Psidium myrtoides O. Berg fruit and leaves: physicochemical characteristics, antifungal activity and chemical composition of their essential oils in different seasons

Larvicidal and Fungicidal Activity of the Leaf Essential Oil of Five Myrtaceae Species

Myrtaceae is one of the most diverse and abundant botanical families, exhibiting wide diversity in the chemical composition of essential oils (EOs). EOs have various biotechnological applications such as controlling the populations of organisms that negatively impact humans. This study aimed to extract EOs from Myrtaceae species, chemically characterize them, and evaluate their larvicidal and fungicidal effects. EOs were extracted from the leaves of Eugenia brasiliensis, Eugenia uniflora, Psidium cattleyanum, Psidium guajava, and Syzygium cumini by hydrodistillation for 3 h and characterized by chromatographic analysis. Larvaes of Aedes aegypti and colonies of Fusarium oxysporum were subjected to increasing EO concentrations to determine the larvicidal and fungicidal potential. The EOs of Eugenia and Psidium species are primarily composed of sesquiterpenes (>80 %), whereas S. cumini EO is rich in monoterpenes (more than 60 %). The Eugenia species had similar amounts of oxygenated monoterpenes, which may explain their higher larvicidal potential compared to other species, with CL50 of 86.68 and 147.46 PPM, respectively. In addition to these two study species, S. cumini showed a high inhibition of fungal growth, with more than 65 % inhibition. We demonstrated that the actions of five EOs from Myrtaceae with different biological activities are associated with chemical diversity.

Essential oil from Sabina chinensis leaves: A promising green control agent against Fusarium sp

Sabina chinensis is a woody plant with important ecological functions in different regions of China, but its essential oils (EO) against plant pathogenic fungi remain largely undetermined. The purpose of our study was to assess the chemical composition and antifungal activity of S. chinensis EO based on optimization of the extraction process. In this study, an actionable and effective model with the experimental results and identified optimum conditions (crushing degree of 20 mesh, liquid-solid ratio of 10.1:1, immersion time of 9.1 h) was established successfully to achieve an extraction yield of 0.54%, which was basically consistent with the theoretical value. A total of 26 compounds were identified using headspace gas chromatography-mass spectrometry (GC-MS) and showed that the major constituent was β-phellandrene (26.64-39.26%), followed by terpinen-4-ol (6.53-11.89%), bornyl acetate (6.13-10.53%), etc. For Petri plate assays, our experiments found for the first time that S. chinensis EO revealed high and long-term antifungal activity against the tested strains, including Fusarium oxysporum and Fusarium incarnatum, at EC₅₀ values of 1.42 and 1.15 µL/mL, which especially reached approximately 76% and 90% growth inhibition at a dose of 0.2 µL/mL, respectively. Furthermore, the antifungal activity of EO from different harvest periods showed remarkable variation. The orthogonal partial least-squares discriminant analysis (OPLS-DA) method revealed 11 metabolites with chemical marker components, and 5 of its potential antifungal activities, terpinen-4-ol, α-terpineol, α-elemol, γ-eudesmol, and bornyl acetate, were strongly correlated with the mycelial inhibition rate. In total, this study explored the antifungal activity of EO against root rot fungus as a potential fungicide and provided valuable information into developing potential products from natural agents.