Cullen corylifolium (PROSEA)

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Plant Resources of South-East Asia Introduction

List of species

Cullen corylifolium (L.) Medik.

Protologue: Vorles. Churpfälz. phys.-öcon. Ges. 2: 381 (1787).

Family: Leguminosae

Chromosome number: 2n = 20, 22, 24

Synonym

• Psoralea corylifolia L. (1753).

Vernacular names

• Indian bread root (En)
• Laos: khad
• Vietnam: dậu miê, phá cố chỉ, bổ cốt chi

Origin and geographic distribution

C. corylifolium is found from Java northward through Peninsular Malaysia to Indo-China and southern China (Yunnan, Sechuan), westward to India, Sri Lanka to Oman and Somalia.

Uses

The seeds of C. corylifolium have long been used in Hindu medicine, and are well known in traditional Chinese medicine. In Vietnam, they are considered a tonic to the genital system, and an aphrodisiac and are prescribed in weakness of the spleen and kidneys, pain in the lower back and knees, rheumatism, impotence, polyuris, urinary incontinence in children and threatened abortion; they are also used for the treatment of leprosy. In India, the drug prepared from the seeds is used as stomachic, anthelmintic, diuretic and febrifuge. It is also prescribed in leucoderma, vitiligo, psoriasis and inflammatory diseases of the skin, both for oral administration and local application. The plant is locally used as fodder for cattle.

Production and international trade

C. corylifolium is not cultivated on a commercial scale; it is locally grown for its seed in some parts of India.

Properties

Besides the presence of several flavonoids, chalcones, coumestans, C. corylifolium is reported to contain psoralen and isopsoralen.

Psoralen belongs to the linear (or 6,7-) furanocoumarins, compounds which are known to have phototoxic activity. The isomeric angular (or 7,8- furanocoumarins e.g. isopsoralen), however, appear to be inactive in this aspect. Dermatosis may arise after plants containing linear furanocoumarins come into direct contact with the skin, if this is immediately followed by exposure to UV-A light, e.g. from the sun. The mechanism of photosensitization by psoralen is based on interference with DNA base pairs. Energy provided by UV-A irradiation leads to the formation of additional products between the furanocoumarin and cytosine and thymine bases. This bridge-building inhibits the replication and transcription of DNA and, consequently, the synthesis of RNA and proteins and the occurrence of cell division. This mechanism makes furanocoumarins such as psoralen, 5- and 8-methoxypsoralen (which are often found all together) suitable for the treatment of psoriasis, a disease characterized by an abnormal production of the outermost layer of the skin.

Isopsoralen administered orally to CD-1 mice daily for 6 days had no effect on liver enzymes like cytochrome P-450. In contrast, orally administered 8-methoxypsoralen induced several hepatic drug-metabolizing enzymes and liver cytochrome P-450.

A fraction from C. corylifolium seeds is cytotoxic to murine ascitic tumour cells, transformed human lymphocytes and KB cells in culture. This fraction also significantly increased the lifespan of EAC ascitic tumour-bearing mice. Activity guided fractionation led to the isolation of several active constituents, e.g. the coumestan derivative psoralidin (against SNU-1 and -16 cell lines in vitro) and (+)-bakuchiol (against five kinds of cultured human cancer cell lines, i.e. the A549, SK-OV-3, SK-MEL-2, XF498 and HCT15). Furthermore, an ethanol extract of C. corylifolium caused strong inhibition of DNA polymerase in a whole cell bioassay (SV40 bioassay using Simian virus 40) specific for inhibitors of DNA replication enzymes. Bioassay-directed purification of the active compounds led to the isolation of corylifolin, bakuchiol, neobavaisoflavone and daidzein as DNA polymerase inhibitors.

Other pharmacological effects include promotion of bone calcification and an increase in serum inorganic phosphorus, by non-polar fractions of a C. corylifolium acetone seed extract in experimental rachitic rats fed with a vitamin D-free, low phosphorus diet.

The methanol extract of the seeds of C. corylifolium also inhibited the aggregation of rabbit platelets induced by arachidonic acid, collagen and platelet activating factor (PAF). Bioassay-directed fractionation led to the isolation of 3 flavonoids, i.e. isobavachalcone, neobavaisoflavone and bavachin. Purified isobavachalcone and neobavaisoflavone inhibited platelet aggregation.

An aqueous extract of the seeds inhibits the growth of Escherichia coli, Staphylococcus aureus, while the alcoholic extract inhibits the growth of Bacillus subtilis, Escherichia coli, Pasteurella multicoda, Pseudomonas aeruginosa, Salmonella pullorum, Staphylococcus aureus, Streptococcus fecalis and Streptococcus pyogenes. The petroleum extract of the seeds is active against strains of Staphylococcus aureus, which are highly resistant to antimicrobials like penicillin, streptomycin, chloramphenicol, erythromycin and tetracycline. Furthermore, the essential oil shows antifungal activity against several species of Alternaria, Aspergillus, Cladosporium, Cunninghamella, Fusarium, Helminthosporium , Microsporium, Mucor, Rhizopus, Trichophython and Trichothecium.

