Ru-Po Lee

Pomegranate juice and extracts provide similar levels of plasma and urinary ellagitannin metabolites in human subjects.

Pomegranate juice (PJ), a rich source of polyphenols including ellagitannins, has attracted much attention due to its reported health benefits. This has resulted in the consumption of liquid and powder pomegranate extracts as alternatives to PJ. Therefore establishing the bioavailability of polyphenols from these extract preparations is necessary. Sixteen healthy volunteers sequentially consumed, with a 1-week washout period between treatments, PJ (8 ounces, Wonderful fruit variety), a pomegranate polyphenol liquid extract (POMxl, 8 ounces), and a pomegranate polyphenol powder extract (POMxp, 1,000 mg). The three interventions provided 857, 776, and 755 mg of polyphenols as gallic acid equivalents, respectively. Plasma bioavailability, judged based on ellagic acid levels over a 6-hour period, did not show statistical differences in area under the curve for the three interventions: 0.14 +/- 0.05, 0.11 +/- 0.03, and 0.11 +/- 0.04 micromol . hour/L for PJ, POMxl, and POMxp, respectively. The time of maximum concentration was delayed for POMxp (2.58 +/- 0.42 hours) compared to PJ (0.65 +/- 0.23 hours) and POMxl (0.94 +/- 0.06 hours). Urolithin-A glucuronide, a urinary metabolite of ellagic acid, was not significantly different with the three interventions, reaching levels of approximately 1,000 ng/mL. This study demonstrates that ellagitannin metabolites, delivered from pomegranate fruits, as PJ, POMxl, and POMxp, reach equivalent levels with a delay in time of maximum concentration of POMxp compared to PJ and POMxl.

Phenolic acid concentrations in plasma and urine from men consuming green or black tea and potential chemopreventive properties for colon cancer

SCOPE Tea polyphenols are metabolized by the colonic microflora yielding phenolic metabolites, which may contribute to the health benefits of tea. We determined the serum and urine concentrations of phenolic acids, hippuric acid, and polyhydroxyphenyl-γ-valerolactones during green tea (GT) and black tea (BT) administration. The effects of (-)-epigallocatechin gallate (EGCG) and 3,4-dihydroxyphenylacetic acid (3,4-DHPAA) alone and in combination on bioavailability, intracellular metabolism, and antiproliferative activity were determined in HCT-116 colon cancer cells. METHODS AND RESULTS The concentration of phenolic metabolites was quantified by HPLC with electrochemical detection and MS. Urine concentrations of 4-hydroxyphenylacetic acid (4-HPAA), 3-hydroxyphenylacetic acid (3-HPAA), and polyhydroxy-γ-valerolactones were increased significantly in men drinking GT compared to control. Urine concentration of 3-O-methylgallic acid (3OMGA) was significantly increased in men drinking BT compared to control. Serum 3,4-DHPAA was significantly increased after consumption of GT and BT and 4-HPAA after GT consumption. In vitro treatment of HCT-116 colon cancer cells with 3,4-DHPAA and EGCG exhibited an additive antiproliferative effect, while methylation of 3,4-DHPAA was significantly decreased. 3OMGA exhibited the strongest antiproliferative activity among the phenolic acids. CONCLUSION The consumption of both, GT and BT, was associated with a significant increase in urinary and serum phenolic acids.

California Hass avocado: profiling of carotenoids, tocopherol, fatty acid, and fat content during maturation and from different growing areas.

