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Marshall J Clark - One of the best experts on this subject based on the ideXlab platform.
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ovicidal and adulticidal activities of Origanum majorana essential oil constituents against insecticide susceptible and pyrethroid malathion resistant pediculus humanus capitis anoplura pediculidae
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Marshall J ClarkAbstract:The toxicity of essential oil constituents from marjoram, Origanum majorana, to eggs and adult females of the susceptible KR-HL and dual malathion- and permethrin-resistant BR-HL strains of human head louse, Pediculus humanus capitis, was examined using contact + fumigant mortality bioassay. Results were compared with those following treatment with two pyrethroid pediculicides, d-phenothrin or pyrethrum. As judged by the lethal time to 50% mortality (LT50) values at the exposure rate of 0.25 mg/cm2, 1,8-cineole (14.1 min) was the most toxic compound, followed by linalool (15.4 min) to KR-HL females. These compounds were faster acting than either d-phenothrin (24.1 min) or pyrethrum (33.4 min). Based on the lethal concentration causing 50% mortality (LC50) values, (−)-camphor (0.022 mg/cm2) was the most toxic compound, followed by linalool (0.035 mg/cm2), (−)-terpinen-4-ol (0.040 mg/cm2), α-terpineol (0.045 mg/cm2), and 1,8-cineole (0.068 mg/cm2) against KR-HL females. These monoterpenoids were less toxic ...
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ovicidal and adulticidal activities of Origanum majorana essential oil constituents against insecticide susceptible and pyrethroid malathion resistant pediculus humanus capitis anoplura pediculidae
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Youngcheol Yang, Si Hyeock Lee, Marshall J ClarkAbstract:The toxicity of essential oil constituents from marjoram, Origanum majorana, to eggs and adult females of the susceptible KR-HL and dual malathion- and permethrin-resistant BR-HL strains of human head louse, Pediculus humanus capitis, was examined using contact + fumigant mortality bioassay. Results were compared with those following treatment with two pyrethroid pediculicides, d-phenothrin or pyrethrum. As judged by the lethal time to 50% mortality (LT(50)) values at the exposure rate of 0.25 mg/cm(2), 1,8-cineole (14.1 min) was the most toxic compound, followed by linalool (15.4 min) to KR-HL females. These compounds were faster acting than either d-phenothrin (24.1 min) or pyrethrum (33.4 min). Based on the lethal concentration causing 50% mortality (LC(50)) values, (-)-camphor (0.022 mg/cm(2)) was the most toxic compound, followed by linalool (0.035 mg/cm(2)), (-)-terpinen-4-ol (0.040 mg/cm(2)), alpha-terpineol (0.045 mg/cm(2)), and 1,8-cineole (0.068 mg/cm(2)) against KR-HL females. These monoterpenoids were less toxic than either d-phenothrin (LC(50), 0.0015 mg/cm(2)) or pyrethrum (0.0013 mg/cm(2)). However, the toxicities of these monoterpenoids were almost identical against females from either of the two strains, even though the BR-HL females exhibited high levels of resistance to d-phenothrin [resistance ratio (RR), 667] and pyrethrum (RR, 754). After a 24 h exposure to linalool, BR-HL egg hatch was inhibited 100 and 84% at 0.25 or 0.125 mg/cm(2), respectively, while (-)-terpinen-4-ol caused 94 and 69% inhibition of egg hatch at 0.25 and 0.125 mg/cm(2). alpha-Terpineol caused 88 and 76% inhibition of egg hatch at 0.5 and 0.25 mg/cm(2), respectively. Thus, certain monoterpenoids from O. majorana essential oil, particularly linalool, (-)-terpinen-4-ol and alpha-terpineol, merit further study as potential pediculicides and ovicides for the control of insecticide-resistant P. h. capitis populations as fumigants with contact action.
Youngcheol Yang - One of the best experts on this subject based on the ideXlab platform.
