Comparative analysis of the polyphenolic compounds accumulation and the antioxidant capacity of fruits of different species of the genus Amelanchier

Abstract

Less common fruit plants of the genus Amelanchier Medik (serviceberry) are a source of biologically active compounds with high antioxidant capacity. In the present study, we studied the accumulation of secondary metabolites and antioxidant properties of the fruits of A. alnifolia (Nutt.) Nutt., A. canadensis (L.) Medik., and A. humilis Wiegand, growing in the steppe zone of Ukraine. The distribution of the main classes of polyphenolic compounds in the peel and pulp of fruits was studied using different spectrophotometric methods. Total polyphenols content (TPC) in the fruit peel and pulp was determined with Folin-Ciocalteu reagent; aluminum chloride method was used to evaluate the total flavonoids content (TFC); ferric-reducing power (FRP) of the plant fruit extracts was evaluated using potassium ferricyanide method, and the total antioxidant capacity (TAC) of peel and pulp extracts was determined by phosphomolybdenum method. Study results revealed the prevalence of phytochemicals accumulation in fruit peel as compared with pulp. Total polyphenols content in serviceberry peel consisted of 73% to 89% of the total sum in the whole fruit. The share of flavonoids in fruit peel varied in the range of 84–94% of the total flavonoids amount. The most reducing power of plant fruits was represented by fruit peel (63–67% of total level). Antioxidant capacity of the serviceberry peel was 59–64% of the whole fruit total antioxidant capacity. Analysis of the indices for whole fruits revealed the statistically significant correlations between TPC and FRP (r = 0.83), between TFC and FRP (r = 0.88), between TPC and TFC (r = 0.99). These findings can indicate the important role of the phenolic compounds in the antioxidant ability of the fruits of A. canadensis, A. humilis and A. alnifolia. Among them, species A. humilis exhibited the highest antioxidant potential; however, all the studied plants are promising for successful cultivation in the steppe zone. Further research is needed to study the bioactivities of plant extracts and polyphenols profile of different species in order to assess the plant resource for the functional nutrition and health promotion.

Keywords

• amelanchier fruits; peel; pulp; secondary metabolites; antioxidant ability; nontraditional crops.