Our earlier studies have shown that the compounds diphenyltin dichloride (DPhT)
and triphenyltinchloride (TPhT) in the presence of UVC radiation enhanced the degree of phosphatidylcholine liposomemem
brane oxidation (
J. Agric. Food Chem. 2005,
53, 76-83). The prooxidative
behavior of thecompounds has now
been confirmed with the electron paramagnetic resonance method, which provedthe possi
bility that the studied compounds can exist in free radical forms. The present work investigatesthe possi
bility of the protective action of quercetin on phosphatidylcholine liposome mem
branesexposed to the prooxidative action of DPhT
and TPhT induced
by UV radiation (<
IMG SRC="/images/gifchars/lam
bda.gif" BORDER=0 > = 253.7 nm). Theconcentrations of quercetin
and its equimolar mixtures with DPhT
and TPhT were determined (
andcompared with well-known antioxidants as st
andards-trolox
and butylated hydroxytoluene, also inthe presence of phenyltins) as those that induce 50% inhi
bition in oxidation of liposomes radiatedwith UV. They are 5.1 ± 0.10, 2.9 ± 0.12,
and 1.9 ± 0.08
M (differences
between the values arestatistically significant), constituting the following sequence of antioxidative activity: quercetin:TPhT> quercetin:DPhT > quercetin. This relation is confirmed
by the results on the antiradical a
bility ofquercetin
and its mixtures with DPhT
and TPhT toward the free radical 1,1-diphenyl-2-pricrylhydrazil.Similar sequences o
btained in
both studies suggest a possi
ble mechanism of the antiradical actionof the mixtures as free radical scavengers. We suggested that (i) quercetin's a
bility, documented
byspectrophotometric, infrared attenuated total reflectance spectroscopy,
1H NMR,
and molecularmodeling methods, to form complexes with phenyltins indicates a possi
ble way of protection againstthe peroxidation caused
by the free radical forms of phenyltins
and (ii) the differentiation in the actionof the quercetin/TPhT
and quercetin/DPhT associates (statisticaly significant) may result from adifferent localization in the liposome mem
brane, which is indicated
by the results of the fluorimetricstudies.