Tribulus (PROSEA)
Introduction |
Tribulus L.
- Protologue: Sp. pl. 1: 386 (1753).
- Family: Zygophyllaceae
- Chromosome number: x= 6;T. cistoides: 2n= 12, (18),T. terrestris: 2n= 12, (22), 24, (32), 36, 48
Major species
Tribulus cistoides L., T. terrestris L.
Vernacular names
- Caltrop, puncture vine (En). Croix de chevalier (Fr).
Origin and geographic distribution
Tribulus consists of about 20-25 closely related species, distributed in tropical and warm regions of the world, especially in the dry regions of Africa (10 species) and Australia.
Uses
T. terrestris has a reputation as a powerful medicine in South and North America, Europe and Africa. It has astringent, abortifacient, emmenagogue, galactagogue, aphrodisiac, diuretic, anthelmintic, tonic and haemostatic properties. The seeds or the fruits are used against abscesses and ulcers, nosebleed, dysentery, sore throat, painful urination, calculous affections and aphthae. In India, a decoction of the leafy stem is applied to scabies and other scaly skin diseases. It is also used as a tonic, diuretic and as an aphrodisiac. In Vietnam and Argentina, the fruits are used externally in ophthalmia, by exposing the eyes to the vapours of a hot infusion, and for ulcers of the mouth, by gargling the infusion. In Pakistan, the fruits are used for painful urination, impotence and haemorrhages. In China, the seeds are used to treat spermatorrhoea, anaemia, coughs, purulent expectorations and haemorrhoids.
In Thailand, the whole plant is considered diuretic, and used in the treatment of dysuria with bladder stones, leucorrhoea, kidney dysfunction and abnormal urination. It is not recommended for people with heart diseases. In China though, the plant is taken for coronary heart diseases, because it is said to dilate the coronary arteries and improve the blood circulation. It is also very popular for treating angina pectoris.
In India, the leaves and tender shoots are eaten by poor people as a pot herb, either alone or mixed with other herbs. They are rich in calcium, but poor in iron. The flour from the seeds is made into a bread which is eaten in times of scarcity. The plant at early post-flowering stage is also used as a fodder for horses, camels and sheep. Dried plants at pre-flowering stage were refused by sheep.
In Mexico, a decoction of the leaves and root of T. cistoides (often used indiscriminately with T. terrestris ) is sweetened and taken as a diuretic and treatment for various kidney complaints. In Venezuela, a decoction of the whole plant is drunk in cases of gonorrhoea, chest congestions and also used as an eyewash and a bath for swollen legs. In El Salvador, the seeds serve as a vermifuge.
The spiny fruits of T. cistoides and T. terrestris cause injury to the feet, skin and stomach of animals, may cause punctures in vehicle tyres and are a nuisance in lawns and playgrounds. They also reduce hay and seed quality.
Production and international trade
Many preparations containing T. terrestris powder are sold on the northern American and European market. The steroidal saponin content acts on testosterone levels in the body. These are sold as a food supplement, claiming to improve reproductive function, libido and ovulation and also performance of athletes, by increasing muscle cell growth and body strength. Prices in 2000 were around US$ 10-20 for 60 capsules containing 500-750 mg of T. terrestris powder, with varying saponin content. Bulgaria and the United States are known to cultivate T. terrestris but no statistics on production and trade are available.
Properties
The whole plant of T. terrestris contains steroidal saponins, which on hydrolysis yield steroidal sapogenins: diosgenin, gitogenin, chlorogenin, ruscogenin, and 25 d-spirosta-3,5-diene. Sapogenins with a high haemolytic index are present in leaves and roots, but absent in stems or seeds. Leaves and fruits also contain kaempferol, kaempferol-3-glucoside, kaempferol-3-rutinoside and the flavonoid tribuloside. The fruits contain a fixed oil (3.5%) consisting mostly of glycerides of unsaturated acids, an essential oil, resin, nitrates and steroidal saponins with aglycones diosgenin, ruscogenin, gitogenin, furostanol, tigogenin, epismilagenin and yamogenin. The fruits also contain N-trans-feruloyltyramine, terrestriamide, N-trans-coumaroyltyramine, terrestrosin A-E, terrestribisamide, 25R-spirost-4-en-3,12-dione, tribulusterine, N-p-coumaroyltyramine, aurantiamide acetate, xanthosine, ferulic acid, vanillin, p-hydroxybenzoic acid andβ-sitosterol. The lignan-amides tribulusamide A and B were also isolated from the fruits and significantly prevented cell death of cultured mouse hepatocytes induced by D-galactosamine tumour necrosis factorα. Several indole alkaloids e.g. harmaline, harmalol, harman, nor-harman and harmine were isolated from the entire plants.
