Hydroxymatairesinol and Sesaminol Act Differently on Tocopherol Concentrations in Rats

Abstract

We have previously reported that sesame seed with the tetrahydrofurofuran type lignans sesamin and sesaminol (SeOH) produced higher tocopherol concentrations, while flaxseed with the dibenzylbutyrolactone type lignans did not cause higher tocopherol concentrations in rats. Sesame seeds also contain the dibenzylbutyrolactone type lignan 7-hydroxymatairesinol (HMR). To clarify whether or not the tocopherol elevating effect is affected by the chemical structure of lignans, the effect of HMR isolated from Norway spruce, was compared with SeOH, isolated from sesame seed. The lignans were added to a low alpha-tocopherol (10 mg/kg) diet, and rats were maintained on these diets for 8 wk. The experimental diet containing 0.2% SeOH elevated alpha-tocopherol content in the plasma liver, kidney, and brain, but HMR (0.2% or 0.5%) had no effects. Dietary HMR and SeOH (both in concentrations of 0.2%) were further compared in rats fed on a gamma-tocopherol (50 mg/kg) containing diet. SeOH produced significantly higher g-tocopherol content in the plasma and tissues, and significantly lower 2,7,8-trimethyl-2(2'-carboxyethyl)-6-hydroxychroman (gamma-CEHC, a gamma-tocopherol metabolite) content in the urine. However, HMR did not show such effects. These results suggest that the sesame lignan SeOH increases tocopherol concentrations in animals by suppressing the conversion of gamma-tocopherol to gamma-CEHC. HMR, a structurally different plant lignan, does not have such properties. Further studies are needed to show the potential health effects associated with an increased tocopherol concentration in the body.