Characterisation of high molecular weight hop proanthocyanidins using Analytical Ultracentrifugation

Gadon, Arthur; Linforth, Robert; Harding, Stephen E.; Cook, David

Abstract

We report the novel application of Analytical Ultracentrifugation (AUCF) to characterise the polymeric proanthocyanidin fraction of hops. Extraction of hop samples with 70% acetone (aq) followed by a C-18 Solid Phase Extraction yielded polyphenolic fractions for AUCF analysis. Sedimentation velocity experiments demonstrated the presence of discrete molecular weight bands of proanthocyanidins, as opposed to a continuous distribution of molecular weights. There were 4 such bands for Saaz hop (0.15, 1.1, 2.7 and 4.4 S) and 3 bands for Magnum (0.15, 1.6 and 3.0 S). The method resulted in a reproducible size (sedimentation coefficient) distribution for replicate runs of the same extract and for extracts prepared from different samples of the same hop variety. Sedimentation equilibrium experiments were then used to fit molecular weight distributions using the new SEDFIT-MSTAR method for the same samples. Thus we report for the first time polymeric proanthocyanidins in hops with molecular weights of up to 100 kDa in Saaz hop (or up to 56 kDa in Magnum). This represents the first application of AUCF to characterise complex fractions of polyphenolics extracted from botanical sources and the methodology developed should find wider application in the study of this diverse and bioactive class of compounds.

Citation

Gadon, A., Linforth, R., Harding, S. E., & Cook, D. (2019). Characterisation of high molecular weight hop proanthocyanidins using Analytical Ultracentrifugation. Scientific Reports, 9(1), Article 12650. https://doi.org/10.1038/s41598-019-49171-4

• Journal Article Type: Article
• Acceptance Date: Aug 16, 2019
• Online Publication Date: Sep 2, 2019
• Publication Date: 2019-12
• Deposit Date: Sep 5, 2019
• Publicly Available Date: Sep 9, 2019
• Journal: Scientific Reports
• Electronic ISSN: 2045-2322
• Publisher: Nature Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 9
• Issue: 1
• Article Number: 12650
• DOI: https://doi.org/10.1038/s41598-019-49171-4
• Keywords: Multidisciplinary
• Public URL: https://nottingham-repository.worktribe.com/output/2571287
• Publisher URL: https://www.nature.com/articles/s41598-019-49171-4
• Additional Information: Received: 20 March 2019; Accepted: 16 August 2019; First Online: 2 September 2019; : The authors declare no competing interests.
• Contract Date: Sep 9, 2019