In the present study, we did not find an increase of TBARS levels in whole saliva in response to an acute psychosocial stressor that might indicate resilience to lipid peroxidation in saliva of young people at stress, possibly because of the enhanced activity of catalase. No difference in TBARS levels was observed between men and women at rest as well as at stress. The side chains of all amino acid residues of proteins are susceptible to oxidation by ROS. Excessive oxidative stress results in carbonylation of proteins that is an irreversible oxidative modification often leading to decrease or loss of protein function. The concentration of carbonyl GDC-0879 groups is a good measure of ROS-mediated protein oxidation. Unexpectedly, in the present study we found that levels of oxidatively modified proteins responded to stress with a substantial decrease that was larger in women than in men. The decrease might be explained by augmented catalase activity and is consistent with the observation that stress caused a greater rise in catalase in women compared to men. In the present study we investigated how psychosocial stress effects levels of free sialic acids in whole saliva. Sialic acids are believed to be important in antioxidant defense. They occupy the terminal position of many glycoproteins, e.g. mucins and have important roles in their functioning. Mucins have been found to be hydroxyl radical scavengers, with sialic acid moieties essential for the role. However, excessive quantities of hydroxyl radicals cause depolimerization of native mucin, while Eguchi et al. showed that the glycosidic linkage of sialic acid is a potential target for superoxide and other related ROS that therefore cause liberation of free sialic acids. Iijima et al. showed that free Nacetylneuraminic acid scavenges hydrogen peroxide under physiological conditions and is a potent defense molecule against oxidative stress. We have found a significant stress-induced increase of free sialic acids in whole saliva of young people at stress. Interestingly, baseline levels of free sialic acids were significantly lower in women than in men. An exposure to a psychosocial stressor caused a sharper increase of sialic acids in saliva of women and resulted in similar concentration of sialic acids in both sexes. The mechanism and the role of the observed stress-induced rise of free sialic acids in saliva is unclear. The rise might be attributed to the intensified damage of mucins at stress. Alternatively, the phenomenon might indicate an additional protective mechanism against oxidative lesions. We tested effects of psychosocial stress on salivary flow rate and total protein concentration to eliminate the possibility that they are confounding factors in the research. Up to now research of effects of stress on salivary flow rate or on total protein concentration in saliva has produced contradictory results. A decreased flow rate was found in an academic stress paradigm.