The California Hass avocado ( Persea americana ) is an example of a domesticated berry fruit that matures on the tree during its growing season but ripens only after being harvested. Avocados are typically harvested multiple times during the growing season in California. Previous research has demonstrated potential health benefits of avocados and extracts of avocado against inflammation and cancer cell growth, but seasonal variations in the phytochemical profile of the fruits being studied may affect the results obtained in future research. Therefore, in the present study, avocados were harvested in January, April, July, and September, 2008, from four different growing locations in California (San Luis Obispo, Ventura, Riverside, and San Diego) and analyzed for total fat content, fatty acid profile, carotenoids, and vitamin E. A significant increase in total carotenoid and fat content of avocados from all regions was noted as the season progressed from January to September. Four carotenoids not previously described in the avocado were quantified. The total content of carotenoids was highly correlated with the total fat content (r = 0.99, p < 0.001) demonstrating a remarkable degree of constancy of carotenoid intake per gram of fat content in the California Hass avocado. Future clinical research on the health benefits of the avocado should specify the time of harvest, degree of ripening, growing area, and the total phytochemical profile of the fruit or extract being studied. These steps will enable researchers to account for potential nutrient-nutrient interactions that might affect the research outcomes.

Green Tea Polyphenols and Metabolites in Prostatectomy Tissue: Implications for Cancer Prevention

Epidemiologic, preclinical, and clinical trials suggest that green tea consumption may prevent prostate cancer through the action of green tea polyphenols including (−)-epigallocatechin-3-gallate (EGCG). To study the metabolism and bioactivity of green tea polyphenols in human prostate tissue, men with clinically localized prostate cancer consumed six cups of green tea (n = 8) daily or water (n = 9) for 3 to 6 weeks before undergoing radical prostatectomy. Using high-performance liquid chromatography, 4″-O-methyl EGCG (4″-MeEGCG) and EGCG were identified in comparable amounts, and (−)-epicatechin-3-gallate was identified in lower amounts in prostatectomy tissue from men consuming green tea (38.9 ± 19.5, 42.1 ± 32.4, and 17.8 ± 10.1 pmol/g tissue, respectively). The majority of EGCG and other green tea polyphenols were not conjugated. Green tea polyphenols were not detected in prostate tissue or urine from men consuming water preoperatively. In the urine of men consuming green tea, 50% to 60% of both (−)-epigallocatechin and (−)-epicatechin were present in methylated form with 4′-O-MeEGC being the major methylated form of (−)-epigallocatechin. When incubated with EGCG, LNCaP prostate cancer cells were able to methylate EGCG to 4″-MeEGCG. The capacity of 4″-MeEGCG to inhibit proliferation and NF-κB activation and induce apoptosis in LNCaP cells was decreased significantly compared with EGCG. In summary, methylated and nonmethylated forms of EGCG are detectable in prostate tissue following a short-term green tea intervention, and the methylation status of EGCG may potentially modulate its preventive effect on prostate cancer, possibly based on genetic polymorphisms of catechol O-methyltransferase. Cancer Prev Res; 3(8); 985–93. ©2010 AACR.

Strawberry Consumption Is Associated with Increased Antioxidant Capacity in Serum

Strawberries are known to contain antioxidants, but the significance of ingesting antioxidant-rich fruits remains to be established. In order to determine whether the consumption of strawberries impacted measures of in vivo antioxidant capacity, frozen strawberries (250 g) were administered daily for 3 weeks to 21 healthy female volunteers. Compliance was confirmed by quantitating pelargonidin-glucuronide, urolithin A-glucuronide, and 2,5-dimethyl-4-hydroxy-3-[(2)H]furanone-glucuronide in plasma and urine by liquid chromatography-mass spectrometry and antioxidant capacity in serum measured by the increase in lag phase of low-density lipoprotein after copper sulfate exposure, DNA strand breaks in lymphocytes, and activity of phase II enzymes. Among these measures lipid peroxidation lag time increased by 20% (P < .01), whereas other measures did not change significantly. The potent antioxidant defenses in humans make determination of changes due to dietary ingestion in healthy individuals difficult. In summary, daily consumption of strawberries resulted in a modest but significant increase in antioxidant capacity in a healthy population.

