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A polyphenol-rich diet protects against chronic pathologies by modulating numerous physiological processes, such as cellular redox potential, enzymatic activity, cell proliferation and signaling transduction pathways. However, polyphenols have a low oral bioavailability mainly due to an extensive biotransformation mediated by phase I and phase II reactions in enterocytes and liver but also by gut microbiota. Despite low oral bioavailability, most polyphenols proved significant biological effects which brought into attention the low bioavailability/high bioactivity paradox . In recent years, polyphenol metabolites have attracted great interest as many of them showed similar or higher intrinsic biological effects in comparison to the parent compounds. There is a huge body of literature reporting on the biological functions of polyphenol metabolites generated by phase I and phase II metabolic reactions and gut microbiota-mediated biotransformation. In this respect, the review highlights the pharmacokinetic fate of the major dietary polyphenols (resveratrol, curcumin, quercetin, rutin, genistein, daidzein, ellagitannins, proanthocyanidins) in order to further address the efficacy of biometabolites as compared to parent molecules. The present work strongly supports the contribution of metabolites to the health benefits of polyphenols, thus offering a better perspective in understanding the role played by dietary polyphenols in human health.

Unlabelled: The plants belonging to Lamiaceae family are widely used in medicine, cosmetic and food industry. Besides volatile oils, the main constituents of these plants are polyphenols. These compounds are secondary metabolites with multiple biological activities useful in the prevention and treatment of many disorders., Aim: To determine the flavonoids. hydroxycinnamic acids and total polyphenols content in several aromatic Lamiaceae plants available in Romanian pharmacies as herbal tea products: Melissa officinalis, Lavandula officinalis, Rosmarinus officinalis, Mentha piperita, Thymus vulgaris and Salvia pratensis., Material and Methods: The quantitative determination of different types of polyphenols was performed in ethanolic extracts 70% and 50%, respectively, of each sample, using spectrophotometric methods., Results and Discussion: The total polyphenols levels in the investigated products ranged between 3.10% and 6.51% (expressed as g GAE/100 g dry weight), the largest amount being identified in Melissa officinalis (6.51%). The samples of Salvia pratensis and Mentha piperita were the richest in flavonoid derivatives expressed as g rutin/100 g dry weight (1.83% and 1.53%, respectively), the optimal extraction being with 70% ethanol. The highest content in hydroxycinnamic acids expressed as g rosmarinic acid/100 g dry weight was found in Melissa officinalis sample (4.15%)., Conclusions: There is a wide variability of polyphenolic content not only by species, but also depending on the polyphenols type or solvent used for extraction. The best extraction rate of total polyphenols in the investigated Lamiaceae species was obtained with 50% ethanol.

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The metabolic processes that take place in plant organisms result in a wide variety of phytocompounds. Among them, polyphenols (PF) and volatile terpenes (TPVL) are the most studied for potential therapeutic uses [1]. Although both PF and TPVL showed a wide spectrum of biological actions (such as antioxidant, antimicrobial, anti-inflammatory, chemopreventive, etc.) when studied in vitro or in vivo on animal models, their clinical use is limited by their stability and pharmacokinetic issues [2,3]. Current studies focus on including these bioactive substances in various delivery systems to protect them while still preserving or even enhancing their bioactivity and bioavailability. Hydrogels (HG) are of increased interest due to the fact that they allow control over composition, presentation, and release pattern [4,5]. This paper aims to present the most common strategies for preparing hybrid HG/PF or HG/TPVL systems, as well as the synergy between the HGs and the phytocompounds in terms of physicochemical and biological properties. [ABSTRACT FROM AUTHOR]

The chemical constituents and biological activity of Pinus cembra L. (Pinaceae), native to the Central European Alps and the Carpathian Mountains, are not well known. The aim of the present work was to examine the phenolic content, antioxidant and antimicrobial effects of hydromethanolic extracts of Pinus cembra L. bark and needles. Bark extract had higher concentrations of total phenolics (299.3 vs. 78.22 mg gallic acid equivalents/g extract), flavonoids (125.3 vs. 19.84 mg catechin equivalents/g extract) and proanthocyanidins (74.3 vs. 12.7 mg cyanidin equivalents/g extract) than needle extract and was more active as a free radical scavenger, reducing agent and antimicrobial agent. The EC50 values in the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline- 6-sulfonic acid) diammonium salt (ABTS) and reducing power assays were 71.1, 6.3 and 26 μg/mL for bark extract and 186.1, 24 and 104 μg/mL for needle extract, respectively. In addition, needle extract showed ferrous ions chelating effects (EC50 = 1,755 μg/mL). The antimicrobial effects against Staphylococcus aureus, Sarcina lutea, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans were assessed by the agar diffusion method. Both extracts (4 mg/well) were active against all the microorganisms tested; bark extract showed higher inhibition on all strains. These results indicate that Pinus cembra L. bark and needles are good sources of phytochemicals with antioxidant and antimicrobial activities. [ABSTRACT FROM AUTHOR]