Absorption of lactulose from mammalian gastrointestinal tract

Surface engineering of chitosan nanosystems and the impact of functionalized groups on the permeability of model drug across intestinal tissue

Surface attributes of nanocarriers are crucial to determine their fate in the gastrointestinal (GI) tract. Herein, we have functionalized chitosan with biochemical moieties including rhamnolipid (RL), curcumin (Cur) and mannose (M). FTIR spectra of functionalized chitosan nanocarriers (FCNCs) demonstrated successful conjugation of M, Cur and RL. The functional moieties influenced the entrapment of model drug i.e., coumarin-6 (C6) in FCNCs with payload-hosting and non-leaching behavior i.e., >91 ± 2.5 % with negligible cumulative release of <2 % for 5 h in KREB, which was further verified in the simulated gastric and intestinal fluids. Consequently, substantial difference in the size and zeta potential was observed for FCNCs with different biochemical moieties. Scanning electron microscopy and atomic force microscopy of FCNCs displayed well-dispersed and spherical morphology. In addition, in vitro cytotoxicity results of FCNCs confirmed their hemocompatibility. In the ex-vivo rat intestinal models, FCNCs displayed a time-dependent-phenomenon in cellular-uptake and adherence. However, apparent-permeability-coefficient and flux values were in the order of C6-RL-FCNCs > C6-M-FCNCs > C6-Cur-FCNCs = C6-CNCs > Free-C6. Furthermore, the transepithelial electrical resistance revealed the FCNCs mediated recovery of membrane-integrity with reversible tight junctions opening. Thus, FCNCs have the potential to overcome the poor solubility and/or permeability issues of active pharmaceutical ingredients and transform the impact of functionalized-nanomedicines in the biomedical industry.

Safety Assessment of Monosaccharides, Disaccharides, and Related Ingredients as Used in Cosmetics

The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of 25 monosaccharides, disaccharides, and related ingredients and concluded these are safe in the present practices of use and concentration described in the safety assessment. Many of these ingredients are common dietary sugars, dietary sugar replacements, or very closely related analogs and salts; 7 of the ingredients are listed by the Food and Drug Administration as generally recognized as safe food substances. The most commonly reported cosmetic function is as a skin-conditioning agent; other commonly reported functions are use as a humectant or as a flavoring agent. The Panel reviewed the animal and clinical data included in this assessment, acknowledged that the oral safety of many of these ingredients has been well established, and found it appropriate to extrapolate the existing information to conclude on the safety of all the monosaccharides, disaccharides, and related ingredients.

Pharmacological inhibition of galectin-1 by lactulose alleviates weight gain in diet-induced obese rats

AIMS

Galectin-1 (GAL1) is an important member of the lectin family with a carbohydrate recognition domain and has recently been demonstrated to be involved in adipose metabolism. In the present study, we investigated the effects of targeted inhibition of GAL1 by its binding inhibitor lactulose under high fat diet (HFD)-induced obesity.

MAIN METHODS

Effects of targeted inhibition of GAL1 by lactulose on lipid metabolism were investigated in vitro and in vivo. Changes in lipogenic capacity in lactulose-treated adipocytes were demonstrated by Oil Red O staining, triglyceride quantification and major adipogenic marker expression patterns. After lactulose treatment in Sprague-Dawley rats, various important body weight parameters, food efficiency, plasma metabolic parameters (glucose, ALT, free fatty acid, triglycerides, leptin, and insulin) and metabolic protein expression patterns were evaluated.

KEY FINDINGS

Lactulose treatment reduced adipogenesis and fat accumulation in vitro by down-regulation of major adipogenic transcription factors such as C/EBPα and PPARγ. In vivo treatment of lactulose to 5-week-old Sprague-Dawley male rats significantly alleviated HFD-induced body weight gain and food efficiency as well as improved plasma and other metabolic parameters. In addition, lactulose treatment down-regulated major adipogenic marker proteins (C/EBPα and PPARγ) in adipose tissue as well as stimulated expression of proteins involved in energy expenditure and lipolysis (ATP5B, COXIV, HSL, and CPT1).

SIGNIFICANCE

In conclusion, reduced adipogenesis and increased energy expenditure mediated by lactulose treatment synergistically contribute to alleviation of HFD-induced body weight gain. Therefore, pharmaceutical targeting of GAL1 using lactulose would be a novel therapeutic approach for the treatment of obesity.

Absorption of glutathione from the gastro-intestinal tract

Transport of the peptide glutathione (GSH) has been studied with the rat small intestine in vitro and the human buccal cavity in vivo. Uptake was found to be sodium-independent in both systems. Saturation kinetics were demonstrated and uptake did not require energy in either system. Transport was inhibited by other small peptides. Carrier-mediated facilitated diffusion was postulated as the mode of transport.

Absorption of homocitrulline from the gastrointestinal tract

1. Transport of L-homocitrulline, an amino acid which occurs in milk products, was studied with rat small intestine in vitro and from the human mouth in vivo. Absorption was partially dependent, in both systems, on the presence of sodium ions. 2. Metabolic inhibitors decreased L-homocitrulline uptake across the small intestine. Transport across the intestine did not occur against the concentration gradient but did show saturation kinetics. 3. The barbiturate, amytal, did not inhibit buccal absorption. Saturation kinetics were demonstrated. 4. Experiments were conducted with L-citrulline, or other amino acids, as possible inhibitors of L-homocitrulline transport. Results were compatible with Na+-dependent carrier-mediated uptake across the buccal mucosa. Active transport could be involved with the small intestine assuming that L-homocitrulline has a low affinity for the carrier system.

Absorption of vitamin C from the human buccal cavity

1. Ascorbic acid was absorbed across the mucosa of the human mouth. 2. Omission of sodium ions from the medium decreased the absorption of ascorbic acid. 3. The presence of D-glucose, or 3-O-methyl-D-glucose, increased the absorption of ascorbic acid but D-fructose had little effect and D-mannitol had no effect. 4. Calcium ions also increased ascorbic acid absorption probably by a secondary effect on "Na+ fluxes. 5. Buccal mucosa was also permeable to dehydroascorbic acid and D-isoascorbic acid.