Lucyna A. Wozniak

A review of natural and synthetic antioxidants important for health and longevity.

Reactive oxygen species (ROS) generated in the presence of O(2) by mitochondria, phagocytic cells, peroxisomes, and cytochrome P450 enzymes under physiological conditions, may play a dual function in the human organism. On the one hand, they participate in cell signal transduction cascades, leading to the activation of some transcription factors responsible for regulating of the expression of genes relevant for cell growth and differentiation. On the other hand, they cause oxidative damage of cellular DNA, protein and lipids, resulting in the initiation or development of numerous diseases such as cancer, cardiovascular diseases, type 2 diabetes mellitus, cataract, rheumatoid arthritis, or different neurodegenerative diseases. Both endogenous compounds (glutathione, ubiquinol, urate, bilirubin) and enzymes (superoxide dismutase, catalase, glutathione peroxidase) are engaged in the detoxification of ROS. In addition, numerous dietary components such as vitamin C, vitamin E, carotenoids, and polyphenols are thought to be involved in the antioxidant defense system. The present review article is focused on the summary and the assessment of research on the impact of dietary antioxidants in the prevention of chronic diseases, particularly cancer and cardiovascular diseases.

Physiological and Pathophysiological Functions of SIRT1

The human SIRT1 is a nuclear enzyme from the class III histone deacetylases (HDACs) which is widely distributed in mammalian tissues. A variety of SIRT1 substrates hints that this protein is involved in the regulation of diverse biological processes, including cell survival, apoptosis, gluconeogenesis, adipogenesis, lipolysis, stress resistance, muscle differentiation, and insulin secretion. This review emphasizes catalytic properties of SIRT1 and its role in apoptosis, insulin pathway, and neuron survival.

The elevated gene expression level of the A2B adenosine receptor is associated with hyperglycemia in women with gestational diabetes mellitus

Adenosine receptors denoted by A1, A2A, A2B, and A3 and encoded by ADORA1, ADORA2A, ADORA2B, and ADORA3 genes, respectively, are adenosine‐activated G‐protein‐coupled receptors that play an important role in obesity and type 2 diabetes mellitus. However, little is known about their significance in gestational diabetes mellitus (GDM). The purpose of this study was to investigate whether there are changes in leukocyte AR expression in GDM patients and whether these alterations are linked to well‐known diabetic genes.

New Insight Into A1 Adenosine Receptors in Diabetes Treatment

The A₁ adenosine receptors (A₁AR), belonging to the rhodopsin-like superfamily of the G-protein-coupled receptors (GPCRs), may regulate many various cellular processes in cardiovascular, renal, and central nervous systems. In addition, since A(1)AR possesses antilipolytic properties, numerous A₁AR agonists and antagonists have been developed, but only some of them with the most promising selective properties in vitro have been advanced to animal studies and clinical trials. In this review, we have summarized the studies on the utility of A₁AR selective agonists and antagonists in the regulation of lipid and carbohydrate metabolism and their potential therapeutic applications in diabetes.

Increased expression of immune-related genes in leukocytes of patients with diagnosed gestational diabetes mellitus (GDM)

Compelling evidence indicates that the immune system is linked to metabolism in gestational diabetes mellitus (GDM), but factors participating in these processes still are awaiting identification. Inducible nitric oxide synthase, encoded by the NOS2 gene, and surfactant protein D, encoded by the SFTPD gene, have been implicated in diabetes. We investigated NOS2 and SFTPD mRNA levels in leukocytes obtained from 125 pregnant women with (nu2009=u200987) or without (control group; nu2009=u200938) GDM, and, in turn, correlated their expression with clinical parameters of subjects. Leukocytes were isolated from the blood of pregnant women and NOS2 and SFTPD expression in these cells was determined by quantitative real time PCR (qRT-PCR). Univariate correlation analyses were performed to assess an association between leukocyte NOS2 and SFTPD expression and clinical characteristics of patients. qRT-PCR experiments disclosed significantly increased leukocyte NOS2 and SFTPD mRNA levels in hyperglycemic GDM patients (Pu2009<u20090.05). In the entire study group, there were significant positive associations of leukocyte NOS2 and SFTPD mRNAs with C-reactive protein. Additionally, transcript level of SFTPD also correlated positively with fasting glycemia and insulin resistance. This study demonstrates that an impaired glucose metabolism in GDM may be predominant predictor of leukocyte NOS2 and SFTPD overexpression in diabetic patients. Furthermore, alterations in the expression of these genes are associated with glucose metabolism dysfunction and/or inflammation during pregnancy. In addition, these findings support the utilization of leukocytes as good experimental model to study a relationship between immune-related genes and metabolic changes in women with GDM, as well as to assess the potential mechanisms underlying these alterations.

Activation of Methylphosphonates and Their Thio- and Seleno Congeners with 1,3,5-Triazinyl Morpholinium Salts. Selenono-Selenolo Isomerization

The stereospecific activation of nucleoside 3′-O-methylphosphonoselenoates ( 1 ) with N-methyl-N-4,6-dimethoxy-1,3,5-triazinyl-yl morpholinium chloride resulted in formation of both O-activated (5) and Se-activated (6) 1,3,5-triazin-yl esters.