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ovicidal and adulticidal activities of Origanum majorana essential oil constituents against insecticide susceptible and pyrethroid malathion resistant pediculus humanus capitis anoplura pediculidae
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Youngcheol Yang, Si Hyeock Lee, Marshall J ClarkAbstract:The toxicity of essential oil constituents from marjoram, Origanum majorana, to eggs and adult females of the susceptible KR-HL and dual malathion- and permethrin-resistant BR-HL strains of human head louse, Pediculus humanus capitis, was examined using contact + fumigant mortality bioassay. Results were compared with those following treatment with two pyrethroid pediculicides, d-phenothrin or pyrethrum. As judged by the lethal time to 50% mortality (LT(50)) values at the exposure rate of 0.25 mg/cm(2), 1,8-cineole (14.1 min) was the most toxic compound, followed by linalool (15.4 min) to KR-HL females. These compounds were faster acting than either d-phenothrin (24.1 min) or pyrethrum (33.4 min). Based on the lethal concentration causing 50% mortality (LC(50)) values, (-)-camphor (0.022 mg/cm(2)) was the most toxic compound, followed by linalool (0.035 mg/cm(2)), (-)-terpinen-4-ol (0.040 mg/cm(2)), alpha-terpineol (0.045 mg/cm(2)), and 1,8-cineole (0.068 mg/cm(2)) against KR-HL females. These monoterpenoids were less toxic than either d-phenothrin (LC(50), 0.0015 mg/cm(2)) or pyrethrum (0.0013 mg/cm(2)). However, the toxicities of these monoterpenoids were almost identical against females from either of the two strains, even though the BR-HL females exhibited high levels of resistance to d-phenothrin [resistance ratio (RR), 667] and pyrethrum (RR, 754). After a 24 h exposure to linalool, BR-HL egg hatch was inhibited 100 and 84% at 0.25 or 0.125 mg/cm(2), respectively, while (-)-terpinen-4-ol caused 94 and 69% inhibition of egg hatch at 0.25 and 0.125 mg/cm(2). alpha-Terpineol caused 88 and 76% inhibition of egg hatch at 0.5 and 0.25 mg/cm(2), respectively. Thus, certain monoterpenoids from O. majorana essential oil, particularly linalool, (-)-terpinen-4-ol and alpha-terpineol, merit further study as potential pediculicides and ovicides for the control of insecticide-resistant P. h. capitis populations as fumigants with contact action.
Silvano, Isabel Claudino - One of the best experts on this subject based on the ideXlab platform.
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Desenvolvimento de filme polimérico contendo extrato de Origanum majorana para aplicação como despigmentante e hidratante
2018Co-Authors: Silvano, Isabel ClaudinoAbstract:Introdução: Dentre os tratamentos de hipercromias disponíveis no mercado, a hidroquinona é um ativo comumente utilizado, porém pode oferecer riscos de toxicidade celular. Já foi comprovado que a arbutina possui atividades clareadores similares as da hidroquinona, porém com menos efeitos adversos. A arbutina está presente na planta Origanum majorana, que por sua vez possui em suas folhas grandes quantidade de polifenóis, os quais também apresentam atividade antioxidante e de clareamento. Diferentes formas farmacêuticas são utilizadas como base para os ativos e o desenvolvimento de uma formulação a base de gel formador de filme podem aumentar o tempo de exposição dos ativos na pele aumentando sua permeação e atividade. Objetivo: Desenvolver e avaliar atividade hidratante e despigmentante de um gel formador de filme com extrato de Origanum majorana rico em polifenóis e arbutina. Métodos: Primeiramente foi preparado o extrato de Origanum majorana rico em polifenóis e arbutina. Em seguida foram preparados géis formadores de filme com uma blenda polimérica de Poli álcool vinílico (PVA) e Poli vinil pirrolidona (PVP) na proporção de (40:60) contendo 14, 16 e 18%. Foram avaliadas as propriedades do gel formador de filme em relação a viscosidade, tempo de secagem, espessura do filme formado e suas atividades de hidratação cutânea para a seleção da formulação para a incorporação do extrato. O extrato foi incorporado na formulação de acordo com a proporção de glicerol presente na formulação e no extrato. foram repetidos os testes anteriores e determinado uma quantidade de gel formador de filme para aplicação no estudo clinico. Foi realizado um estudo clínico com abordagem quantitativa para determinar atividade hidratante e despigmentante do gel formador de filme com extrato de Origanum majorana. Resultados: O extrato produzido apresentou 1,76% de arbutina e 22,30% de polifenóis. A formulação selecionada para a incorporação do extrato de Origanum majorana foi a com 16% de PVA/PVP na formulação (F16OM), resultando na concentração de 0,11% de arbutina. Esta quando aplicada na massa de 5mg/cm² apresentou 5 minutos no tempo de secagem na pele. O estudo clínico foi realizado com amostra de 16 voluntárias para o teste de sensibilidade cutânea (7 dias), hidratação e despigmentação (30 dias). Houve uma exclusão por esquecimento da aplicação do produto por 6 dias. Os voluntários utilizaram uma formulação em cada antebraço (antebraço esquerdo F16, antebraço direito F16OM). Os sujeitos do estudo não apresentaram nenhuma sensibilidade ou irritação durante a utilização das formulações. Um aumento significativo para a hidratação da pele foi observado, porém sem diferenças entre a formulação controle e F16OM. O gel formador de filme F16OM promoveu redução significativa da pigmentação, sendo duas vezes superior a efeito da formulação controle. Conclusão: A formulação F16OM apresentou características físico-químicas que proporcionam uma adequada aplicação na pele e resultados significativos de incremento de hidratação e de despigmentação cutânea, apresentando-se como alternativa potencial para tratamento de hipercromias
