Gerd Würtele

Characterization and quantitation of polyphenolic compounds in bark, kernel, leaves, and peel of mango (Mangifera indica L.).

The contents of secondary plant substances in solvent extracts of various byproducts (barks, kernels, peels, and old and young leaves) in a range of Brazilian mango cultivars were identified and quantitated. The results show that the profiles of secondary plant substances such as xanthone C-glycosides, gallotannins, and benzophenones in different byproducts vary greatly but are fairly consistent across cultivars. The free radical scavenging activity of the solvent extracts was evaluated using a high-performance liquid chromatography-based hypoxanthine/xanthine oxidase assay and revealed dose-dependent antioxidant capacity in all extracts. Four (mangiferin, penta- O-galloyl-glucoside gallic acid, and methyl gallate) of the major phenolic compounds detected were also evaluated in additional in vitro bioassay systems such as oxygen radical absorbance capacity, 2,2-diphenyl-1-picrylhydrazyl, and ferric reducing ability of plasma. Mangiferin in particular, detected at high concentrations in young leaves (Coite = 172 g/kg), in bark (Momika = 107 g/kg), and in old leaves (Itamaraka = 94 g/kg), shows an exceptionally strong antioxidant capacity.

Isolation and characterization of ellagitannins as the major polyphenolic components of Longan (Dimocarpus longan Lour) seeds

Longan (Dimocarpus longan Lour, syn. Euphoria longan Lam.) represents an important fruit in Northern Thailand and has significant economic impact. The fruit is either consumed fresh or as commercially prepared dried and canned products. The canning industry in Thailand produces considerable quantities of waste products, in particular Longan seeds. Because these seeds may be an exploitable source of natural phenolic antioxidants, it was of interest to identify, purify and quantitate the major potential antioxidant phenolics contained therein. The polyphenolic fraction from ground Longan seeds was obtained by extraction with methanol after delipidation with hexane. The hexane extract contained predominantly long-chain fatty acids with major contributions from palmitic (35%) and oleic (28%) acids. The polyphenolic fraction (80.90 g/kg dry weight) was dominated by ellagic acid (25.84 g/kg) and the known ellagitannins corilagin (13.31 g/kg), chebulagic acid (13.06 g/kg), ellagic acid 4-O-α-l-arabinofuranoside (9.93 g/kg), isomallotinic acid (8.56 g/kg) and geraniin (5.79 g/kg). Structure elucidation was performed with mass spectrometry and complete assignment of (1)H and (13)C NMR signals. The methanol extracts exhibited strong antioxidant capacities with an IC(50) of 154 μg/ml for reactive oxygen species attack on salicylic acid and 78 μg/ml for inhibition of xanthine oxidase in the hypoxanthine/xanthine oxidase assay. The extracts were less effective in the 2-deoxyguanosine assay (IC(50)=2.46 mg/ml), indicating that gallates along with ellagic acid and its congeners exert their potential antioxidant effects predominantly by precipitation of proteins such as xanthine oxidase. This was confirmed for the pure compounds gallic acid, methyl gallate, ellagic acid and corilagin.

Urinary excretion of N-nitrosodiethanolamine in rats following its epicutaneous and intratracheal administration and its formation in vivo following skin application of diethanolamine

Urinary excretion of unchanged N-nitrosodiethanolamine (NDElA) following its epicutaneous and intratracheal administration was determined. Excretion rate was between 73–89% of the given dose, which was between 24 and 184 mg/animal. Formation in vivo of NDElA was demonstrated by NDElA exretion in urine in nitrite-fed rats after skin treatment with the parent amine diethanolamine (DElA). The data suggest the possibility of biological monitoring of human NDElA exposure by analysing its urinary excretion.

Urinary excretion of N-nitrosodiethanolamine administered orally to rats

N-Nitrosodiethanolamine (NDE1A) was administered by gavage to male rats in single doses of 1000, 500 and 100 mg/kg body wt. More than 70% of a given dose was excreted unchanged in the urine, essentially within the first 24 h after exposure. This high excretion rate might explain the relatively low carcinogenic potential of NDE1A, and also offers a possible method of monitoring exposure to this compound under occupational and/or environmental conditions.

