Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects – A review

The biological properties of dietary polyphenols are greatly dependent on their bioavailability that, in turn, is largely influenced by their degree of polymerization. The gut microbiota play a key role in modulating the production, bioavailability and, thus, the biological activities of phenolic metabolites, particularly after the intake of food containing high-molecular-weight polyphenols. In addition, evidence is emerging on the activity of dietary polyphenols on the modulation of the colonic microbial population composition or activity. However, although the great range of health-promoting activities of dietary polyphenols has been widely investigated, their effect on the modulation of the gut ecology and the two-way relationship "polyphenols ↔ microbiota" are still poorly understood. Only a few studies have examined the impact of dietary polyphenols on the human gut microbiota, and most were focused on single polyphenol molecules and selected bacterial populations. This review focuses on the reciprocal interactions between the gut microbiota and polyphenols, the mechanisms of action and the consequences of these interactions on human health.

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Benefits of polyphenols on gut microbiota and implications in human health.

In vitro human digestion models for food applications

Synergism between natural products and antibiotics against infectious diseases

In this paper, the biosynthesis process of phenolic compounds in plants is summarized, which includes the shikimate, pentose phosphate and phenylpropanoid pathways. Plant phenolic compounds can act as antioxidants, structural polymers (lignin), attractants (flavonoids and carotenoids), UV screens (flavonoids), signal compounds (salicylic acid and flavonoids) and defense response chemicals (tannins and phytoalexins). From a human physiological standpoint, phenolic compounds are vital in defense responses, such as anti-aging, anti-inflammatory, antioxidant and anti-proliferative activities. Therefore, it is beneficial to eat such plant foods that have a high antioxidant compound content, which will cut down the incidence of certain chronic diseases, for instance diabetes, cancers and cardiovascular diseases, through the management of oxidative stress. Furthermore, berries and other fruits with low-amylase and high-glucosidase inhibitory activities could be regarded as candidate food items in the control of the early stages of hyperglycemia associated with type 2 diabetes.

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An Overview of Plant Phenolic Compounds and Their Importance in Human Nutrition and Management of Type 2 Diabetes

In the current study, we screened 7 clonal lines from single seed phenotypes of Lamiaceae family for the inhibition of alpha-amylase, alpha-glucosidase and angiotensin converting enzyme (ACE) inhibitory activity. Water extracts of oregano had the highest alpha-glucosidase inhibition activity (93.7%), followed by chocolate mint (85.9%) and lemon balm (83.9%). Sage (78.4 %), and three different clonal lines of rosemary: rosemary LA (71.4%), rosemary 6 (68.4%) and rosemary K-2 (67.8%) also showed significant alpha-glucosidase inhibitory activity. The alpha-glucosidase inhibitory activity of the extracts was compared to selected specific phenolics detected in the extracts using HPLC. Catechin had the highest alpha-glucosidase inhibitiory activity (99.6 %) followed by caffeic acid (91.3 %), rosmarinic acid (85.1%) and resveratrol (71.1 %). Catechol (64.4%), protocatechuic acid (55.7%) and quercetin (36.9%) also exhibited significant alpha-glucosidase inhibitory activity. Results suggested that alpha-glucosidase inhibitory activity of the clonal extracts correlated to the phenolic content, antioxidant activity and phenolic profile of the extracts. The clonal extracts of the herbs and standard phenolics tested in this study did not have any effect on the alpha-amylase activity. We also investigated the ability of the clonal extracts to inhibit rabbit lung angiotensin I-converting enzyme (ACE). The water extracts of rosemary, rosemary LA had the highest ACE inhibitory activity (90.5%), followed by lemon balm (81.9%) and oregano (37.4 %). Lower levels of ACE inhibition were observed with ethanol extracts of oregano (18.5 %) and lemon balm (0.5 %). Among the standard phenolics only resveratrol (24.1 %), hydroxybenzoic acid (19.3 %) and coumaric acid (2.3 %) had ACE inhibitory activity.

Evaluation of clonal herbs of Lamiaceae species for management of diabetes and hypertension.

Phenolic antioxidants from clonal oregano (Origanum vulgare) with antimicrobial activity against Helicobacter pylori

Emerging epidemiological evidence is increasingly pointing to the beneficial effects of fruits and vegetables in managing chronic and infectious diseases. These beneficial effects are now suggested to be due to the constituent phenolic phytochemicals having antioxidant activity. Cranberry like other fruits is also rich in phenolic phytochemicals such as phenolic acids, flavonoids and ellagic acid. Consumption of cranberry has been historically been linked to lower incidences of urinary tract infections and has now been shown to have a capacity to inhibit peptic ulcer-associated bacterium, Helicobacter pylori. Isolated compounds from cranberry have also been shown to reduce the risk of cardiovascular diseases. Recent evidence suggests the ability of phytochemical components in whole foods in being more effective in protectively supporting human health than compared to isolated individual phenolic phytochemicals. This implies that the profile of phenolic phytochemicals determines the functionality of the whole food as a result of synergistic interaction of constituent phenolic phytochemicals. Solid state bioprocessing using food grade fungi common in Asian food cultures as well as cranberry phenolic synergies through the addition of functional biphenyls such as ellagic acid and rosmarinic acid along with processed fruit extracts have helped to advance these concepts. These strategies could be further explored to enrich cranberry and cranberry products with functional phytochemicals and further improve their functionality for enhancing health benefits.

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Enhancing health benefits of berries through phenolic antioxidant enrichment: focus on cranberry.

Ellagic acid production and phenolic antioxidant activity in cranberry pomace (Vaccinium macrocarpon) mediated by Lentinus edodes using a solid-state system

Cranberry pomace is a byproduct of the cranberry processing industry that can be targeted for production of value-added phenolic ingredients. Bio-processing of pomace by solid state fermentation (SSF) using food grade fungi provides unique strategies to improve nutraceutical properties and to produce functional phenolic ingredients. Several functional phenolic phytochemicals exist as glycosides or as other conjugated forms with reduced biological activity. We hypothesize that during SSF the fungal glycosidases mobilize some phenolic antioxidants in cranberry pomace and their activity by hydrolysis via β-glucosidase and releasing the aglycone. To develop this strategy we used food grade fungus Rhizopus oligosporus. Our goal was to target the release of simple phenolic aglycones and mobilized diphenyls. SSF of cranberry pomace was done for 16 days with nitrogen sources, ammonium nitrate (NH4NO3) and fish protein hydrolysate (FPH). The two nitrogen treatments increased water extractable phenolics by...

Dhiraj A Vattem

Papers

Evaluation of clonal herbs of Lamiaceae species for management of diabetes and hypertension.

Phenolic antioxidants from clonal oregano (Origanum vulgare) with antimicrobial activity against Helicobacter pylori

Enhancing health benefits of berries through phenolic antioxidant enrichment: focus on cranberry.

Ellagic acid production and phenolic antioxidant activity in cranberry pomace (Vaccinium macrocarpon) mediated by Lentinus edodes using a solid-state system

Solid-state production of phenolic antioxidants from cranberry pomace by rhizopus oligosporus