Compositions analysis and insecticidal activity of Aconitum polycarpum Chang ex W.T.Wang petroleum ether fractions and essential oils.

Ethnopharmacological Relevance: The Aconitum genus plants as a natural pesticide for insecticide and rodent control has been recorded in Chinese folk. However, the insecticide effect, mechanism, and active composition of Aconitum polycarpum Chang ex W.T.Wang have not been studied further.
Aim of the Study: This study was designed to analyze the chemical composition, evaluate contact toxicity of petroleum ether extracts (PEEs) and essential oils (EOs) of A. polycarpum, and further explore their possible insecticidal mechanism.
Materials and Methods: The roots of A. polycarpum were extracted with 90% methanol, and then extracted with petroleum ether to obtain PEEs; the EOs was extracted by distillation. The chemical compositions of PEEs and EOs were analyzed by GC-MS. Contact toxicity was evaluated by the immersion method. Exploring insecticidal mechanisms through in vitro enzyme inhibitory activity.
Results: 12 compounds were identified from PEEs by GC-MS, mainly including aliphatic (94.8%), the main compositions were Octadecadienol (ODO) (aliphatic, 53.2%) and L-Ascorbyl dipalmitate (LADP) (aliphatic, 36.1%). 24 compounds were identified in EOs. About 44.6% of the identified components were terpenoids and their derivatives, and the rest were mainly aliphatic (34.7%) and phenols (3.0%). The main chemical components were L (-)-Borneol (LB) (terpenoid, 28.3%), LADP (aliphatic, 19.1%), and Isoborneol (terpenoid, 9.1%). The contact toxicity indicated that the PEEs showed great contact toxicity against Spodoptera exigua (LC ₅₀  = 126.2 mg/L). Meanwhile, LADP (LC ₅₀  = 128.1 mg/L) and ODO (LC ₅₀  = 121.3 mg/L) was similar to that of Cyhalothrin (LC ₅₀  = 124.2 mg/L) in contact toxicity. In addition, we found that LADP and ODO exhibited excellent inhibitory activity against CarE (IC ₅₀  = 58.0, 56.1 mg/L, respectively) by measuring in vitro enzyme inhibitory activity, which was superior than Cyhalothrin (IC ₅₀  = 68.1 mg/L).
Conclusions: The chemical compositions and contact toxicity of EOs and PEEs of A. polycarpum were analyzed and evaluated, and their insecticidal mechanisms were preliminarily discussed for the first time. It proved PEEs of A. polycarpum and its main components (LADP and ODO) exhibited excellent contact toxicity against S. exigua, and CarE was identified as a potential target for contact toxicity. This study indicated that the insecticidal activity of petroleum ether extracts from A. polycarpum is quite promising, and provides a practical and scientific basis for the development and application of botanical pesticides.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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