Nowadays, there is considerable interest in finding out about antioxidants that are consumed in the habitual diet. It is known that polyphenols are involved in reducing the risk of diseases associated with oxidative stress. The in vitro antioxidant activity of the principal wine polyphenolic compounds (catechins, procyanidins, anthocyanins and pyranoanthocyanins) was studied in this work. Four distinct methods were used to assess the antioxidant capacity of the tested compounds: inhibition of peroxynitrite mediated tyrosine nitration, TEAC (Trolox equivalent antioxidant capacity assay), FRAP (Ferric reducing/antioxidant power assay) and TBARS (thiobarbituric acid reactive substances) methods. In general, it could be concluded that procyanidins were, among the in vitro tested groups, the ones which showed more antioxidant capacity using the four different methods, followed by anthocyanins and pyranoanthocyanins. On the basis of the simple regression testing, there was a statistically significant relationship between these different methods used in aqueous phase (r > 0.92). However, no correlation was found between the results obtained in lipid media with the TBARS method and those obtained in the aqueous media (peroxynitrite scavenging activity, TEAC and FRAP methods).Int. J. Mol. Sci. 2007, 8 798

Cudraflavone B (1) is a prenylated flavonoid found in large amounts in the roots of Morus alba, a plant used as a herbal remedy for its reputed anti-inflammatory properties. The present study shows that this compound causes a significant inhibition of inflammatory mediators in selected in vitro models. Thus, 1 was identified as a potent inhibitor of tumor necrosis factor α (TNFα) gene expression and secretion by blocking the translocation of nuclear factor κB (NF-κB) from the cytoplasm to the nucleus in macrophages derived from a THP-1 human monocyte cell line. The NF-κB activity reduction resulted in the inhibition of cyclooxygenase 2 (COX-2) gene expression. Compound 1 acts as a COX-2 and COX-1 inhibitor with higher selectivity toward COX-2 than indomethacin. Pretreatment of cells by 1 shifted the peak in an regulatory gene zinc-finger protein 36 (ZFP36) expression assay. This natural product has noticeable anti-inflammatory properties, suggesting that 1 potentially could be used for development as a nonsteroidal anti-inflammatory drug lead.

Inhibition of the metalloenzyme urease has important pharmacologic applications in the field of antiulcer and antigastric cancer agents. Urease is involved in many serious infections caused by Helicobacter pylori in the gastric tract as well as by Proteus and related species in the urinary tract. Although numerous studies have described several novel urease inhibitors (UIs) used for the treatment of gastric and urinary infections, all these compounds have exhibited severe side effects, toxicity, and instability. Therefore, to overcome such problems, it is necessary to search for new sources of UIs, such as natural products, that provide reduced side effects, low toxicity, greater stability, and bioavailability. As limited studies have been conducted on plant-derived UIs, this paper aims to highlight and summarize the most promising compounds isolated and identified from plants, such as terpenoids, phenolic compounds, alkaloids, and other substances with inhibitory activities against plant and bacterial ureases; these are in vitro and in vivo studies with an emphasis on structure-activity relationship studies and types of inhibition that show high and promising levels of anti-urease activity. This will aid medicinal chemists in the design and synthesis of novel and pharmacologically potent UIs useful for the development of antiulcer drugs.

Antiradical and cytoprotective activities of several flavanones isolated from Paulownia tomentosa (Thunb.) Steud. (Scrophulariaceae) have been evaluated using different in vitro and in vivo methods. The capacity of flavanones to scavenge radicals was measured in vitro by means of DPPH and ABTS assays, the inhibition of hydroxyl radicals produced in Fenton reactions, FRAP, scavenging superoxide radicals using enzymatic and nonenzymatic assays and the inhibition of peroxynitrite-induced nitration of tyrosine. The in vivo testing involved measuring the cytoprotective effect of chosen flavanones against alloxan-induced diabetes in mice. The activity of tested compounds was expressed either as a Trolox® equivalent or was compared with rutin or morine as known antioxidant compounds. The highest activity in most tests was observed for diplacone and 3´-O-methyl-5´-hydroxydiplacone, and the structure vs. the antioxidant activity relationship of geranyl or prenyl-substituted flavonoids with different substitutions at the B and C ring was discussed.

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