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Desenvolvimento de filme polimérico contendo extrato de Origanum majorana para aplicação como despigmentante e hidratante
2018Co-Authors: Silvano, Isabel ClaudinoAbstract:Submitted by Isabel Claudino Silvano (isabel.silvano@unisul.br) on 2019-07-31T19:38:40Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO_ISABEL.pdf: 2117079 bytes, checksum: 3eddb92a1d989c27bf71e30d4dca38da (MD5)Rejected by Silvane Cauz (silvane.cauz@unisul.br), reason: A dissertação anexada deverá conter a folha de rosto assinada pelos avaliadores da banca (substituir pela folha que está com os nomes sem a assinatura). Obrigada. Att. on 2019-08-02T13:35:32Z (GMT)Submitted by Isabel Claudino Silvano (isabel.silvano@unisul.br) on 2019-09-03T23:00:12Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO_ISABEL.pdf: 2369872 bytes, checksum: f29eb3fb7231060df4cdcdd4c2d70db1 (MD5)Approved for entry into archive by Silvane Cauz (silvane.cauz@unisul.br) on 2019-09-06T17:36:21Z (GMT) No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO_ISABEL.pdf: 2369872 bytes, checksum: f29eb3fb7231060df4cdcdd4c2d70db1 (MD5)Made available in DSpace on 2019-09-06T17:36:21Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO_ISABEL.pdf: 2369872 bytes, checksum: f29eb3fb7231060df4cdcdd4c2d70db1 (MD5) Previous issue date: 2018Introdução: Dentre os tratamentos de hipercromias disponíveis no mercado, a hidroquinona é um ativo comumente utilizado, porém pode oferecer riscos de toxicidade celular. Já foi comprovado que a arbutina possui atividades clareadores similares as da hidroquinona, porém com menos efeitos adversos. A arbutina está presente na planta Origanum majorana, que por sua vez possui em suas folhas grandes quantidade de polifenóis, os quais também apresentam atividade antioxidante e de clareamento. Diferentes formas farmacêuticas são utilizadas como base para os ativos e o desenvolvimento de uma formulação a base de gel formador de filme podem aumentar o tempo de exposição dos ativos na pele aumentando sua permeação e atividade. Objetivo: Desenvolver e avaliar atividade hidratante e despigmentante de um gel formador de filme com extrato de Origanum majorana rico em polifenóis e arbutina. Métodos: Primeiramente foi preparado o extrato de Origanum majorana rico em polifenóis e arbutina. Em seguida foram preparados géis formadores de filme com uma blenda polimérica de Poli álcool vinílico (PVA) e Poli vinil pirrolidona (PVP) na proporção de (40:60) contendo 14, 16 e 18%. Foram avaliadas as propriedades do gel formador de filme em relação a viscosidade, tempo de secagem, espessura do filme formado e suas atividades de hidratação cutânea para a seleção da formulação para a incorporação do extrato. O extrato foi incorporado na formulação de acordo com a proporção de glicerol presente na formulação e no extrato. foram repetidos os testes anteriores e determinado uma quantidade de gel formador de filme para aplicação no estudo clinico. Foi realizado um estudo clínico com abordagem quantitativa para determinar atividade hidratante e despigmentante do gel formador de filme com extrato de Origanum majorana. Resultados: O extrato produzido apresentou 1,76% de arbutina e 22,30% de polifenóis. A formulação selecionada para a incorporação do extrato de Origanum majorana foi a com 16% de PVA/PVP na formulação (F16OM), resultando na concentração de 0,11% de arbutina. Esta quando aplicada na massa de 5mg/cm² apresentou 5 minutos no tempo de secagem na pele. O estudo clínico foi realizado com amostra de 16 voluntárias para o teste de sensibilidade cutânea (7 dias), hidratação e despigmentação (30 dias). Houve uma exclusão por esquecimento da aplicação do produto por 6 dias. Os voluntários utilizaram uma formulação em cada antebraço (antebraço esquerdo F16, antebraço direito F16OM). Os sujeitos do estudo não apresentaram nenhuma sensibilidade ou irritação durante a utilização das formulações. Um aumento significativo para a hidratação da pele foi observado, porém sem diferenças entre a formulação controle e F16OM. O gel formador de filme F16OM promoveu redução significativa da pigmentação, sendo duas vezes superior a efeito da formulação controle. Conclusão: A formulação F16OM apresentou características físico-químicas que proporcionam uma adequada aplicação na pele e resultados significativos de incremento de hidratação e de despigmentação cutânea, apresentando-se como alternativa potencial para tratamento de hipercromias
Brahim Marzouk - One of the best experts on this subject based on the ideXlab platform.
