The Three Catecholics Benserazide, Catechol and Pyrogallol are GPR35 Agonists

Small phenolic and indolic gut-dependent molecules in the primate central nervous system: levels vs. bioactivity

INTRODUCTION

A rapidly growing body of data documents associations between disease of the brain and small molecules generated by gut-microbiota (GMB). While such metabolites can affect brain function through a variety of mechanisms, the most direct action would be on the central nervous system (CNS) itself.

OBJECTIVE

Identify indolic and phenolic GMB-dependent small molecules that reach bioactive concentrations in primate CNS.

METHODS

We conducted a PubMed search for metabolomic studies of the primate CNS [brain tissue or cerebrospinal fluid (CSF)] and then selected for phenolic or indolic metabolites that (i) had been quantified, (ii) were GMB-dependent. For each chemical we then conducted a search for studies of bioactivity conducted in vitro in human cells of any kind or in CNS cells from the mouse or rat.

RESULTS

36 metabolites of interests were identified in primate CNS through targeted metabolomics. Quantification was available for 31/36 and in vitro bioactivity for 23/36. The reported CNS range for 8 metabolites 2-(3-hydroxyphenyl)acetic acid, 2-(4-hydroxyphenyl)acetic acid, 3-(3-hydroxyphenyl)propanoic acid, (E)-3-(3,4-dihydroxyphenyl)prop-2-enoic acid [caffeic acid], 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 2-acetamido-3-(1H-indol-3-yl)propanoic acid [N-acetyltryptophan], 1H-indol-3-yl hydrogen sulfate [indoxyl-3-sulfate] overlapped with a bioactive concentration. However, the number and quality of relevant studies of CNS neurochemistry as well as of bioactivity were highly limited. Structural isomers, multiple metabolites and potential confounders were inadequately considered.

CONCLUSION

The potential direct bioactivity of GMB-derived indolic and phenolic molecules on primate CNS remains largely unknown. The field requires additional strategies to identify and prioritize screening of the most promising small molecules that enter the CNS.

Bioactive Polyphenols and Neuromodulation: Molecular Mechanisms in Neurodegeneration

The interest in dietary polyphenols in recent years has greatly increased due to their antioxidant bioactivity with preventive properties against chronic diseases. Polyphenols, by modulating different cellular functions, play an important role in neuroprotection and are able to neutralize the effects of oxidative stress, inflammation, and apoptosis. Interestingly, all these mechanisms are involved in neurodegeneration. Although polyphenols display differences in their effectiveness due to interindividual variability, recent studies indicated that bioactive polyphenols in food and beverages promote health and prevent age-related cognitive decline. Polyphenols have a poor bioavailability and their digestion by gut microbiota produces active metabolites. In fact, dietary bioactive polyphenols need to be modified by microbiota present in the intestine before being absorbed, and to exert health preventive effects by interacting with cellular signalling pathways. This literature review includes an evaluation of the literature in English up to December 2019 in PubMed and Web of Science databases. A total of 307 studies, consisting of research reports, review articles and articles were examined and 146 were included. The review highlights the role of bioactive polyphenols in neurodegeneration, with a particular emphasis on the cellular and molecular mechanisms that are modulated by polyphenols involved in protection from oxidative stress and apoptosis prevention.

Phenotypic assessment and ligand screening of ETA/ETB receptors with label-free dynamic mass redistribution assay

Endothelin receptors, consisting of two subtypes, ETA and ETB, are expressed in various tissues and widely regulate cardiovascular systems. The two receptors show distinct biological characteristics and are involved in different downstream pathways. Hence, to evaluate the ETA and ETB receptors on the same platform is helpful to display their pharmacological features. In this study, we developed a label-free dynamic mass redistribution (DMR) assay to investigate the phenotypic features of the ETA and ETB receptors in native cell lines. Meanwhile, specific agonists and antagonists were investigated for their pharmacological parameters. Results indicated that the DMR response of endothelin 1 (ET-1, an endogenous ETA/ETB agonist) was cell line dependent on ETA receptors and this ligand generated a biphasic dose-response curve in SH-SY5Y as well as PC3 cell lines. ET-1 and IRL 1620 (an ETB agonist) showed different DMR responses in U251 cells. IC₅₀ values of antagonists were consistent with the K_i values previously reported. Furthermore, a list of compounds was screened on the ETA and ETB receptor models established by the high-throughput DMR assays. This study demonstrated that the DMR assay had great potential in the phenotypic-based investigation and ligand screening of GPCRs.

Phenolic Metabolites Modulate Cardiomyocyte Beating in Response to Isoproterenol

Cardiovascular disease (CVD) is a public health concern, and the third cause of death worldwide. Several epidemiological studies and experimental approaches have demonstrated that consumption of polyphenol-enriched fruits and vegetables can promote cardioprotection. Thus, diet plays a key role in CVD development and/or prevention. Physiological β-adrenergic stimulation promotes beneficial inotropic effects by increasing heart rate, contractility and relaxation speed of cardiomyocytes. Nevertheless, chronic activation of β-adrenergic receptors can cause arrhythmias, oxidative stress and cell death. Herein the cardioprotective effect of human metabolites derived from polyphenols present in berries was assessed in cardiomyocytes, in response to chronic β-adrenergic stimulation, to disclose some of the underlying molecular mechanisms. Ventricular cardiomyocytes derived from neonate rats were treated with three human bioavailable phenolic metabolites found in circulating human plasma, following berries' ingestion (catechol-O-sulphate, pyrogallol-O-sulphate, and 1-methylpyrogallol-O-sulphate). The experimental conditions mimic the physiological concentrations and circulating time of these metabolites in the human plasma (2 h). Cardiomyocytes were then challenged with the β-adrenergic agonist isoproterenol (ISO) for 24 h. The presence of phenolic metabolites limited ISO-induced mitochondrial oxidative stress. Likewise, phenolic metabolites increased cell beating rate and synchronized cardiomyocyte beating population, following prolonged β-adrenergic receptor activation. Finally, phenolic metabolites also prevented ISO-increased activation of PKA-cAMP pathway, modulating Ca²⁺ signalling and rescuing cells from an arrhythmogenic Ca²⁺ transients' phenotype. Unexpected cardioprotective properties of the recently identified human-circulating berry-derived polyphenol metabolites were identified. These metabolites modulate cardiomyocyte beating and Ca²⁺ transients following β-adrenergic prolonged stimulation.

R. R, Thomas S, Nisha P. Musa paradisiaca inflorescence induces human colon cancer cell death by modulating cascades of transcriptional events

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