Pilot Walnut Intervention Study of Urolithin Bioavailability in Human Volunteers

A pilot intervention study was conducted in human volunteers (n = 4) to establish the bioavailability of urolithins, which are the terminal end-products of ellagitannin metabolism by the gastrointestinal microflora. Biospecimens (blood, feces, and urine) along with urolithins purified therefrom were analyzed for their antioxidant capacity in a range of in vitro assays. Urolithin metabolites were identified and quantitated in the biospecimens by negative ion mode HPLC-ESI-MS analysis. The data in this pilot study show that the metabolism of ellagitannins in the four volunteers gave rise to a diverse profile and a highly variable concentration of urolithins in urine. The concentration of glucuronidated urolithins in blood and urine did not correlate with antioxidant capacity. However, the antioxidant capacity of urine, but not plasma biospecimens, was highly correlated with uric acid concentration. The antioxidant capacity of fecal extracts correlated positively with the concentration of urolithin D in both the DPPH and FRAP assays, but not in the ORAC assay, which was entirely consistent with the in vitro assays for pure urolithin D.

Polyphenol Composition and Antioxidant Potential of Hibiscus esculentus L. Fruit Cultivated in Nigeria

Consumption of certain fruits and vegetables is now widely associated with chemoprevention of degenerative diseases like cancer and cardiovacsular disorders because of their antioxidant components. Polyphenols, a heterogeneous group of compounds, are one of these constituents. Hibiscus esculentus L. (Family Malvaceae), commonly referred to as okro, okra, or ladys finger, is an important component of diet in Nigeria and other countries in sub-Saharan Africa. In this article, we describe the polyphenol composition and antioxidant potential of H. esculentus of Nigerian origin. Quercetin glucoside (quercetrin) and an unidentified flavonoid were detected. In vitro antioxidant assay of methanol extract of the fruits showed potent antioxidant/radical scavenging activities with 50% inhibitory concentration values of 25 and 43 microL when analyzed by the xanthine oxidase and 2-deoxyguanosine methods, respectively. These data suggest that H. esculentus, popular especially during the rainy season in Nigeria and many tropical West, Central, and Eastern African countries, is a good contributor to the antioxidant status and disease chemoprevention of people in these countries.

Evaluation of the Polyphenol Composition and Antioxidant Activity of African Variety of Dacryodes edulis (G.Don) H.J Lam Fruit

Polyphenols are abundant micronutrients in our diet that have been credited with chemoprevention of diseases associated with oxidative stress. In this study, we investigated the whole ripened fruit of Dacryodes edulis (G.Don) H.J Lam, a multipurpose tree growing in West and Central Africa and other countries bordering the Gulf of Guinea, for polyphenol content as well as its antioxidant/radical scavenging capacity. Analysis of the methanol extract of the fruit by high-performance liquid chromatography coupled to an ultraviolet dual-array detector and mass-selective detector revealed the presence of catechol (9.27 mg/kg), gallate (10.40 mg/kg), methylgallate (0.88 mg/kg), ellagic acid (3.10 mg/kg), quercetin (0.21 mg/kg), and quercetin rhamnoside (0.76 mg/kg). The extract showed very high antioxidant potential (50% inhibitory concentration [IC(50)] = 14 microL), but a rather weak radical scavenging activity (IC(50) = 357 microL), when tested in vitro with the xanthine oxidase and 2-deoxyguanosine assay model systems, respectively. These results suggest that consumption of D. edulis could contribute to prevention of diseases that are related to oxidative stress.

Plasma 25-hydroxyvitamin D3, folate and vitamin B12 biomarkers among international colorectal cancer patients: A pilot study

Vitamin D and folate are associated with decreased colorectal cancer risk and their association with colorectal cancer prognosis is under investigation. We assessed the levels of plasma 25-hydroxyvitamin D3 (25(OH)D3), folate and vitamin B12 in an international pilot study in order to determine variability of these biomarkers based on geographical location. Plasma 25(OH)D3, folate and vitamin B12 concentrations were measured in 149 invasive, newly diagnosed colorectal cancer cases from Heidelberg (Germany), Seattle (WA, USA), and Tampa (FL, USA) and in ninety-one age- and sex-matched controls. Their associations with potential predictors were assessed using multivariate linear regression analyses. Plasma 25(OH)D3, folate and vitamin B12 concentrations differed by location. Other predictors were season for 25(OH)D3 and tumour stage (vitamin B12). Season-corrected average 25(OH)D3 concentrations were higher in Heidelberg (31·7 ng/ml; range 11·0–83·0 ng/ml) than in Seattle (23·3 ng/ml; range 4·0–80·0 ng/ml) and Tampa (21·1 ng/ml; range 4·6–51·6 ng/ml). In Heidelberg, a strong seasonal variation was observed. Folate (11·1 ng/ml) and vitamin B12 (395 pg/ml) concentrations in Heidelberg were lower than those in Seattle (25·3 ng/ml and 740 pg/ml, respectively) and Tampa (23·8 ng/ml and 522 pg/ml, respectively). Differences in plasma 25(OH)D3 and folate concentrations between Heidelberg and the US sites were observed, probably reflecting variation in outdoor activities and sun-avoidance behaviour during summer as well as in folic acid fortification and supplement use. Intra-site differences at each study location were greater than between-location variability, suggesting that individual health behaviours play a significant role. Nevertheless, the intra-site differences we observed may be due to chance because of the limited sample size. Our pilot study illustrates the value of an international cohort in studying colorectal cancer prognosis to discern geographical differences in a broad range of exposures.