Molecular Mechanisms Underlying Curcumin-Mediated Therapeutic Effects in Type 2 Diabetes and Cancer

The growing prevalence of age-related diseases, especially type 2 diabetes mellitus (T2DM) and cancer, has become global health and economic problems. Due to multifactorial nature of both diseases, their pathophysiology is not completely understood so far. Compelling evidence indicates that increased oxidative stress, resulting from an imbalance between production of reactive oxygen species (ROS) and their clearance by antioxidant defense mechanisms, as well as the proinflammatory state contributes to the development and progression of the diseases. Curcumin (CUR; diferuloylmethane), a well-known polyphenol derived from the rhizomes of turmeric Curcuma longa, has attracted a great deal of attention as a natural compound with beneficial antidiabetic and anticancer properties, partly due to its antioxidative and anti-inflammatory actions. Although this polyphenolic compound is increasingly being recognized for its growing number of protective health effects, the precise molecular mechanisms through which it reduces diabetes- and cancer-related pathological events have not been fully unraveled. Hence, CUR is the subject of intensive research in the fields Diabetology and Oncology as a potential candidate in the treatment of both T2DM and cancer, particularly since current therapeutic options for their treatment are not satisfactory in clinics. In this review, we summarize the recent progress made on the molecular targets and pathways involved in antidiabetic and anticancer activities of CUR that are responsible for its beneficial health effects.

Melatonin as a Pleiotropic Molecule with Therapeutic Potential for Type 2 Diabetes and Cancer

BACKGROUNDnThe incidence of both type 2 diabetes (T2DM) and cancer is increasing worldwide, making these diseases a global health problem along with increasing healthcare expenditures. The current therapeutic approaches for treating these multifactorial diseases are far from satisfactory. As increasing evidence shows beneficial effects of melatonin (MLT) on typical pathological changes occurring during the development of T2DM and cancer, the present review focuses on molecular aspects of antidiabetic and anticancer activities of MLT and, moreover, discusses several future directions of research regarding MLT application as potential therapeutic agent.nnnMETHODSnCritical literature analysis in PubMed central combined with personal expertise.nnnRESULTSnNumerous in vitro and in vivo studies have revealed that MLT possesses a number of antidiabetic health benefits by diminishing hyperglycemia, insulin resistance, oxidative stress, and inflammation through modulating various intracellular signaling pathways or other targets involved in the pathophysiology of this disease. Mounting evidence also indicates that MLT exhibits multi-targeted anticancer effects in numerous human malignancies, mainly resulting from its ability to modulate several signal transduction pathways associated with cell survival, proliferation, and apoptosis. Furthermore, beneficial synergistic action of MLT with chemotherapy and radiotherapy has also been observed. Importantly, no adverse outcomes have been found from the clinical use of MLT, which highlights its therapeutic usefulness, either alone or in combination with other conventional therapies, in cancer treatment.nnnCONCLUSIONnThe findings described in this review suggest that MLT may confer potential benefits to human health, particularly in respect to T2DM and cancer.

Dual Stimulus-Dependent Effect of Oenothera paradoxa Extract on the Respiratory Burst in Human Leukocytes: Suppressing for Escherichia coli and Phorbol Myristate Acetate and Stimulating for Formyl-Methionyl-Leucyl-Phenylalanine

Although a growing body of evidence suggests that plant polyphenols can modulate human immune responses, their simultaneous action on monocyte and neutrophil oxidative burst is currently poorly understood. Based on the hypothesis that various polyphenols contained in plant extracts might affect the oxidative burst of phagocytes, we evaluated the effects of ethanolic O. paradoxa extract polyphenols on monocyte and neutrophil oxidative burst in vitro activated by different stimuli, including opsonized bacteria E. coli, phorbol 12-myristate 13-acetate (PMA), and formyl-methionyl-leucyl-phenylalanine (fMLP). Samples were analyzed by the dihydrorhodamine flow cytometry assay. Our results showed that the extract repressed significantly and dose-dependently reactive oxygen species production in both cell types stimulated with E. coli and PMA (P < 0.05) and its inhibitory efficiency was stimulus- and cell-type-dependent. Interestingly, there was significant stimulatory effect of the extract on bursting phagocytes induced by fMLP (P < 0.05). Additionally, several flavonoids and phenolic compounds as well as penta-galloyl-β-(D)-glucose (PGG), the representative of hydrolyzable tannins, were identified in the 60% extract by high-performance liquid chromatography (HPLC) coupled to electrospray ionization in negative ion mode. In summary, the ethanolic O. paradoxa extract, rich in flavonoids and phenolic compounds, exhibits dual stimulus-dependent effect on the respiratory burst in human leukocytes; hence, it might affect immune responses in humans.

Molecular Mechanisms of Diabetes Prevention by Structurally Diverse Antioxidants

Since oxidative stress mediated by hyperglycemia-induced production of reactive oxygen and nitrogen species (ROS/RNS) contributes to the development and progression of type 2 diabetes mellitus (T2DM), many studies have been focused on seeking novel and effective antioxidants from natural sources as potential agents for the prevention and alternative treatment of this serious disease. There is currently a strong interest in the effects of both alpha-lipoic acid (LA) and tea catechins, especially epigallocatechin gallate (EGCG), on carbohydrate and lipid metabolism and its association with diabetes. Therefore, this chapter focuses on the role of the above-mentioned antioxidants in diabetes and its complications and, additionally, on the proposed molecular mechanisms by which these compounds may offer protection against the initiation and development of this disease.