Senem Kamiloglu

Anthocyanin Absorption and Metabolism by Human Intestinal Caco-2 Cells--A Review.

Anthocyanins from different plant sources have been shown to possess health beneficial effects against a number of chronic diseases. To obtain any influence in a specific tissue or organ, these bioactive compounds must be bioavailable, i.e., effectively absorbed from the gut into the circulation and transferred to the appropriate location within the body while still maintaining their bioactivity. One of the key factors affecting the bioavailability of anthocyanins is their transport through the gut epithelium. The Caco-2 cell line, a human intestinal epithelial cell model derived from a colon carcinoma, has been proven to be a good alternative to animal studies for predicting intestinal absorption of anthocyanins. Studies investigating anthocyanin absorption by Caco-2 cells report very low absorption of these compounds. However, the bioavailability of anthocyanins may be underestimated since the metabolites formed in the course of digestion could be responsible for the health benefits associated with anthocyanins. In this review, we critically discuss recent findings reported on the anthocyanin absorption and metabolism by human intestinal Caco-2 cells.

Influence of different processing and storage conditions on in vitro bioaccessibility of polyphenols in black carrot jams and marmalades

Black carrot is indicated to play an important role in nutrition, as it comprises a variety of health-promoting components, including polyphenols. The objective of the present study was to monitor the stability of total phenolics, antioxidant capacity and phenolic acids in black carrot jams and marmalades after processing, storage and in vitro gastrointestinal digestion. Total phenolic content and antioxidant capacity were determined using spectrophotometric methods, whereas phenolic acids were identified using HPLC-PDA. Jam and marmalade processing significantly decreased total phenolics (89.2-90.5%), antioxidant capacity (83.3-91.3%) and phenolic acids (49.5-96.7%) (p < 0.05). After 20 weeks of storage, the percent decrease in total phenolics in samples stored at 25 °C (26.4-48.0%) was slightly higher than the samples stored at 4 °C (21.0-42.5%). In addition, jam and marmalade processing led to increases in the percent recovery of bioaccessible total phenolics (7.2-12.6%) and phenolic acids (4.7-31.5%), as well as antioxidant capacity (1.4-8.1%). In conclusion, current study highlighted black carrot jams and marmalades as good sources of polyphenols, with high bioaccessibility levels.

Home processing of tomatoes (Solanum lycopersicum): effects on in vitro bioaccessibility of total lycopene, phenolics, flavonoids, and antioxidant capacity.

BACKGROUND In order to investigate the effect of home processing on the bioaccessibility of health-related constituents of tomatoes, total lycopene, phenolics, flavonoids and antioxidant capacity were determined from seven different tomato products using an in vitro gastrointestinal digestion model. Additionally, the changes in the contents of the major tomato phenolics were determined and compared for these different tomato products using HPLC. RESULTS The results revealed that paste processing and drying significantly increased the bioaccessible total lycopene content (2.2- and 3.8-fold, respectively), total phenolic content (2.3- and 2.0-fold, respectively), total flavonoid content (9.0- and 2.5-fold, respectively) and total antioxidant capacity (6.3- and 8.0-fold for the DPPH assay, 26- and 33-fold for the CUPRAC assay, respectively) (P < 0.05) compared to fresh tomatoes. HPLC analysis revealed significantly lower (P < 0.05) rutin content in puree and juice. The loss of naringenin chalcone in some tomato products, as well as its conversion into naringenin in heat-treated products was observed. CONCLUSION The current study provided valuable insights into the changes in the content and bioaccessibility of tomato antioxidants as a result of home processing.

Bioaccessibility of Polyphenols from Plant-Processing Byproducts of Black Carrot (Daucus carota L.).

Plant-processing byproducts of black carrot represent an important disposal problem for the industry; however, they are also promising sources of polyphenols, especially anthocyanins. The present study focused on the changes in polyphenols from black carrot, peel, and pomace during in vitro gastrointestinal digestion. Total phenolic content (TPC), total monomeric anthocyanin content (TMAC), and total antioxidant capacity (TAC) were determined using spectrophotometric methods, whereas identification and quantification of polyphenols were carried out using UPLC-ESI-MS(E) and HPLC-DAD, respectively. TPC, TMAC, and TAC significantly decreased (23-82%) as a result of in vitro gastrointestinal digestion. Nevertheless, the amount of pomace anthocyanins released at all stages of in vitro gastrointestinal digestion was higher than black carrot anthocyanins, suggesting that pomace may be a better source of bioaccessible anthocyanins. Overall, the current study highlighted black carrot byproducts as substantial sources of polyphenols, which may be used to enrich food products.

A Review on the Effect of Drying on Antioxidant Potential of Fruits and Vegetables

The role of antioxidants in human nutrition has gained increased interest, especially due to their associated health beneficial effects for a number of chronic diseases, including cardiovascular diseases and certain types of cancer. Fruits and vegetables are perishable and difficult to preserve as fresh products. Dried fruits and vegetables can be easily stored, transported at relatively low cost, have reduced packing costs, and their low water content delays microbial spoilage. Air-, freeze-, microwave- and sun-drying are among the most thoroughly studied drying methods. This review provides an overview of recent findings on the effects of different drying techniques on major antioxidants of fruits and vegetables. In particular, changes in ascorbic acid, carotenoids, flavonoids, phenolic acids, total phenolics, and antioxidant activity are discussed in detail.

