Please cite this article as: Santamarina, M.P., Roselló, J., Giménez, S., Blázquez, M.A., Commercial Laurus nobilis L. and Syzygium aromaticum L. Merr. & Perry essential oils against post-harvest phytopathogenic fungi on rice, ABSTRACT 18 Rice is exposed in the field and in stored conditions to a great variety of fungi that can cause a lot of 19 diseases with potential risk to consumers. In the present study, the chemical composition of commercial 20 Laurus nobilis L. and Syzygium aromaticum L. Merr. & Perry essential oils and antifungal activity against 21 five pathogenic fungi isolated from Mediterranean rice grains has been investigated. Thirty-seven 22 compounds accounting for more than 99.5% of the total essential oil were identified by GC and GC/MS. 23 1,8-Cineole (51.95%), α-terpinyl acetate (12.93%) and the monoterpene hydrocarbon sabinene (9.56%) 24 were the main compounds in bay leaf essential oil, while the phenylpropanoid eugenol (88.58%), and the 25 sesquiterpene hydrocarbons β-caryophyllene (8.13%) and α-humulene (2.35%) were found in clove 26 essential oil. Clove essential oils at 300 µg/mL showed more antifungal effect than bay leaf essential oil 27 against all tested strains. S. aromaticum essential oil showed the best antifungal activity towards 28 Fusarium graminearum and similar antifungal activity compared to pure eugenol against all tested 29 phytopathogenic fungi. In inoculated rice grain, clove essential oil significantly reduced the fungal 30 infection in food so S. aromaticum essential oil could be a good alternative as preservative in stored rice 31 grain. 32

Commercial thyme and lavender essential oils were analysed by GC/MS. Sixty-six compounds accounting for 98.6-99.6% of total essential oil were identified. Thymol (52.14 ± 0.21%), followed by p-cymene (32.24 ± 0.16%), carvacrol (3.71 ± 0.01%) and γ-terpinene (3.34 ± 0.02%), were the main compounds in thyme essential oil, while large amounts of oxygenated monoterpenes linalool acetate (37.07 ± 0.24%) and linalool (30.16 ± 0.06%) were found in lavender one. In vitro antifungal activity of the essential oils was evaluated at 200 and 300 μg/mL against 10 phytopathogenic and post-harvest fungi, which significantly affect agriculture. Micelial growth inhibition was calculated for each tested fungus and dose. Thyme essential oil showed satisfactory results with 90-100% growth inhibition in almost all the assayed fungi at 300 μg/mL, while lavender essential oil showed no noteworthy inhibition data at either dose, and its growth was even enhanced. Thyme essential oil represents a natural alternative to control harvest and post-harvest fungi, and to extend the shelf-life of agriculture products.

Chemical composition of commercial Origanum compactum and Cinnamomum zeylanicum essential oils and the antifungal activity against pathogenic fungi isolated from Mediterranean rice grains have been investigated. Sixty-one compounds accounting for more than 99.5% of the total essential oil were identified by using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Carvacrol (43.26%), thymol (21.64%) and their biogenetic precursors p-cymene (13.95%) and γ-terpinene (11.28%) were the main compounds in oregano essential oil, while the phenylpropanoids, eugenol (62.75%), eugenol acetate (16.36%) and (E)-cinnamyl acetate (6.65%) were found in cinnamon essential oil. Both essential oils at 300 μg/mL showed antifungal activity against all tested strains. O. compactum essential oil showed the best antifungal activity towards Fusarium species and Bipolaris oryzae with a total inhibition of the mycelial growth. In inoculated rice grains at lower doses (100 and 200 μg/mL) significantly reduced the fungal infection, so O. compactum essential oil could be used as ecofriendly preservative for field and stored Valencia rice.

The chemical composition of commercial Syzygium aromaticum, Cinnamomum verum, and Laurus nobilis essential oils as well as their antifungal activity against four pathogenic fungi isolated from Mediterranean rice grains has been investigated. Eighty nine compounds accounting for between 98.5 and 99.4% of the total essential oil were identified. The phenylpropanoids eugenol (89.37 ± 0.29%) and eugenol (56.34 ± 0.41%), followed by eugenol acetate (19.48 ± 0.13%) were, respectively, the main compounds in clove and cinnamon essential oils, whereas large amounts of the oxygenated monoterpenes 1,8-cineole (58.07 ± 0.83%) and α-terpinyl acetate (13.05 ± 0.44%) were found in bay leaf essential oil. Clove and cinnamon oils showed the best antifungal activity results against all tested fungi. Against Alternaria alternata, clove essential oil displayed the best antifungal effect, whereas against Curvularia hawaiiensis, cinnamon essential oil was more active. Both essential oils showed a similar antifungal effect towards Fusarium proliferatum and Fusarium oxysporum. In vitro studies in inoculated rice grains showed that clove and cinnamon totally inhibited pathogenic fungal development after 30 days of incubation. In vivo studies showed that eugenol used with a polysaccharide such as agar–agar formed a fine coat which wraps the inoculated rice grains, creating a natural biofilm and reducing the development of all pathogenic fungi (80–95%) for 30 days.