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effect of growth stages on phenolics content and antioxidant activities of shoots in sweet marjoram Origanum majorana l varieties under salt stress
African Journal of Biotechnology, 2012Co-Authors: Olfa Baatour, Brahim Marzouk, Rym Kaddour, Imen Tarchoun, Nawel Nasri, Jamel Harrathi, E Drawi, Mouhiba Mouhiba, Ben Nasriayachi, Mokhtar LachaâlAbstract:We investigated the contributions of salinity and development stage on total polyphenols, flavonoids, condensed tannins contents, phenolic content, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide scavenging activities at three phenolic stages: early vegetative stage (EVS), late or prefloral vegetative (LVS) stage and flowering stage (FS). The total phenolic, flavonoids and condensed tannins contents were more important in the presence and absence of salt at prefloral or building stage than at EVS and FS. In addition, salt stress increased total polyphenol and individual phenolic contents in shoots of Origanum majorana. This increase was more important in LVS than in EVS and FS. Moreover, the antiradical activity of the shoots (DPPH) decreased with the addition of NaCl. In fact, LVS extracts showed the highest antioxidant properties. Furthermore, at LVS, marjoram grown at 75 mM showed a higher antiradical ability against DPPH radical and antioxidant activity, compared to EVS and LVS. Data reported here revealed the variation of phenolic compound contents at different stages of growth of O. majorana, and the possible role of these changes in the response of the plant to salt was also discussed. Key words : Antiradical activity, Origanum majorana, early vegetative stage (EVS), late or prefloral vegetative (LVS) stage and flowering stage (FS), phenolic content.
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modification of fatty acid essential oil and phenolic contents of salt treated sweet marjoram Origanum majorana l according to developmental stage
Journal of Food Science, 2012Co-Authors: Olfa Baatour, Brahim Marzouk, Rym Kaddour, Imen Tarchoun, Nawel Nasri, Hela Mahmoudi, Maha Zaghdoudi, H Ghaith, Mouhiba Ben Nasriayachi, Mokhtar LachaâlAbstract:Variation in the composition of Origanum majorana L. essential oil (EO) and fatty acids were studied under salt treatment. Plant material has been harvested at 2 phenological stages: early vegetative stage (EVS) and late vegetative stage (LVS) or prefloral. Our results showed that the application of 75 mM NaCl increased total lipid contents in marjoram shoots and caused great qualitative changes in the fatty acids profiles. NaCl treatment reduced and stimulated the EO yields, respectively, at EVS and LVS and induced quantitative changes in the chemical EO composition in shoots. Phenolic contents were higher during the LVS than EVS in the absence and the presence of salt. Under control conditions, RP-HPLC analysis of the methanolic extract of marjoram dried shoots showed a predominance of flavonoid during the EVS whereas phenolic acids predominated during the LVS. However, under 75 mM NaCl, we noted a predominance of flavonoid at LVS and constant levels of phenolic and flavonoid classes at the EVS. For control treatment and at both EVS and LVS, the main components identified were respectively rosmarinic acid gallic as phenolic acids and amentoflavone as flavonoid. In the presence of salt and at the EVS, we observed a significant increase in trans-2 hydrocinnamic, gallic acid and quercetin-3-galactoside contents. However, for the LVS, salt induced a stimulation of gallic acid, apigenin, and amentoflavone. Our results showed that LVS had the highest contents of bioactive compounds, and could be considered as the best stage for harvesting marjoram plants. Practical Application: In this study, the fatty acid composition, essential oil, and phenolic content of Origanum majorana were investigated. This is important for potential application of marjoram as functional food at the late vegetative stage. The richness of O. majorana in volatile and phenolic active compounds known for their antioxidant, antimicrobial, and insecticidal activities could support the utilization of this plant in a large field of application including cosmetic, pharmaceutical, agro alimentary, and biological defense.
