Identification of Larvicidal Constituents of the Essential Oil of Echinops grijsii Roots against the Three Species of Mosquitoes

Abstract

The screening of Chinese medicinal herbs for insecticidal principles showed that the essential oil of Echinops grijsii Hance roots possessed significant larvicidal activity against mosquitoes. The essential oil was extracted via hydrodistillation and its constituents were determined by gas chromatography-mass spectrometry (GC-MS) analysis. GC-MS analyses revealed the presence of 31 components, with 5-(3-buten-1-yn-1-yl)-2,2′-bithiophene (5-BBT, 27.63%), α-terthienyl (α-T, 14.95%), 1,8-cineole (5.56%) and cis-β-ocimene (5.01%) being the four major constituents. Based bioactivity-directed chromatographic separation of the essential oil led to the isolation of 5-BBT, 5-(4-isovaleroyloxybut-1-ynyl)-2,2′-bithiophene (5-IBT) and α-T as active compounds. The essential oil of E. grijsii exhibited larvicidal activity against the fourth instar larvae of Aedes albopictus, Anopheles sinensis and Culex pipiens pallens with LC50 values of 2.65 μg/mL, 3.43 μg/mL and 1.47 μg/mL, respectively. The isolated thiophenes, 5-BBT and 5-IBT, possessed strong larvicidal activity against the fourth instar larvae of Ae. albopictus (LC50 = 0.34 μg/mL and 0.45 μg/mL, respectively) and An. sinensis (LC50 = 1.36 μg/mL and 5.36 μg/mL, respectively). The two isolated thiophenes also had LC50 values against the fourth instar larvae of C. pipiens pallens of 0.12 μg/mL and 0.33 μg/mL, respectively. The findings indicated that the essential oil of E. grijsii roots and the isolated thiophenes have an excellent potential for use in the control of Ae. albopictus, An. sinensis and C. pipiens pallens larvae and could be used in the search for new, safer and more effective natural compounds as larvicides.

Comparative chemical analysis of volatile compounds of Echinops ilicifolius using hydrodistillation and headspace solid-phase microextraction and the antibacterial activities of its essential oil

“…Like many other representatives of the family Compositae, Echinops species produce essential oils and volatile components, but in spite of the large size of this genus, the composition of the volatile constituents is known only for a small number of species [9,25,[31][32][33][34][35]; therefore, developing different techniques can be used for the extraction of volatile organic components from plants. Hydrodistillation (HD) and headspace solid-phase microextraction (HS-SPME) are common extraction methods.…”

Phytochemical Composition and Biological Activities of Dyssodia tagetiflora Lag.

“…anthemidifolia . α ‐Terthienyl and BBT have allelochemical activities; both compounds are considered phototoxins with insecticidal activity . On the other hand, α ‐terthienyl has photooxidant [ ][ ] and anti‐HIV properties .…”

“…[4] a-Terthienyl and BBT have allelochemical activities; [21] both compounds are considered phototoxins with insecticidal activity. [22] On the other hand, a-terthienyl has photooxidant [23] [24] and anti-HIV properties. [25] Note that 5-methyl-2,2 0 :5 0 ,2″-terthiophene (6) has shown antileishmanial activity.…”

The Genus Echinops: Phytochemistry and Biological Activities: A Review

“…Bioactivity-directed chromatographic separation of the essential oil obtained from E. grijsii led to the isolation of thiophenes. The larvicidal effects of the isolated compounds, 5-(3-buten-1-yn-1-yl)-2,2′-bithiophene ( 1 ) (LC 50 0.34, 1.36, and 0.12 µg/mL), α-terthienyl ( 2 ) (LC 50 1.41, 1.79, and 1.38 µg/mL), and 5-(4-isovaleroyloxybut-1-ynyl)-2,2'-bithiophene ( 18 ) (LC 50 0.45, 5.36, and 0.33 µg/mL) against the three organisms mentioned above was described (Zhao et al, 2017). On the contrary, the larvicidal activity of essential oils from E. giganteus against Culex quinquefasciatus was relatively low (LC 50 = 227.4 μL/L) (Pavela et al, 2016).…”