ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Preparation and characterization of antioxidant flavonoid-enriched extract from saffron by-product: a combination of ultrasound-assisted extraction and macroporous resin purification

Na Chen, Junjie Xiang, Yuling Liu, Hua Li, and Bin Yang

Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, People’s Republic of China

E-mail: ylliu@icmm.ac.cn

Received: 20 October 2020  Accepted: 15 January 2021

Abstract:

The stigma of saffron, a precious spice widely used in the world, takes only 7.4% (w/w) of the total weight of the flower, resulting in wasting the rest 92.6% of the flower. The utilization of the waste saffron floral bio-residues (SFB) has hence attracted people’s attention. In this paper, ultrasound-assisted extraction (UAE) associated with macroporous resin (MPR) purification step was successfully applied to enrich antioxidant flavonoid in SFB extract for the first time, resulting in significant increase in flavonoid content compared with other extraction method reported in literatures. The yield of the extract was up to 10%, and the content of kaempferol-3-O-sophoroside (KS) in the obtained extract was more than 50%, which was much higher than the total flavonoid content (2.05–19.2%) reported in other literatures. UAE procedure was optimized by studying the influence of parameters, e.g., extracting solvent, time, temperature and sample–solvent ratio, based on contents of KS and delphinidin-3,5-di-O-glucoside (DG) and the antioxidant activity of the extract. Further enrichment of flavonoid was achieved by D-101 MPR with optimum purification conditions. Furthermore, 52 flavonoids, 8 alkaloids and 10 polyols were identified or putatively characterized from the SFB extract using UPLC-MS, and the contents of KS and DG were determined to be 501.90 and 22.01 mg/g, respectively. Besides, the SFB flavonoid extract showed good antioxidant activities with IC₅₀ 33.79 μg/mL for DPPH scavenging effect and 39.65 μmol/mg trolox for ORAC values

Keywords: Saffron floral bio-residues; Ultrasound-assisted extraction; Macroporous resin purification; Antioxidant activity; Chemical character

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01522-0

Chemical Papers 75 (6) 2749–2763 (2021)