T. terrestris is known to cause photosensitivity in small livestock, and is responsible for the disease "geeldikkop" (South Africa) or "bighead" (Australia, United States) among sheep. It is also found to occur among sheep in East Africa, Colombia and Argentina. This condition is characterized by oedema of the head, fever and jaundice, finally leading to death. The plant causes liver damage followed by photosensitivity of the skin cells from phylloerythrine, a derivative of chlorophyll. Hepatogenous photosensitization occurs mainly when the animals are in short supply of pasture. The disease was found to occur only in white (unpigmented) sheep, not in black sheep. In South Africa, "geeldikkop" was induced in sheep by oral administration of crude steroidal saponins from T. terrestris . The chemical composition of biliary crystals that are formed during the disease was shown to be a 6:1 mixture of the calcium salts of theβ-D-glucuronides of the steroidal sapogenins epismilagenin and episarsasapogenin.
The ether extract, but not the aqueous extract, of the fruits caused diuresis and increased creatinine renal clearance in anaesthetized dogs. The diuretic effect is likely due to the abundance of nitrates. Another study reported prolonged diuretic activity of a 10% infusion of whole plants. An extract from the leaves showed hypotensive activity in anaesthetized dogs, which was probably due toγ-aminobutyric acid.
The effect of an aqueous extract of the whole plant on the metabolism of oxalate was tested in male rats fed sodium glycolate, resulting in hyperoxaluria and increased activities of oxalate synthesizing enzymes in the liver. The extract showed a significant decrease in urinary oxalate excretion, and a significant increase in urinary glyoxylate excretion. An aqueous or ethanolic extract of the fresh leaves and stems showed antispasmodic activity on guinea-pig ileum. In rabbits, it showed a positive effect on spontaneous pendulum movement and tone of the duodenum, but negative effect on rate, amplitude and rhythm of the isolated heart.
A preliminary study of the effects of lyophilized saponin mixture from the aerial parts on several smooth muscle preparations in vitro showed a significant decrease of peristaltic movements of isolated sheep ureter and rabbit jejunum preparations in a dose-dependent manner. No effect was observed on isolated rabbit aorta and its contractile response to KCl or noradrenaline. The saponin mixture might be of some use on some smooth muscle spasms or colic pains.
In China, the fruits of T. terrestris are traditionally used in the treatment of vitiligo. An aqueous extract of the fruits though showed significant stimulation of melanocyte proliferation of a mouse pigmented cell line.
The effects of a commercial herbal preparation of T. terrestris on body composition and exercise performance in resistance-trained males were tested. Body weight, body composition, maximal strength, dietary intake and mood states were determined before and after an 8-week training and supplementation period (3.2 mg/kg body weight daily) but failed to show any significant differences with a placebo group.
The pro-erectile pharmacological effects of an extract of T. terrestris , containing protodioscin (PTN), on the corpus cavernosum of white rabbits were investigated at different doses, 2.5, 5 and 10 mg/kg respectively. PTN was found to have no effect on the isolated corpus cavernosal strips; however, the relaxant responses to acetylcholine, nitroglycerin and electrical field stimulation increased by more than 10%, 24% and 10% respectively compared to their control values, and the lack of such effect on the contractile response to noradrenaline and histamine would indicate that PTN does have pro-erectile activity. The enhanced relaxant effect observed is probably due to increase in the release of nitric oxide from the endothelium and nitrergic nerve endings, which may account for its claims as an aphrodisiac. In another test, protodioscin was tested as a medicine to treat erectile dysfunction and was found to improve sexual desire and enhance erection via the conversion of protodioscine to de-hydro-epi-androsterone (DHEA). In Russia, China and Bulgaria, the medicinal preparation "Tribestan", based on the total glycosides of T. terrestris , is used for treating impotence and female infertility. The preparation was found to stimulate blood testosterone and testicular maturation of ram lambs when given orally at 250 mg daily for 40 days. It is also claimed to enhance testosterone levels by increasing luteinizing hormone, follicle stimulating hormone levels and estradiol. Methanol extracts of whole plants, given at 560 mg/kg to nursing rats, increased milk yield significantly compared with control groups. In a second trial, an extract in 10% methanol, given at 450 mg/kg, increased milk yield of nursing rats compared with controls but a hexane extract had no effect. Another extract, given at 200 mg/kg for 6 days, was able to produce an oestrogenic response in ovariectomized, anoestrous rats as indicated by vaginal cornification (90%) and glycogen deposition (100%).
The root extract of T. terrestris significantly and strikingly inhibits the growth of Pennisetum glaucum R.Br. seedlings, in field experiments. In another test, at 200 ppm, an extract of T. terrestris plants was found to have 100% molluscicidal activity for Bulinus truncatus . An ethyl ether and ethanol extract were found to be significantly active against Staphylococcus aureus and Candida albicans .
