Influence of sunflower oil qualities and antioxidants on oxidative stability on whey-based salad dressings.

The antioxidant effect of ascorbic acid and EDTA (ethylenediaminetetraacetic acid) in food emulsions, based on whey and sunflower oils with enhanced oleic acid, α- and ß- tocopherol content, was not described up to now. Salad dressings based on cold-pressed high-oleic/α-, ß- tocopherol sunflower oil were oxidatively stable after 3 months of storage at 25 °C regarding primary (peroxide value, PV) and secondary (hexanal) lipid oxidation products (PV = 0.34 mmol O2 kg-1, hexanal value = 1.54 mg kg-1). Slight enhancement of PV and hexanal values was recorded in salad dressings prepared with cold-pressed medium-oleic/α-, ß- tocopherol oil, after 3 months of storage at 25 °C, and was inhibited by ascorbic acid or EDTA. Ascorbic acid (0.50 g kg-1) reduced PV by 80% and hexanal value by 32%. EDTA (0.075 g kg-1) reduced PV by 60% and hexanal value by 27%. In salad dressings, containing linoleic/a- tocopherol sunflower oil, the antioxidant effects of ascorbic acid and EDTA were as following: ascorbic acid (0.25-4.00 g kg-1) reduced PV by 83-100% and hexanal value by 82-73%; EDTA (0.075 g kg-1) reduced PV by 75% and hexanal value by 76%, after 12 months of storage at 4 °C.

Docking studies suggest ligand-specific delta-opioid receptor conformations.

An automated docking procedure was used to study binding of a series of delta-selective ligands to three models of the delta-opioid receptor. These models are thought to represent the three ligand-specific receptor conformations. Docking results are in agreement with point mutation studies and suggest that different ligands--agonists and antagonists--may bind to the same binding site under different receptor conformations. Docking to different receptor models (conformations) also suggests that by changing to a receptor-specific conformation, the receptor may open or close different binding sites to other ligands.

Steric interactions and the activity of fentanyl analogs at the mu-opioid receptor.

Fentanyl is a highly potent and clinically widely used narcotic analgesic. The synthesis of its analogs remains a challenge in the attempt to develop highly selective mu-opioid receptor agonists with specific pharmacological properties. In this paper, the use of flexible molecular docking in a study of the formation of complexes between a series of active fentanyl analogs and the mu-opioid receptor is described. The optimal position and orientation of fourteen fentanyl analogs in the binding pocket of the mu-receptor were determined. The major receptor amino acids and the ligand functional groups participating in the complex formation were identified. Stereochemical effects on the potency and binding are explained. The proposed model of ligand-receptor binding is in agreement with point mutation experiments explaining the role of the amino acids: Asp147, Tyr148, Asn230, His297, Trp318, His319, Cys321, and Tyr326 in the complex formation. In addition, the following amino acids were identified as being important for ligand binding or receptor activation: Ile322, Gly325, Val300, Met203, Leu200, Val143, and Ile144.