Limonins

Crowell PL and Gould MN. 1994. Chemoprevention and therapy of cancer by D-limonine. Crit Rev Oncog 5 1-22. 

Sharma M. 2005. Transposon mutagenesis of gene involved in limonin degradation in Pseudomonas putida. M.C. diss., Patiala. 

Mansell RL, McIntosh CA (1991) Citrus spp. in vitro culture and the production of naringin and limonin. In Bajaj YPS (ed) Biotechnology of medicinal and aromatic plants, vol. 3. Springer, New York, NY, pp 193-210... 

Dictamnus albus L. subsp. dasycarpus (Turcz.) Winter D. dasycarpus Turcz. Bai Xian Pi (Fraxinella) (root bark) Dictamnine, skimmianine, saponins, preskinnianine, choline, fragarine, aurapten, bergapten, isomaculosindine, limonin, obakinone, fraxinellone, psoralen, trigonelline.50 60 Antifungal, antipyretic, antiseptic, antitussive, sedative, emmenagogue, tonic. 

Evodia rutaecarpa (Juss.) Berth Wu Zhu Yu (Evodia) (fruit) Alkyl methyl quinolone alkaloids, evodiamine, limonin, evocarpine, rutaecarpine, N-methyl anthranilic acid, evodol, hydroxyevodiamine, N-methylanthranflamide, N,N-dimethyl-5 -methoxytryptamine, dehydroevodiamine.32,33,237 Antiemetic, analgesic, lower blood pressure, antibacterial. 

Poncirus trifoliata Rafin Gou Gi (Trifoliate orange) (fruit) Poncirin, limonin, imperatorin, bergapten, neohesperidin, citrifoliol, myrcene, camphene, gamma-terpinene.33 Treat gastric pain, constipation, and prolapse of the uterus or rectum. 

Flavones contribute to plant tissue color provided that they occur in high concentrations or are complexed with metal ions. Some flavones participate in taste for example, the highly methoxylated aglycones nobiletin, sinensetin and tangeretin are responsible for the bitter taste of citrus peel. On the other hand, some glycosylated flavones (for instance neodiosmin and rhoifolin) reduce the bitterness of some substances (limonin, naringin, caffeine, quinine) [2]. 

XXXV) 1 3 - imi the fall poison pierotoxiain (XXXVI), ae well as coriamyrtin1 73 and related substanoes the citrus bitter principle limonin (XXXVII) and the related substances nomilin and obaou-none 4" and the terpenoid substances clerodin1 7.1 and oedre-kne.im.iMa... 

These techniques are useful for the separation of complex mixtures. Quantitative analyses have been reported on malathion pesticide in vegetable matter, limonin in grapefruit peel, and additives in compound rubber by means of SEC and RPC126>. SEC was performed with unstabilized THF and monitored at 215 nm. Working so near to the UV cut-off (210 nm) of THF was possible through the use of a detector with a flowing reference installed between the pump and the sample valve. Then the eluent passed the column and finally the analytical cell. Since the column back pressure never exceeded 10 MPa, this eluent line caused no problems. 

A number of other processes have become commonplace in the manufacture of fruit juices. For example, if oranges of the varieties Navel or Navellina are processed the juice becomes unpleasantly bitter because of the biochemical development of a glycoside, limonin. This substance can be partially or totally removed by the use of appropriate ion-exchange resins to yield a juice of acceptable taste. 

Apart from the more obvious benefits of fruit juice, such as being a source of potassium, it contains other substances that have or are claimed to have useful pharmacological activity. For example, limonin and other related limonoid substances present in citrus fruit are believed to have a role in inhibiting certain forms of cancer. Sorbitol, which occurs in many fruit juices, has a laxative effect. 

Fruit juices can be deacidified with a weak base anion-exchange resin. Removal of compounds which cause a bitter taste is a more popular application (26,27). It is accomplished with resins that have no ion-exchange fimctionality. In essence, they are similar to the copolymer intermediates used by resin manufacturers in the production of macroporous cation and anion exchangers. These products are called polymeric adsorbents. They are excellent for removal of limonin [1180-71-8] and naringin [1023647-2], the principal compounds responsible for bitterness in orange, lemon, and grapefruit juices. The adsorbents are regenerated with steam or alcohol. Decaffeination of coffee (qv) and tea (qv) is practiced with the same polymeric adsorbents (28). 

Limonoids are a group of chemically related triterpene derivatives found in the Rutaceae and Meliaceae. Limonin, a bitter member of the group, occurs widely in citrus juices. It has commercial significance because bitterness (excessive bitterness in the case of grapefruit) reduces juice quality. Dreyer (1) and Connolly et al. (2) have reviewed the chemistry and biochemistry of limonoids. 

More recently Maier et al. (3) published a comprehensive review of the limonoid constituents of Citrus and the impact of limonin bitterness on juice quality. This paper summarizes the chemical, biochemical and juice quality aspects of limonoids in Citrus (and related genera) and presents relevant advances since previous reviews. 

---