Angelica sinensis (Umbelliferae) with proven repellent properties against Aedes aegypti, the primary dengue fever vector in Thailand

Abstract

Botanical resources with great diversity in medicinal and aromatic plants are a rich and reliable source for finding insect repellents of plant origin, which are widely popular among today's consumers. Although some herbal-based repellents have been proven comparable to or even better than synthetics, commercially available natural repellents generally tend to be expensive, with short-lived effectiveness. This critical flaw leads to ongoing research for new and effective repellents, which provide longer protection against vector and nuisance-biting insects, while remaining safe, user friendly, and reasonably priced. This study aimed to evaluate the repellent activity of plant-derived products against the primary dengue vector, Aedes aegypti, by following the human bait technique of World Health Organization guidelines. Preliminary laboratory screening tests for repellency of 33 plant species clearly demonstrated Angelica sinensis as the most effective repellent from each kind of extracted product, with its essential oil and ethanolic extract having median complete protection times of 7.0 h (6.0-7.5) and 2.5 h (2.0-2.5), respectively. Due to its low yield (0.02 %), pungent smell, and little cause of irritation, A. sinensis essential oil did not qualify as a candidate for further repellent assessment. However, subsequent extractions of A. sinensis with different organic solvents of increasing polarity provided four extractants with varying degrees of repellency against A. aegypti. The hexane extract of A. sinensis provided excellent repellency, with a median complete protection time of 7.5 h (6.5-8.5), which was longer than that of ethanol (2.5, 2.0-2.5 h), acetone (1.75, 0.5-2.5 h), and methanol extracts (0.5, 0-1.0 h). By being the most effective product, A. sinensis hexane extract gave significant protection comparable to that of its essential oil and the standard synthetic repellent, N,N-diethyl-3-methylbenzamide (DEET: 6.25, 5.0-6.5 h). Qualitative gas chromatography/mass spectrometry analysis demonstrated the presence of phthalides and phthalates, including 3-N-butylphthalide, butylidenephthalide, ligustilide, and di-iso-octyl phthalate, as the principal constituents in A. sinensis products. The success of A. sinensis products, particularly that of hexane extract, has proved their potential as bioactive candidates in the next step for developing and producing alternative natural repellents with commercial aspirations.

Assessment of Angelica sinensis (Oliv.) Diels as a repellent for personal protection against mosquitoes under laboratory and field conditions in northern Thailand

“…The percentage composition of the remaining 18 compounds ranged from 0.16 to 3.70 %. This GC-MS profile corresponded relatively to that of AHE analyzed in a previous study [ 21 ], which revealed the presence of 13 chemicals, representing 95.17 % of the total quantities. The most abundant compound was 3- N -butylphthalide (70.14 %), whereas ligustilide (8.34 %) and butylidenephthalide (4.85 %) were minor constituents.…”

“…1 ) is a promising plant that has attracted substantial interest. Preliminary repellent assessments of various plant products, essential oils and solvent extracts, against laboratory-reared female Aedes aegypti mosquitoes highlighted A. sinensis hexane extract (AHE) as offering the longest-lasting protection time of 7.5 (6.5–8.5) h [ 21 ]. Phthalides, including 3- N -butylphthalide (70.14 %), ligustilide (8.34 %) and butylidenephthalide (4.85 %) were reported as the main and minor constituents in AHE, respectively.…”

“…Phthalides, including 3- N -butylphthalide (70.14 %), ligustilide (8.34 %) and butylidenephthalide (4.85 %) were reported as the main and minor constituents in AHE, respectively. No local skin reaction such as rash, irritation, hot sensation or swelling was observed in AHE-applied volunteers during the study period [ 21 ]. Interestingly, A. sinensis known commonly as dong quai (English) and dang gui (Chinese), the name of its root, has a history of medical application.…”

A Review of the Composition of the Essential Oils and Biological Activities of Angelica Species

“…Among them, the EO of A. dahurica showed a significant toxic effect against early fourth-stage larvae of Aedes aegypti, with a LC 50 value of 43.12 ppm. In another study, out of 33 plant species tested, A. sinensis EO showed the best repellent activity against Aedes aegypti, with a median complete protection time of 7.0 h [ 35 ].…”

Effects of Soil Sterilization on Growth of Angelica sinensis Plant and Soil Microbial Populations in a Continuous Mono-cropping Soil

“…Diels, is a perennial herb belonging to family Apiaceae, and commonly used in Traditional Chinese Medicine since ancient times (Zhang and Cheng, 1989). In addition, A. sinensis is widely used as an ingredient in cosmetic and health beverage at present (Chen, 2002;Champakaew et al, 2015). In order to meet its demand, areas of continuous cropped for A. sinensis have been increased dramatically in the last decade.…”