Determination of free, esterified, bound bioactive compound contents of Euphorbia cyparissias organs and their biological activities

Abstract

Euphorbia plants have long been used as herbs in numerous traditional medicines in Anatolia. They were employed for the treatment of microbial infections, skin wounds and gastrointestinal diseases. Euphorbia species are rich sources of phenolic acids, flavonoids and many other natural compounds with antioxidant effects. In the context of this study the phenolic content, antioxidant activity and antidiabetic effect of Euphorbia cyparissias (E. cyparissias) leaf, flower and stalk extracts were evaluated. Three separate phenolic fractions namely free, esterified and bound extracts were prepared from leaf, stalk, and flower organs. Enzymatic treatment was utilized to remove bound phenolics from the cellular structures. A total of nine different extracts obtained from E. cyparissias organs. The highest phenolic fraction was bound phenolics in all three assayed extracts. The highest total phenolic compound (TPC) was found as bound phenolic fraction form in leaf extracts (21.088±0.32 mg GAE/g). Similarly the leaf samples displayed the highest total flavonoid contents (TFC) as bound form (1.798±0.02 mg CE/g). Four different methods were employed to determine the antioxidant potencies of the extracts. In parallel with the TPC and TFC results the bound fraction of leaf extract displayed the highest antioxidant capacities when evaluated with DPPH, ABTS and CUPRAC assays. According to FRAP analysis, free phenolic compounds of the leaves had the highest antioxidant potential. Free, esterified and bound phenolic compound fractions were all displayed inhibitory activity against α-amylase and α-glycosidase enzymes which is associated with their antidiabetic effects. Especially esterified phenolic compounds displayed significant inhibitory activity against α-amylase while bound fractions found in stalks and flowers exhibited stronger α-glycosidase activities.