Tumour suppressor p53, which is encoded by theTP53gene, is widely known to play an important role in response to DNA damage and various stresses. It has recently been reported that p53 regulates glucose metabolism and that an increase in p53 protein level is induced after serum deprivation or treatments with a natural compound,trans-Resveratrol (Rsv). In this study, we constructed a Luciferase expression vector, pGL4-TP53-551, containing 551 bp of the 5'-upstream region of the humanTP53gene, which was then transfected into HeLa S3 cells. A Luciferase assay showed that Rsv treatment increased the promoter activity of theTP53gene in comparison to that ofPIF1 Detailed deletion and mutation analyses revealed that Nkx-2.5 and E2F-binding elements are required in addition to duplicated GGAA (TTCC), for the regulation ofTP53promoter activity. In this study, it is suggested that the transient induction ofTP53gene expression by Rsv treatment might be partly involved in its anti-aging effect through maintenance of chromosomal DNAs.

In a rapid increase in cases of diabetes mellitus worldwide, there has been interested in the use of plant-derived polyphenols as nutraceuticals to prevent the onset and progression of diabetes mellitus and its associated complications. Aspalathus linearis, commonly known as rooibos, is a rich source of uncommon glycosylated plant polyphenols with various critical health-promoting properties, including the prevention and treatment of diabetes mellitus (DM). This study aimed to examine these effects by meta-analyzing the current evidence in diabetic rodent models. Peer-reviewed studies written in English from two databases, PubMed and Embase, were searched up to 28 February 2018. Studies reporting blood glucose levels in diabetic rodents with and without receiving rooibos extracts or their major phenolic compounds are included. Twelve studies enrolling 88 diabetic rodents treated with rooibos extracts or their polyphenols and 85 diabetic control males reported blood glucose levels. The pooled effect size was −0.89 (95% CI: −1.44 to −0.35) with a substantial heterogeneity (I2 = 67.0%). This effect was likely to be modified by type of rooibos extracts and their polyphenols and treatment period. Blood glucose levels were significantly lower in diabetic rodent models treated with the phenolic compound rich in rooibos extracts, PPAG.

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