In vitro and in silico Activity of Iridoids Against Leishmania amazonensis.

BACKGROUND: Leishmaniasis reaches millions of people around the world. The control of the disease is difficult due to the restricted access to the diagnosis and medication, and low adherence to the treatment. Thus, more efficient drugs are needed and natural products are good alternatives. Iridoids, natural products with reported leishmanicidal activity, can be exploited for the development of anti- Leishmania drugs. The aim of this study was to isolate and to investigate the in vitro activity of iridoids against Leishmania amazonensis and to compare the activity in silico of these compounds with those reported as active against this parasite. METHODS: Iridoids were isolated by chromatographic methods. The in vitro activity of asperuloside (1) and geniposide (2) from Escalonia bifida, galiridoside (3) from Angelonia integerrima and theveridoside (4) and ipolamiide (5) from Amphilophium crucigerum was investigated against promastigote forms of Leishmania amazonensis. Molecular modeling studies of 1-5 and iridoids cited as active against Leishmania spp. were performed. RESULTS: Compounds 1-5 (5-100 µM) did not inhibit the parasite survival. Physicochemical parameters predicted for 1-5 did not show differences compared to those described in literature. The SAR and the pharmacophoric model confirmed the importance of maintaining the cyclopentane[C]pyran ring of the iridoid, of oxygen-linked substituents at the C1 and C6 positions and of bulky substituents attached to the iridoid ring to present leishmanicidal activity. CONCLUSION: The results obtained in this study indicate that iridoids are a promising group of secondary metabolites and should be further investigated in the search for new anti-Leishmania drugs.

Characterization of Phloroglucinol-enriched Fractions of Brazilian Hypericum Species and Evaluation of Their Effect on Human Keratinocytes Proliferation.

In this study, a phytochemical and biological investigation on five South Brazilian Hypericum species (Hypericum caprifoliatum, Hypericum carinatum, Hypericum connatum, Hypericum myrianthum, and Hypericum polyanthemum) was carried out. The phloroglucinol-enriched fractions (PEF) of the flowering aerial parts were analyzed by high-performance liquid chromatography for the content of uliginosin A (1), japonicin A (2), uliginosin B (3), hyperbrasilol B (4), and the three benzopyrans, that is, 6-isobutyryl-5,7-dimethoxy-2,2-dimethyl-benzopyran (HP1) (5), 7-hydroxy-6-isobutyryl-5-methoxy-2,2-dimethyl-benzopyran (HP2) (6), and 5-hydroxy-6-isobutyryl-7-methoxy-2,2-dimethyl-benzopyran (HP3) (7). After chemical characterization, the PEF were assayed for cell proliferation on human keratinocyte cell line by MTT. The H. carinatum and H. polyanthemum PEF demonstrated better results with an increase in cell proliferation (138.7% and 120.6%, respectively). The cell counting and Ki-67 assay with H. carinatum PEF confirmed the MTT results. The cell cycle distribution indicates an increase in the cells at S and G2/M phases, which is indicative of proliferation induction. In summary, the results indicate an induction of HaCaT proliferation by the treatment with H. carinatum PEF (at 10 and 15 µg/mL), suggesting a possible use as wound healing agent. Copyright © 2016 John Wiley & Sons, Ltd.

The monoamine oxidase inhibitory activity of essential oils obtained from Eryngium species and their chemical composition.

CONTEXT: Monoamine oxidase (MAO) inhibitors are used in the treatment of depression, anxiety disorders, and the symptomatic treatment of Parkinson's disease. Eryngium, the most representative of the Apiaceae family, is well known for the presence of essential oils (EOs), which have already demonstrated MAO inhibitory potential. OBJECTIVE: The objective of this study is to evaluate the MAO inhibitory capacity of the EOs obtained from Eryngium floribundum Cham. & Schlecht. (EF), E. eriophorum Cham. & Schlecht. (EE), E. nudicaule Lam. (EN), E. horridum Malme (EH), and E. pandanifolium Cham. & Schlecht. (EP). MATERIALS AND METHODS: EOs were obtained from fresh whole plants by hydrodistillation (3 h). Chemical analyses were performed by GC/MS using apolar and polar columns, with oven temperature from 60 to 300 °C at 3 °C/min. The MAO-A and -B activities were evaluated in vitro by an end-point method using kynuramine as the substrate and mitochondrial suspension or human recombinant enzymes as the enzymatic source. DMSO 2%, clorgyline 10(-7) M, and pargyline 10(-6) M were used as controls. RESULTS AND DISCUSSION: EFEO, EEEO, ENEO, EHEO, and EPEO GC/MS analysis showed (E)-caryophyllene (4.9-10.8%), germacrene D (0.6-35.1%), bicyclogermacrene (10.4-17.2), spathulenol (0.4-36.0%), and globulol (1.4-18.6%) as main constituents. None of the EOs inhibited MAO-A activity (4 and 40 µg/mL). However, EHEO inhibited MAO-B activity with an IC50 value of 5.65 µg/mL (1-200 µg/mL). Pentadecane (10 µM), its major constituent (53.5%), did not display significant MAO-B inhibition. CONCLUSION: The study demonstrates the promising application of Eryngium species as a source of potential central nervous system bioactive secondary metabolites, specially related to neurodegenerative disorders.

Multifunctional Monoamine Oxidases and Cholinesterases Inhibitory Effects, as well as UPLC-DAD-MS Chemical Profile of Alkaloid Fractions Obtained from Species of the Palicoureeae Tribe.

In the present study, the effects were evaluated of alkaloid fractions (AFs) from Psychotria species and correlated genera, Palicourea and Rudgea, on monoamine oxidases (MAOs) and cholinesterases (ChEs). By HPLC-DAD and UPLC-DAD-MS analyses, indole alkaloids (IA) were detected in all AFs. For the Psychotria and Palicourea species, these IA corresponded to tetrahydro-p-carboline alkaloids (THPCA). On the other hand, pyrrolidinoindoline core compounds were observed for Rudgea species. Regarding their pharmacological activities, none of the AFs was able to inhibit AChE. However, the BChE activity was impaired by the Psychotria and Palicourea AFs. In addition, MAO-A was inhibited by both AFs, but only Psychotria nemorosa AF was able to inhibit significantly MAO-B. Rudgea AFs demonstrated a poor inhibitory profile on MAO-A. Taken together, our results highlighted the Psychotria and Palicourea genera as important sources of scaffolds for the development of MAO-A and BChE inhibitors aiming at the treatment of neurodegenerative and neuropsychiatric diseases.