Antioxidant potential and its relationship with polyphenol content and degree of polymerization in Opuntia elatior Mill. fruits

BACKGROUND: Opuntia elatior Mill. (Nagaphani) fruits are traditionally recommended as an expectorant, remedy for whooping cough, asthma, gonorrhea, ulcers, tumors, in the treatment of diarrhea and syphilis. Many of these diseases are allied with oxidative stress caused by free radicals. Thus, current research is directed towards finding naturally-occurring antioxidants of plant origin. AIM: To evaluate antioxidant potential of hydro-alcoholic extract of the O. elatior fruits (HAOE) and its fractions. MATERIALS AND METHODS: Using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide radical scavenging assay, total polyphenolic, flavonoid (FA), flavanone (FO) contents and degree of polymerization in relation with its antioxidant activity were examined. RESULTS: The experimental data indicated that the HAOE, ethyl acetate (EAOE) and butanol (BFOE) soluble fractions have shown significant antioxidant activity. The highest polyphenolic, FA, FO contents and degree of polymerization were found in EAOE. The scavenging potential was in the order of Ascorbic Acid > EAOE > BFOE > HAOE > BIOE, where ascorbic acid was used as a positive control. The increased antioxidant potential of EAOE and BFOE fractions over HAOE extract may be attributed to the purification achieved by fractionation of the extract which in turn resulted in an increase in the degree of polymerization and segregation of secondary metabolites. CONCLUSION: The fruit of O. elatior can be used as the best alternative for synthetic antioxidants.