Limonin activity

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. 

Limonin D-ring lactonase was shown to be markedly heat resistant, retaining about 30% of its activity after 5 min at 100 C (54). 

Recently, a nonspecific enzyme capable of degrading the precursor was extracted from Navel orange albedo (63). Nicol and Chandler (63) used a proximate assay for the degrading enzyme that is, the substrate was not identified except as a limonin precursor. The crude extracts from albedo contained degradation activity that was concentrated by 40 to 60% saturation with (NH J SO. Instability of the enzyme prevented further purification. 

Pectinesterase and limonin D-ring lactonase are the only enzymes known to catalyze reactions that adversely affect the quality of citrus juices. Bruemmer et al. (64) listed other enzymes that have been detected in citrus juices and described some of the reactions that can occur in the juices. None of the reactions appear to noticeably affect the quality of commercial juices. Freshly extracted citrus juices contain esterase (EC 3.1.1.1) (65, 66) and phosphatase (EC 3.1.32) (66, 67) activities. Native substrates in orange juice for peroxidase... 

A. Hasegawa, S. Metabolism of limonoids Limonin D-ring lactone hydrolase activity in Pseudomonas. J. Agri. Food Chem., 1976, 2A, 2A-26. 

Several limonoids are known to be bitter principles of citrus (Rutaceae). A typical example is limonin. Although fresh juice does not elicit a bitter taste, sometimes it becomes bitter after heating or storage. This is explained by the formation of bitter-tasting limonin by deglycosylation and further cyclization from limonin glucoside, which is present in citrus fruit tissue and seeds and does not exhibit bitterness.146 Recently, it was reported that limonin had antitumor activity.147 Besides limonin, nomilin and obakunone, which are considered to be... 

Limonoids are C2(, nortriterpenoids deriving from a C30 triterpene precursor. The best known limonoids are the Azadirachta indica (neem tree) antifeedant azadirachtin (C50L C40 C6 -C60(epoxide methylene cross-link) furan) and the Citrus species (Rutaceae) bitter antifeedant limonin (G50L G40 G6 G6 C50L(epoxide)-furan). Limonin gives a delayed bitter taste to Citrus fruit. The limonoids are typically bitter compounds with insect antifeedant activity... 

Other possible enzymes. Limonol (9) is a nonbitter limonoid (21). This compound is a minor limonoid and the pathway from limonin to limonol has not been investigated. This enzyme gene may be useful as specific target enzyme gene, but we assume that the activity is very low and it may not be practical to isolate the enzyme from citrus tissues. Deoxylimonin (8) is also a nonbitter limonoid present in Citrus. (20). The conversion of limonin to deoxylimonin requires a multienzyme system. Therefore, it is not practical to utilize this pathway for genetic engineering manipulation. 

We proceeded with the bioassay-directed chemical study of this plant. From the active fractions we isolated bisabolene- and silphinene-type sesquiterpenes (23 and 24). These compounds are strong CPB antifeedants in both choice and no-choice assays, the adult insects being the most sensitive to their action (table 6) [32], Their antifeedant potencies were similar (23) or stronger than that of limonin (24), a CPB antifeedant triterpene [33],... 

Mechanism-based inhibition of the drug-metabolizing isoenzyme CYP3A4 was observed in human liver microsomes treated with the compounds rutaecarpine or limonin, with activity reported as preincubation time dependent (Iwata et al. 2005). 

Limonoids (Tetranortriterpenoids) Quassinoids (Decanortriterpenoids) Pentanortriterpenoids Chemosystematic Studies Biological Activity Antifeedant Activity Medicinal and Antitumor Properties Limonin in Orange Juice References... 

Citrus limonoids are furanoid natural products found in citrus fruits. The most abundant limonoids, limonin and nomdin, have been determined to induce increased activity of GST and inhibit chemically induced carcinogenesis (6,7). These findings with furan containing natural products led to the investigation of mono and disubstituted furan and the corresponding sulfur containing thiophene compounds that are found in complex mixtures of beef aroma. 

Limonoid aglycones have been shown to possess certain biological activities such as the inhibition of cancerous tumour growth in laboratory animals (Lam et al. 1989 a,b Miller et al. 1989) and antifeedant activities against insects (Alford and Bentley 1986 Liu et al. 1990). Recently, the glucoside of limonin, limonin 17-P-d-glucopyranoside, was found to possess anticancer activities as well (Miller et al. 1992). 

Limonoids also have significant antiviral activity. Limonin and nomilin showed inhibitory effects on HIV-1 replication in peripheral blood mononuclear cells and monocytes/macrophages, which was not cytotoxic at the active concentrations (BattineUi et al. 2003). The antiviral activity was not much influenced by structural differences by limonin and nomilin in this study (BattineUi et al. 2003). 

Root contains 0.19-0.39% alkaloids, mainly quinoline type (dictamnine, skimmianine, preskimmianine, isodictamnine, dasycarpa-mine, y-fagarine (8-methoxydictamnine), iso-maculosindine, trigonelline, choline, etc.) lactones (dictamnolactone, obaculactone or limonin, rutaevin, fraxinellone, etc.) sterols (sitosterol and campesterol) saponins and volatile oil. Fraxinellone has antifertility (anti-implantation) activities. ... 

---