Oxidative stress-induced modifications of lipoproteins and antioxidant status in cigarette smoke exposed rats: protective actions of essential oil and methanol fractions from nigella sativa seeds

Abstract

The combined in vitro and in vivo results presented in the thesis can be summarized as follows: Comparison of DPPH scavenging activities of methanol and EO extracts of NS seed powder with pure TQ and pure LMN, two constituents of EO, used in the present study, revealed that they directly reacted with and quenched DPPH radicals in a concentration dependent manner in the order ME gt pure TQ gt EO extract gt pure LMN. It is noteworthy that among the four test fractions/compounds, ME had the strongest DPPH scavenging activity with an IC50 value of 40 µg/ml, followed by 58 and 86 µg/ml for pure TQ and EO extract, while an IC50 value of 8.5 mg/ml was obtained for pure LMN. These results established that ME of NS seeds exhibited 115 % and 45 % higher antioxidant capacity than EO extract and pure TQ. This is apparently due to the presence of all the nonsaponifiable antioxidant compounds of hydrodistilled TQ rich EO as well as additional mixture of phytosterols and other antioxidants, which are also fractionated in ME, as NSF, during extraction of NS seed powder with methanol. Thus, ME enriched with all the nonsaponifiable DPPH radical scavenging agents of TQ rich EO extract plus good amount of mixture of phytosterols which evidently contributed independently or synergistically with TQ to substantially enhance it s total antioxidant efficacy. Daily 10-min exposure of CS to rats for 30 days was associated with increased ROS production, lipid peroxidation and hyperlipidemia in plasma, erythrocytes and liver with depletion in overall plasma antioxidant capacity, significant weakening of enzymatic and nonenzymatic antioxidant defense systems in erythrocytes and liver. Exposure of erythrocytes to these prooxidant conditions caused decreases in activities of SOD, CAT, Gred, total and Na+/K+-dependent ATPases, along with both free and membrane-linked-sulfhydryl groups of glutathione, coupled with an increased Gpx activity, oxidized glutathione (GSSG) and GSSG:GSH ratio levels, which may be due to their increased utilization