The desert locust Schistocerca gregaria was found to prefer feeding on T. terrestris plants from populations in Mauritania that are rich in quercetin glycosides. An extract of the plant significantly increased the growth and development of silkworms ( Bombyx mori ), silk gland weight and silk thread length.
T. cistoides has been found to be poisonous to animals in Australia, Colombia and Venezuela. A methanol extract from the roots contains the cardioactive saponin-3, which also occurs in the leaves, and also tribulosin (a pregnane-type glycoside) and 8 cholestane-type glycosides. Three steroid sapogenins and 2 N-acyltyramines were isolated from a petrol extract of the leaves and stems, whereas the methanol extract gave 9 steroid sapogenins, among them the cardioactive cistocardin, saponin-3, saponin-4 and saponin-7. The extract also contained a furostanol diglycoside, 5'-(hydroxysulphonyloxy)-jasmonic acid, D-(+)-pinitol and sucrose. An aqueous seed extract was sprayed on 15-day-old rice seedlings, before inoculating them with viruliferous Nephotettix virescens , causing rice tungro virus. The seedlings showed a 45% infection reduction. The extract was also very effective against the larvae of the nematode Meloidogyne incognita .
Adulterations and substitutes
Dioscorea L., Brachiaria decumbens Stapf and Trigonella foenum-graecum L. contain similar steroidal saponins to those found in T. terrestris . Also, pastures of Brachiaria decumbens in Java and Brazil were found to cause the same photosensitization disease in sheep as T. terrestris does in South Africa.
Description
Annual or perennial herbs, branches prostrate to ascending, with silky white hairs; taproot long. Leaves opposite, paripinnate, anisophyllous; stipules present. Flowers actinomorphic, 5-merous, bisexual, solitary on pseudo-axillary peduncles, next to shorter leaves. Sepals 5, free, imbricate, persistent or caducous; petals 5, free, patent, imbricate, delicate, early caducous, white or yellow; disk annular, lobed or not; stamens 10, in 2 whorls, subequal or unequal, the inner whorl at base with an abaxial appendage and an adaxial scale (gland), scales free or laterally connate, anthers dorsifixed; ovary superior, sessile, 5-12-lobed, 5-12-celled, densely hairy, style short, thick, stigmas 5(-12), decurrent, ovules 3 or more per cell. Fruit composed of 5 mericarps (cocci), angled or 5-12-winged; cocci partly abortive, spinous or tuberculate, indehiscent with 3-5 superposed seeds, separated by septa; seeds obliquely pendulous. Seed ovoid, flattened, 2.5 m long, tip pointed, whitish, embryo exalbuminous. Seedling with hypogeal germination; cotyledons lanceolate; first leaves paripinnate.
Growth and development
T. terrestris is able to reach water at depths of 1-2.5 m with its taproot, and also has an extensive lateral root system at the end of the growing season. It can become perennial when enough water is available throughout the year. After germination, the seedling grows very rapidly, producing its first flowers after 3-5 weeks, and its first fruits after 5-6 weeks. Fruits mature in 2 weeks, splitting into segments soon thereafter. Although they are normally prostrate plants, T. terrestris and T. cistoides can grow almost upright in dense crop stands with shading.
T. cistoides begins to flower and set seeds 3-4 weeks after germination and continues to flower throughout the year when enough water is available. It can form large pure patches near the coast. In Java it flowers during the rainy season, from March-July. Flowers open in the morning and close after sunset, lasting for 2 days.
Tribulus is pollinated mainly by honeybees, foraging for nectar and pollen, and by solitary bees, foraging for pollen.
The spiny fruit segments (cocci) of Tribulus have probably been transported over the world in the wool of sheep. They are often first reported near agricultural communities, railroad yards or coastal towns, in hay, straw or manure. The spines on the fruits are arranged at different angles, thus picked up easily by hoofs, shoes or tyres and transported over some distance.
Other botanical information
Zygophyllaceae s.l. are a heterogeneous family of trees, shrubs and herbs, and the systematic status of some groups within the family has been disputed. Balanites and the group consisting of Tribulus , Kallstroemia and Kelleronia probably deserve to be distinguished at least at subfamily level. Tribulus is sometimes even put into a family of its own, Tribulaceae , but this view is not shared here. Tribulus is one of the few pantropical genera that thrives in (semi-)arid conditions. Several species are highly polymorphic, and many intermediate forms exist, sometimes distinguished at variety level. Especially the T. terrestris complex is in need of a world revision. The common name, caltrop, refers to the resemblance of the fruits to the medieval spiked weapon called tribolos.
Ecology
T. cistoides and T. terrestris are well adapted to dry, loose, sandy soils, such as coastal or inland dunes or field margins, but also grow in heavier, moist and fertile soils, such as playgrounds or waste land.
