Citrus ichangensis

Citrus ichangensis possesses an unusual distribution of limonoids (20). Unlike other species of citrus, fruit tissues and seeds of . ichangensis contain very high concentrations of nonbitter ichangensin and very low concentrations of bitter limonin. It also contains relatively high concentration of nonbitter deacetylnomilin. Quantitative analysis showed that a ratio of ichangensin to limonin in the fruit tissue is approximately 50 to 1. 

Unlike most other citrus species in which limonin is predominant (over 50% of total limonoids) Citrus ichangensis accumulates ichangensin (11) as the predominant limonoid in its fruit tissues and seeds (26). Fruit tissues contain 50 times as much ichangensin as limonin. They also contain relatively high concentrations of deacetylnomilin (12). 

Nomilin deacetylase As previously discussed. Citrus ichangensis and its hybrids possess another limonoid biosynthetic pathway from nomilin (3) to deacetylnomilin (12) (26, 27, 31). The conversion of nomilin to deacetylnomilin is catalyzed by an enzyme, nomilin deacetylesterase. The existence of nomilin deacetylase in C. ichangensis has been demonstrated by radioactive tracer work... 

The above HPLC methods are used for the analysis of limonin and/or nomilin in citrus juices. Herman et al. (1989) used a reverse phase HPLC method to quantify limonoids in fruits, seeds, leaves, stems and seedlings of Citrus ichangensis. The extraction procedure of Hasegawa et al. (1984) as described in Section 2.1.1 was followed. The dried extracts were dissolved in 50% methanol prior to injection. A reverse phase C-18 column (4.6 X 250 mm) was used. The column was eluted isocratically with water-methanol-acetonitrile (49 41 10) at a flow rate of 1 ml/min. Limonoids were detected by UV absorption at 210 nm. This... 

Hendrickson R, Edwards GJ (1958) Ultraviolet absorption technique to determine the naringin content of grapefruit juice. Proc Fla State Hortic Soc 71 194-198 Herman Z, Hasegawa S, Fong CH, Ou P (1989) Limonoids in Citrus ichangensis. J Agric Food Chem 37 850-851... 

Berhow, M.A., Omura, M., Ohta, H., Ozaki, Y., and Hasegawa, S. 1994. Limonoids in seeds of three citrus hybrids related to citrus ichangensis. Phytochemistry, 36, (4), 923-925. Schwager, J., Mohajeri, M.H., Fowler, A., and Weber, P. 2008. Challenges in discovering bioactives for the food industry. Current Opinion in Biotechnology, 19, (2), 66—72. 

---