Potential Use of Turkish Medicinal Plants in the Treatment of Various Diseases

Medicinal plants are sources of health-promoting substances, including phytochemicals and phytoalexins that comprise polyphenols, flavonoids, carotenoids, vitamins A, C, E and several other constituents. Many studies have indicated that medicinal plants have been used to treat human diseases for thousands of years owing to their antimicrobial and antioxidant activities. Medicinal plants reduce the oxidative stress in cells and prevent cancer, cardiovascular and inflammatory diseases, neurodegenerative and digestive system disorders. These potential beneficial effects have been attributed to the presence of bioactive compounds that show antioxidant properties by acting as free radical scavengers or metal chelators, reducing the reactions that produce reactive oxygen and nitrogen species (ROS/RNS). Considering the importance of medicinal plants in terms of their beneficial health effects, some of the medicinally important plants grown in Turkey are covered in this review with respect to their antioxidant potential and phytochemical profile.

Antioxidant activity and polyphenol composition of black mulberry (Morus nigra L.) products

BACKGROUND: Today, due to its nutritive value, black mulberry (Morus nigra L.) is consumed both as fresh and in processed forms. OBJECTIVE: In order to investigate the health-related constituents of black mulberry products, total phenolics, flavonoids, anthocyanins, antioxidant capacity and major phenolic compounds were determined for different products including fresh mulberry, dried mulberry, mulberry wine, molasses, ice cream, juice, jam and syrup. METHODS: Samples were obtained as three replicates, and total phenolics, flavonoids, anthocyanins, antioxidant capacity were determined by spectrophotometric methods, whereas major phenolic compounds were detected using high-performance liquid chromatography (HPLC) coupled with a photodiode array (PDA) detector. RESULTS: In analyzed samples, chlorogenic acid, rutin and cyanidin-3-O-glucoside were confirmed as the major phenolic acid, flavonol and anthocyanin, respectively. In general, fresh mulberry showed higher contents of total phenolics (0.49–57 fold higher), flavonoids (0.02–162 fold higher), anthocyanins (6-12209 fold higher) and antioxidant capacity (0.72–691 fold higher) compared to other products. Total flavonoids and phenolics showed a linear relationship with antioxidant capacity (CUPRAC: R2 = 0.9070 and R2 = 0.8959, respectively), indicating that flavonoids and phenolics were the major contributors to the antioxidant capacity. CONCLUSIONS: These results provide valuable insights into the biochemical composition of black mulberry and how this may change during fruit processing.

Anti-inflammatory potential of black carrot (Daucus carota L.) polyphenols in a co-culture model of intestinal Caco-2 and endothelial EA.hy926 cells

SCOPE The present study was developed to determine the ability of polyphenol-rich black carrot and its by-products, i.e., peel and pomace, to modulate the inflammatory response in tumor necrosis factor α (TNF-α) treated endothelial cells after gastrointestinal digestion and in a co-culture of intestinal Caco-2 and endothelial EA.hy926 cell model. RESULTS The results indicated that after 4 h of treatment, the transport of anthocyanins and phenolic acids was higher for digested samples (1.3-7%) compared to the undigested samples (0-3.3%). The transported polyphenols were able to downregulate the secretion of pro-inflammatory markers, i.e. IL-8, monocyte chemoattractant protein 1, vascular endothelial growth factor, and intercellular adhesion molecule 1, under normal and tumor necrosis factor α induced inflammatory conditions. The most pronounced protective effects were observed with digested samples under inflammatory conditions, which significantly decreased the secretion of all markers from 120-203% down to 34-144% (p < 0.001). CONCLUSIONS Overall, these results show that the polyphenol-rich black carrot absorption products may function through an inhibitory regulation of the inflammatory cascade in endothelial cells.

Polyphenol Content in Figs (Ficus carica L.): Effect of Sun-Drying

In order to investigate the effect of sun-drying on the health-related constituents as well as bioaccessibility of figs; total phenolics, flavonoids, proanthocyanidins, anthocyanins, antioxidant capacity, and major phenolic compounds were determined for two commercial figs (Sarilop and Bursa siyahi) with different color (yellow and purple). In addition, release of phytochemical was studied by simulating of in vitro gastrointestinal digestion. In both varieties, rutin and cyanidin-3-rutinoside were confirmed as the major flavonol and anthocyanin, respectively. For both varieties, analyses of total phenolics, anthocyanins and antioxidant activity revealed lower levels after sun-drying. On the other hand, 75 and 71% higher total flavonoid and proanthocyanidin contents were observed for yellow figs.

Cell Systems to Investigate the Impact of Polyphenols on Cardiovascular Health

Polyphenols are a diverse group of micronutrients from plant origin that may serve as antioxidants and that contribute to human health in general. More specifically, many research groups have investigated their protective effect against cardiovascular diseases in several animal studies and human trials. Yet, because of the excessive processing of the polyphenol structure by human cells and the residing intestinal microbial community, which results in a large variability between the test subjects, the exact mechanisms of their protective effects are still under investigation. To this end, simplified cell culture systems have been used to decrease the inter-individual variability in mechanistic studies. In this review, we will discuss the different cell culture models that have been used so far for polyphenol research in the context of cardiovascular diseases. We will also review the current trends in cell culture research, including co-culture methodologies. Finally, we will discuss the potential of these advanced models to screen for cardiovascular effects of the large pool of bioactive polyphenols present in foods and their metabolites.