Impact of Polyphenols on Inflammatory and Oxidative Stress Factors in Diabetes Mellitus: Nutritional Antioxidants and Their Application in Improving Antidiabetic Therapy.

Diabetes mellitus is a chronic metabolic disorder characterized by hyperglycaemia and oxidative stress. Oxidative stress plays a crucial role in the development and progression of diabetes and its complications. Nutritional antioxidants derived from dietary sources have gained significant attention due to their potential to improve antidiabetic therapy. This review will delve into the world of polyphenols, investigating their origins in plants, metabolism in the human body, and relevance to the antioxidant mechanism in the context of improving antidiabetic therapy by attenuating oxidative stress, improving insulin sensitivity, and preserving ß-cell function. The potential mechanisms of, clinical evidence for, and future perspectives on nutritional antioxidants as adjuvant therapy in diabetes management are discussed.

Evidence from a Systematic Review and Meta-Analysis Pointing to the Antidiabetic Effect of Polyphenol-Rich Plant Extracts from Gymnema montanum, Momordica charantia and Moringa oleifera.

In vitro and animal model studies are of great interest for selecting new phytochemicals, including polyphenols with antioxidative properties, as candidates for antidiabetic drugs. This review provides evidence from a critical literature data analysis on the effects of plant extract supplementation in diabetes mellitus management. We considered and meta-analyzed the efficacy of oral supplementation of plant extracts in animal model studies and examined physiological and oxidative stress parameters. Finally, 23 articles were included in the meta-analysis, revealing three plants with experimentally confirmed in vivo and in vitro antidiabetic properties: Gymnema montanum, Momordica charantia and Moringa oleifera. The following parameter changes resulted from an investigation of the supplementation: reduced oxidative stress, decreased insulin resistance, increased insulin release, reduced adiposity, and a modulatory effect on glycolysis and gluconeogenesis, as well as attenuation of diabetes-associated weight loss, reduced fasting blood glucose and lowered oxidative status. A comparison of Gymnema montanum versus Glybenclamide revealed the superiority of extracts over drug administration in some aspects. Although the analyzed extracts are promising candidates for antidiabetic treatment, there is much inconsistent data in the literature. Therefore, ultimate references for using these compounds in the prevention of diabetes are currently not applicable.

Polyphenol Extract from Evening Primrose (Oenothera paradoxa) Inhibits Invasion Properties of Human Malignant Pleural Mesothelioma Cells.

Extracts from the defatted evening primrose (Oenothera paradoxa Hudziok) seeds are the source of a range of stable polyphenolic compounds, including ellagic acid, gallic acid, and catechin. Our studies evaluate, for the first time, the influence of evening primrose isopropanol extract (EPE) on malignant pleural mesothelioma (MPM) cells. MPM is rarely diagnosed, its high aggressiveness and frequently noted chemoresistance limit its treatment schemes and it is characterized by low prognostic features. Here, we demonstrate that EPE inhibited MPM growth in a dose-dependent manner in cells with increased invasion properties. Moreover, EPE treatment resulted in cell cycle arrest in the G2/M phase and increased apoptosis in invasive MPM cell lines. Additionally, EPE strongly limited invasion and MMP-7 secretion in MPM cancer cells. Our original data provide evidence about the potential anti-invasive effects of EPE in MPM therapy treatment.

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-ß-(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.