Planta Med 2008; 74 - PC120
DOI: 10.1055/s-0028-1084638

The synephrine content of Shiikuwasha (Citrus depressa HAYATA) fruit: Analytical method and change during fruit growth

K Miyagi 1, T Fujise 1, N Koga 1, K Wada 2, M Yano 3, H Ohta 1
  • 1Department of Nutritional Sciences, Nakamura Gakuen University, Fukuoka, 814–0198, Japan
  • 2Department of Bioresource Science, Ryukyu University, Okinawa, 903–0213, Japan
  • 3Department of Cituculture, National Institute of Fruit Tree Science, Shizuoka, 424–020, Japan

Shiikuwasha fruit, a citrus species, is very popular as flavour enhancer in Okinawa, southern part of Japan. In the course of our study on Shiikuwasha fruit paste applied to the obesity volunteers for 35 days, we confirmed the significant decrease of %FAT (fat % by specific electro-conductivity)[1]. This decrease was considered to attribute to synephrine in the fruit. Synephrine, a sort of an adrenergic amine, has weight loss effects due to increasing metabolic rate. Whereas, integrated effect of synephrine was reported to increase circulation of blood through the heart and cerebral tissue, and the elevated blood pressure [2]. Thus, correct determination of synephrine was necessary. The objectives of this study were to develop the analytical method of synephrine in Shiikuwsha fruit, to select the optimal extracting solvent from fruit samples, and to investigate the change of synephrine content during the fruit growth and development. Aqueous to 100 methanol extracts were prepared from the freeze-drying peel prepared from the Shiikuwasha fruit harvested in 2005 seasons (August to January). The HPLC conditions were as follows: (i) column, Lichrospher RP-18 (4.0×250mm); mobile phase, 0.02M citric acid -0.02M NaH2PO4 (7:3 v/v); detection, 220nm. (ii) column, Develosil ODS-5 (4.6×250mm); mobile phase, acetonitrile-H2O (2:98)-10mM phosphoric acid; detection, 223nm. HPLC condition (ii) used Develosil ODS-5 column gave a sharp good peak (Rt=4.70min) with a sufficient separation. Synephrine recovery was best in pure water (100%), while no synephrine was detected in methanol solution (over than 50% concentration of methanol). As a result, 8.8mg of synephrine per 1g dry sample peel was detected in August. The synephrine concentration decreased gradually during fruit growth and development. In January, 2.3mg of synephrine was found.

Acknowledgement: This work was supported by a grant from the Bio-oriented Technology Research Advancement Institution, Japan.

References: 1. Koga, R. et al. (2003) 49th Annual Meeting of Japanese Society of Nutrition & Dietetics, Abstract book. p.251.

2. Thomas, S. H. et al. (1991) Br. J. Clin. Pharmacol 32:705–711.