Effect of Larrea divaricata Cav. extract and nordihydroguaiaretic acid upon peroxidase secretion in rat submandibulary glands

Free radicals are involved in several diseases, including cancer, central nervous system alterations and inflammatory pathologies. Peroxidase is an oral enzyme implicated in the defence of oral cavity. It has been determined that flavonoids and lignans possess antioxidant and free radical scavenging either directly or indirectly, usually by means of increasing the secretion of free radicals scavenger enzymes. Larrea divaricata Cav. is a plant used in folk Argentine medicine for the treatment of cancer and inflammatory ailments. In this study, we have determined the effect and mechanism of action of an aqueous extract of the leaves of L. divaricata and NDGA on peroxidase secretion in female rat submandibular glands. The extract significantly increased the secretion and total peroxidase. % of secreted peroxidase (X +/- S.E.M.): extract maximum response: 150 +/- 10; % of total peroxidase (X S.E.M.): extract maximum response: 1000 +/- 90. The effect of the extract on peroxidase secretion was mediated by beta(1) adrenoceptors (% of secreted peroxidase: extract + atenolol maximum response: 50 +/- 4). Meanwhile, NDGA produced a decrease in peroxidase secretion (peroxidase secreted: basal: 0.44 +/- 0.03; NDGA 2.5 x 10(-6) M: 0.20 +/- 0.02; prostaglandins E-2 (PGE(2)) 10(-7) M: 1.32 +/- 0.5; NDGA + PGE(2): 0.46 +/- 0.035), an effect that was exerted by the inhibition on prostaglandins synthesis. (C) 2003 Elsevier Ltd. All rights reserved.