title: Assessment of Angelica sinensis (Oliv.) Diels as a repellent for personal protection against mosquitoes under laboratory and field conditions in northern Thailand.
abstract: Angelica sinensis (Oliv.) hexane extract (AHE) has been reported as a proven and impressive repellent against laboratory-reared female Aedes aegypti mosquitoes. With the aim of promoting products of plant origin as a viable alternative to conventional synthetic substances, this study was designed to transform AHE-based repellents for exploitable commercial production by enhancing their efficacy and assessing their physical and biological stability as well as repellency against mosquitoes under laboratory and field conditions.
  
  
  
  The chemical profile of AHE was analyzed by qualitative gas chromatography-mass spectrometry (GC-MS) technique. AHE was supplemented with vanillin, as a fixative, and then investigated for repellency and comparison to the standard synthetic repellent, DEET, under both laboratory and field conditions. Determination of physical and biological stability as a repellent was carried out after keeping AHE samples under varying temperatures and for different storage times.
  
  
  
  GC-MS analysis revealed that AHE contained at least 21 phytochemical compounds, constituting 95.74 % of the total content, with the major constituent of 3-N-butylphthalide (66.67 %). Ethanolic formulations of AHE and DEET showed improvement of repellency in a dose-dependent manner when vanillin was added in laboratory assessment. While 5-25 % AHE alone provided median complete-protection times of 2.0-6.5 h against Ae. aegypti, these times were increased to 4.0-8.5 h with a combination of AHE and 5 % vanillin (AHEv). Protection times against Ae. aegypti were extended from 2.25 to 7.25 h to 4.25-8.25 h when 5-25 % DEET was combined with 5 % vanillin (DEETv). In determining stability, all stored AHE samples exhibited similar characteristics such as liquid phases with aromatic odor comparable to those of fresh preparations. Furthermore, repellent activity of stored AHE samples lasted for at least six months, with varied efficacy (4.5-10.0 h) against Ae. aegypti. Field trials revealed strong repellency from both 25 % AHEv and 25 % DEETv, with complete protection (100 %) against a wide range of local mosquito populations. A total of 5,718 adult female mosquitoes, with the most predominant being Culex quinquefasciatus (41.47 %), Armigeres subalbatus (41.13 %), and Culex vishnui (10.53 %), was collected during field applications. No local skin reaction or other allergic responses was observed during both laboratory and field study periods.
  
  
  
  Angelica sinensis proved to have not only impressive repellency against both laboratory Ae. aegypti and a wide range of natural mosquito populations, but also relative stability in physical and biological performance.
authors.affiliation: Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
authors.forename: Danita
authors.initials: D
authors.lastname: Champakaew
authors.affiliation: Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
authors.forename: Anuluck
authors.initials: A
authors.lastname: Junkum
authors.affiliation: Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
authors.forename: Udom
authors.initials: U
authors.lastname: Chaithong
authors.affiliation: Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
authors.forename: Atchariya
authors.initials: A
authors.lastname: Jitpakdi
authors.affiliation: Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
authors.forename: Doungrat
authors.initials: D
authors.lastname: Riyong
authors.affiliation: Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
authors.forename: Anchalee
authors.initials: A
authors.lastname: Wannasan
authors.affiliation: Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
authors.forename: Jitrawadee
authors.initials: J
authors.lastname: Intirach
authors.affiliation: Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
authors.forename: Roongtawan
authors.initials: R
authors.lastname: Muangmoon
authors.affiliation: Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand.
authors.forename: Arpaporn
authors.initials: A
authors.lastname: Chansang
authors.affiliation: Department of Food Industry and Service, School of Culinary Arts, Suan Dusit Rajabhat University Lampang, Lampang, 52000, Thailand.
authors.forename: Benjawan
authors.initials: B
authors.lastname: Tuetun
authors.affiliation: Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand. benjawan.p@cmu.ac.th.
authors.forename: Benjawan
authors.initials: B
authors.lastname: Pitasawat
mesh_terms: D029971:Angelica sinensis / Q000737:chemistry*; D000818:Animals; D001572:Benzofurans / Q000737:chemistry; D009033:Culicidae / Q000187:drug effects*; D005260:Female; D006801:Humans; D007302:Insect Repellents / Q000737:chemistry / Q000494:pharmacology*; D019787:Linoleic Acid / Q000737:chemistry; D008297:Male; D015394:Molecular Structure; D010796:Phthalic Anhydrides / Q000737:chemistry; D010936:Plant Extracts / Q000494:pharmacology; D013785:Thailand
chemical_list: D001572:Benzofurans; D007302:Insect Repellents; D010796:Phthalic Anhydrides; D010936:Plant Extracts; C027125:3-n-butylphthalide; D019787:Linoleic Acid; C026105:butylidenephthalide
keywords: Aedes aegypti; Angelica sinensis; DEET; Dong quai; Field repellent; Mosquito repellency