Caracterização química de Selaginella sellowii Hieron. (Selaginellaceae) e atividades antileishmania e antibacteriana

Abstract

Selaginella sellowii Hieron. (Selaginellaceae), belongs to the Selaginellaceae family, is a desiccation resistant species. The polar extract of this species exhibited in its composition biflavonoids and phenylpropanoids, in addition it also exhibited potent activity against Leishmania amazonensis. However, there is still a shortage in the literature regarding the structural information of phenylpropanoids and their role in this potent antileishmanial activity. Due to the different epidemiological scenarios, the surveillance and control of leishmaniasis remain a challenge, which makes them a constant public health problem in the Americas. Allied to this, throughout history, pentavalent antimonials have been used as the first option for treating infection by L. amazonensis, however, these have several side effects, in addition to increasing the levels of resistance of the parasites. In addition to parasitic infections, it is necessary to consider bacterial diseases. The excessive and inappropriate use of antibiotics has led to the development of bacterial resistance, which is considered a serious public health problem worldwide, with approximately 80% of infections are associated with bacterial biofilms. Thus, the development of new treatment strategies is necessary, as well as the expansion of research in search of antileishmania, antibiofilms and antibacterial agents. Here, we developed a method to obtain two enriched fractions composed of biflavonoids and phenylpropanoid derivatives, aiming to understand a possible role of these different components for antileishmania, antibacterial and antibiofilm activities. The extracts were obtained by accelerated solvent extraction (ASE) with solvents to obtain ethanol and water 7:3 v/v (SsEtH) and ethyl acetate and methanol 1:1 v/v (SsAcMe) extracts. The SsEtH extract was subjected to liquid-liquid extraction and its ethyl acetate (SsEtH_FrAc) and hydromethanolic (SsEtH_FrMe) fractions showed mainly bioflavonoids and phenylpropanoid derivatives in their composition, respectively. The SsAcMe extract and the SsEtH_FrDC fraction showed better antileishmania and antibiofilm activity. The SsAcMe extract exhibited an IC50 of 78.8 µg/mL against amastigotes of L. amazonensis, as well as inhibiting the formation of Staphylococcus aureus biofilm by 90% and without affecting bacterial growth. The SsEtH_FrDC fraction showed an IC50 of 34.1 µg/mL against amastigotes of L. amazonensis and inhibited biofilm formation, but at the highest concentration evaluated (0.5 mg/mL) it also reduced bacterial growth. Samples were analyzed by LC-DAD and LC-DAD-MS. The biflavonoids amentoflavone (14), robustaflavone (15) and robustaflavone methyl ether (16) were the main annotated metabolites of SsEtH_FrAc. From the SsEtH_FrMe fraction, glycosylated derivatives of phenylpropanoids were annotated, including tri-O-hexosyl caffeic acid (1), hexa-O-hexosyl tetra caffeic acid (2, 4, 9, 11, 12), hexa-O- hexosyl di-caffeic acid (3), tetra-O-hexosyl di-caffeic acid (5, 7), hepta-O-hexosyl tetra-caffeic acid (6, 8), penta-O-hexosyl tri-caffeic acid (10 ) and tri-O-hexosyl tetracaffeic acid (13). Compounds 6, 7, 8, 9 and 10 were isolated by reverse phase semi-prep scale DAD-HPLC and structurally characterized by NMR. Substance 9 was characterized as the new glycosylated phenylpropanoid derivative bis-1”-O-caffeoyl(1”→4)-β-gluco/galacpyranosyl(9→2”’)-α-gluco/galactopyranosyl(1”’→3””)-caffeoyl-(2”’→9’)-β-gluco/galactopyranosyde,

Keywords: Phenylpropanoid, Leishmania, biflavonoid, Caffeic acid, antibacterial, antibiofilm