Quantitative structure-activity relationships studies of antioxidant hexahydropyridoindoles and flavonoid derivatives

Structure-Activity Relationship and Prediction of the Electron-Transfer Potential of the Xanthones Series

The structure-activity relationships of 31 xanthones were analyzed by using the ferric reducing antioxidant power (FRAP) assay to determine their electron-transfer (ET) potential. It was proven that the ET potential of xanthones was dominated by four moieties (i.e. hydroquinone moiety, 5,6-catechol moiety, 6,7-catechol moiety, and 7,8-catechol moiety) and was only slightly affected by other structural features, including a single phenolic OH group, the resorcinol moiety, the transannular dihydroxy moiety, a methoxy group, a sugar residue, an isoprenyl group, a cyclized isoprenyl group, and an isopentanol group. The results could be used to predict the ET potentials of other antioxidant xanthones.

Pro-oxidative and antioxidative controls and signaling modification of polyphenolic phytochemicals: contribution to health promotion and disease prevention?

Polyphenolic phytochemicals (PPs) have been extensively studied as potential nutriceuticals for maintenance of health and treatment of cancer, inflammation, and neurodegeneration. However, the reported beneficial outcomes are inconsistent. The biological activities of PPs have been attributed to their pro-oxidative and antioxidative actions and effects on signaling mechanisms and epigenomic modifications. These diversified properties were described or postulated on the basis of a variety of experimental studies using cell culture and animal models, even though most have not been replicated and results are not validated. This review attempts to give an overview of biological properties of PPs, based on the coherent results from relevant studies, and evaluate critically the experimental conditions and possible artifacts. Complicated molecular mechanisms and multitargeting genomic interactions of PPs are discussed, with a view that reasonable mechanistic propositions are usually obtained from well-designed in vivo studies.

A QCAR model for predicting antioxidant activity of wild mushrooms

Wild mushrooms have been described as sources of natural antioxidants, particularly phenolic compounds. However, many other compounds present in wild mushrooms can also act as antioxidants (reducers), so whole extracts from a wide range of species need to be examined. To gain further knowledge in this area, the relationship between the antioxidant potential (scavenging effect and reducing power) and chemical composition of twenty three samples from seventeen Portuguese wild mushroom species was investigated. A wide range of analytical parameters reported by our research group (including ash, carbohydrates, proteins, fat, monounsaturated fatty acids, polyunsaturated fatty acids, saturated fatty acids, phenolics, flavonoids, ascorbic acid and beta-carotene) were studied and the data were analysed by partial least squares (PLS) regression analysis to allow correlation of all the parameters. Antioxidant activity correlated well with phenolic and flavonoid contents. A QCAR (Quantitative Composition-Activity Relationships) model was constructed, using the PLS method, and its robustness and predictability were verified by internal and external cross-validation methods. Finally, this model proved to be a useful tool in the prediction of mushrooms' reducing power.