Chemical constituents from the flowers of Satsuma mandarin and their free radical scavenging and α-glucosidase inhibitory activities

Abstract

Flowers of Citrus plants are used as mild sedatives and for the treatment of insomnia in traditional medicines. In Japan, tea made from the flowers of Satsuma mandarin is consumed as healthy drink. Hesperidin (1), hesperetin (2), rutin (3), quercetin (4), nicotiflorin (5), eriocitrin (6), narirutin (7), phenylethyl glucoside (8) and unshuoside A (9) were isolated from the MeOH extract of fresh flowers. Structure elucidation of these compounds was performed on the basis of NMR spectroscopic data. Among them, rutin (3), quercetin (4) and eriocitrin (6) showed potent free radical scavenging activity, whereas hesperetin (2) and quercetin (4) showed potent α-glucosidase inhibitory activity.

Keywords:

• Satsuma mandarin
• Citrus unshiu
• Citrus reticulata
• Unshiu-mikan
• flowers
• flavonoids

Acknowledgements

We would like to thank Ms. Ukiko Murakami, Orange Blossom Co., Ltd., Kawachi, Kumamoto, Japan for providing the flowers of Satsuma mandarin.