Anti-inflammatory and anti-hypersensitive effects of the chalcone isocordoin and its semisynthetic derivatives in mice.

Isocordoin (1), a chalcone isolated from different plants, has been found to present a range of interesting biological properties. This study aimed to evaluate the anti-hypersensitive and anti-inflammatory effects of isocordoin (1) and several natural and semisynthetic derivatives (2-10). Initial evaluation of (1), dihydroisocordoin (2) and six semisynthetic derivatives (3-8) in the inhibition of abdominal writhes induced by acetic acid model showed that only isocordoin dimethylether (5) caused more than 70% of inhibition. Further evaluation of 5 for its anti-oedematogenic activity and anti-hypersensitivity effect induced by carrageenan, lipopolysaccharide (LPS), bradykinin (BK), prostaglandin E2 (PGE2), and epinephrine showed that isocordoin dimethylether (5) presented a discrete inhibition of carrageenan- and LPS-induced hypersensitivity, and of carrageenan-induced paw oedema, and that it was able to significantly reduce both the oedema and hypersensitivity induced by BK. Furthermore, when tested in the PGE2 model, 5 interfered only with the paw-oedema, without showing any effect against the paw-hypersensitivity. Evaluation of the natural isocordoin (1), together with the semisynthetic derivatives isocordoin dimethylether (5), isocordoin methylether (9), and dihydroisocordoin methylether (10) in the BK-induced oedema and hypersensitivity showed that the monoalkylated derivatives 10 and 9 had the strongest antinociceptive activity. The results of this investigation indicate that both monoalkylation of the C-4' phenolic hydroxyl group and reduction of the double bond in the α,ß-unsaturated system of the chalcone skeleton favor activity.

Anti-inflammatory and anti-hypersensitive effects of the crude extract, fractions and triterpenes obtained from Chrysophyllum cainito leaves in mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Chrysophyllum cainito, popularly known as "star apple", caimito, "abiu-roxo" or "abiu-do-Pará", is a tree of about 25m in height. Besides its culinary use, it is also used in folk medicine for the treatment of diabetes mellitus and several inflammatory diseases. MATERIALS AND METHODS: The crude methanolic extract (CME) was submitted to phytochemical studies for obtaining fractions and isolated compounds. They were monitored by thin-layer-chromatography (TLC). The biological activity was evaluated in mice using the carrageenan-induced mechanical hypersensitivity and paw oedema. Biochemical assays, such as myeloperoxidase (MPO) and activity and cytokines levels quantification, were carried out to analyse the involvement of neutrophil migration and IL-1ß and TNFα production. Some adverse effects were investigated using the open-field and rota-rod tests, and it was also measured the rectal temperature. RESULTS: This study demonstrates, for the first time, the anti-hypersensitivity and anti-inflammatory effects of CME, fractions and two isolated triterpenes obtained from the leaves of Chrysophyllum cainito on carrageenan-induced hypersensitivity and paw-oedema. The mice treated with CME or chloroform fraction (CHCl3) presented reduction in mechanical hypersensitivity. The effect of the CME seemed to be partially related to the anti-inflammatory activity, as the paw-oedema and MPO activity were also significantly inhibited. The isolated compound Lup-20(29)-en-3ß-O-hexanoate demonstrated more reduction of the hypersensitivity than 3ß-Lup-20(29)-en-3-yl acetate, suggesting that this molecule might be partially responsible for the biological effects obtained with CME and CHCl3 fractions. Finally, animals treated with CME and CHCl3 did not present changes in locomotor activity, motor performance or body temperature. CONCLUSIONS: Our data demonstrates, for the first time, that the crude extract, fractions and pure compounds obtained from the Chrysophyllum cainito leaves possess important anti-hypersensitive properties against inflammatory pain in mice. The mechanisms through which Chrysophyllum cainito exerts its anti-hypersensitive actions are still unclear, and require further investigation; however, this could well constitute a new and attractive alternative for the management of persistent inflammatory and neuropathic pain in humans.

Indole alkaloids and semisynthetic indole derivatives as multifunctional scaffolds aiming the inhibition of enzymes related to neurodegenerative diseases--a focus on Psychotria L. Genus.