Antioxidant-rich spice added to hamburger meat during cooking results in reduced meat, plasma, and urine malondialdehyde concentrations

Background: Emerging science has shown the effect of oxidation products and inflammation on atherogenesis and carcinogenesis. Cooking hamburger meat can promote the formation of malondialdehyde that can be absorbed after ingestion. Objective:We studied the effect of an antioxidant spice mixture on malondialdehyde formation while cooking hamburger meat and its effects on plasma and urinary malondialdehyde concentrations. Design: Eleven healthy volunteers consumed 2 kinds of burgers in a randomized order: one burger was seasoned with a spice blend, and one burger was not seasoned with the spice blend. The production of malondialdehyde in burgers and malondialdehyde concentrations in plasma and urine after ingestion were measured by HPLC. Results:Rosmarinic acid from oregano was monitored to assess the effect of cooking on spice antioxidant content. Forty percent (19 mg) of the added rosmarinic acid remained in the spiced burger (SB) after cooking. There was a 71% reduction in the malondialdehyde concentration (mean ± SD: 0.52 ± 0.02 μmol/250 g) in the meat of the SBs compared with the malondialdehyde concentration (1.79 ± 0.17 μmol/250 g) in the meat of the control burgers (CBs). The plasma malondialdehyde concentration increased significantly in the CB group as a change from baseline (P = 0.026). There was a significant time-trend difference (P = 0.013) between the 2 groups. Urinary malondialdehyde concentrations (μmol/g creatinine) decreased by 49% (P = 0.021) in subjects consuming the SBs compared with subjects consuming the CBs. Conclusions: The overall effect of adding the spice mixture to hamburger meat before cooking was a reduction in malondialdehyde concentrations in the meat, plasma, and urine after ingestion. Therefore, cooking hamburgers with a polyphenol-rich spice mixture can significantly decrease the concentration of malondialdehyde, which suggests potential health benefits for atherogenesis and carcinogenesis. This trial was registered at clinical trials.gov as NCT01027052.

Cyclic GMP and photoreceptor function.

A single photon can be detected by a rod photoreceptor cell. The absorption of light by rhodopsin triggers a cascade of reactions that amplifies the photon signal and results in ion channel closure with hyperpolarization of the rod photoreceptor cell. Light‐induced conformational changes in rhodopsin facilitate the binding of a guanosine nucleotide‐binding protein, transducin, which then undergoes aGTP‐GDP exchange reaction and dissociation of the transducin complex. A subunit of transducin then activates a phosphodiesterase complex that hydrolyzes cyclic GMP. In darkness, cyclic GMP binds to cation channels of the photoreceptor plasma membrane, maintaining them in an open configuration. The light‐induced reduction in cyclic GMP concentration dissociates the bound cyclic GMP, resulting in channel closure and hyperpolarization. Down‐regulation of the cascade involves other proteins that block the interaction of transducin with rhodopsin and another protein that may interfere with transducin recycling. Cone photoreceptors possess a light‐activated cascade that follows the rod format, but it is composed of proteins that are homologous to those of rod photoreceptors. Phototransduction in invertebrate photoreceptors uses rhodopsin to activate a cascade that uses phosphoinositides and calcium ion to regulate membrane polarization.— Lolley, R. N.; Lee, R. H. Cyclic GMP and photoreceptor function. FASEB J. 4: 3001‐3008; 1990.

International multidimensional authenticity specification (IMAS) algorithm for detection of commercial pomegranate juice adulteration.

