Danny E. C. van Hoorn

Bio: Danny E. C. van Hoorn is an academic researcher from VU University Amsterdam. The author has contributed to research in topics: Xanthine oxidase & Oxidative stress. The author has an hindex of 6, co-authored 6 publications receiving 2842 citations.

Basic nutritional investigation Preoperative feeding preserves heart function and decreases oxidative injury in rats

Abstract: Objective: The nutritional status of a patient has been implicated as an important factor in the development of postoperative complications. Fasting before an operation may have detrimental effects on the metabolic state. We hypothesized that there was a positive correlation between preoperative nutritional status and postoperative organ function. Methods: Preoperative feeding was compared with fasting with respect to effects on organ function and biochemical parameters in an animal model of extensive large abdominal surgery. Male Wistar rats were fed ad libitum or fasted for 16 h, after which the arteria mesenterica superior was clamped for 60 min followed by 180 min of reperfusion. Results: After the ischemic period, heart function was significantly better in animals that were fed ad libitum than in fasted animals. Moreover, after intestinal ischemia and reperfusion, fed rats showed significantly higher levels of intestinal adenosine triphosphate and a significantly higher malondialdehyde concentration in the intestine and lung than did fasted rats. The ratio of adenosine triphosphate to adenosine diphosphate in the liver, an indicator of energy status, in fed rats was similar to that in a sham group, whereas fasted animals showed a significantly lower value. Conclusions: Preoperative nutrition in contrast to fasting may attenuate ischemia/reperfusion- induced injury and preserve organ function in the rat. © 2005 Elsevier Inc. All rights reserved.

Effects of Preoperative Flavonoid Supplementation on Different Organ Functions in Rats

Abstract: Background Previously it has been reported that preoperative feeding preserves heart function in rats after intestinal ischemia-reperfusion. To further improve postoperative organ function, bioactive nutrition compounds were selected in vitro against the xanthine oxidase radical cascade, an enzyme suggested to play a key role in the induction of single- or multiple-organ dysfunction. Methods Flavonoids were selected in vitro for their capacity to (1) inhibit xanthine oxidase, (2) scavenge superoxide, and (3) scavenge peroxylradicals. The most bioactive flavonoids were added to the preoperative nutrition to study their effect on postintestinal ischemia-reperfusion organ function. Results A combination of flavonoids selected on basis of effective flavonoid xanthine oxidase inhibition and superoxide scavenging resulted in increased superoxide scavenging. In vivo, the selected flavonoid mixture significantly lowered postischemic intestinal apoptosis and intestinal oxidative stress indicated by malondialdehyde concentration when compared with ischemia-reperfusion fasted and sham-fasted animals. Moreover, this flavonoid mixture significantly lowered plasma creatinine and urea concentration, both indicating a better postoperative kidney function. Furthermore, oxidative stress measured as this flavonoid mixture when compared with control significantly lowered plasma malondialdehyde concentration in fed rats. Conclusions Coadministration of bioactive flavonoid mixture to preoperative nutrition, in contrast to fasting, attenuates ischemia-reperfusion injury by preserving kidney function in the rat and decreasing apoptosis in the intestine.

Flavonoids: an overview

Abstract: Flavonoids, a group of natural substances with variable phenolic structures, are found in fruits, vegetables, grains, bark, roots, stems, flowers, tea and wine. These natural products are well known for their beneficial effects on health and efforts are being made to isolate the ingredients so called flavonoids. Flavonoids are now considered as an indispensable component in a variety of nutraceutical, pharmaceutical, medicinal and cosmetic applications. This is attributed to their anti-oxidative, anti-inflammatory, anti-mutagenic and anti-carcinogenic properties coupled with their capacity to modulate key cellular enzyme function. Research on flavonoids received an added impulse with the discovery of the low cardiovascular mortality rate and also prevention of CHD. Information on the working mechanisms of flavonoids is still not understood properly. However, it has widely been known for centuries that derivatives of plant origin possess a broad spectrum of biological activity. Current trends of research and development activities on flavonoids relate to isolation, identification, characterisation and functions of flavonoids and finally their applications on health benefits. Molecular docking and knowledge of bioinformatics are also being used to predict potential applications and manufacturing by industry. In the present review, attempts have been made to discuss the current trends of research and development on flavonoids, working mechanisms of flavonoids, flavonoid functions and applications, prediction of flavonoids as potential drugs in preventing chronic diseases and future research directions.

Free radicals, natural antioxidants, and their reaction mechanisms

Abstract: The normal biochemical reactions in our body, increased exposure to the environment, and higher levels of dietary xenobiotic's result in the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The ROS and RNS create oxidative stress in different pathophysiological conditions. The reported chemical evidence suggests that dietary antioxidants help in disease prevention. The antioxidant compounds react in one-electron reactions with free radicals in vivo/in vitro and prevent oxidative damage. Therefore, it is very important to understand the reaction mechanism of antioxidants with the free radicals. This review elaborates the mechanism of action of the natural antioxidant compounds and assays for the evaluation of their antioxidant activities. The reaction mechanisms of the antioxidant assays are briefly discussed (165 references). Practical applications: understanding the reaction mechanisms can help in evaluating the antioxidant activity of various antioxidant compounds as well as in the development of novel antioxidants.

Flavonoids in Food and Their Health Benefits

Abstract: There has been increasing interest in the research of flavonoids from dietary sources, due to growing evidence of the versatile health benefits of flavonoids through epidemiological studies. As occurrence of flavonoids is directly associated with human daily dietary intake of antioxidants, it is important to evaluate flavonoid sources in food. Fruits and vegetables are the main dietary sources of flavonoids for humans, along with tea and wine. However, there is still difficulty in accurately measuring the daily intake of flavonoids because of the complexity of existence of flavonoids from various food sources, the diversity of dietary culture, and the occurrence of a large amount of flavonoids itself in nature. Nevertheless, research on the health aspects of flavonoids for humans is expanding rapidly. Many flavonoids are shown to have antioxidative activity, free-radical scavenging capacity, coronary heart disease prevention, and anticancer activity, while some flavonoids exhibit potential for anti-human immunodeficiency virus functions. As such research progresses. further achievements will undoubtedly lead to a new era of flavonoids in either foods or pharmaceutical supplements. Accordingly, an appropriate model for a precise assessment of intake of flavonoids needs to be developed. Most recent research has focused on the health aspects of flavonoids from food sources for humans. This paper reviews the current advances in flavonoids in food, with emphasis on health aspects on the basis of the published literature, which may provide some guidance for researchers in further investigations and for industries in developing practical health agents.