Objectives Protocatechuic acid (PCA) possesses numerous pharmacological activities, including antioxidative and anti-inflammatory activities. This study seeks to investigate its underlying mechanism of action in the liver and brain toxicity induced by CCl4 in male albino rats. Methods Rats were given PCA at 10 and 20 mg/kg daily and orally as a pretreatment for seven days. A single injection of CCl4 was given 2 h later to induce brain and liver toxicity. Results CCl4 moderately elevated the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP). PCA lowered AST level significantly when compared to control. Total protein and albumin levels presented insignificant changes (p>0.05) in all groups while lipid profile showed increased total cholesterol level and reduced high-density lipoprotein (HDL) by CCl4. PCA (10 mg/kg) significantly reduced the cholesterol level while the 20 mg/kg dose moderately prevented HDL reduction. There was an increased MDA production with a corresponding low GSH level in the group treated with CCl4. Activities of superoxide dismutase, catalase, and glutathione-S-transferase in both organs also declined. PCA, especially at 10 mg/kg attenuated lipid peroxidation by increasing GSH level in the organs. Biochemical assays revealed the improvement of antioxidant enzyme activities by PCA in these organs. Furthermore, PCA lowered the level of proinflammatory cytokine COX 2 in the brain and liver while NF-kB expression was inhibited in the brain. Histopathology reports validated the effects of PCA. Conclusions PCA exhibited protection against toxicity in these tissues through antioxidant and anti-inflammatory activities and the potential mechanism might be through modulation of the NF-κB/COX-2 pathway.

Studies suggest that extracts from plant materials could play protective roles against various disorders associated with the interplay between oxidative response and inflammatory disorders. The aim of this study was to investigate the potential antioxidant and anti-inflammatory properties, and phytochemical analyses of methanol extract of ripe and unripe peels of Ananas comosus (L.) Merr. The antioxidant properties were investigated through the analyses of ferric ion reducing antioxidant capacities, ascorbic acid equivalent antioxidant capacities, and nitric oxide scavenging capacities of the extracts. The anti-inflammatory potentials of the extracts were assessed through albumin denaturation inhibition and proteinase inhibition assays. Further investigation was carried out on the phytochemical composition of the extracts. There was no significant difference in the antioxidant potentials of the extracts assessed through the reduction of ferric ion. However, the ascorbic acid equivalent capacities and nitric oxide scavenging potential revealed that the antioxidant potentials of the extract of the unripe peel of A. comosus were significantly higher (p < 0.05) than the antioxidant potentials of the extract of ripe peel. Albumin denaturation inhibitory potential was significantly higher (p < 0.05), but there was no significant difference in the protease inhibitory potentials of both extracts. The estimated amounts of total flavonoids present in the extract of ripe peel of A. comosus were significantly higher (p < 0.05) than the estimates in the extract of unripe peels. This study gave a comprehensive insight into the antioxidant properties, anti-inflammatory properties and phytochemical compositions of the methanol extracts of the peels of ripe and unripe A. comosus which could be exploited as an alternative and complementary medicine in the treatment of different ailments associated with inflammatory disorders.