Abstract
Laureliopsis philippiana (Looser) R. Schodde (Monimiaceae) is a native tree widespread in the forest areas in the south of Chile and Argentina, known for its medicinal properties and excellent wood. The aim of this study was to evaluate the chemical composition of L. philippiana leaf and bark essential oils (EOs) using gas chromatography-mass spectrometry (GC-MS), and to quantify its anti-oomycete activity, specifically against Saprolegnia parasitica and S. australis. Only six components were identified in leaf EO, 96.92% of which are phenylpropanoids and 3.08% are terpenes. As for bark EO, 29 components were identified, representing 67.61% for phenylpropanoids and 32.39% for terpenes. Leaf EO was characterized mainly by safrole (96.92%) and β-phellandrene (1.80%). Bark EO was characterized mainly by isosafrole (30.07%), safrole (24.41%), eucalyptol (13.89%), methyleugenol (7.12%), and eugenol (6.01%). Bark EO has the most promising anti-Saprolegnia activity, with a minimum inhibition concentration (MIC) value of 30.0 µg/mL against mycelia growth and a minimum fungicidal concentration (MFC) value of 50.0 μg/mL against spores; for leaf EO, the MIC and MFC values are 100 and 125 µg/mL, respectively. These findings demonstrate that bark EO has potential to be developed as a remedy for the control of Saprolegnia spp. in aquaculture.
Highlights
Saprolegnia species, commonly known as water molds (Saprolegniaceae, Saprolegniales, oomycetes), are widespread in fresh water and represent the most significant infections affecting wild and cultured shellfish and fish [1,2]
The major aim of this study was to investigate the substitution of bronopol with L. philippiana natural essential oils (EOs), or purified compounds, to treat infections of Saprolegnia spp. and, if possible, to test the top performing candidates on S. parasitica and S. australis
The results indicate that anti-oomycete activity was diminished at 72 h post-inoculation
Summary
Saprolegnia species, commonly known as water molds (Saprolegniaceae, Saprolegniales, oomycetes), are widespread in fresh water and represent the most significant infections affecting wild and cultured shellfish and fish [1,2]. Besides being a problem for the fish farming industry, S. parasitica has been implicated in wild salmon population decline around the world [9]. The increasing public concerns over fungicide safety and possible damages to the environment have resulted in increased attention given to natural products for use in control and prevention of the disease [13,14]. In this context, a well-known way to reduce the proliferation of microorganisms is through the use of essential oils (EOs) or plant extracts [15], due to a lesser chance of their being toxic. EOs have proven to be inhibitory against Saprolegnia spp., depending upon their concentration, method of testing, and the active constituents present [20,21,22]
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