Comparative analysis of specialized metabolites and antioxidant capacity in vitro of different natural populations of Globularia spp.

Abstract

AbstractTotal phenolic, flavonoid, condensed tannin and iridoid content, as well as antioxidant capacityin vitro,were determined spectrophotometrically in methanolic extracts of different plant parts of the Mediterranean medicinal plantGlobularia alypumL. and three widespread European species of the same genus:G. cordifoliaL.,G. meridionalis(Podp.) O. Schwarz andG. punctataLapeyr. In order to consider possible environmental influences on the production of specialized metabolites, each species, exceptG. alypum, was collected from three different natural populations. Great variations in the amounts of specialized metabolites were observed among different plant parts and species. For example, total phenolic content ranged from 10.13 (G. punctata, flowers) to 44.90 (G. cordifolia, flower stems) mg gallic acid equivalent g−1dry weight. Moreover, great differences, attributed to location-specific environmental factors, were observed among different populations of the same species. For example, a strong positive correlation was observed among mean monthly temperatures and total phenolic contents in the leaves of studiedGlobulariaspp. (r = 0.75, p = 0.019). However, despite these differences, all species were rich in bioactive substances when compared toG. alypum, especially in their aerial parts. A very good positive correlation was observed between total phenolic content and DPPH radical scavenging capacity (r = 0.86, p < 0.001)/ABTS radical scavenging capacity (r = 0.83, p < 0.001). The results obtained show thatG. cordifolia,G. meridionalisandG. punctataare rich in bioactive substances, providing support for their pharmaceutical utilization. Further investigations are needed to verify the possibility of their medicinal use.