In vitro biological evaluation of eight different essential oils against Trypanosoma cruzi, with emphasis on Cinnamomum verum essential oil.

BACKGROUND: Essential oils (EOs) are complex mixtures of secondary metabolites from various plants. It has been shown that several EOs, or their constituents, have inhibitory activity against trypanosomatid protozoa. Thus, we analyzed the biological activity of different EOs on Trypanosoma cruzi, as well as their cytotoxicity on Vero cells. METHODS: The following EOs were evaluated on T. cruzi epimastigote forms: Cinnamomum verum, Citrus limon, Cymbopogon nardus, Corymbia citriodora, Eucalyptus globulus, Eugenia uniflora, Myrocarpus frondosus, and Rosmarinus officinalis. Inhibitory activity against T. cruzi (IC50/24 h) and cytotoxicity against Vero cells (CC50/24 h) were evaluated by the MTT assay. The EO of C. verum was selected for further evaluation against trypomastigotes and intracellular amastigotes, as well as on parasite metacyclogenesis. Constituents of C. verum EO were identified by GC-MS. One-way ANOVA statistical analysis was performed with GraphPad version 5.01. RESULTS: Cinnamomum verum EO was the most effective against T. cruzi epimastigotes (IC50/24 h = 24.13 µg/ml), followed by Myrocarpus frondosus (IC50/24 h = 60.87 µg/ml) and Eugenia uniflora (IC50/24 h = 70 µg/ml). The EOs of C. citriodora, E. globulus, and R. officinalis showed no activity at concentrations up to 300 µg/ml. Incubation of T. cruzi metacyclic trypomastigotes and intracellular amastigotes with C. verum EO resulted in IC50/24 h values of 5.05 µg/ml and 20 µg/ml, respectively. Therefore, trypomastigotes are more susceptible than epimastigotes, with selectivity index (SI) about 4.7-fold higher (9.78 and 2.05, respectively). Analysis of C. verum EO by GC-MS showed mainly (E)-cinnamaldehyde (81.52%) and eugenol (16.68%). CONCLUSIONS: C. verum essential oil is effective against T. cruzi (epimastigotes, trypomastigotes and amastigotes) and interferes with the parasite differentiation process in vitro. Thus, it represents a strong candidate for further studies to improve its activity on pathogenic trypanosomatids.

Ocotea porosa: Anatomy and Histochemistry of Leaves and Stems, Chemical Composition, Cytotoxicity and Insecticidal Activities of Essential Oil

Abstract Ocotea porosa (Nees & Mart.) Barroso, commonly known as "imbuia", "canela-imbuia" or "imbuia-amarela" in Brazil, is a tree of the Southern Atlantic Forest. The present study investigates the anatomy of leaf and stem, volatile oil chemistry, as well as cytotoxicity and insecticidal activities of the essential oil of O. porosa. Species identification was achieved by anatomy features, mainly due to paracytic and anomocytic stomata; non-glandular trichomes; biconvex midrib and petiole with a collateral open arc vascular bundle; presence of a sclerenchymatous layer, starch grains and crystal sand in the stem; and the presence of phenolic compounds in the epidermis, phloem and xylem of the midrib, petiole and stem. The main volatile components of the essential oil were α-pinene (19.71%), β-pinene (13.86%) and bicyclogermacrene (24.62%). Cytotoxicity against human cancer cell (MCF-7), mouse cancer cell (B16F10) and mouse non-tumoral cell (McCoy) was observed as well as insecticidal activity of the essential oil against susceptible 'Ft. Dix' bed bugs (Cimex lectularius L.) by topical application.

Anatomy and volatile oil chemistry of Eucalyptus saligna cultivated in South Brazil

ABSTRACT Eucalyptus saligna Sm., Myrtaceae, commonly known as Sydney blue gum, is often confused with several other species in the genus. The leaf volatile oils of the species have been reported to have antimicrobial, insecticidal, nematicidal, repellent and cytotoxicity properties. The present work provides anatomy as well as volatile oil chemistry of the species collected from South Brazil. The anatomy and histochemistry of the leaves and stems were investigated by light and scanning electron microscopy, and the leaf and stem volatile oils were analyzed by GC-MS. Amphistomatic leaves, anomocytic stomata, presence of papillae and epicuticular waxes, slightly biconvex midrib with a bicollateral vascular bundle in open arc and two dorsal traces, secretory cavities, calcium oxalate druses and prismatic crystals, rounded petiole with a bicollateral vascular bundle in open arc with invaginated ends and rounded stem with sclerenchyma abutting the internal and external phloem are observed in this species. The main components of the volatile oil were p-cymene (28.90%) and cryptone (17.92%). These characteristics can help in the identification and quality control of E. saligna.