Antistress and antioxidant activity in mice after repeated treatment with St. John's wort extracts of different hyperforin content
Recent data from several reports indicate that free radicals are involved in the biochemical mechanisms underlying neuropsychiatric disorders in humans . These reports suggest that there is a therapeutic benefit from antioxidant supplementation in manic-depressive patients [1,2]. In this study, we aimed to investigate the in vitro antioxidant capacity of chemically different St. John's wort (SJW) extracts using the ORAC assay and to determine in vivo the effect of subchronic treatment with the SJW extracts on antioxidant enzyme activities such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in mouse brain homogenates as well as erythrocyte lysates. Temperature stress (50°C) applied to SJW extracts significantly lowered the amount of hyperforin (extract A, no temperature stress, 3.26% hyperforin; extract B, 50°C for 8 days, 1.37% hyperforin; extract C, 50°C for 19 days, 0.14% hyperforin). The amount of hypericin only marginally changed under these conditions, no changes were observed for the flavonoids. The ORAC values for extract A, B and C ranged from 11.89 to 12.50µmol of TE/g of dried weight; the results correlate with published data . The decrease of hyperforin in the SJW extracts did not affect their in vitro antioxidant capacity which, therefore seems to be related to its phenolic compounds. Extract B and C increased enzyme activities in mouse brain homogenates (SOD, CAT, 41% and 44% vs. control) and erythrocytes lysates (GSH-Px, 56% and 61% vs. control) after 14 days of daily treatment comparable to fluoxetine and buspirone, indicating greater reduction of oxidative stress.
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