Characterization of antifungal compounds from X. prockia leaves

Xylosma prockia (Fig. 1)1, known as sucará, is a plant belonging to the family Salicaceae, native of Brazil, found mainly in the northeast, southeast and south of the country2. There are no ethnobotanical reports on the medicinal use of the specie, as well chemical and pharmacological studies are scarce. Previous studies of this research group have found great potential for antifungal activity for X. prockia leaves, which justifies the present work3. The aims of this study were the characterization of secondary metabolites in polar fractions of X. prockia leaves (SisGEN A66F830). The ethanolic extract was suspended in water for partition with solvents of increasing polarity, getting five fractions. Due to its best antifungal activity, the ethyl acetate fraction (EAF) was selected. The HPLC-MS analysis of EAF obtained using ESI in the negative ionization mode allowed the visualization of fifteen major peaks (Fig. 2), that were assembled in three distinct groups of compounds (I, caffeoyl-quinic acid derivatives; II, coumaroyl-glucosides derivatives; III caffeoyl-glucosides/deoxyhexosyl-caffeoyl glucosides derivatives). The compounds having the highest relative abundance in the chromatogram showed intense fragment ions at m/z 325, 205, 163, 145 and 119 and molecular ion [M-H]- 419 m/z corresponding to a molecular formula of C21H24O9 (Fig. 3), being consistent with the presence of coumaroate, glucose and an additional residue, C6H7O, in the metabolites4. Although similar compounds with a C6 residue attached to the sugar has been reported5, the preliminary spectroscopic data would indicate that they have different structure and further isolation would be mandatory to assess the complete characterization of these isomeric compounds. The majority substances from the EAF fraction have been isolated and studies are being conducted in order to perform the complete characterization.