Abstract 79: The relationship between abdominal fat distribution, vitamin D levels, and physical activity in colorectal cancer patients: A pilot study.

Abstract Introduction: Abdominal obesity, low physical activity and low levels of Vitamin D (Vit D) are associated with an increased risk for colorectal cancer (CRC). Physical inactivity contributes to obesity – an emerging global health burden. Individuals with the same body mass index (BMI) may vary in the distribution of subcutaneous and visceral abdominal fat. Subcutaneous and visceral fat differ in their metabolic functions. Moreover, Vit D is metabolized in adipose tissue; however, it is unclear if Vit D levels are influenced by the amount and the distribution of adipose tissue. Decreased levels of Vit D are found in obese subjects and a positive association between physical activity and Vit D levels is currently discussed. It is still unknown how this triangle relationship is displayed in CRC patients and how it might influence the course of disease. Thus, within this pilot study we explored the relationship between abdominal fat distribution, plasma levels of Vit D, and metabolic equivalent of task (MET) level as a marker for intensity and energy expenditure of physical activity in CRC patients. Methods: This pilot study was conducted on 194 CRC patients from the ColoCare Study, a cohort of newly-diagnosed stage I-IV CRC patients (age>18). Plasma 25(OH)VitD3 levels were measured by LC/MSD. BMI was calculated (kg/m2) and the absolute abdominal fat and the distribution of subcutaneous and visceral abdominal fat was assessed by abdominal computed tomography (CT) scans. The total (TFA), subcutaneous (SFA) and visceral fat area (VFA) is presented as an area (cm2) on level L3/L4. To assess physical activity we calculated the individual MET h/week from questionnaire data (based on the VITAL study questionnaire, FHCRC, Seattle). Spearman correlation analysis was used to assess the relationship between abdominal fat distribution, Vit D levels (adjusted for season), and METs. Moreover, subgroup analyses in male subjects were performed whereas sample size was too small for further subgrouping. Results: Study participants were on average 62 years old and diagnosed with either colon (44%), rectal (50%) or rectosigmoid (6%) primary cancer. Data were available on n=186 (BMI), n=118 (CT scans), n=133 (Vit D) and n=96 (MET) subjects based on sequential implementation of assessments. Only correlations with at least 40 individuals are reported. Our evaluation suggests a negative association between Vit D and VFA (r=-0.14, p=0.20). However, no association was found for BMI with Vit D and MET levels, respectively. MET levels were negatively correlated with VFA/SFA ratio (r=-0.22, p=0.13). In male patients MET levels were positively correlated with SFA (r=0.27, p=0.08) and negatively correlated with VFA/SFA ratio (r=-0.41, p<0.01). Conclusion: Our pilot data suggest that an increased portion of visceral but not subcutaneous fat may be linked to lower levels of Vit D. Furthermore, higher MET levels may be associated with a higher visceral/subcutaneous fat ratio and might influence Vit D levels by changes in abdominal fat distribution. Additional data collection is underway and will be presented. Citation Format: Jürgen Staffa, Johanna Welzel, Katharina Buck, Hanna Högenauer, Petra Schrotz-King, Nina Habermann, Dominique Scherer, Stephanie Tosic, Verena Widmer, Clare Abbenhardt, Gerd Würtele, Robert Owen, Michael Hoffmeister, Hermann Brenner, Jenny Chang-Claude, Hans-U. Kauczor, Cornelia M. Ulrich. The relationship between abdominal fat distribution, vitamin D levels, and physical activity in colorectal cancer patients: A pilot study. [abstract]. In: Proceedings of the AACR Special Conference on Post-GWAS Horizons in Molecular Epidemiology: Digging Deeper into the Environment; 2012 Nov 11-14; Hollywood, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(11 Suppl):Abstract nr 79.