Ixora (PROSEA Medicinal plants)

Plant Resources of South-East Asia Introduction

List of species

Ixora L.

Protologue: Sp. pl. 1: 110 (1753); Gen. pl. ed. 5: 48 (1754).

Family: Rubiaceae

Chromosome number: x= 11;I. chinensis,I. coccinea,I. javanica,I. nigricans: 2n= 22

Ixora chinensis Lamk, I. coccinea L., I. javanica (Blume) DC., I. longifolia J.E. Smith, I. nigricans R.Br. ex Wight & Arn.

• Indonesia: soka (general), ki soka (Sundanese), areng-arengan (Javanese)
• Malaysia: pechah priok, jarum-jarum, todong periok (Peninsular)
• Philippines: santan (Tagalog). Burma (Myanmar): ponna, pan
• Cambodia: chann tanea, tè prey
• Thailand: kheme (general)
• Vietnam: dơn, bông trang.

Ixora consists of about 400 species, and is distributed throughout the tropics. The Indo-Malesian region is richest in species. In Malesia about 160 species occur; the highest number of species (about 65) is found in Borneo, most of them endemic.

Several Ixora species are used in traditional medicine, e.g. as an astringent and to treat dysentery and tuberculosis. The use in China and India is widespread. An infusion of the leaves or flowers of several species is administered to treat fever, headache and colic. A decoction of the roots is used as a sedative; the roots are believed to be more potent. The internal application is based on stomachic and antiseptic properties, while external applications are based on astringent and antiseptic properties.

Ixora species are well known as ornamentals (e.g. I. chinensis , I. coccinea , I. javanica ), and are commonly planted in gardens, parks and along roadsides. The fruits of I. philippinensis Merr. are edible. The wood of Ixora is occasionally used, often for implements and comparatively small objects; only a few species reach timber size.

In a modified tumour promotion test, complete inhibition of all kinds of tumours was exhibited by decoctions of flowers of I. coccinea and I. chinensis . The antitumour factor from I. javanica flowers showed broad activity against transplantable solid tumours in mice by inhibiting the growth of tumours and arresting the growth of already formed tumours; it showed lesser activity against ascites tumours. In vitro studies showed 50% cytotoxicity to Dalton's lymphoma and Ehrlich ascites tumour cells at concentrations of 12 μg and 65 μg, respectively, with no activity against normal lymphocytes but preferential activity against lymphocytes derived from leukaemia patients and K 562 suspension cell culture. Topical application of 100 mg/kg body weight of I. javanica flower extract inhibited the growth and delayed the onset of papilloma formation in mice initiated with 7,12-dimethylbenz-α-anthracene (DMBA) and promoted by using croton oil. When administered orally at the same dose the extract significantly inhibited the growth of soft tissue fibrosarcomas induced by subcutaneously injected 20-methylcholanthrene. Oral administration of 200 mg/kg of the extract inhibited the growth of intraperitoneally transplanted sarcoma-180 and Ehrlich ascites carcinoma tumours and also showed an increase in the life span of the treated mice. Toxicity studies showed that the blood urea nitrogen levels were elevated after treatment. Furthermore, tritiated thymidine incorporation studies indicated that the mechanism of action of the factor is at the site of DNA synthesis. The purified fractions contained ferulic acid, pyrocatechuic acid and caffeic acid. The compounds responsible for the inhibitory effects on tumour growth were identified as ferulic acid (4-hydroxy-3-methoxycinnamic acid) and its structural isomer, 3-hydroxy-4-methoxycinnamic acid.

Antimutagenity tests with I. coccinea by the Rec-Assay and the Micronucleus Test revealed that the crude alcoholic extract and the ethyl acetate fraction showed antimutagenic activity. Fractions obtained from the ethyl acetate extract were found to be antimutagenic against a known carcinogen, 4-nitroquinoline, in two Bacillus subtilis strains. After purification the antimutagenic fraction was identified by spectroscopic methods as ursolic acid. The activity of the isolated compound was confirmed by the Rec-Assay.

The saponifiable fraction of the petroleum ether extract of I. coccinea root was found to have anti-inflammatory activity in carrageen-induced paw oedema in albino rats. The ethanol (50%) extract of the aerial parts potentiates barbiturate activity and causes semen coagulation. The same type of extract of aerial parts of I. nigricans showed antiviral and hypothermic activities.

The roots of I. coccinea contain an acrid aromatic oil, tannin, fatty acids, and a white crystalline substance. The root bark contains δ-9,11-octadecadienoic acid, mannitol and myristic acid. The flowers have a yellow colouring matter related to quercitrin, an astringent principle, wax, and a neutral crystalline substance. The roots of I. chinensis also contain an iridoid derivative called ixoside (1,8-dehydroxyforsythide).

