Next Article in Journal
Oxidative Imbalance and Kidney Damage in Cafeteria Diet-Induced Rat Model of Metabolic Syndrome: Effect of Bergamot Polyphenolic Fraction
Previous Article in Journal
Liver Injury Induced by Carbon Tetrachloride in Mice Is Prevented by the Antioxidant Capacity of Anji White Tea Polyphenols
Previous Article in Special Issue
Enhanced Antioxidant Activity under Biomimetic Settings of Ascorbic Acid Included in Halloysite Nanotubes
Article Menu
Issue 3 (March) cover image

Export Article

Open AccessArticle

Effect of Side Chain Functional Groups on the DPPH Radical Scavenging Activity of Bisabolane-Type Phenols

Department of Chemistry and Life Science, YOKOHAMA National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
Author to whom correspondence should be addressed.
Antioxidants 2019, 8(3), 65;
Received: 31 January 2019 / Revised: 9 March 2019 / Accepted: 11 March 2019 / Published: 16 March 2019
(This article belongs to the Special Issue The Chemistry of Antioxidant Activity)
PDF [2661 KB, uploaded 16 March 2019]


Methods for improving the antioxidant activity of phenolic compounds have been widely investigated; however, most studies have focused on the structure–activity correlations of substituents on the aromatic rings of catechols or flavonoids. We investigated the influence of side chain functional groups on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of xanthorrhizol and curcuphenol analogues. These compounds were synthesised by the side chain functional group conversion of curcumene, followed by direct oxidation of the aromatic ring. We determined the DPPH radical scavenging activity from the half-maximal effective concentration (EC50) obtained from a DPPH assay in methanol. The positional relationships of the side chain with the aromatic ring and phenolic OH group were determined using density functional theory calculations, and the stability of different conformations was compared. Electron transfer-proton transfer was determined to be the dominant mechanism in the DPPH reaction with xanthorrhizol analogues, based on the correlation between the EC50 and ionisation potential. The radical cation was greatly stabilised in the structure where the side chain functional group was close to the aromatic ring. Stabilisation also depended on the phenolic OH group position. In future antioxidant design, aromatic ring substituent conversion and the use of functional groups far from the OH group or ring should be explored. View Full-Text
Keywords: curcuphenol; electron proton transfer; phenols; sesquiterpenes; xanthorrhizol curcuphenol; electron proton transfer; phenols; sesquiterpenes; xanthorrhizol

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Ichikawa, K.; Sasada, R.; Chiba, K.; Gotoh, H. Effect of Side Chain Functional Groups on the DPPH Radical Scavenging Activity of Bisabolane-Type Phenols. Antioxidants 2019, 8, 65.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Antioxidants EISSN 2076-3921 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top