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essential oil yield and trichomes structure in two sweet marjoram Origanum majorana l varieties under salt stress
Journal of Medicinal Plants Research, 2012Co-Authors: Olfa Baacirc, Rym Kaddour, Imen Tarchoun, Hela Mahmoudi, Mouhiba Ben Nasriayachi, Nawel Nassri, Jamel Ghaith Hamdaoui, Mokhtar Lachaacirc, Brahim MarzoukAbstract:Origanum majorana L. shoots were investigated for their essential oil (EO) yield, composition and the structures responsible for its biosynthesis. Shoots EO was extracted by hydrodistillation and composition was determined by gas chromatography–mass spectrometry (GC-MS) method. Fresh Leaves were observed by light microscopy (LM). Plants were cultivated for 17 days in a basal medium supplemented with 75 mM NaCl. Salt decreased the essential oil yield in Tunisian variety (TV), but an increase was shown in Canadian variety (CV). Salt constraint induced a change in EO chemotype of two varieties. Their anatomical study showed three types of trichomes: (i) non-glandular, simple hairs; (ii) small, capitate glandular trichomes; (iii) and peltate glandular trichomes. Non-glandular trichomes provided of three types at the TV against two at the Canadian one at control. Indeed, with TV we observed; multicellular (M), bicellular (B) and unicellular (U) trichomes. Bicellular trichomes (BT) were observed in CV, and multicellular (MT) and bicellular (UT) in TV at salt constraint. The increase and the decrease of EO yield in CV and TV was respectively due to the presence of three type of EO secretion which seemed to make defect in Tunisian one. Key words: Trichomes, non-glandular, capitate, peltate, glandular, salt, chemotype.
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salinity effects on growth essential oil yield and composition and phenolic compounds content of marjoram Origanum majorana l leaves
Journal of Food Biochemistry, 2011Co-Authors: Nahida Jelali, Thouraya Chahed, Wissal Dhifi, Brahim MarzoukAbstract:The effect of irrigation with different NaCl levels (0.9, 5 and 10 ds/m) on growth, essential oil yield and composition, in addition to polyphenol content of Tunisian marjoram (Origanum majorana L.) leaves was investigated. Plant growth and chlorophyll content were significantly decreased with increasing NaCl levels. The essential oil yield increased significantly up to 55.5% with 5 ds/m NaCl and decreased significantly at high salinity. Terpinene-4-ol, γ-terpinene, cis-sabinene-hydrate and α-terpineol were found as the main volatile compound of marjoram leaf essential oil. Further, salinity effect was highly significant for the content of these compounds and depending on the treatment level. The most represented class was monoterpene alcohols (870.6 µg/g dry weight [DW]) represented by terpinene-4-ol (555.1 µg/g DW) and remains the major one at different salt levels, followed by monoterpene hydrocarbons (335.54 µg/g DW). Moreover, salinity affected differently phenolic compounds content of marjoram leaves. PRACTICAL APPLICATIONS This work was carried out as a first step for a chemical and biological activity of Tunisian Origanum majorana through phenolic and essential oil composition. A further identification, isolation and purification of O. majorana phenolics and volatiles will be associated to an application in food industry as antioxydants, additives for food preservation and for enhancing their nutritional value and organoleptic quality. This study could be continued by the investigation of the antimicrobial activity of O. majorana bioactive compounds with the purpose of an eventual use to prevent growth of many foodborne and food spoilage microorganisms in foods. Furthermore, a pharmacological study could be established through in vivo assays in order to discover new anticarcenogenic, antinflammatory, antimutagenic and other activities of O. majorana. Such results could be used in pharmaceutical formulations leading to new human drugs from this medicinal plant.
