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- Myrtus communis essential oils: insecticidal, antioxidant and antimicrobial activities: a reviewPublication . Hennia, Aicha; Nemmiche, Said; Dandlen, Susana; Miguel, Maria GracaMyrtle (Myrtus communis L.) is a wild aromatic plant that laboratorial works have demonstrated the insecticidal, antioxidant, anti-inflammatory and antimicrobial activities of myrtle essential oils (EOs). The chemical composition may change according to several factors; nevertheless, it was constant in practically all EOs the presence of 1,8-cineole and α-pinene, as main components (>5%). The biological activities, generally low or moderate depended on the organism (insecticidal) and microorganism and on the chemical composition. Generally, the contribution of the components on the biological activities was not determined; nevertheless, they were generally attributed to the presence of the main components (1,8-cineole, α-pinene, eugenol, methyleugenol, myrtenyl acetate, among other components depending on the property). The antioxidant activity of myrtle oil was predominantly determined in cell-free methods, though very few works also used cell model methods. In all cases, the activities were also low to moderate due to the absence of phenol compounds.
- Quick decline and stem pitting Citrus tristeza virus isolates induce a distinct metabolomic profile and antioxidant enzyme activity in the phloem sap of two Citrus speciesPublication . Dandlen, Susana; Da Silva, José Paulo; Miguel, Maria Graca; Duarte, Amilcar; Power, Deborah; Marques, NatáliaSusceptibility to the severe Citrus tristeza virus (CTV), T36, is higher for Citrus macrophylla (CM) than for C. aurantium (CA). How host-virus interactions are reflected in host physiology is largely unknown. In this study, the profile of metabolites and the antioxidant activity in the phloem sap of healthy and infected CA and CM plants were evaluated. The phloem sap of quick decline (T36) and stem pitting (T318A) infected citrus, and control plants was collected by centrifugation, and the enzymes and metabolites analyzed. The activity of the antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), in infected plants increased significantly in CM and decreased in CA, compared to the healthy controls. Using LC-HRMS2 a metabolic profile rich in secondary metabolites was assigned to healthy CA, compared to healthy CM. CTV infection of CA caused a drastic reduction in secondary metabolites, but not in CM. In conclusion, CA and CM have a different response to severe CTV isolates and we propose that the low susceptibility of CA to T36 may be related to the interaction of the virus with the host’s metabolism, which reduces significantly the synthesis of flavonoids and antioxidant enzyme activity.