Total Phenols, Flavonoids and Antioxidant Activity in Annona muricata and Annona purpurea Callus Culture

Callus cultures of Annona muricata and Annona purpurea were induced in Murashige and Skoog (MS) medium supplemented with different concentrations of 1-naphthylacetic acid (NAA), 6-benzyladenine (BA) and 2,4-dichlorophenoxyacetic acid (2,4-D) utilized hypocotyls with explant. The highest percentage of callus formation was the treatment supplemented with 3 mg L-1 NAA for A. muricata (100%) while for A. purpurea in lower percentage (75%). BA stimulated the formation of shoots in all the evaluated concentrations, being the concentration of 2 mg L-1 the one that induced the greater formation of shoots for A. muricata (23 shoots/explant) and A. purpurea (28 shoots/explant). The content of total phenols, flavonoids and antioxidant activity was measured in the callus obtained from both species. The results showed that a higher content of total phenols was quantified in callus of A. purpurea (27.8 mg g(-1) dw) compared to A. muricata (23.2 mg g(-1) dw). The highest content of total flavonoids was observed in the callus of A. purpurea (8.0 ng g(-1) dw). Antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydracil radical assay. The concentration required for 50% inhibition (IC50) of the 2,2-diphenyl-1-picrylhydracil radicals were 4.22 mu g mL(-1) in methanolic extracts of callus of A. muricata, while in extracts of callus of A. purpurea was 2.86 mu g mL(-1), in both cases was greater than that found for leaves. Callus culture of the species studied in this work represents an alternative for the production of natural antioxidants.