The Brazilian Myrtaceae family includes 23 genera and 1034 species which can occur distributed in all regions in Brazil. They are used in folk medicine to treat diabetes, diarrhea, diuretic, hypertension and ulcers1. This activity is frequently attributed to their phenolics compounds and terpenes derivatives1. So, here, we present the main phenolic constituents of Myrcia fallax and Myrcia guianensis hydroethanolic leaves extracts using ESI-MS technique. Those phenolics was gotten from by direct insertion of Myrcia sp extracts, in negative mode, onto 6550 iFunnel Q-TOF LC/MS system (Agilent, Santa Clara, CA, USA). ESI-MS has been used for the fingerprinting characterization of plant extracts mixtures, since it would provide an elemental composition from accurate mass measurement and metabolite structures with high degrees of certainty without the need of standards, saving time of sample preparation steps or prior chromatographic separation method.2 The leaves of Myrcia sp were collected at Horto Florestal, Assis, São Paulo. Dried leaves were extracted by dynamic maceration with Ethanol:H2O 70:30 v/v (1:10 plant/solvent ratio, 3x2h), at r.t, filtered and evaporated to provide hydroethanolic extract. Myrcia sp leaves extracts was found quinic acid (m/z 191), quercetin (m/z 301) and myricetin (m/z 317). Quinic acid showed a water loss fragmentation to MS/MS m/z 173 and MS/MS of m/z 111 resulting from a retro Diels-Alder (RDA) ring opening mechanism3. Quinic acid has already found in other plants of Myrtaceae genus4. Characteristic fragmentations of quercetin are resulted from cleavage of ring B after RDA elimination, forming the fragment of m/z 179 and loss of a carbonyl group (fragment of m/z 151). Myricetin showed a characteristic fragmentation ion of m/z 1795. Both Myrcia sp. showed ion of m/z 447, which was assigned to quercetin-3-O-deoxipentose4. Its MS/MS data showed an aglycone fragment of m/z 301 due loss a sugar moiety of 146 Da and m/z 271 typical of flavon-3-O-monoglycoside. In Myrcia sp extracts was also found flavonols with fragment ion m/z 463 and m/z 631. First compound produced a MS/MS ion of m/z 317(loss of a sugar moiety of 146 Da), indicating that compound is a myricetin monohexoside (myricetin 3-O-glucoside)5. The second, m/z 631 [M–H]- produced the ion product Y1- (m/z 479 [M– 152– H]-) which produced the product ion Y0- of m/z 316 [M – 152–16 –2H]- which was characterized to myricetin galloyl galactoside.6 It was also detected, in M. fallax, HHDP derivatives which were not found in M. guianensis. As example, HHDP-glucose showed a deprotonate ion molecule of m/z 481, which was followed by an ion fragment of m/z 301 (ellagic acid) after the loss of one unit of glucose. After the spontaneous lactonization of HHDP, ellagic acid was formed with a subsequent decarboxylation to yield an ion m/z 275 [M - H - 44]- 7. It also detected in M. fallax extract, a fragment ion m/z 1085 with MS/MS fragment of m/z 783, loss of ellagic acid [M-H-302]-, were assigned to eucalbanin A or its isomer cornussin B. They have been previously found in leaves and fruits of Eucalyptus species8, but they have never been reported in Myrcia sp8. So, once again, direct infusion ESI-MS was a fast method which have provided us Myrtaceae fingerprinting extracts.4 As the phenolic composition of Myrcia fallax and M. guianensis are different, their extracts could be biologically active in a different way, too. For this reason, more studies are underway in our lab, trying to correlate phenolic found in both Myrcia sp and their biological activities.
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