Molecular and phytochemical characterization of F1 Streptocarpus hybrids and antioxidant potential of their flower extracts

Abstract

Streptocarpus x hybridus is a very popular houseplant with colourful flowers arousing thus the interest of plant breeders. Its potential value is even higher since different chemical compounds could be identified and used for food and pharmaceutical industries. Therefore, the objectives of this study were: to determine genetic relationships between twelve F1 Streptocarpus hybrids and their genitors; to determine the total phenolic and flavonoid content; to evaluate the antioxidant activity of the analysed individuals. Although 12 out of the 24 RAPD primers detected polymorphism among the individuals, the UPGMA dendrogram did not show a very clear grouping pattern for flower colour. In contrast, the phytochemical dendrogram shed more light on the dissimilarities among Streptocarpus flowers in terms of their polyphenolic content. The total phenolic and flavonoid content of the flower extracts determined by the Folin-Ciocalteau and aluminium chloride colorimetric methods ranged from 680.02 to 2360.57 mg of GAE/100 g FW and from 12.52 to 78.36 mg QE/100 g FW. The radical scavenging activity against ABTS ranged from 27.17 to 130.35 µM Trolox/g FW. Due to its ornamental value, H12 was screened by HPLC-PDA-ESI-MS to identify and quantify the chemical compounds involved in flower colour. Among the six compounds that were identified and quantified (i.e. cyanidin-3-O-galactoside, cyanidin-3-O-xyloside, cyanidin-3-O-glucoside, cyanidin-3-O-arabinoside, peonidin-3-O-glucoside and apigenin-6-C-glucoside), isovitexin reached the highest concentration 4183 µg rutin/100 g FW. These preliminary results, showing high total polyphenolic content and ABTS antioxidant activity, suggest that Streptocarpus flowers could be a valuable source of antioxidants.