Jonathan Santas

Selective in vivo effect of chitosan on fatty acid, neutral sterol and bile acid excretion: A longitudinal study

Chitosan, a deacetylated form of chitin, is a dietary fibre known for its hypolipidemic properties, which are mainly attributed to its unique cationic characteristics. We studied the selective in vivo effect of chitosan on fat excretion in order to elucidate its hypolipidemic mechanism. A 4-week longitudinal study was conducted in guinea pigs and the effect of chitosan on fat-absorption was compared to that of a soluble fibre: digestion-resistant maltodextrin. Animals were fed with high-fat isocaloric diets containing 12/100g of cellulose, digestion-resistant maltodextrin or chitosan. Subsequently, the excretion of fatty acids, neutral sterols and bile acids was determined. Chitosan selectively reduced fat absorption in comparison to digestion-resistant maltodextrin. The excretion of lauric, myristic and palmitic fatty acids of animals fed with chitosan was more than 10-, 5- and 2-fold higher, respectively, than in the cellulose group, whereas stearic acid excretion was not significantly altered. Oleic, linoleic and α-linolenic acid excretion were also significantly higher (P<0.001). The n-6/n-3 ratio in faeces of the chitosan group was 23.68, compared to 13.95 in the cellulose group. Total neutral sterol excretion was increased by both dietary fibres, whereas bile acid excretion was only increased by chitosan. Nevertheless, chitosan inhibited the intestinal bioconversion of cholesterol and primary bile acids to secondary metabolites. Hence, these results reveal that chitosan and digestion resistant maltodextrin exert their hypolipidemic activity by different mechanisms.

Determination of total plasma hydroperoxides using a diphenyl-1-pyrenylphosphine fluorescent probe

Plasma hydroperoxides (HPs) are widely accepted to be good indicators of oxidative stress. By means of the method proposed here, which uses diphenyl-1-pyrenylphosphine (DPPP) as a fluorescent probe, all types of plasma HP were determined. The limits of detection and quantification of the method were 0.08 and 0.25 nmol of cumene hydroperoxide (CHP) equivalents in 40 μl of plasma, respectively. The method is satisfactory in terms of precision (5.3% for 14.5 μM CHP eq., n=8), and the recoveries were 91% and 92% after standard additions of 26 and 52 μM CHP, respectively. The selectivity of the proposed method is higher than 96%. Moreover, optimization of the reaction conditions and the addition of ethylenediaminetetraacetic acid (EDTA) disodium salt and 2,6-di-tert-butyl-4-methylphenol (BHT) prevented the formation of HP artifacts during the analysis. Therefore, the proposed method is useful for simple and quantitative determination of total plasma HPs.

High-throughput analysis of lipid hydroperoxides in edible oils and fats using the fluorescent reagent diphenyl-1-pyrenylphosphine.

A fluorometric method for the determination of hydroperoxides (HP) in edible oils and fats using the reagent diphenyl-1-pyrenylphosphine (DPPP) was developed and validated. Two solvent media containing 100% butanol or a mixture of chloroform/methanol (2:1, v/v) can be used to solubilise lipid samples. Regardless of the solvent used to solubilise the sample, the DPPP method was precise, accurate, sensitive and easy to perform. The HP content of 43 oil and fat samples was determined and the results were compared with those obtained by means of the AOCS Official Method for the determination of peroxide value (PV) and the ferrous oxidation-xylenol orange (FOX) method. The proposed method not only correlates well with the PV and FOX methods, but also presents some advantages such as requiring low sample and solvent amounts and being suitable for high-throughput sample analysis.

Effect of a polysaccharide-rich hydrolysate from Saccharomyces cerevisiae (LipiGo®) in body weight loss: randomised, double-blind, placebo-controlled clinical trial in overweight and obese adults

BACKGROUND In the present study we evaluated the weight loss effect of a polysaccharide-rich food supplement, LipiGo®, comprising a specific β-glucan-chitin-chitosan fraction (BGCC) obtained from the chemical hydrolysis of Saccharomyces cerevisiae, resulting as a by-product of the brewing process. RESULTS A randomised, double-blind, placebo-controlled clinical trial was performed enrolling 56 overweight and obese subjects (body mass index, BMI, 25-35 kg m-2 ) who were not following any specific diet, and were given placebo or BGCC (3 g d-1 ) for 12 weeks. Results were analysed by intention-to-treat (ITT) and per-protocol (PP) methods. Body weight increased in the placebo group compared to baseline (ITT: 1.0 kg, P < 0.001; PP: 1.5 kg, P = 0.003), while it was slightly lowered in the BGCC group (ITT: -0.8 kg, P = 0.210; PP: -1.1 kg, P = 0.182). BGCC, but not the consumption of placebo, also resulted in a reduction of waist circumference and body fat compared to baseline. CONCLUSIONS Results suggest that daily supplementation of BGCC may be useful for improving body weight and waist circumference in overweight and obese subjects, without relevant adverse effects.