Objective: To determine the potential antioxidant effect of rutin (quercetin-3-O-b-rutinoside) supplementation. Design: A 6-week randomized single-blind placebo controlled trial was conducted; 500 mg rutin supplement was compared to an equivalent amount of glucose placebo. In addition, a pharmacokinetic study was carried out. Setting: The Rowett Research Institute, Aberdeen, UK. Subjects: Eighteen healthy non-obese normocholesterolaemic female volunteers in the age range 18 ± 48 y. Main outcome measures: Plasma¯avonoids, ascorbic acid, tocopherols and carotenoids, plasma antioxidant capacity, lymphocyte DNA damage, blood chemistry and haematology, liver function tests, urinary malondialdehyde, 8-hydroxy-2H -deoxyguanosine and 8-iso-prostaglandin F 2a . Results: Eighteen volunteers completed the trial. Rutin supplementation did not induce any adverse changes in blood chemistry or indices of liver function. Plasma¯avonoids were signi®cantly elevated in the rutinsupplemented group. Endogenous oxidation of pyrimidines was signi®cantly decreased in both rutin-and placebo-treated volunteers. There was no signi®cant change in the level of urinary 8-hydroxy-2 H -deoxyguanosine or urinary malondialdehyde in either group. A linear correlation was observed between urinary malondialdehyde and urinary 8-iso-prostaglandin F 2a (R 0.54, P`0.01). Conclusion: Six weeks' rutin supplementation signi®cantly elevated the levels of three plasma¯avonoids (quercetin, kaempferol and isorhamnetin) but there was no signi®cant change in plasma antioxidant status. The decrease in the level of endogenous base oxidation in lymphocyte DNA seen in both the placebo-and rutinsupplemented subjects may re¯ect seasonal changes in other dietary antioxidants.

Skin protein modification (haptenation) is thought to be a key step in the manifestation of sensitization to low molecular mass chemicals (<500 g/mol). For sensitizing chemicals that are not protein reactive, it is hypothesised that metabolic activation can convert such chemicals into protein reactive toxins within the skin. trans-Cinnamaldehyde, alpha-amyl cinnamaldehyde, and trans-cinnamic alcohol are known sensitizers with differing potencies in man, where the former two are protein reactive and the latter is not. Here, we have used immunochemical methods to investigate the extent of protein-cinnamaldehyde binding in rat and human skin homogenates that have been incubated (for either 5, 15, 30, or 60 min) at 37 degrees C with cinnamaldehyde, alpha-amyl cinnamaldehyde (at concentrations of between 1 and 40 mM), and cinnamic alcohol (at higher concentrations of 200 or 400 mM). Cinnamaldehyde specific antiserum was raised specially. A broad range (in terms of molecular mass) of protein-cinnamaldehyde adducts was detected (as formed in a time- and concentration-dependent manner) in skin treated with cinnamaldehyde and cinnamic alcohol but not with alpha-amyl cinnamaldehyde. Mechanistic observations have been related to relative skin sensitization potential, as determined using the local lymph node assay (LLNA) as a biological read-out. The work presented here suggests that there is a common hapten involved in cinnamaldehyde and cinnamic alcohol sensitization and that metabolic activation (to cinnamaldehyde) is involved in the latter. Conversely, there does not appear to be a common hapten for cinnamaldehyde and alpha-amyl cinnamaldehyde. Such mechanistic work on protein modification is important in understanding the early mechanisms of skin sensitization. Such knowledge can then be used in order that effective and appropriate in vitro/in silico tools for predicting sensitization potential, with a high confidence, can be developed.