Absorption, metabolism, and excretion of cider dihydrochalcones in healthy humans and subjects with an ileostomy.

The phloretin-O-glycosides, phloretin-2'-O-glucoside and phloretin-2'-O-(2''-O-xylosyl)glucoside, are thought to be unique to apples and apple products. To investigate the metabolism and bioavailability of these compounds, nine healthy and five ileostomy human subjects consumed 500 mL of Thatchers Redstreak apple cider containing 46 micromol of phloretin-O-glycosides. Over the ensuing 24 h period, plasma, urine, and ileal fluid were collected prior to analysis by high-performance liquid chromatography-mass spectrometry (HPLC-MS). The sole metabolite present in quantifiable amounts in plasma was phloretin-2'-O-glucuronide, which reached a peak concentration (C(max)) of 73 nmol/L and 0.6 h after ingestion (T(max)) with the healthy subjects, and statistically similar values were obtained with the ileostomy volunteers. Phloretin-2'-O-glucuronide was also detected in urine along with two additional phloretin-O-glucuronides and a phloretin-O-glucuronide-O-sulfate. The quantity of phloretin metabolites excreted in urine represented 5.0 + or - 0.9% of intake in healthy volunteers and 5.5 + or - 0.6% in ileostomy volunteers. The similarity in the excretion levels of the two groups and the rapid plasma T(max) indicate absorption of the dihydrochalcones in the small intestine. Of the two major phloretin-O-glycosides in cider, only phloretin-2'-O-(2''-O-xylosyl)glucoside was recovered in ileal fluid in quantities corresponding to 22% of intake. The absence of phloretin-2'-O-glucoside in ileal fluid suggests that it is more readily absorbed than phloretin-2'-O-(2''-O-xylosyl)glucoside. Phloretin-2'-O-glucuronide, two other phloretin-O-glucuronides, one phloretin-O-glucuronide-O-sulfate, two phloretin-O-sulfates, and the aglycone phloretin were also detected in the ileal fluid. This implies that the wall of the small intestine contains beta-glycosidase, sulfuryltransferase, and UDP-glucuronosyltransferase activities and that, as well as being absorbed, sizable amounts of the phloretin metabolites that are formed efflux back into the lumen of the gastrointestinal tract. The overall recovery of the dihydrochalcones and their metabolites in the ileal fluid was equivalent to 38.6% of intake.

Flavonoid and hydroxycinnamate profiles of english apple ciders.

Seventeen phenolic compounds in 23 English apple ciders were identified and quantified by HPLC-PDA-MS (2). The total phenolic content of the ciders varied greatly ranging from 44 to 1559 mg/L. Four groups of compounds were identified, flavan-3-ols, hydroxycinnamates, flavonols, and dihydrochalcones. Hydroxycinnamates were the predominant group of phenolics in the majority of the ciders. Procyanidins were analyzed by HPLC after thiolysis, and total procyanidin content ranged from 8 to 722 mg/L and an average degree of polymerization of 2.5-3.5. This investigation of a wide range of ciders has shown a substantial variation in the profile and quantity of the phenolics. The analysis of single variety ciders highlighted the importance of using an apple cultivar with a high phenolic content to produce a phenolic-rich cider. Adaptations to the cider-making process could be used to increase the phenolic content with potential health benefits.

Evaluation of phenolic compounds in commercial fruit juices and fruit drinks.

The total phenolic content of 13 commercially available fruit juices and juice drinks, selected to represent the most popular juice flavors in the United Kingdom, were analyzed using the Folin-Ciocalteu assay. Individual phenolic compounds were identified and quantified using HPLC-PDA-MS2. The catechin content and degree of polymerization of proanthocyanidins were also analyzed. Purple grape juice contained the largest number of individual phenolic compounds and also the highest concentration of total phenolics. The main components were flavan-3-ols, anthocyanins, and hydroxycinnamates, which accounted for 93% of the total phenolic content. In contrast, white grape juice, which contained principally hydroxycinnamates, had the lowest total phenolic content. Antioxidant activity was measured using the ORAC and FRAP assays, and the data obtained were in broad agreement with total phenol content. In view of the recent findings of the Kame project indicating that long-term fruit juice consumption can provide protection against Alzheimer's disease (Dai et al. Am. J. Med. 2006, 379, 464-475), it is suggested that the protective effects may be enhanced by consumption of a combination of juices rich in phenolics and containing a diverse variety of individual phenolic compounds, namely, juices derived from purple grapes, grapefruit, cranberries, and apples.