Crude extracts of Limonium tetragonum and their solvent-partitioned fractions were evaluated for their potential to scavenge authentic <TEX>$ONOO^-$</TEX>, and <TEX>$ONOO^-$</TEX> derived from 3-morpholinosydnonimine (SIN-1). Four flavonol glycosides (1-4) were isolated by activity-guided separation. Their chemical structures were elucidated by extensive 2 D NMR experiments and by comparison with published spectral data. These compounds were also estimated for their peroxynitrite scavenging effects. The scavenging ratios of compounds 1-4 on authentic <TEX>$ONOO^-$</TEX> were 56, 37, 56, and 54%, respectively, at a concentration of 1 <TEX>${\mu}M$</TEX>. On the other hand, the inbihition ratios of compounds 1-4 against <TEX>$ONOO^-$</TEX> generation from SIN-1 were 59, 39, 44, and 54% at the same concentration, respectively.