Iridoid glycosides from the flower buds of Lonicera japonica and their nitric oxide production and α-glucosidase inhibitory activities

• Published in: Journal of functional foods 2015-10, Vol.18, p.512-519
• Main Authors: Liu, Zhi-Xiang, Liu, Chun-Ting, Liu, Qing-Bo, Ren, Jie, Li, Ling-Zhi, Huang, Xiao-Xiao, Wang, Zhen-Zhong, Song, Shao-Jiang
• Format: Article
• Language: English
• Subjects: Diabetes mellitus (DM); Functional foods; Iridoid glycosides; Lonicera japonica; Nitric oxide; α-glucosidase
• ISSN: 1756-4646; 2214-9414
• DOI: 10.1016/j.jff.2015.08.017

•Twenty-eight iridoid glycosides were isolated from the flower buds of Lonicera japonica.•Three were new and three others were obtained from this species for the first time.•Two bis-secoiridoid glucosides (12–13) gave significant anti-inflammatory activities.•Most compounds exhibited potent α-glucosidase inhibitory activities. The flower buds of Lonicera japonica are commonly used as popular healthy beverages that are also effective in the prevention and cure of a variety of chronic diseases, such as diabetes, and also as an anti-inflammatory treatment for thousands of years. In this study, three new iridoid glycosides along with twenty-five known analogues were isolated from the aqueous extract of L. japonica. Their structures were determined by extensive 1D NMR, 2D NMR and HR-ESIMS spectroscopic data analyses, and all the isolates were investigated with regard to lipopolysaccharide (LPS)-induced nitric oxide (NO) production and α-glucosidase inhibitory effects. Among these compounds, 12 and 13 exhibited strong NO inhibitory activities and no cytotoxic effects. Moreover, most compounds were potent α-glucosidase inhibitors compared with the positive control acarbose. These findings will enhance knowledge about the bioactive components of L. japonica and help promote its potential application in functional foods.