Polyphenols: Extraction Methods, Antioxidative Action, Bioavailability and Anticarcinogenic Effects

Abstract

Abstract:Being secondary plant metabolites, polyphenols represent a large and diverse group of substances abundantly present in a majority of fruits, herbs and vegetables. The current contribution is focused on their bioavailability, antioxidative and anticarcinogenic properties. An overview of extraction methods is also given, with supercritical fluid extraction highlighted as a promising eco-friendly alternative providing exceptional separation and protection from degradation of unstable polyphenols. The protective role of polyphenols against reactive oxygen and nitrogen species, UV light, plant pathogens, parasites and predators results in several beneficial biological activities giving rise to prophylaxis or possibly even to a cure for several prevailing human diseases, especially various cancer types. Omnipresence, specificity of the response and the absence of or low toxicity are crucial advantages of polyphenols as anticancer agents. The main problem represents their low bioavailability and rapid metabolism. One of the promising solutions lies in nanoformulation of polyphenols that prevents their degradation and thus enables significantly higher concentrations to reach the target cells. Another, more practiced, solution is the use of mixtures of various polyphenols that bring synergistic effects, resulting in lowering of the required therapeutic dose and in multitargeted action. The combination of polyphenols with existing drugs and therapies also shows promising results and significantly reduces their toxicity.

Essential Roles of Natural Products and Gaseous Mediators on Neuronal Cell Death or Survival

“…Carotenoids, which are produced in red or yellow fruits and vegetables, are the most abundant plant-derived compounds. Natural polyphenols are the largest group of phytochemicals, and have antioxidant, cardioprotective, anticancer, anti-aging, and anti-inflammatory properties [22,23]. They are found in many plants, such as grapes, olives, and blueberries, and in plant-based foods, such as coffee, green tea, and wine [22].…”

The potential use of flavonoids as venoactive drugs and the role of citrus fruits

“…Taking into account the maximum concentration of total Fl in grapefruit juice (up to 84.28 mg/100 ml) [36], the average for commercial grapefruit juice (65 mg/100 ml) [4] and the higher content of Fl in whole fruits than in juice [21,37], consumption of 1-2 grapefruits means the intake of about 500 mg of Fls (naringin, narirutin, hesperidin, etc.) Naringin and naringenin are bitter and occur predominantly in grapefruits [4,5]. Relatively high concentration of hesperidin (a component of MPFF) was found in orange and mandarin juices (25-40 mg/100 ml), being the highest in C. clementina (39.9 mg/100 ml on average) [4].…”

“…Potential difficulties in performing water volumetry are described in [39]. Finally, considering limited bioavailability and rapid metabolism of some dietary polyphenols [5,40,41], further research and review of pharmacokinetics of different Fls is needed.…”

“…Fls constitute the largest part of dietary polyphenols; they can be found in many fruits, vegetables, and cereals [4,5]. Some supposedly venoactive Fls (rutin, escin, quercetin) have been extracted from medicinal plants.…”

“…Without going into details of Fl biology, their role as repellents should be noted, protecting plants from herbivores. Certain Fls were reported to be toxic for insects or other organisms [5,33,34]. Presumably, Fls may act as mild toxin stimulating endogenous defense mechanisms [35], so that their abundant intake is not a priori beneficial especially for individuals with compromised defense mechanisms, e.g., in chronic diseases or advanced age [2].…”