Antioxidant activity of limonene on normal murine lymphocytes: relation to H2O2 modulation and cell proliferation.

Limonene is a monoterpene present in citrus fruit and is used as flavouring agents of foods. It was shown that monoterpenes possess antioxidant activity. Previously, it was demonstrated that limonene exerts anti-proliferative action on a lymphoma cell line without modifying normal lymphocyte viability. H(2)O(2) has a modulator role in cell proliferation. In the present study, the effect of limonene on normal lymphocytes proliferation and its relation with H(2)O(2) level modulation was analysed, evaluating its effect on the activity of cell antioxidant enzymes, such as catalase, peroxidase and superoxide dismutase. Limonene exerted a biphasic effect on cell proliferation; the increase in cell proliferation was related to the decrease in H(2)O(2) level by the increase in catalase and peroxidase activities. Moreover, limonene protected the cells to the oxidative stress induced by exogenous addition of H(2)O(2). In view of these results, it is possible that limonene could protect normal lymphocytes from diseases related to oxidative stress, including cancer, but further research is necessary to establish the role of limonene as a potential antioxidant that can effectively protect lymphocytes from oxidative stress and mitochondrial dysfunction.

Effect of Ilex extracts and isolated compounds on peroxidase secretion of rat submandibulary glands.

Free radicals are involved in diverse disorders such as tumoral, central nervous system alterations, immunological and inflammatory pathologies. Peroxidase is an oral enzyme involved in the defense of the oral cavity. Ilex species such as Ilex paraguariensis St. Hil. and the commercial product made with it "Yerba Mate" are used traditionally as antirheumatics and for the treatment of gastrointestinal diseases among others and also as a beverage with nutritional and stimulant properties. The presence of polyphenolic derivatives and flavonoids in the aqueous extract has been determined by HPLC analysis. In this study, the activity of aqueous extracts of I. paraguariensis and "Yerba Mate" on peroxidase secretion in female rat submandibular glands was investigated. The contribution to this pharmacological activity by some major hydrocynnamic acid derivatives present in the crude extracts, such as chlorogenic acid and caffeic acid and the most abundant methylxanthine, caffeine, was also evaluated. Spectrophotometrical determination of peroxidase activity showed that both extracts produced a significant increase in both secreted peroxidase and total peroxidase activity, though "Yerba Mate" showed a higher activity (EC(50) "Yerba Mate": 148+/-10 microg/ml; EC(50)I. paraguariensis: 841+/-20 microg/ml). The HPLC/DAD analysis of the crude extracts was performed and chlorogenic acid, caffeic acid and caffeine were identified and quantified. The results (expressed as W/W percentage of dried material) were as follows: I. paraguariensis: chlorogenic acid: 2.80+/-0.30, caffeic acid: 0.023+/-0.004, caffeine: 1.06+/-0.06; "Yerba Mate": chlorogenic acid: 1.98+/-0.37; caffeic acid: 0.020+/-0.003, caffeine: 0.70+/-0.06. Caffeine and chlorogenic acid were proved to play an important role in the induction of peroxidase secretion induced by the extracts.