Petroleum ether extracts of C. corylifolium at 0.5% give almost complete protection to black gram (Vigna mungo (L.) Hepper) against the bruchid Callosobruchus chinensis infestation for up to 135 days. Furanocoumarins (psoralen, isopsoralen) from the roots are possibly responsible for antifeedant activity. Application of C. corylifolium extract to mulberry leaves once during the 3rd instar larvae phase of Bombyx mori suppresses the incidence of grasserie disease by 60%. This disease is caused by a nuclear polyhedrosis virus and enhances larval and cocoon parameters.

Adulterations and substitutes

Several other Leguminosae, Moraceae, Rutaceae and Umbelliferae are known to contain phototoxic furanocoumarins such as psoralen, 5- and 8-methoxypsoralen, e.g. Ammi species (Ammi majus L.), Pimpinella species, Angelica species, Heracleum species (Heracleum mantegazzianum Somm. & Levier), Fatoua villosa (Thunb. ex Murray) Nakai and Citrus bergamia Risso & Poiteau.

Description

• An erect annual or short-lived perennial herb up to 1.5 m tall, commonly branched from the base, arising from the crown of a taproot; all parts moderately white-strigose and densely brown-glandular.
• Leaves alternate, 1-foliolate; petiole 0.5-3.5 cm long, pulvinate; stipules asymmetrically lanceolate-ovate to deltoid, 3.5-7 mm × 2-3 mm, persistent; leaflet narrowly to broadly ovate, 3-11 cm × 2-7.5 cm, base cuneate to cordate, apex acute, margin variably dentate, glabrescent, glandular punctate on both sides; petiolule 2-3 mm long.
• Inflorescence an axillary, condensed pseudoraceme, consisting of 20-more flowers; bracts lanceolate, 3 mm long, persistent, rachis 1-4 cm long, peduncle 3-7.5 cm long.
• Flowers papilionaceous, calyx urceloate-campanulate, 5-lobed, 3-4 mm long, lower lobe 5.5 mm long, glandular; corolla 5-6 mm long, standard obovate to broadly elliptical, clawed, wings oblong, clawed, keel petals clawed, white to bluish-purple; stamens diadelphous; ovary 1-ovuled.
• Fruit a reniform-ellipsoid pod, 5 mm × 3 mm, indehiscent, with persistent calyx and style, densely black-glandular.
• Seed adhered to the pericarp.

Growth and development

Flowering and fruiting of C. corylifolium occurs throughout the year following sufficient rain. It is capable of binding atmospheric nitrogen with a cowpea-type Rhizobium. However, symbiosis is classified as promiscuous but often ineffective. Roots were found heavily infected with vesicular-arbuscular mycorrhizal endophytes. It absorbs and accumulates nitrogen and potassium most speedily in periods of branching, flowering and fruiting, and phosphate at full flowering and fruiting. Phosphate is accumulated mainly in the seed and potassium in the stem. The nutrient accumulation is positively correlated with that of the dry substances. To produce 100 kg of C. corylifolium, an absorption of 10.6 kg of nitrogen, 3.7 kg of phosphate and 10.2 kg of potassium is required. Soaking seed in triacontanol, ammonium molybdate and gibberellin can promote the growth of C. corylifolium, reduces premature flower and fruit drop, raises the fruit-bearing rate by 7-17%, and fruit-bearing number by 22-28%, thereby increasing the yield per unit area by 32-35%.

Other botanical information

Cullen is a member of the tribe Psoraleae, all 9 genera of which are characterized by uni-ovulate ovaries, indehiscent fruits, and the presence of furanocoumarins. Psoralea sensu Forbes, with about 120 species, has been split into 5 genera. All Asian and Australian species have been reclassified in Cullen. Cullen consists of 32 species, widely dispersed in the Old World from southern Africa north to Spain, throughout the Mediterranean east to Asia Minor and Asia and south into Australia. In Australia, 26 out of 32 species are found, and 24 of them are endemic. In Malesia a total of 4 species occur, the best-known being C. corylifolium. Of the other species C. stipulaceum (Decne.) J.W. Grimes extends its range from Australia to Timor, C. gaudichianum (Decne.) J.W. Grimes occurs in Timor, Bali, Sumbawa, Flores and Alor. C. badocanum (Blanco) Verdcourt is found in the Philippines, Indonesia (Timor), New Guinea and Australia. The roots are traditionally consumed roasted in Australia. The well-known medicinal plant from the Mediterranean and Near-East Psoralea bituminosa L., has been renamed Bituminaria bituminosa (L.) C.H. Stirton.

Ecology

C. corylifolium is relatively common in disturbed habitats, such as escarpments roadsides, banks and cropped land, often weedy.

