[Kinetics and action mechanism of vitamin D3 in the process of lipid and blood plasma oxidation in model system].

Kinetics and mechanism of vitamin D3 action were investigated in the process of initiated oxidation of various modeling systems in comparison with activity of various antioxidants such as: alpha-tocopherol, dibunol, alpha-tocopheryl quinone, ubiquinone Q10, philloquinone and beta-carotene. Vitamin D3 addition increased initial and maximal rates of oxygen consumption. The length of circuits, value of a kinetic parameter k2/square root k6, describing oxidability of system as a whole was also increased.

Selective mono-O-acylation of C2V-symmetrical calix[4]arenediols with acylisocyanates.

Calix[4]arenedialkyl ethers 3 react with an excess of acylisocyanates to give selectively monoacylated products 4. Intramolecular hydrogen bonds and steric effects of the acylcarbamate fragments are most likely responsible for the high selectivity of this monoprotection. [reaction: see text]

[Intermolecular interactions of dipeptide triterpene derivatives and natural quinones with alpha-tocopherol].

In modeling system of the initiated oxidation of methyl oleate the antioxidation activity of a series of dipeptide derivatives of betulonic and glycyrrhetic acids, natural quinones (ubiquinone, philloquinone and menadione) and the kinetic effects of their combined action with alpha-tocopherol were studied. The same extreme character of the dependence of inhibitory action on the concentration of all investigated substances was found. Combined addition of triterpenoids or quinones together with alpha-tocopherol attenuated their effect.