Determination of singlet oxygen quenching and protection of biological systems by various extracts from seed of Rumex crispus L

The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging effect and total phenolic contents were evaluated for the screening of singlet oxygen (1O2) quenching efficacy of various seed extracts from Rumex crispus L. The butanol and ethyl-acetate extracts displayed remarkable effect of DPPH as compared to positive control ascorbic acid. The concentrations (QC50) of butanol and ethyl-acetate extracts required to exert 50% reducing effect on 1O2 were found to be 116 and 82 μg mL−1, respectively. Both extracts were also found to protect the in vitro biological system from the detrimental effect of 1O2 on type II photosensitization in Escherichia coli, red blood cell, lactate dehydrogenase and histidine. Among all the tested extracts, the ethyl-acetate and butanol extracts contained higher amount of total phenolic contents. The results suggest that our study may contribute to the development of new bioactive products with potential applications to reduce photo-produced oxidative stress involving reactive oxygen species in living organisms.