Research - Onions / Allium cepa
Effects of a quercetin-rich onion skin extract on 24 h ambulatory blood pressure and endothelial function in overweight-to-obese patients with (pre-)hypertension: a randomised double-blinded placebo-controlled cross-over trial
Verena Brülla1, Constanze Buraka1, Birgit Stoffel-Wagnera2, Siegfried Wolfframa3, Georg Nickeniga4, Cornelius Müllera4, Peter Langgutha5, Birgit Altehelda1, Rolf Fimmersa6, Stefanie Naafa7, Benno F. Zimmermanna7a8, Peter Stehlea1 and Sarah Egerta1 c1
a1 Department of Nutrition and Food Sciences, Nutritional Physiology, University of Bonn, 53115 Bonn, Germany
a2 Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, 53127 Bonn, Germany
a3 Institute of Animal Nutrition and Physiology, Christian-Albrechts-University Kiel, 24118 Kiel, Germany
a4 Department of Cardiology, Angiology and Pneumology, University Hospital Bonn, 53127 Bonn, Germany
a5 Department of Biopharmaceutics and Pharmaceutical Technology, Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, 55099 Mainz, Germany
a6 Institute of Medical Biometry, Informatics and Epidemiology, University Hospital Bonn, 53127 Bonn, Germany
a7 Institut Prof. Dr. Georg Kurz GmbH, 50933 Köln, Germany
a8 Department of Nutrition and Food Sciences, Food Technology and Biotechnology, University of Bonn, 53117 Bonn, Germany
Abstract
The polyphenol quercetin may prevent CVD due to its antihypertensive and vasorelaxant properties. We investigated the effects of quercetin after regular intake on blood pressure (BP) in overweight-to-obese patients with pre-hypertension and stage I hypertension. In addition, the potential mechanisms responsible for the hypothesised effect of quercetin on BP were explored. Subjects (n 70) were randomised to receive 162 mg/d quercetin from onion skin extract powder or placebo in a double-blinded, placebo-controlled cross-over trial with 6-week treatment periods separated by a 6-week washout period. Before and after the intervention, ambulatory blood pressure (ABP) and office BP were measured; urine and blood samples were collected; and endothelial function was measured by EndoPAT technology. In the total group, quercetin did not significantly affect 24 h ABP parameters and office BP. In the subgroup of hypertensives, quercetin decreased 24 h systolic BP by −3·6 mmHg (P=0·022) when compared with placebo (mean treatment difference, −3·9 mmHg; P=0·049). In addition, quercetin significantly decreased day-time and night-time systolic BP in hypertensives, but without a significant effect in inter-group comparison. In the total group and also in the subgroup of hypertensives, vasoactive biomarkers including endothelin-1, soluble endothelial-derived adhesion molecules, asymmetric dimethylarginine, angiotensin-converting enzyme activity, endothelial function, parameters of oxidation, inflammation, lipid and glucose metabolism were not affected by quercetin. In conclusion, supplementation with 162 mg/d quercetin from onion skin extract lowers ABP in patients with hypertension, suggesting a cardioprotective effect of quercetin. The mechanisms responsible for the BP-lowering effect remain unclear.
Source : British Journal of Nutrition
Link to Full Article
Evaluation of antidiarrhoeal activity of aqueous bulb extract of Allium cepa against castor oil-induced diarrhoea
Author(s):K. Rajesh kumar, Afsar shaik, J. Venu Gopal, P. Raveesha
Abstract:
The objective of this study was to evaluate antidiarrhoeal activity of aqueous bulb extract of Allium cepa. The Antidiarrhoeal effect was evaluated by castor oil- induced diarrhoeal model in rats. Loperamide (3 mg/kg, p.o.) was taken as standard, aqueous bulb extract of Allium cepa 150 & 300 mg/kg was used as a test doses.The results showed significant (p<0.05) antidiarrhoeal activity on gastrointestinal motility with castor oil- induced diarrhoeal model in rats. The extract tested at 150 and 300 mg/kg shown similar effect as that of standard drug (loperamide) by significantly inhibiting the frequency of defecation droppings compared to untreated control rats. This result is in support of previous claims in respect of antidiarrhoeal herbs.The study revealed that the aqueous bulb extract possess Pharmacological activity against diarrhoea and may possibly explain the use of the plant in traditional medicine.
Source : International Journal of Herbal Medicine
Link to Full Article