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Nuclear factor kappa B (NF-kB), which has been implicated in the regulation of gene transcription, is essential for the expression of genes controlled by the long terminal repeat of human immunodeficiency virus type 1. Studies have shown that reactive oxygen species are involved in signal transduction pathways leading to NF-kB activation. We have reported that calf thymic peptides (TP) protect various cell types from oxidant injury. In this study, we determined the effects of TP on NF-d activation in human T lymphocytes (Jurkat cells) induced by two stimuli: tumor necrosis factor a and phorbol 12-myristate 13-acetate. Activated NF-kB in nuclear extracts was measured by an electrophoretic mobility shift assay (EMSA) using 32P-labeled probe. TP consistently exhibited a dose-dependent inhibition of NF-kB activation induced by both stimuli. Supershift with specific antibodies to NF-kB subunits confirmed that the inducible retarded bards observed in the EMSA are p6.5-p50 heterodimer of the NF-kB/Rel protein. Our data suggest that TP may act via antioxidant mechanisms to block NF-kB activation in Jurkat cells.

Pycnogenol (procyanidins extracted from Pinus maritima) has been reputed as a potent free-radical scavenger and an antioxidant phytochemical. We previously reported that pycnogenol prevents vascular endothelial cells from injury induced by an organic oxidant t-butyl hydroperoxide. In this study, we determined the effects of pycnogenol on (a) oxidative burst of macrophages, (b) oxidation of plasma low density lipoprotein (LDL), and (c) hydroxyl radical-induced breakage of plasmid DNA. Pycnogenol was incubated with J774 murine macrophages at 37°C and 5% CO2 and oxidative burst was triggered by zymosan. The intensity of fluorescence was measured. Pycnogenol exhibited a concentration-dependent inhibition of oxidative burst. CuSO4 was used to oxidize human plasma LDL and the formation of thiobarbituric acid reactive substances (TBARS) was determined. Co-incubation with pycnogenol resulted in a concentration-dependent inhibition of LDL oxidation. Exposure ofpBR322 plasmid DNA to iron/ascorbic acid system resulted in cleavage/damage of DNA by hydroxyl radical, measured by agarose gel electrophoresis. Pycnogenol significantly minimized this cleavage. The results indicate that pycnogenol exhibits an extensive antioxidant effect in all three in vitro systems.