentration to inhibit 50% (EC50) of egg hatching was 0.65%, 0.66%, 0.85%, 1.47%, and 2.87% for eugenol, geraniol, citral, terpinen-4-ol, and linalool, respectively. In conclusion, eugenol, geraniol, citral, terpinen-4-ol, and linalool should be considered as promising agents for the development of botanical acaricides against Psoroptes cuniculi.
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Affiliation(s)
- Fang Fang
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Meilin Li
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Zitao Jiang
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Xiaodan Lu
- College of Animal Science and Technology, Guangxi University, Nanning, China
| | - Jacques Guillot
- Research Group Dynamyc, Ecole Nationale Vétérinaire d'Alfort, UPEC, USC ANSES, Maisons-Alfort, France
| | - Hongbin Si
- College of Animal Science and Technology, Guangxi University, Nanning, China.
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Gu X, Gu J, Ren Y, Zheng Y, Yang G, Zhou X, Xie Y. Evaluation of an Indirect ELISA Using Recombinant Arginine Kinase for Serodiagnosis of Psoroptes ovis var. cuniculi Infestation in Rabbits. Front Vet Sci 2019; 6:411. [PMID: 31824969 PMCID: PMC6879429 DOI: 10.3389/fvets.2019.00411] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 11/05/2019] [Indexed: 11/23/2022] Open
Abstract
Psoroptes ovis var. cuniculi is a common ectoparasite of the wild and domestic rabbits worldwide, which causes significant economic losses in commercial rabbit breeding. In China, the diagnosis of rabbits infested with P. ovis var. cuniculi currently relies on detection of clinical signs and Psoroptes mites in skin scrapings by microscopy examination. However, this method is not very efficient in detection of the low mite loads and/or sub-clinical infections. In the present study, we cloned and expressed an arginine kinase homolog gene from P. ovis var. cuniculi (Poc-AK) and used its recombinant protein rPoc-AK to develop an indirect enzyme-linked immunosorbent assay (iELISA) method for diagnosis of P. ovis var. cuniculi infestation in rabbits. The results showed that the rPoc-AK protein was ~61 kDa and had no signal peptide. The rPoc-AK-based iELISA achieved a 94.4% sensitivity and a 88.2% specificity, and was able to detect P. ovis var. cuniculi infection as early as the 1st week post-infection, prior to the appearance of clinical signs. Further field study showed 24.94% (66.33/266) clinically normal rabbits were seropositive with the highest and lowest seropositive rates for California (35.71%) and Belgian (15.14%), respectively. These results suggested that the rPoc-AK has potential as a diagnostic antigen for early P. ovis var. cuniculi infestation in rabbits.
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Affiliation(s)
- Xiaobin Gu
- Department of Parasitology, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Jiang Gu
- Department of Parasitology, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yongjun Ren
- Institute of Veterinary Pharmacology, Sichuan Animal Science Academy, Chengdu, China.,Animal Breeding and Genetics Key Laboratory of Sichuan Province, Sichuan Animal Science Academy, Chengdu, China
| | - Youle Zheng
- Department of Parasitology, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Guangyou Yang
- Department of Parasitology, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xuan Zhou
- Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
| | - Yue Xie
- Department of Parasitology, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
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Chen Z, van Mol W, Vanhecke M, Duchateau L, Claerebout E. Acaricidal activity of plant-derived essential oil components against Psoroptes ovis in vitro and in vivo. Parasit Vectors 2019; 12:425. [PMID: 31464634 PMCID: PMC6714348 DOI: 10.1186/s13071-019-3654-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 08/01/2019] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Treatment of Psoroptes ovis in cattle is limited to topical acaricides or systemic treatment with macrocyclic lactones. Treatment failure of macrocyclic lactones has been reported. The aim of this study was to evaluate a potential alternative treatment against P. ovis. METHODS The acaricidal activity against P. ovis of four plant-derived essential oil components, i.e. geraniol, eugenol, 1,8-cineol and carvacrol, was assessed in vitro and in vivo. In vitro contact, fumigation and residual bioassays were performed. In addition, 12 Belgium Blue cattle were artificially infested and treated topically once a week for three successive weeks with carvacrol in Tween-80 (treatment group) or with Tween-80 alone (control). The efficacy of carvacrol was determined by the reduction in lesion size and mite counts. Six additional animals were topically treated with carvacrol to assess local adverse reactions. RESULTS Three components showed a concentration-dependent acaricidal activity in a contact assay, with LC50 of 0.56, 0.38 and 0.26% at 24 h for geraniol, eugenol, and carvacrol, respectively. However, 1,8-cineol showed no activity at any of the tested concentrations in a contact bioassay. In a fumigation bioassay, carvacrol killed all mites within 50 min after treatment, whereas geraniol, eugenol and 1,8-cineol needed 90 to 150 min. Following a 72 h incubation period in a residual bioassay, carvacrol killed all mites after 4 h of exposure to LC90, while geraniol and eugenol killed all mites only after 8 h exposure. Based on these results, carvacrol was further assessed in vivo. Mite counts in the treatment group were reduced by 98.5 ± 2.4% at 6 weeks post-treatment, while in the control group the mite population had increased. Topical application of carvacrol only caused mild and transient erythema 20 min after treatment. No other side effects were observed. CONCLUSIONS Considering the strong acaricidal activity of carvacrol in vitro and in vivo and the mild and transient local side effects, carvacrol shows potential as an acaricidal agent in the treatment of P. ovis in cattle.
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Affiliation(s)
- Zhenzhen Chen
- Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Wouter van Mol
- Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Marieke Vanhecke
- Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Luc Duchateau
- Biometrics Research Center, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - Edwin Claerebout
- Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
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