Indole alkaloids and synthetic indole derivatives are well known for their therapeutic importance. In fact, preclinical and clinical studies had already demonstrated several pharmacological activities for these compounds. Here, we overview the multifunctional potential of these molecules for the inhibition of enzymes related to neurodegenerative disease: acetylcholinesterase (AChE), butyrylcholinesterase (BChE), monoamine oxidases A and B (MAO-A and MAO-B). A focus will be given on Psychotria L. genus, considering its reported central effects. Finally, three Psychotria alkaloids, namely desoxycordiofoline (61), bahienoside A (64) and bufotenine (65), along with the synthetic indole derivatives (5S)- 5-(1H-indol-3-ylmethyl)imidazolidine-2,4-dione (66), 5-(1H-indol-3-ylmethyl)-2-thioxoimidazolin-4-one (67), 5-(1Hindol- 3-ylmethyl)-3-methyl-2-thioxoimidazolidin-4-one (68), and methyl 2-(aminoN-(2-(4-methylcyclohex-3-enyl)propan- 2-yl)methanethioamino)-3-(1H-indol-3-yl)propanoate (69), were evaluated in vitro regarding their interactions with AChE, BChE, MAO-A and MAO-B. It was observed that 66 and 68 were able to inhibit MAO-A activity with IC50 value of 8.23 and 0.07 µM. Molecular docking calculations were performed in order to understand the interactions between both ligands (66 and 68) and MAO-A. It was observed that the indole scaffold of both compounds bind into the MAO-A active site in the same orientation, establishing van der Waals contacts with lipophilic amino acids. Additionally, the hydantoin ring of 66 is able to interact by hydrogen bonds with two conserved water molecules in the MAO-A active site, while the methyl-thiohydantoin ring of 68 is within hydrogen bond distance from the hydrogen atom attached to the (N-5) of FAD cofactor. Taking together, our findings demonstrate that the indolyl-hydantoin and indolylmethyl-thiohydantoin rings might consists of good scaffolds for the development of new MAO-A inhibitors possessing neuroprotective properties.

Alkaloids as a source of potential anticholinesterase inhibitors for the treatment of Alzheimer's disease.

OBJECTIVES: The inhibition of acetylcholinesterase (AChE), the key enzyme in the breakdown of acetylcholine, is currently the main pharmacological strategy available for Alzheimer's disease (AD). In this sense, many alkaloids isolated from natural sources, such as physostigmine, have been long recognized as acetyl- and butyrylcholinesterase (BChE) inhibitors. Since the approval of galantamine for the treatment of AD patients, the search for new anticholinesterase alkaloids has escalated, leading to promising candidates such as huperzine A. This review aims to summarize recent advances in current knowledge on alkaloids as AChE and BChE inhibitors, highlighting structure-activity relationship (SAR) and docking studies. KEY FINDINGS: Natural alkaloids belonging to the steroidal/triterpenoidal, quinolizidine, isoquinoline and indole classes, mainly distributed within Buxaceae, Amaryllidaceae and Lycopodiaceae, are considered important sources of alkaloids with anti-enzymatic properties. Investigations into the possible SARs for some active compounds are based on molecular modelling studies, predicting the mode of interaction of the molecules with amino acid residues in the active site of the enzymes. Following this view, an increasing interest in achieving more potent and effective analogues makes alkaloids good chemical templates for the development of new cholinesterase inhibitors. SUMMARY: The anticholinesterase activity of alkaloids, together with their structural diversity and physicochemical properties, makes them good candidate agents for the treatment of AD.

Antiulcerogenic activity of extract, fractions, and some compounds obtained from Polygala cyparissias St. Hillaire & Moquin (Polygalaceae).

The present study evaluates the gastroprotective properties of acetone extract, chloroform, and methanol fractions, alpha-spinasterol (1); 1,3-dihydroxy-7-methoxyxanthone (2); and 1,7-dihydroxy-2,3-methylenedioxyxanthone (3) obtained from Polygala cyparissias (Polygalaceae). Gastroprotective assays were performed in mice using ethanol/HCl and nonsteroidal anti-inflammatory drug (NSAID)/bethanechol-induced ulcer models. Chloroformic fraction showed no interesting results. On the other hand, in the ethanol/HCl-induced ulcer model, the treatment using doses of 50, 125, and 250 mg/kg promoted ulcer inhibition of 45.19+/-12.93%, 62.99+/-3.49%, and 67.40+/-4.75% for acetone extract and 43.70+/-5.12%, 64.56+/-5.64%, and 74.49+/-6.13% for methanol fraction. In the model of NSAID/bethanechol-induced ulcer, the ulcer inhibitions in the same doses were 28.12+/-12.45%, 60.16+/-6.58%, and 77.86+/-7.18% for the acetone extract and 46.09+/-6.92%, 67.45+/-4.36%, and 75.00+/-2.92% for the methanol fraction. In view of the antiulcer potential of the acetone extract and its high yield and xanthone content, it was submitted to chromatographic procedures, giving compounds 1-3, which were also evaluated in the ethanol-induced ulcer model. The results showed that at a dose of 50 mg/kg, these compounds reduced the percentage of ulcer by around 71.26+/-9.40%, 81.10+/-5.75%, and 86.22+/-3.42%, for compounds 1, 2, and 3, respectively. The antiulcerogenic activity of P. cyparissias may be attributed, at least in part, to these compounds.