Environmentally-safe scCO2P. pinaster branches extracts: Composition and properties

Marisa C Gaspar,Hermínio C De Sousa,Inês J Seabra,Mara E.M Braga

doi:10.1016/j.jcou.2019.11.027

Marisa C Gaspar, Hermínio C De Sousa + Show 2 more

Open Access

https://doi.org/10.1016/j.jcou.2019.11.027

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Abstract

Considering the vast array of compounds that plants manufacture that help protect them against insects’ attacks, plant raw materials are a potential source of future insecticides/larvicides. In this work, volatiles from maritime pine (Pinus pinaster) branches, a pruning residue, were extracted by supercritical carbon dioxide (scCO2), and also by hydrodistillation for comparison purposes. The volatiles naturally emitted from the pine branches were identified as well. Experimental design results showed higher extraction yields (up to 6%), when scCO2 density and temperature increased, while the inverse occurred for total phenolic contents (1.2–3.3% GAE, gallic acid equivalents). Emitted volatiles from the branches were mainly α-pinene, β-pinene, β-myrcene, limonene, and β-caryophyllene. In general, the volatile profiles of the scCO2 and hydrodistillation extracts were quite similar, revealing abietadiene, the precursor of abietic acid, as the main compound. Oxidation inhibitions of ∼42 – 59% were obtained for the scCO2 extracts in the β-carotene assay. The acetylcholinesterase inhibitory activity assay revealed the potential of these extracts to have insecticidal/larvicidal activity, with IC50 values of 2.8–10.7 mg/mL. Overall, these extracts may be applied in environmentally-safe insect/larvae control strategies, in formulations that benefit from the presence of antioxidants.

Highlights

Natural compounds with repellent or insecticidal activity may be solvent-extracted from a wide number of plants, including those from the pine species
For the scCO2 extracts, IC50 values were in the 2.83–10.7 mg/mL
Abietadiene, the precursor of abietic acid, which is produced by conifer species as a defensive secretion against insect and pathogen attacks, was the main volatile compound in all scCO2 extracts and it was present in higher percentages in extracts obtained at lower temperatures and CO2 densities

Summary

Introduction

Natural compounds with repellent or insecticidal activity may be solvent-extracted from a wide number of plants, including those from the pine species. Monoterpenes, which are widely known constituents of conifers and citrus plants, can be detected by insects, and act as toxins, as feeding and oviposition deterrents, or as attractants for those insects [3] Their commercialization is still scarce, volatile oils obtained from a wide range of plant species have revealed insecticidal, antifungal and/or repellent activities towards several insects, presenting lower impacts on ecosystems, environment and health when compared to synthetic insecticides. Β-pinene and its analogues have already been reported to have antifeedant and antimicrobial activities [6] These compounds may potentially be extracted from a number of residues that derive from pine industries, including wood pieces, bark, cones, branches, and needles. Only a few studies have focused on the investigation of volatiles emitted from pine tree branches, which is an gathered pruning residue [11]

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