The pomegranate fruit ( Punica granatum ) has become an international high-value crop for the production of commercial pomegranate juice (PJ). The perceived consumer value of PJ is due in large part to its potential health benefits based on a significant body of medical research conducted with authentic PJ. To establish criteria for authenticating PJ, a new International Multidimensional Authenticity Specifications (IMAS) algorithm was developed through consideration of existing databases and comprehensive chemical characterization of 45 commercial juice samples from 23 different manufacturers in the United States. In addition to analysis of commercial juice samples obtained in the United States, data from other analyses of pomegranate juice and fruits including samples from Iran, Turkey, Azerbaijan, Syria, India, and China were considered in developing this protocol. There is universal agreement that the presence of a highly constant group of six anthocyanins together with punicalagins characterizes polyphenols in PJ. At a total sugar concentration of 16 degrees Brix, PJ contains characteristic sugars including mannitol at >0.3 g/100 mL. Ratios of glucose to mannitol of 4-15 and of glucose to fructose of 0.8-1.0 are also characteristic of PJ. In addition, no sucrose should be present because of isomerase activity during commercial processing. Stable isotope ratio mass spectrometry as > -25 per thousand assures that there is no added corn or cane sugar added to PJ. Sorbitol was present at <0.025 g/100 mL; maltose and tartaric acid were not detected. The presence of the amino acid proline at >25 mg/L is indicative of added grape products. Malic acid at >0.1 g/100 mL indicates adulteration with apple, pear, grape, cherry, plum, or aronia juice. Other adulteration methods include the addition of highly concentrated aronia, blueberry, or blackberry juices or natural grape pigments to poor-quality juices to imitate the color of pomegranate juice, which results in abnormal anthocyanin profiles. To adjust the astringent taste of poor-quality juice or peel extract, addition of nonpomegranate sugars is a commonly detected adulteration method. The profile generated from these analyses combined with information from existing databases and published literature has been integrated into a validated IMAS for PJ, which can be utilized to detect PJ adulteration. In this survey of commercial pomegranate juices, only 6 of 23 strictly met all of the IMAS criteria.

Absence of Pomegranate Ellagitannins in the Majority of Commercial Pomegranate Extracts: Implications for Standardization and Quality Control

The health benefits associated with pomegranate juice have led to the development of pomegranate extracts as botanical dietary supplements. Pomegranates contain hydrolyzable tannins in the form of punicalagins and punicalin as well as tannin-based complex oligomers that account for much of the antioxidant activity in juice. The content of ellagic acid has been used to standardize most pomegranate extract dietary supplements marketed. However, supplements can be adulterated with ellagic acid from less expensive plant sources and undercut this method of standardization. To compare the phytochemical contents and antioxidant activities of commercially available pomegranate extract dietary supplements beyond their content of ellagic acid, a total of 27 different supplements in the form of capsules, tablets, and soft gels were studied. Total phenolics were measured using both gallic acid equivalent (GAE) and ellagic acid equivalent (EAE) assays. Punicalagins, punicalin, and ellagic acid contents were determined by HPLC, whereas antioxidant capacity was measured using the Trolox equivalent antioxidant capacity (TEAC) assay. Of the 27 supplements tested, only 5 had the typical pomegranate tannin profile by HPLC, 17 had ellagic acid as the predominant chemical with minor or no detectable pomegranate tannins, and 5 had no detectable tannins or ellagic acid. Therefore, standardization of pomegranate extract supplements based on their ellagic acid content does not guarantee pomegranate supplement authenticity. Future research is needed to assess the health impact of substituting ellagic acid for the complex mix of phytochemicals in a pomegranate extract dietary supplement.

Variability in the Antioxidant Activity of Dietary Supplements from Pomegranate, Milk Thistle, Green Tea, Grape Seed, Goji, and Acai: Effects of in Vitro Digestion

The antioxidant activity (AA) of fruits and vegetables has been thoroughly investigated but less is known about the AA of dietary supplements (DS). We therefore assessed the AA of three to five DS each from pomegranate, milk thistle, green tea, grapes, goji, and acai using four widely used standard methods. The secondary objective was to determine the effects of in vitro digestion on their AA. The AA of the DS prior to digestion ranked as follows: pomegranate > resveratrol > green tea > grape seed > milk thistle and very low in goji and acai with significant group variability in AA. The AA after in vitro simulated digestion of the mouth, stomach, and small intestine compared to undigested supplement was decreased for green tea and grape seed but increased for pomegranate, resveratrol, milk thistle, goji, and acai to various extents. Although polyphenols provide the major antioxidant potency of the tested supplements, our observations indicate that digestion may alter antioxidant properties depending in part on the variations in polyphenol content.