Design, synthesis, molecular modeling and neuroprotective effects of a new framework of cholinesterase inhibitors for Alzheimer's disease.

In search of a novel class of compounds against Alzheimer's disease (AD), a new series of 7-chloro-aminoquinoline derivatives containing methylene spacers of different sizes between the 7-chloro-4-aminoquinoline nucleus and imino methyl substituted phenolic rings, and also their reduced analogues, were designed, synthesized and evaluated as neuroprotective agents for AD in vitro. In spite of the multifaceted feature of AD, cholinesterases continue to be powerful and substantial targets, as their inhibition increases both the level and duration of the acetylcholine neurotransmitter action. The compounds presented inhibitory activity in the micromolar range against acetylcholinesterase (AChE) (imines and amines) and butyrylcholineterase (BChE) (amines). The SAR study revealed that elongation of the imine side chain improved AChE activity, whereas the reduction of these compounds to amines was crucial for higher activity and indispensable for BChE inhibition. The most promising selective inhibitors were not cytotoxic and did not stimulate pro-inflammatory activity in glial cells. Kinetic and molecular modeling studies indicated that they also show mixed-type inhibition for both enzymes, behaving as dual-site inhibitors, which can interact with both the peripheral anionic site and the catalytic anionic site of AChE. They could therefore restore cholinergic transmission and also may inhibit the aggregation of Aß promoted by AChE. Additionally, one compound showed promising anti-inflammatory activity by reducing the microglial release of NO• at a concentration that is equivalent to the IC50 against BChE (30.32 ± 0.18 µM) and 15-fold greater than the IC50 against AChE (1.97 ± 0.20 µM).Communicated by Ramaswamy H. Sarma.

Microglial lysophosphatidic acid promotes glioblastoma proliferation and migration via LPA1 receptor.

Glioblastomas (GBMs) are highly aggressive primary brain tumors characterized by cellular heterogeneity, insensitivity to chemotherapy and poor patient survival. Lysophosphatidic acid (LPA) is a lysophospholipid that acts as a bioactive signaling molecule and plays important roles in diverse biological events during development and disease, including several cancer types. Microglial cells, the resident macrophages of the central nervous system, express high levels of Autotaxin (ATX,Enpp2), an enzyme that synthetizes LPA. Our study aimed to investigate the role of LPA on tumor growth and invasion in the context of microglia-GBM interaction. First, through bioinformatics studies, patient data analysis demonstrated that more aggressive GBM expressed higher levels of ENPP2, which was also associated with worse patient prognosis with proneural GBM. Using GBM-microglia co-culture system we then demonstrated that GBM secreted factors were able to increase LPA1 and ATX in microglia, which could be further enhanced by hypoxia. On the other hand, interaction with microglial cells also increased ATX expression in GBM. Furthermore, microglial-induced GBM proliferation and migration could be inhibited by pharmacological inhibition of LPA1 , suggesting that microglial-derived LPA could support tumor growth and invasion. Finally, increased LPA1 expression was observed in GBM comparing with other gliomas and could be also associated with worse patient survival. These results show for the first time a microglia-GBM interaction through the LPA pathway with relevant implications for tumor progression. A better understanding of this interaction can lead to the development of new therapeutic strategies setting LPA as a potential target for GBM treatment.

Geissoschizoline, a promising alkaloid for Alzheimer's disease: Inhibition of human cholinesterases, anti-inflammatory effects and molecular docking.

Due to the lack of effective pharmacotherapy options to treats Alzheimer's disease, new strategies have been approached in the search for multi-target molecules as therapeutic options. In this work, four indole alkaloids, geissoschizoline, geissoschizone, geissospermine, and 3',4',5',6'-tetradehydrogeissospermine were isolated from Geissospermum vellosii (Pao pereira) and evaluated for their anticholinesterase activities. While geissospermine inhibited only butyrylcholinesterase (BChE), the other alkaloids behaved as non-selective inhibitors of acetylcholinesterase (AChE) and BChE. In cell viability tests, only geissoschizoline was not cytotoxic. Therefore, geissoschizoline actions were also evaluated in human cholinesterases, where it was twice as potent inhibitor of hBChE (IC50 = 10.21 ± 0.01 µM) than hAChE (IC50 = 20.40 ± 0.93 µM). On enzyme kinetic studies, geissoschizoline presented a mixed-type inhibition mechanism for both enzymes. Molecular docking studies pointed interactions of geissoschizoline with active site and peripheral anionic site of hAChE and hBChE, indicating a dual site inhibitor profile. Moreover, geissoschizoline also played a promising anti-inflammatory role, reducing microglial release of NO and TNF-α at a concentration (1 µM) ten and twenty times lower than the IC50 values of hBChE and hAChE inhibition, respectively. These actions give geissoschizoline a strong neuroprotective character. In addition, the ability to inhibit hAChE and hBChE, with approximate inhibitory potencies, accredits this alkaloid for therapeutic use in the moderate to severe phase of AD. Thus, geissoschizoline emerges as a possible multi-target prototype that can be very useful in preventing neurodegeneration and restore neurotransmission.