Shrubs to small or sometimes medium-sized trees up to 25 m tall; bark surface smooth, lenticellate, fissured or scaly, greyish-brown; twigs terete, often with series of rather close, leafless nodes especially at branching points. Leaves opposite or sometimes in whorls of 3, simple, entire, broadly elliptical to linear, herbaceous to coriaceous, base usually acute or cuneate, apex obtuse to acute, acuminate or caudate, almost always glabrous; petiole usually present, concave or canaliculate; stipules interpetiolate, connate at base, distinctly cuspidate or with a long, stiff, needle-like extension at the tips. Inflorescence a terminal corymb or corymbose panicle, peduncle short with an erect inflorescence or longer with a nodding or pendulous inflorescence, often puberulous or pubescent, usually 45-300-flowered. Flowers often 3 together, bisexual, 4-merous, fragrant or not, protandrous; calyx often divided to the base; corolla with a cylindrical tube, lobes contorted in bud, spreading and flat or reflexed in the open flower, often white but sometimes pink, yellow or red; stamens inserted at corolla throat, with short filaments, anthers dorsifixed, sagittate and reflexed, usually yellow; disk annular; ovary inferior, 2(-3)-locular with 1 ovule per cell, style filiform, slightly exserted from the corolla tube, the exserted part not longer than the corolla lobes, stigma 2-lobed, the lobes linear and recurved. Fruit a globose to 2-lobed drupe, 5-15 mm in diameter, ripening red to black, with 1-2 pyrenes; pyrenes 1-seeded, thin-walled, plano-convex, with a round excavation inside. Seed with thin testa, endosperm entire. Seedling with epigeal germination; cotyledons leafy, green.

Malesian Ixora species are generally evergreen. Flowering is seasonal but cultivars may bloom throughout the year. The flowers are mainly pollinated by moths and butterflies probing for the nectar at the corolla base, but honey-suckers may also visit the flowers, particularly the reddish ones. The seeds are probably dispersed by fruit-eating birds.

As a rule the Malesian Ixora species have a rather local distribution. I. nigricans is an exception, ranging from India to Bali. Many of the species in Java are endemic, as are most of the Bornean species. The New Guinean species are all endemic.

Pavetta closely resembles Ixora , but can be distinguished by its long-exserted style with coherent stigmas, whereas the anthers are conspicuously twisted. The differences between the widely cultivated I. chinensis and I. coccinea are sometimes obscure as a result of selection for rare or extreme forms. Accidental or deliberate hybridization appears to occur.

Ixora species are usually confined to lowland and lower montane forest up to 1700 m altitude. Some species are also found in swampy locations in the vicinity of rivers or occasionally in rice fields (e.g. I. grandifolia ).

Ixora may be propagated by seed, although ornamental species are usually propagated by cuttings. Both seeds and sown fruits of I. lobbii have been found to have about 25% germination in 1-3 months. Treating I. coccinea cuttings of 15 cm long by dipping them in indole butyric acid at 2000 ppm for 10 seconds, gave a rooting success of 87%, the development of a high number of primary roots and a survival of 96%. This was considerably better than the performance of untreated cuttings: only 40% rooting success and 67% survival.

The high incidence of endemism in Ixora may increase the risk of genetic erosion. However, the species with a reported medicinal use have a relatively large area of natural distribution or are widely cultivated.

The reported antitumour and antimutagenic activities of Ixora may justify more research, which might result in future applications in modern medicine. Moreover, several species are attractive ornamentals.

• Bremekamp, C.E.B., 1937. The Malaysian species of the genus Ixora (Rub.). Contributions à l'étude de la flore des Indes Néerlandaises XXXIV. Bulletin du Jardin Botanique de Buitenzorg, Série III, 14: 197-367.
• Burkill, I.H., 1966. A dictionary of the economic products of the Malay Peninsula. Revised edition, vol. 2. Ministry of Agriculture and Co-operatives, Kuala Lumpur, Malaysia. pp. 1280-1283.
• Fosberg, F.R. & Sachet, H.H., 1989. Three cultivated Ixoras (Rubiaceae). Baileya 23(2): 74-85.
• Gupta, V.N. & Kher, M.A., 1989. A note on the effect of root promoting hormones on rooting of Ixora coccinea L. by tip cuttings under intermittent mist. Progressive Horticulture 21(1-2): 138-140.
• Nair, S.C. & Panikkar, K.R., 1990. Antitumour principles from Ixora javanica. Cancer Letters 49(2): 121-126.
• Nair, S.C., Panikkar, B., Akamanchi, K.F. & Panikkar, K.R., 1991. Inhibitory effects of Ixora javanica extract on skin chemical carcinogenesis in mice and its antitumour activity. Cancer Letters 60(3): 253-258.
• Padmaja, V., Sudhakaran Nair, C.R., Velayudha Panicker, P. & Hisham, A., 1993. Anti-inflammatory activity of the saponifiable fraction of the petroleum ether extract of the root of Ixora coccinea Linn. Indian Journal of Pharmaceutical Sciences 55(1): 28-32.
• Panlilio, B., Aguinaldo, A., Yamauchi, T., Abe, F., Lim-Sylianco, C.Y. & Guevara, B, 1992. An antimutagenic constituent from Ixora coccinea Linn. (Rubiaceae). Paper presented at 7th Asian Symposium on Medicinal Plants, Spices, and other Natural products (ASOMPS VII) February 2-7, 1992, Manila, the Philippines.
• Quisumbing, E., 1978. Medicinal plants of the Philippines. Katha publishing Co., Quezon City, the Philippines. pp. 912-913.
• Serrame, E. & Lim-Sylianco, C.Y., 1995. Anti-tumor promoting activity of decoctions and expressed juices from Philippine medicinal plants. Philippine Journal of Science 124(3): 275-281.

M.C. Ysrael & J.L.C.H. van Valkenburg