The biological responses to resveratrol and other polyphenols from alcoholic beverages

The Role of Antioxidants on Oxidative Stress in Diabetes Mellitus

Objective:

To evaluate the literature on the role of oxidative stress in diabetes mellitus and search sources of promising antioxidants: pharmaceutical, dietary supplements, or investigational compounds.

Data Sources:

A preliminary literature search of PubMed (1966-June 2010) was performed, using the MeSH database when possible, with the terms antioxidants, oxidative stress, antioxidants and diabetes, insulin resistance, and antioxidants and diabetic neuropathy. Bibliographies of all articles retrieved were also reviewed.

Study Selection and Data Extraction:

All studies published in English with data describing the role of antioxidants and oxidative stress in humans or animals were included.

Data Synthesis:

Oxidative stress plays a significant role in the pathogenesis of diabetes and insulin resistance. α-Lipoic acid (ALA) and N-acetylcysteine (NAC) were shown to be potent antioxidants in several clinical trials, including the SYDNEY trial, SYDNEY 2 trial, and ALADIN III study, in diabetes with albuminuria, and in women with polycystic ovarian syndrome.

Conclusions:

ALA and NAC supplementations, along with a well-balanced diet rich in fruits and vegetables containing antioxidants, provide a potential approach in the treatment of diabetes associated with oxidative stress.

Bioavailability of the polyphenols: status and controversies

The current interest in polyphenols has been driven primarily by epidemiological studies. However, to establish conclusive evidence for the effectiveness of dietary polyphenols in disease prevention, it is useful to better define the bioavailability of the polyphenols, so that their biological activity can be evaluated. The bioavailability appears to differ greatly among the various phenolic compounds, and the most abundant ones in our diet are not necessarily those that have the best bioavailability profile. In the present review, we focus on the factors influencing the bioavailability of the polyphenols. Moreover, a critical overview on the difficulties and the controversies of the studies on the bioavailability is discussed.

Consuming a diet supplemented with resveratrol reduced infection-related neuroinflammation and deficits in working memory in aged mice

Aged mice treated peripherally with lipopolysaccharide (LPS) show an exaggerated neuroinflammatory response and cognitive deficits compared to adults. Considerable evidence suggests resveratrol, a polyphenol found in red grapes, has potent antiinflammatory effects in the periphery, but its effects on the central inflammatory response and cognitive behavior are unknown. Therefore, the current study investigated if resveratrol dietary supplementation would inhibit neuroinflammation as well as behavioral and cognitive deficits in aged mice given LPS to mimic a peripheral infection. In initial studies, adult (3-6 months) and aged (22-24 months) mice were provided control or resveratrol-supplemented diet for 4 weeks and then injected intraperitoneally (i.p.) with saline or LPS, and locomotor activity and spatial working memory were assessed. As anticipated, deficits in locomotor activity and spatial working memory indicated aged mice are more sensitive to LPS compared to adults. More importantly, the LPS-induced deficits in aged animals were mitigated by dietary supplementation of resveratrol. In addition, resveratrol consumption reduced LPS-induced interleukin-1beta (IL-1beta) in plasma and the IL-1beta mRNA in the hippocampus of aged mice. Finally, pretreatment of BV-2 microglial cells with resveratrol potently inhibited LPS-induced IL-1beta production. These data show that aged mice are more sensitive than adult mice to both the inflammatory and cognitive effects of peripheral immune stimulation and suggest that resveratrol may be useful for attenuating acute cognitive disorders in elderly individuals with an infection.