Propagation and planting
T. cistoides and T. terrestris both reproduce by seed. Without competition, one T. terrestris plant can produce thousands of seeds. In the field, germination starts 5-7 days after the first rains of the season and continues throughout the season. Germination is very erratic under laboratory conditions, ranging from 0-22%, and more research is needed to clarify the pattern. Some dormancy does exist in seeds buried in the soil for 3-4 years, but in general they do not show dormancy. The woody mesocarp will protect the seed for some time from the influence of water.
In vitro production of active compounds
Steroidal sapogenins such as diosgenin and hecogenin, used in the synthesis of medicinal steroids, are known to occur in their glycosylated forms in T. terrestris but not in economic quantities. Callus cultures were induced from leaf and stem portions on Murashige and Skoog medium containing 2,4-D and kinetin. Lignin, saponins, flavonoids spirosta-3,5-dienes, and free and glycosylated steroidal sapogenins were detected in the cultures. Free sapogenins were not present in the explant sources.
Diseases and pests
Tribulus is an alternate primary host for Cuscuta hyalina Roth in India. Biological control of T. cistoides and T. terrestris has been found to be very successful in India, Hawaii, Australia and the United States using a fruit-infesting weevil ( Microlarinus lareynii ) and a stem- and a crown-mining weevil ( M. lypriformis ). Other potential biological control agents against T. terrestris in southern Africa are a seed-sucking bug ( Deroplax sp.), a noctuid defoliator ( Prodotis stolida ) and a downy mildew ( Peronospora tribulina ). In India and the Mediterranean region, leaf-feeding moths ( Ephysteris subdimintella and Tegostoma comparalis ) and a leaf mite ( Eriophyes tribuli ) have also been found to be promising for biological control. Other Tribulus can serve as a host for most of these agents.
Harvesting
The fruits of T. terrestris are harvested in Vietnam from August to October.
Yield
In T. terrestris from India, the maximum diosgenin content occurred in the seeds, being 6.2 mg/g dry weight, compared with 3.1% and 3.8% in the roots and leafy stems, respectively.
Preliminary observations suggest that T. terrestris grown on different soils does not consistently produce the active compound protodioscin.
Handling after harvest
Leafy stems, roots or fruits of T. terrestris are used fresh or dried for storage.
Genetic resources and breeding
Both Tribulus species treated here are weeds with a wide distribution, and are not likely to be threatened with genetic erosion. The steroidal saponin content apparently differs greatly in different populations, and breeding for medicinal purposes should concentrate on this aspect. A breeding programme is known to exist in Bulgaria.
Prospects
Although Tribulus does not have a history of medicinal use in Malesia, it shows some potential because of the steroidal saponins present, especially in the fruits. The pharmacological effects shown in in vitro and in vivo tests are promising and merit further research. T. terrestris is not mentioned as a weed in South-East Asia, but it is most likely to occur here, especially in drier regions.
Literature
- Adaikan, P.G., Gauthaman, K., Prasad, R.N. & Ng, S.C., 2000. Proerectile pharmacological effects of Tribulus terrestris extract on the rabbit corpus cavernosum. Annals of the Academy of Medicine, Singapore 29(1): 22-26.
- Antonio, J., Uelmen, J., Rodriguez, R. & Earnest, C., 2000. The effects of Tribulus terrestris on body composition and exercise performance in resistance-trained males. International Journal of Sport Nutrition and Exercise Metabolism 10(2): 208-215.
- Cruz, C., Driemeier, D., Pires, V.S., Colodel, E.M., Taketa, A.T.C. & Schenkel, E.P., 2000. Isolation of steroidal sapogenins implicated in experimentally induced cholangiopathy of sheep grazing Brachiaria decumbens in Brazil. Veterinary and Human Toxicology 42(3): 142-145.
- Holm, L.G., Plucknett, D.L., Pancho, J.V. & Herberger, J.P., 1977. The world's worst weeds. Distribution and biology. East-West Center, the University Press of Hawaii, Honolulu, United States. pp. 465-473.
- Li, J.X., Shi, Q., Xiong, Q.B., Prasain, J.K., Tezuka, Y., Hareyama, T., Wang, Z.T., Tanaka, K., Namba, T. & Kadota, S., 1998. Tribulusamide A and B, new hepatoprotective lignanamides from the fruits of Tribulus terrestris: indications of cytoprotective activity in murine hepatocyte culture. Planta Medica 64(7): 628-631.
- van Steenis, C.G.G.J., 1949. Zygophyllaceae. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana. Series 1, Vol. 4. Noordhoff-Kolff, Djakarta, Indonesia. p. 64.
Authors
Wongsatit Chuakul, Noppamas Soonthornchareonnon & Orawan Ruangsomboon