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effect of growth stage on the content and composition of the essential oil and phenolic fraction of sweet marjoram Origanum majorana l
Industrial Crops and Products, 2009Co-Authors: Ibtissem Hamrouni Sellami, Emna Maamouri, Thouraya Chahed, Wissem Aidi Wannes, Mohamed Elyes Kchouk, Brahim MarzoukAbstract:Abstract The variation in the content and composition of Origanum majorana L. essential oil has been studied. Plant material has been harvested at four phenological stages (early vegetative, late vegetative, budding and full-flowering). Essential oil yield varied from 0.04 to 0.09% reached during the full-flowering stage. Analysis of the essential oils by GC and GC/MS revealed the presence of 38 components represented mainly by oxygenated monoterpenes (64.01–71.4%), monoterpene hydrocarbons (21.73–29.92%) and sesquiterpene hydrocarbons (1.47–4.05%). The main components were terpinen-4-ol (29.13–32.57%), cis-sabinene hydrate (19.9–29.27%), trans-sabinene hydrate (3.5–11.61%), γ-terpinene (2.11–8.20%), bornyl acetate (1.52–2.94%) and linalool (1.05–1.39%). On the other hand, phenolic contents varied from 2.706 to 6.834 mg/g of dry weight obtained during the later vegetative stage. RP-HPLC analysis of the methanolic extract of O. majorana L. dried aerial parts showed the predominance of phenolic acids during the early vegetative stage whereas flavonoids predominate during the other stages of growth. The main phenolic acids identified were trans-2-hydroxycinnamic, rosmarinic, vanillic, chlorogenic, gallic and cinnamic whereas the main flavonoids were amentoflavone, apigenin, quercetin, luteolin, coumarin and rutin. Results obtained showed that later vegetative stage is characterized by the highest contents of bioactive compounds and therefore it could be considered as the best stage for harvesting marjoram plants.
Si Hyeock Lee - One of the best experts on this subject based on the ideXlab platform.
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ovicidal and adulticidal activities of Origanum majorana essential oil constituents against insecticide susceptible and pyrethroid malathion resistant pediculus humanus capitis anoplura pediculidae
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Youngcheol Yang, Si Hyeock Lee, Marshall J ClarkAbstract:The toxicity of essential oil constituents from marjoram, Origanum majorana, to eggs and adult females of the susceptible KR-HL and dual malathion- and permethrin-resistant BR-HL strains of human head louse, Pediculus humanus capitis, was examined using contact + fumigant mortality bioassay. Results were compared with those following treatment with two pyrethroid pediculicides, d-phenothrin or pyrethrum. As judged by the lethal time to 50% mortality (LT(50)) values at the exposure rate of 0.25 mg/cm(2), 1,8-cineole (14.1 min) was the most toxic compound, followed by linalool (15.4 min) to KR-HL females. These compounds were faster acting than either d-phenothrin (24.1 min) or pyrethrum (33.4 min). Based on the lethal concentration causing 50% mortality (LC(50)) values, (-)-camphor (0.022 mg/cm(2)) was the most toxic compound, followed by linalool (0.035 mg/cm(2)), (-)-terpinen-4-ol (0.040 mg/cm(2)), alpha-terpineol (0.045 mg/cm(2)), and 1,8-cineole (0.068 mg/cm(2)) against KR-HL females. These monoterpenoids were less toxic than either d-phenothrin (LC(50), 0.0015 mg/cm(2)) or pyrethrum (0.0013 mg/cm(2)). However, the toxicities of these monoterpenoids were almost identical against females from either of the two strains, even though the BR-HL females exhibited high levels of resistance to d-phenothrin [resistance ratio (RR), 667] and pyrethrum (RR, 754). After a 24 h exposure to linalool, BR-HL egg hatch was inhibited 100 and 84% at 0.25 or 0.125 mg/cm(2), respectively, while (-)-terpinen-4-ol caused 94 and 69% inhibition of egg hatch at 0.25 and 0.125 mg/cm(2). alpha-Terpineol caused 88 and 76% inhibition of egg hatch at 0.5 and 0.25 mg/cm(2), respectively. Thus, certain monoterpenoids from O. majorana essential oil, particularly linalool, (-)-terpinen-4-ol and alpha-terpineol, merit further study as potential pediculicides and ovicides for the control of insecticide-resistant P. h. capitis populations as fumigants with contact action.