Brain ageing is a complex physiological process that includes several mechanisms. It is characterized by neuronal/glial dysfunction, alterations in brain vasculature and barriers, and the decline in brain repair systems. These disorders are triggered by an increase in oxidative stress and a proinflammatory state, without adequate antioxidant and anti-inflammatory systems, as it occurs in young life stages. This state is known as inflammaging. Gut microbiota and the gut–brain axis (GBA) have been associated with brain function, in a bidirectional communication that can cause loss or gain of the brain’s functionality. There are also intrinsic and extrinsic factors with the ability to modulate this connection. Among the extrinsic factors, the components of diet, principally natural components such as polyphenols, are the most reported. The beneficial effects of polyphenols in brain ageing have been described, mainly due to their antioxidants and anti-inflammatory properties, including the modulation of gut microbiota and the GBA. The aim of this review was, by following the canonical methodology for a state-of-the-art review, to compose the existing evidenced picture of the impact of the gut microbiota on ageing and their modulation by polyphenols as beneficial molecules against brain ageing.

A large number of studies have demonstrated the implication of oxidative stress (OxS) in the pathogenesis of ageing-related muscle decline and atrophy. The key mechanism is related to the OxS-induced production of free radicals, with the consequent increase in oxidative damage, resulting in affected muscle quality and strength. The present study aimed to evaluate the efficacy of a grape polyphenol-based nutraceutical formulation (Taurisolo^®) in reducing the OxS in muscle of aged rats. A group of 16 aged (20 months) rats were orally administered with Taurisolo^® (n = 8; 100 mg/kg Taurisolo^®) or placebo (n = 8; 50 mg/kg maltodextrin); an additional group of eight young (three months) rats were also treated with placebo. All the treatments were orally administered for 30 days. The activities of antioxidant enzymes, the levels of malondialdehyde (MDA) and nitrotyrosine (N-Tyr) and the expression of OxS- and inflammation-related genes were evaluated on the gastrocnemius muscle. In muscle samples of the treated-group, increased activity of antioxidant enzymes, reduced MDA and N-Tyr levels and increased expression of antioxidant and anti-inflammatory genes were observed in respect to the placebo. Data herein presented suggest that the chronic treatment with Taurisolo^® significantly reduces oxidative damage and improves muscle performance in aged rats.

Aging is a normal physiological process influenced by the combination of multiple mechanisms, primarily oxidative stress and neuroinflammation, which impact general physiology and brain function. Phenolic compounds have demonstrated the ability to slow down the aging process of the brain due to their antioxidant and anti-inflammatory effects. This study assessed the protective properties of catechin and polyphenon-60 in non-pathologically aged rats regarding visuo-spatial learning and the oxidative status of the frontal cortex. Old animals were treated with catechin or green tea extract (polyphenon-60) for 36 days, daily. Healthy old and young rats were used as controls. During the first training phase, treated rats executed the test better, locating the target in less time compared with the controls. Biomarkers of oxidative stress (catalase activities, superoxide dismutase, glutathione reductase, and glutathione S-transferase) were reduced in the brain of old animals, although their activities were partially improved after both antioxidant treatments. Furthermore, the rise in the production of reactive oxygen species and malondialdehyde levels—a marker of lipid peroxidation—in the frontal cortex of aged animals was significantly ameliorated after the interventions. In conclusion, old rats exhibited enhanced cognitive function and reduced stress levels following the administration of catechin and polyphenon-60.

There is a paucity of in vivo assays to investigate the potential deleterious effects of plastic-laden compounds in the gastrointestinal tract of mammals, compared to in vitro testing and ecotoxicity assays in marine organisms. This work aims to fill this gap through a comprehensive evaluation of the acute toxicokinetics and bioavailability of bisphenol A (BPA)-adsorbed medium-density polyethylene (PE) microplastics (MPs) (ca. 3000 μg BPA/g), with a mean particle size of 136 μm, which were administered via oral gavage at a mere 0.67 mg BPA/kg body weight for 24 h using a murine model. The determination of plasma BPA-glucuronide revealed that BPA associated with MPs (PE-BPA) is bioavailable to a similar extent to that of freely dissolved BPA, with Area Under the Curves (AUC) values of 1249 ± 182 and 928 ± 276 μg h·L^-1 for the 0 → 6 h interval (AUC_0→6h), and 3586 ± 526 and 2325 ± 634 μg h·L^-1 for the 0 → 24 h interval (AUC_0→24h), corresponding to PE-BPA and free BPA, respectively. Several biomarker assays of the small intestine and liver, and the investigation of the gut barrier function were conducted to elucidate the potential deleterious effects of PE-BPA as compared to BPA and PE alone. Acute exposure to PE-BPA increased the expression of the detoxification biomarkers multidrug resistance protein 1 (MDR1) and UDP-glucuronosyltransferase 2b1 (UGT2b1) in the jejunum, particularly when PE and BPA occurred together, likely due to the extended intestinal residence time of the BPA-laden MPs. Oxidative stress markers, such as superoxide dismutase activity, and inflammatory responses, evaluated by myeloperoxidase activity, were also elevated in the PE-BPA group, suggesting a defensive response but without evidence of oxidative damage as determined by the malondialdehyde levels. In conclusion, the findings suggest that BPA associated with MPs exhibits similar bioavailability than that of freely dissolved BPA, with the subsequent activation of detoxification pathways and inflammatory responses.