title: Eugenol, α-pinene and β-caryophyllene from Plectranthus barbatus essential oil as eco-friendly larvicides against malaria, dengue and Japanese encephalitis mosquito vectors.
abstract: Mosquito-borne diseases represent a deadly threat for millions of people worldwide. Eco-friendly mosquitocides are a priority. In Ayurvedic medicine, Plectranthus species have been used to treat heart disease, convulsions, spasmodic pain and painful urination. In this research, we evaluated the acute toxicity of essential oil from Plectranthus barbatus and its major constituents, against larvae of the malaria vector Anopheles subpictus, the dengue vector Aedes albopictus and the Japanese encephalitis vector Culex tritaeniorhynchus. The chemical composition of P. barbatus essential oil was analyzed by gas chromatography-mass spectroscopy. Nineteen components were identified. Major constituents were eugenol (31.12%), α-pinene (19.38%) and β-caryophyllene (18.42%). Acute toxicity against early third-instar larvae of An. subpictus, Ae. albopictus and Cx. tritaeniorhynchus was investigated. The essential oil had a significant toxic effect against larvae of An. subpictus, Ae. albopictus and Cx. tritaeniorhynchus, with 50% lethal concentration (LC50) values of 84.20, 87.25 and 94.34 μg/ml and 90% lethal concentration (LC90) values of 165.25, 170.56 and 179.58 μg/ml, respectively. Concerning major constituents, eugenol, α-pinene and β-caryophyllene appeared to be most effective against An. subpictus (LC50 = 25.45, 32.09 and 41.66 μg/ml, respectively), followed by Ae. albopictus (LC50 = 28.14, 34.09 and 44.77 μg/ml, respectively) and Cx. tritaeniorhynchus (LC50 = 30.80, 36.75 and 48.17 μg/ml, respectively). Overall, the chance to use metabolites from P. barbatus essential oil against mosquito vectors seems promising, since they are effective at low doses and could be an advantageous alternative to build newer and safer mosquito control tools.
authors.affiliation: Unit of Vector Control, Phytochemistry and Nanotechnology, Department of Zoology, Annamalai University, Annamalai Nagar, 608002, Tamil Nadu, India. drgovindzoo@yahoo.com.
authors.forename: Marimuthu
authors.initials: M
authors.lastname: Govindarajan
authors.affiliation: Unit of Vector Control, Phytochemistry and Nanotechnology, Department of Zoology, Annamalai University, Annamalai Nagar, 608002, Tamil Nadu, India.
authors.forename: Mohan
authors.initials: M
authors.lastname: Rajeswary
authors.affiliation: Regional Medical Research Centre, Nehru Nagar, Belgaum, 590010, Karnataka, India.
authors.forename: S L
authors.initials: SL
authors.lastname: Hoti
authors.affiliation: Nanotechnology Section, Department of Biomedical Engineering, Rajiv Gandhi Institute of Technology, RT Nagar, Hebbal, Bangalore, 560032, India.
authors.forename: Atanu
authors.initials: A
authors.lastname: Bhattacharyya
authors.affiliation: Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, 56124, Pisa, Italy. benelli.giovanni@gmail.com.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Benelli
mesh_terms: D000330:Aedes / Q000187:drug effects; D000818:Animals; D000852:Anopheles / Q000187:drug effects; D000081008:Bicyclic Monoterpenes; D003465:Culex / Q000187:drug effects; D003715:Dengue / Q000635:transmission; D004672:Encephalitis, Japanese / Q000635:transmission; D005054:Eugenol / Q000737:chemistry / Q000494:pharmacology; D008401:Gas Chromatography-Mass Spectrometry; D007194:India; D007303:Insect Vectors / Q000187:drug effects; D007306:Insecticides / Q000737:chemistry / Q000494:pharmacology; D007814:Larva / Q000187:drug effects; D007928:Lethal Dose 50; D008288:Malaria / Q000635:transmission; D039821:Monoterpenes / Q000737:chemistry / Q000494:pharmacology; D009032:Mosquito Control / Q000379:methods*; D009822:Oils, Volatile / Q000737:chemistry* / Q000302:isolation & purification; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D031346:Plectranthus / Q000737:chemistry*; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes / Q000737:chemistry / Q000494:pharmacology; D013047:Specific Pathogen-Free Organisms
chemical_list: D000081008:Bicyclic Monoterpenes; D007306:Insecticides; D039821:Monoterpenes; D009822:Oils, Volatile; D010936:Plant Extracts; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes; D005054:Eugenol; C024714:caryophyllene; C005451:alpha-pinene
keywords: Aedes albopictus; Anopheles subpictus; Culex tritaeniorhynchus; Culicidae; GC-MS; Mosquito-borne diseases; Plant-borne larvicides