ANTIOXIDANT PROPERTIES AND PHYTOCHEMICAL PRINCIPLES OF SOME MEDICINAL PLANTS: ADENIUM OBESUM (FORSSK.) ROEM. & SCHULT., IXORA COCCINEA LINN. AND AEGLE MARMELOS LINN.
The methanolic extracts, fractions and sub-fractions of Adenium obesum (Forssk.) Roem. & Schult., Ixora coccinea Linn. and Aegle marmelos Linn. were screened for their free radical scavenging ability by using ascorbic acid and butylated hydroxytoulene (BHT) as standard antioxidants and evaluated through DPPH free radical scavenging assay. I. coccinea exhibited strongest inhibition, followed by A. obseum, and A. marmelos. The methanolic extracts of I. coccinea leaves proved to be the most potent antioxidant among these extracts with IC50 0.00315 ± 0.0001 mg/mL. Upon the purification of the active fractions twenty-six (1-26) pure chemical constituents were isolated and examined for their antioxidant inhibition ability, out of which 5-O-caffeoyl quinic acid (19) isolated from the active fraction of I. coccinea flower found to be potent antioxidant with IC50 value 0.0467 ± 0.0018 mg/mL as compared to standard ascorbic acid (0.0491 ± 0.0009) and BHT (0.0407 ± 0.003).