Oxidised derivatives of silybin and their antiradical and antioxidant activity.
Carboxylic acids derived from silybin (1) and 2,3-dehydrosilybin (2) with improved water solubility were prepared by selective oxidation of parent compounds and a new inexpensive method for preparation of 2,3-dehydrosilybin from silybin was developed and optimised. The antioxidative properties of the above-mentioned compounds and of side product 3a from oxidation of compound 1 were determined by cyclic voltammetry, free radical scavenging (DPPH, superoxide) assays, and by inhibition of in vitro generated liver microsomal lipid peroxidation. Dehydrogenation at C((2))-C((3)) in flavonolignans (silybin vs 2,3-dehydrosilybin; silybinic acid vs 2,3-dehydrosilybinic acid) strongly improved antioxidative properties (analogously as in flavonoids taxifolin vs quercetin). Thus, in antioxidative properties, dehydrosilybin was superior to silybin by one order, but its water solubility is too low for application in aqueous milieu. On the other hand, 2,3-dehydrosilybinic acid is a fairly soluble derivative with antilipoperoxidation and antiradical activities better than that of silybin.
Institute of Microbiology, Academy of Sciences of the Czech Republic, Laboratory of Biotransformation, Vídenská 1083, CZ-142 20 Prague, Czech Republic.
Radek
R
Gazák
Alena
A
Svobodová
Jitka
J
Psotová
Petr
P
Sedmera
Vera
V
Prikrylová
Daniela
D
Walterová
Vladimír
V
Kren
D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D016166:Free Radical Scavengers / Q000737:chemistry / Q000494:pharmacology*; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D051381:Rats; D000077385:Silybin; D012838:Silymarin / Q000737:chemistry* / Q000494:pharmacology*
D000975:Antioxidants; D016166:Free Radical Scavengers; D012838:Silymarin; D000077385:Silybin