Identification of bioactive compounds from Rhaponticoides iconiensis extracts and their bioactivities: An endemic plant to Turkey flora

Abstract

Rhaponticoides iconiensis (Hub.-Mor.) M.V.Agab. & Greuter. (Asteraceae) is an endemic species spread in several small populations in the province of Konya (Turkey). It is critically endangered with an extremely high risk of extinction. Recently, based on the molecular phylogenetic and eco geographical studies on Cardueae-Centaureinae, the genus Rhaponticoides Vaill. was separated from Centaurea L. Antioxidant properties and enzyme inhibition, as well as the phenolic and flavonoid contents, of the methanol (Soxhlet extraction and maceration) and water (infusion) extracts of R. iconiensis leaves, roots, and flower heads were determined. The methanol extracts of R. iconiensis leaves contained the highest amount of phenolic (52.37 and 54.37 mg gallic acid equivalent/g) and flavonoids (74.13 and 80.75 mg rutin equivalent/g). Accordingly, the leaves methanol extracts showed the highest antioxidant potential. Interestingly, the roots methanol extracts were the most potent acetylcholinesterase (4.75 mg galantamine equivalent/g) and butyrylcholinesterase inhibitors (5.26 and 5.14 mg galantamine equivalent/g). The leaves and roots methanol extracts exhibited high α-glucosidase (2.48–3.08 mmol acarbose equivalent/g) and α-amylase (0.17−0.70 mmol acarbose equivalent/g) inhibition. The highest tyrosinase inhibition was recorded for leaves methanol extracts (138.79 and 140.34 mg kojic acid equivalent/g). 87 natural products (including hydroxybenzoic, hydroxycinnamic and acylquinic acids, flavones, flavonols, flavanones and anthocyanins) were unambiguously identified or tentatively annotated in the studied extracts. Findings presented in the present study appraise the bioactivity of R. iconiensis, an understudied species.