Evaluation of the Antioxidant Activity of the Secondary Metabolites from Piliostigma reticulatum (DC.) Hochst

The ethyl acetate extract of Piliostigma reticulatum leaves was investigated for its antioxidant constituents. Isolated secondary metabolites of the leaves extract include: 2-O-(p-hydroxyphenyl)-5-hydroxy-6-C-methyl-7-methoxychromone (piliostigmin) 1, 6-C- methylkaempferol- 3-methyl ether 2, quercetin 3, quercetrin (quercetin-3-O-rhamnose) 4, and Isoquercetrin (quercetin-3-O-glucoside) 5. These compounds were evaluated for their antioxidant potentials. A rapid test for antioxidants using DPPH (1,1-dipheny-2-picryhydrazyl) TLC screening, demonstrated considerable radical scavenging activity for all the compounds. The DPPH spectrophotometric method was employed for quantitative determination of radical scavenging activity. The activity was expressed as EC50 value, which ranges between 4.68 0.03 and 50.76 1.71 for the flavonoids constituent.