Structural characterization of a proanthocyanidin-rich fraction from Hancornia speciosa leaves and its effect on the release of pro-inflammatory cytokines and oxidative stress in THP-1 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: In Brazil, the leaves of Hancornia speciosa Gomes have a traditional use for treating hypertension and diabetes. Experimental investigations have confirmed the anti-hypertensive and hypoglycemic properties of extracts derived from H. speciosa leaves across various experimental models. These biological activities have been mostly ascribed to its major constituent, bornesitol, along with other cyclitols, flavonoids, and cinnamic acid derivatives. AIM OF STUDY: The objective of this study was to characterize the chemical structure of proanthocyanidins from H. speciosa leaves and explore their in vitro activity on the release of pro-inflammatory cytokines and oxidative stress. MATERIAL AND METHODS: The acetone/water (7:3) extract of H. speciosa leaves (HsE) was prepared by percolation and fractionated by column chromatography over Sephadex LH20 to afford the proanthocyanidin-rich fraction HsFr3. Structure characterization of the proanthocyanidins constituents of HsFr3 was accomplished by extensive UPLC-DAD-ESI-MS/MS analysis coupled to degradation reaction through thiolysis. The effect of HsE, HsFr3, and bornesitol on the release of TNF, IL-1ß and IL-6 in LPS-stimulated THP-1 cells was assayed by ELISA. The effect of the samples on oxidative stress induced by LPS in THP-1 cell was investigated using a DCFH-DA fluorescent assay. RESULTS: Fractionation of HsE afforded HsFr3, primarily composed of six proanthocyanidins. Their chemical structures were characterized as dimeric (4 isomers) and trimeric (2 isomers) procyanidins C-glycosides of the B-type. HsE, HsFr3, and bornesitol reduced the release of pro-inflammatory cytokines TNF and IL-1ß in LPS-stimulated THP-1 cells, while no significant effect was observed on IL-6. All samples reduced the oxidative stress induced by LPS in THP-1 cells, whereas bornesitol, tested at lower concentrations, induced an equivalent response to HsE and HsFr3. CONCLUSIONS: Our findings provide additional evidence to support the ethnomedical use of H. speciosa in managing hypertension and hyperglycemia, due to the direct association of oxidative stress, TNF, and IL-1ß with the maintenance and aggravation of these deleterious conditions. The dimeric and trimeric procyanidin C-glycosides, characterized in the species, contribute to diminish oxidative stress and the release or pro-inflammatory cytokines, whereas bornesitol was shown to induce similar effect at lower concentrations.

A positive allosteric modulator of mGluR5 promotes neuroprotective effects in mouse models of Alzheimer's disease.

Alzheimer's Disease (AD) is the most prevalent neurodegenerative disorder. Despite advances in the understanding of its pathophysiology, none of the available therapies prevents disease progression. Excess glutamate plays an important role in excitotoxicity by activating ionotropic receptors. However, the mechanisms modulating neuronal cell survival/death via metabotropic glutamate receptors (mGluRs) are not completely understood. Recent data indicates that CDPPB, a positive allosteric modulator of mGluR5, has neuroprotective effects. Thus, this work aimed to investigate CDPPB treatment effects on amyloid-ß (Aß) induced pathological alterations in vitro and in vivo and in a transgenic mouse model of AD (T41 mice). Aß induced cell death in primary cultures of hippocampal neurons, which was prevented by CDPPB. Male C57BL/6 mice underwent stereotaxic surgery for unilateral intra-hippocampal Aß injection, which induced memory deficits, neurodegeneration, neuronal viability reduction and decrease of doublecortin-positive cells, a marker of immature neurons and neuronal proliferation. Treatment with CDPPB for 8 days reversed neurodegeneration and doublecortin-positive cells loss and recovered memory function. Fourteen months old T41 mice presented cognitive deficits, neuronal viability reduction, gliosis and Aß accumulation. Treatment with CDPPB for 28 days increased neuronal viability (32.2% increase in NeuN+ cells) and reduced gliosis in CA1 region (Iba-1+ area by 31.3% and GFAP+ area by 37.5%) in transgenic animals, without inducing hepatotoxicity. However, it did not reverse cognitive deficit. Despite a four-week treatment did not prevent memory loss in aged transgenic mice, CDPPB is protective against Aß stimulus. Therefore, this drug represents a potential candidate for further investigations as AD treatment.