Does rainfall affect the antioxidant capacity and production of phenolic compounds of an important medicinal species?

- The antioxidant activity the barks of A. colubrina vary from a few months.
- The concentrations of major phenolic compounds vary from a few months.
- Only one major compound remained stable during the study year.
- The antioxidant activity was not correlated with rainfall.
- The concentrations of major phenolic compounds were not correlated with rainfall.
- Phenolic compounds are not associated with antioxidant activity of A. colubrina.

The variation in water availability can cause oxidative stress in plant species, which respond by producing antioxidants. Phenolic compounds are among the primary substances responsible for antioxidant activities. Thus, the goal of this study was to evaluate whether rainfall in a dry forest in Brazil affects the antioxidant activity and the major phenolic compounds in the stem bark of Anadenanthera colubrina, an economically important species from the semi-arid region of Brazil. Monthly samplings were performed over one year for the analysis of free radical sequestration by the DPPH method and for the identification and quantification of major phenolic compounds by HPLC. These data were correlated with each other and with the monthly rainfall. Three major phenolic compounds were identified, one of which was hyperin. The stem bark was highly capable of scavenging free radicals. The antioxidant activity and the production of the three compounds only slightly varied during the year, despite the significant differences among a few of the months studied. These differences are apparently unrelated to rainfall. No correlation was found between the major compounds and free radical scavenging. Our results suggest that rainfall was not the environmental factor responsible for monthly differences in the antioxidant activity of and concentrations of major phenolic compounds in the bark of A. colubrina.

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