Chemical Composition and Biological Activities of Chromolaena odorata (L.) R.M.King & H.Rob. Essential Oils from Central Vietnam

Abstract

The chemical composition of leaf essential oil of the harmful invasive species Chromolaena odorata collected in Vietnam was analyzed by GC/MS and chiral GC. All three essential oil samples (O1, O2 and O3) in this study fell into chemotype I characterized by α-pinene/geigerene/germacrene D/(E)-β-caryophyllene from a total of six different chemotypes. Chemotype I demonstrated larvicidal effects against Aedes aegypti (Linnaeus, 1762), Aedes albopictus Aedes albopictus (Skuse, 1894), Culex fuscocephala (Theobald, 1907) and Culex quinquefasciatus (Say, 1823), with 24 h LC₅₀ values ranging from 11.73 to 69.87 µg/mL. In contrast, its microemulsion formulation exhibited enhanced toxicity, yielding 24 h LC₅₀ values between 11.16 and 32.43 µg/mL. This chemotype also showed repellent efficacy against Ae. aegypti, with protection times ranging from 70.75 to 122.7 min. Fumigant toxicity was observed against Aedes aegypti, with LC₅₀ values of 40.27% at 0.5 h and 0.34% at 24 h. Molluscicidal activity was recorded with 48 h LC₅₀ values between 3.82 and 54.38 µg/mL against Indoplanorbis exustus (Deshayes, 1833), Pomacea canaliculate (Lamarck, 1822), Physa acuta (Draparnaud, 1805). Additionally, the chemotype exhibited acetylcholinesterase inhibitory activity, with an IC₅₀ value of 70.85 µg/mL. Antimicrobial potential was also demonstrated, with MIC values ranging from 2.0 to 128.0 µg/mL against Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus, Escherichia coli, Salmonella enterica, and Candida albicans. The C. odorata essential oil can be considered as a potential bioresource for human health protection strategies.

Keywords: Aedes spp.; Culex spp.; antimicrobial; biopesticide; intermediate host.

Figure 1

Dendrogram based on agglomerative hierarchical cluster analysis of chemical compositions of Chromolaena odorata essential oils. Principal component analysis of chemical compositions of Chromolaena odorata essential oils. Details on the components, full chemical composition, and collection locations of the essential oil samples corresponding to codes O1 to O40 are available in Supplementary Material Table S1.

Figure 2

Principal component analysis of chemical compositions of C. odorata essential oils. O4: [27]; O5: [28]; O6: [29]; O7: [30]; O8: [31]; O9: [4]; O10: [32]; O11: [32]; O12: [3]; O13: [33]; O14: [33]; O15–O22: [34]; O23–O29: [35]; O30: [36]; O31: [37]; O32–O36: [38]; O37: [39]; O38–O39: [40]; and O40: [41]. Details on the components, full chemical composition, and collection locations of the essential oil samples corresponding to codes O1 to O40 are available in Supplementary Material Table S1.

Figure 3

Dynamic light scattering (DLS) traces of microemulsions (MEs) at different timepoints (t1 and t30 days).

Figure 4

Mortality rate (%) of mosquito larvae at different concentrations of samples O1, O2, O3 and MO1 after 24 h of exposure, with mean ± SE. Values followed by the same letter (a–c) at each concentration are not statistically different at p < 0.05 as measured by Tukey’s test. (A) Aedes aegypti. (B) Aedes albopictus. (C) Culex quinquefasciatus. (D) Culex fuscocephala.

Figure 5

Mortality rate (%) of mosquito larvae at different concentrations of samples O1, O2, O3 and MO1 after 48 h of exposure, with mean ± SE. Values followed by the same letter (a–c) at each concentration are not statistically different at p < 0.05 as measured by Tukey’s test. (A) Aedes aegypti. (B) Aedes albopictus. (C) Culex quinquefasciatus. (D) Culex fuscocephala.

Figure 6

Repellent efficacy (mean ± SD) of Chromolaena odorata essential oils (O1 and O3) and DEET against Aedes aegypti. Bars with the same letters are not significantly different (p > 0.05, ANOVA followed by Tukey’s test).

Figure 7

Mortality rate (%) of snails at different concentrations of samples O1, O2, O3, and MO1 with mean ± SE. Values followed by the same letter (a–c) at each concentration are not statistically different at p < 0.05 as measured by Tukey’s test. (A) Physa acuta. (B) Indoplanorbis exustus. (C) Pomacea canaliculata.