Inflammation and oxidative stress are common aspects of most neurodegenerative diseases in the central nervous system. In this context, microglia and astrocytes are central to mediating the balance between neuroprotective and neurodestructive mechanisms. Flavonoids have potent anti-inflammatory and antioxidant properties. Here, we have examined the anti-inflammatory and neuroprotective potential of the flavonoid agathisflavone (FAB), which is derived from the Brazilian plant Poincianella pyramidalis, in in vitro models of neuroinflammation. Cocultures of neurons/glial cells were exposed to lipopolysaccharide (LPS, 1 µg/mL) or interleukin (IL)-1β (10 ng/mL) for 24 h and treated with FAB (0.1 and 1 µM, 24 h). FAB displayed a significant neuroprotective effect, as measured by nitric oxide (NO) production, Fluoro-Jade B (FJ-B) staining, and immunocytochemistry (ICC) for the neuronal marker β-tubulin and the cell death marker caspase-3, preserving neuronal soma and increasing neurite outgrowth. FAB significantly decreased the LPS-induced microglial proliferation, identified by ICC for Iba-1/bromodeoxyuridine (BrdU) and CD68 (microglia M1 profile marker). In contrast, FAB had no apparent effect on astrocytes, as determined by ICC for glial fibrillary acidic protein (GFAP). Furthermore, FAB protected against the cytodestructive and proinflammatory effects of IL-1β, a key cytokine that is released by activated microglia and astrocytes, and ICC showed that combined treatment of FAB with α and β estrogen receptor antagonists did not affect NF-κB expression. In addition, qPCR analysis demonstrated that FAB decreased the expression of proinflammatory molecules TNF-α, IL-1β, and connexins CCL5 and CCL2, as well as increased the expression of the regulatory molecule IL-10. Together, these findings indicate that FAB has a significant neuroprotective and anti-inflammatory effect in vitro, which may be considered as an adjuvant for the treatment of neurodegenerative diseases.

Amburana cearensis A.C. Smith is an endemic tree from Northeastern Brazil used in folk medicine as teas, decocts and syrups for the treatment of various respiratory and inflammatory diseases, since therapeutic properties have been attributed to compounds from its stem bark and seeds. Numerous pharmacological properties of semi-purified extracts and isolated compounds from A. cearensis have been described in several biological systems, ranging from antimicrobial to anti-inflammatory effects. Some of these activities are attributed to coumarins and phenolic compounds, the major compounds present in A. cearensis seed extracts. Multiple lines of research demonstrate these compounds reduce oxidative stress, inflammation and neuronal death induced by glutamate excitotoxicity, events central to most neuropathologies, including Alzheimer’s disease (AD) and Parkinson’s Disease (PD). This review focuses on the botanical aspects, folk medicine use, biological effects and pharmacological activities of A. cearensis compounds and their potential as novel non-toxic drugs for the treatment of neurodegenerative diseases.

Amburana cearensis is a plant native to Brazil used in folk medicine for the treatment of several pathological conditions including stroke. Previous research indicates that a dichloromethane extract of A. cearensis seeds (EDAC), rich in coumarins, protects neural cells against oxygen and glucose deprivation (OGD) and glutamate-induced stress. However, further studies are needed to elucidate the role of coumarin, in the protective effect of EDAC. Glutamatergic excitotoxicity is an important cause of neuronal loss involved in the pathogenesis of Alzheimer’s disease, Huntington’s disease, Parkinson’s disease, and ischemic stroke. Therefore, this study aimed to investigate the protective effects of coumarin isolated from EDAC against glutamate excitotoxicity in regulating MAPK pathway proteins and reactive oxygen species (ROS) production on PC12 cells. Furthermore, we aimed to investigate the protective effects of coumarin against cell death induced by OGD. We characterized the isolated compound from EDAC as coumarin by ¹H and ¹³C-NMR. Thus, PC12 cells were exposed to OGD or glutamate (20 mM) and/or treated with EDAC or coumarin (500 μg/mL) for 24 h. Subsequently, cell viability was assessed by propidium iodide staining or by MTT test. Furthermore, the expression of MAPK pathway proteins was investigated by Western blot analysis and the expression of cleaved caspase-3 by immunofluorescence. Furthermore, reactive oxygen species (ROS) production was assessed by 2′,7′-dichlorofluorescein diacetate and CellROX. We observed that EDAC and coumarin were able to protect PC12 cells against OGD conditions. Moreover, EDAC totally inhibited the glutamate toxicity in PC12 cells. Meanwhile, coumarin mitigated the glutamate toxicity. Both were able to downregulate the expression of ERK1/2 and phosphorylated ERK and inhibit caspase-3 activation. EDAC and coumarin also prevented the increase of ROS induced by treatment with H₂O₂ or glutamate. Our results evidenced that coumarin from A. cearensis is antioxidative and is an important cytoprotective compound in EDAC against glutamate excitotoxicity or OGD injury.