Abstract
Objective : Peroxynitrite $(ONOO^-)$, formed from the reaction of $O_2^-$ and NO, is a cytotoxic species that can oxidize several cellular components such as proteins, lipids and DNA. It has been implicated in the aging process and age-related disease such as Alzheimer's disease, rheumatoid arthritis, cancer and atherosclerosis. The aim of this study was to investigate scavenging activities of $ONOO^-$ and its precursors. NO and $O_2^-$ and its scavenging mechanism using fluorescent probes, DCFDA, DAF-2 and DHR 123.. Methods : Psoralea corylifolia was crushed. The crushed Psoralea corylifolia was extracted 3 times, each time with 3 volumes of methyl alcohol at $60^{\circ}C$ for 24 h. The extract was filtered and evaporated under reduced pressured using a rotary evaporator to yield 16g. This was done to investigate scavenging activities of $ONOO^-$, NO, $O_2^-$ and its scavenging mechanism using fluorescent probes, DCFDA, DAF-2 and DHR 123. Results : After Psoralea corylifolia was added authentic $ONOO^-,\;{\cdot}\;O_2^-$ and NO was markedly scavenged. Also, $ONOO^-$ induced by $O_2^-$ and NO (these derived from SIN-1) was inhibited. The data showed a decrease in $ONOO^-$ mediated nitration of tyrosine through electron donation after Psoralea corylifolia was added. Data showed a dose-dependent correlation with inhibition of nitration of bovine serum albumin induced by $ONOO^-$, Furtheremore, LPS-induced ROS and RNS generation was blocked. Conclusions: These results suggest potential for use of Psoralea corylifolia as an effective $ONOO^-$ scavenger to counter the aging process and age-related diseases.