Identification and quantification of anthocyanins, flavonoids, and phenolic acids in flowers of Rhododendron arboreum and evaluation of their antioxidant potential.

Abstract

The current study aimed to investigate the anthocyanins, non-anthocyanins (flavonoids and phenolic acids), and free radicals scavenging potential in the flowers of Rhododendron arboreum using ultra high performance liquid chromatography with ion mobility quadrupole time of flight tandem mass spectrometry. A total of 25 constituents including nine anthocyanins, six phenolic acids, and ten flavonoids were identified in the flower extract. The major anthocyanins identified were cyanidin-3-O-β-galactoside (1), cyanidin-3-O-α-arabinoside (4), and cyanidin-3-O-rhamnoside (8), while quercetin glycosides were the main identified flavonoids in R. arboreum flowers. Additionally, ultra high performance liquid chromatography methods were developed and validated for the quantification of nine compounds (anthocyanins, flavonoid glycosides, and phenolic acids); five of them were quantified using internal standards. The extracts were analyzed for total phenolics (123.6mg GAE/g), anthocyanin content (1.76% w/w), and evaluated for antioxidant properties against 2,2-diphenyl-1-picrylhydrazyl radical (IC50 : 102.06 and 96.92 μg/mL) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical cation (112.25 and 45.59 μM TE/g) assays. The profiling of R. arboreum for anthocyanins is reported for the first time. The findings suggest that the flowers are a promising source of bioactive constituents and could be used as functional food, antioxidants, and nutraceuticals.