Propagation and planting

The most effective way of softening the hard seeds of C. corylifolium is by soaking them in concentrated sulphuric acid for 5 minutes, followed by soaking in water for 4 hours and a second dip in sulphuric acid for 20 minutes. This treatment increases germination from 8% to 94%. Mechanical scarification, rubbing between sandpaper for 10 minutes, is also an efficient method, which raises germination from 8% to 79%. Plants can also be propagated by shoot tip and axillary bud culture on Murashige and Skoog medium supplemented with 0.5 mg 6-benzyladenine (BA) and 0.01 mg indole acetic acid (IAA)/litre. Further addition of 0.05 mg giberellic acid (GA3)/litre to this medium improved shoot elongation. Rooting is readily induced in the in vitro-raised shoots by transferring them to MS basal medium supplemented with 2% sucrose. Plantlets can be successfully grown in soil under greenhouse conditions.

Husbandry

Seed of C. corylifolium is sown in March-April in lines, 30 cm apart, at a rate of 7 kg per ha in India. Flowering starts following rain and seeds mature in November. Under proper management, the crop may continue to grow for 5-7 years.

Diseases and pests

C. corylifolium may suffer from stem rot caused by Sclerotinia sclerotiorum, but this can be effectively controlled by the fungi Gliocladium virens and Trichoderma harzianum.

Yield

Remarkably high concentrations (more than 2 g/kg dry weight) of the anticancer metabolite genistein have been found in the leaves of C. corylifolium.

Genetic resources and breeding

C. corylifolium is very poorly represented in genebanks. However, in view of the large natural distribution, and its preference for disturbed habitats, it does not seem to be threatened by genetic erosion.

Prospects

Furanocoumarins induce skin photosensitization followed by skin hyperpigmentation and specific photolesions to the DNA molecule. These activities have led to increasing demand for furanocoumarins, since they are widely used both in cosmetics (sun-tanning products) and dermatology for photochemotherapy of vitiligo and skin diseases characterized by hyperproliferative conditions, such as psoriasis and mycosis fungides. More research is needed to evaluate the potential of C. corylifolium as a local or industrial source of psoralens. Other interesting pharmacological effects include cytotoxic, DNA polymerase inhibiting and bone calcification promotive activities.

Literature

• Bickers, D.R., Mukhtar, H., Mulica, S.J. & Pathak, M.A., 1982. The effect of psoralens on hepatic and cutaneous drug metabolizing enzymes and cytochrome P-450. Journal of Investigative Dermatology 79(3): 201-205.
• Grimes, J.W., 1997. A revision of Cullen (Leguminosae: Papilionoideae). Australian Systematic Botany 10: 565-648.
• Latha, P.G. & Panikkar, K.R., 1998. Antitumour active fraction from Psoralea corylifolia seeds. Fitoterapia 69(5): 451-455.
• Miura, H., Nishida, H. & Iinuma, M., 1996. Effect of crude fractions of Psoralea corylifolia seed extract on bone calcification. Planta Medica 62(2): 150-153.
• Sun, N.J., Woo, S.H., Cassady, J.M. & Snapka, R.M., 1998. DNA polymerase and topoisomerase II inhibitors from Psoralea corylifolia. Journal of Natural Products 61(3): 362-366.
• Yang, Y.M., Hyun, J.W., Sung, M.S., Chung, H.S., Kim, B.K., Paik, W.H., Kang, S.S. & Park, J.G., 1996. The cytotoxicity of psoralidin from Psoralea corylifolia. Planta Medica 62(4): 353-354.

Other selected sources

• [74] Backer, C.A. & Bakhuizen van den Brink Jr, R.C., 1964—1968. Flora of Java. 3 volumes. Noordhoff, Groningen, the Netherlands. Vol. 1 (1964) 647 pp., Vol. 2 (1965) 641 pp., Vol. 3 (1968) 761 pp.
• [215] Council of Scientific and Industrial Research, 1948—1976. The wealth of India: a dictionary of Indian raw materials & industrial products. 11 volumes. Publications and Information Directorate, New Delhi, India.
• [739] Nguyen Van Duong, 1993. Medicinal plants of Vietnam, Cambodia and Laos. Mekong Printing, Santa Ana, California, United States. 528 pp.
• [786] Perry, L.M., 1980. Medicinal plants of East and Southeast Asia. Attributed properties and uses. MIT Press, Cambridge, Massachusetts, United States & London, United Kingdom. 620 pp.
• [850] Ryu, S.Y., Choi, S.U., Lee, C.O. & Zee, O.P., 1992. Antitumor activity of Psoralea corylifolia. Archives of Pharmacal Research (Seoul) 15(4): 356—359.
• [942] Sivaprakasam, N. & Rabindra, R. J., 1996. Integrated disease management methods for grasserie in silkworm Bombyx mori L. Indian Journal of Sericulture 35(2): 12—127.
• [1013] Tsai, W.J., Hsin, W.C. & Chen, C.C., 1996. Antiplatelet flavonoids from seeds of Psoralea corylifolia. Journal of Natural Products 59(7): 671—672.
• [1038] Verdcourt, B., 1979. A manual of New Guinea legumes. Botany Bulletin No 11. Office of Forests, Division of Botany, Lae, Papua New Guinea. 645 pp.

Authors

• L.J.G. van der Maesen