Leaf Spray Mass Spectrometry guided by Histochemistry in Eugenia pitanga (O.Berg) Nied and Eugenia dysenterica DC. leaves

Eugenia is a genus from Brazilian cerrado and belong to the Myrtaceae family. Eugenia dysenterica DC. and E. pitanga (O.Berg) Nied. are species from this genus; the first one is popularly known as “cagaita” and has an extensive set of chemical and biological studies, included of their essential oils (DUARTE et al., 2010). Scientific studies of E. pitanga are still incipient but stimulant, antipiretic antidiahrrea and antireumatic properties have already been reported (LORENZI et.al.,2002). In this work, histochemical and leaf-spray mass spectrometry (LSMS) analysis of leaves of E. pitanga and E. dysenterica were proposed, aiming the in situ localization and identification of terpenoids, phenolic and nitrogen compounds. Histochemical methodology was performed with focus in the presence of store sites of chemical substances produced in the secondary metabolism of the species. LSMS was standardized by direct infusion of crude extract, prepared from the central region of leaves from each species, previously determined by the histochemistry. After this, the LSMS analysis was performed following the same procedure as the standadization. The histochemistry provided the visualization of essential oils and phenolic compounds in the leaf blade of both species; in E. pitanga, it was verified also the presence of nitrogen compounds, but this result was not confirmed by LSMS. However, by LSMS it was possible to detect the alkaloid uniflorine in E. dysenterica, described by the first time in this species. Furthermore, LSMS provided the assignment of characteristic markers of each species, sucrose and uniflorine from E. pitanga and E. dysenterica, respectively, based on the most intense signal of their spectra. Uniflorine is a α-glucosidase, maltase and sucrase inhibitor, which can explain the higher signal intensity of sucrose in E. dysenterica species (MATSUMURA et al., 2000; PARMEGGIANI et al., 2009). In conclusion, the histochemistry was an important tool to guide the search for compounds by LSMS; however, this study is in progress and can lead towards the identification of other secondary metabolites, which are important for chemical knowledge for these species.

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