Antioxidant capacity, radical scavenging kinetics and phenolic profile of methanol extracts of wild plants of Southern Sonora, Mexico

Purpose: To investigate the antioxidant and phenolic profiles of methanol extracts from Rhizophora mangle L, Krameria erecta, Lycium berlandieri Dunal, Vallesia glabra Link and Forchammeria watsonii Rose.

Methods: The free radical 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method was used for antioxidant assay of methanol plant extracts. Phenolic compounds determination was carried out by high performance liquid cromatography (HPLC) using an analytical C18 column eluting with acetonitrile on a gradient program.

Results: Extract from Rhizophora mangle L and Krameria erecta displayed 5-fold higher antioxidant capacity than ascorbic acid with DPPH reduction values of 95.71 and 91%, respectively. Anti-radical kinetic analysis and stoichiometric constant values suggest that the compounds responsible for antioxidant activity are polyphenols and flavonoids with a free or mono-substituted catechol group. Ferulic and vanillic acids had higher contents in Rhizophora mangle L (688.45 ± 18.21 and 7.13 ± 0.125 mg/g, respectively) and Krameria erecta (619.92 ± 28.16 mg/g and 22.29 ± 0.72 mg/g, respectively) than the other constituents.

Conclusion: Rhizophora mangle and Krameria erecta possess five times the antioxidant activity of ascorbic acid and also demonstrate high phenolic contents, which supports the beneficial properties attributed to these plants in traditional medicine, and also justifies the use of the plants as alternative medicines.