396

12(1): Medicinal and poisonous plants 1

Pueraria montana (Lour.) Merr.

Trans. Amer. Philos. Soc. n.s. 24(2): 210 (1935).

LEGUMINOSAE

2n = 22, 24

Var. lobata: Pueraria thunbergiana (Sieb. & Zucc.) Benth. (1867), Pueraria lobata (Willd.) Ohwi (1947).

Kudzu, Japanese arrowroot (En). Koudzou (Fr). Indonesia: bitok, tobi (Madurese), tebi (Kangean). Philippines: baai (Igorot), tahaunon (Manubo). Laos: chüa tau kung, khauz pièd (northern). Thailand: tamyakhrua, phakpeetpe. Vietnam: s[aws]n d[aa]y, c[as]t c[aw]n.

Pueraria consists of 16 species of Asian origin. Pueraria montana has a large area of distribution, ranging from eastern India, Burma (Myanmar), Indo-China, China, Korea and Japan, through Thailand and the Malesian region, to the Pacific islands and northern Australia. It was successfully introduced into South America and the southern United States, but did not become established in Africa. The commonest variety in the Malesian region is var. lobata (Willd.) v.d. Maesen & Almeida; it has been reported in Peninsular Malaysia, the Philippines, the Lesser Sunda Islands, the Moluccas and Papua New Guinea.

In Chinese medicine the tuber of kudzu is known as 'Radix Puerariae', and it is one of the most important crude drugs. Tea from the tubers is used in China and Indo-China against colds, fever, influenza, diarrhoea, dysentery and hang-overs. The flower buds are used as a diaphoretic and febrifuge. In China, its clinical use for various diseases in internal medicine, surgery, pediatrics and dermatology has been reported. The most important efficacy is for arrhythmia. The starch from the tuber is used medicinally in Japan in soup or tea to restore intestinal and digestive disorders. The extract is effective in lessening alcohol intoxication.
Kudzu tuber is esteemed for its fine starch, used especially in China, Japan and Papua New Guinea for sauces, soups, jelled salads, noodles, porridges, jelly puddings, confectionary and beverages. Elsewhere in South-East Asia the tubers are used in times of famine. The stem fibres are used for binding (ropes), weaving (clothes, fishing lines, baskets) and for paper production. The young leaves, shoots and flowers may be consumed as a vegetable. Kudzu is excellent for fodder and silage, if mixed with grass. It is effective for erosion control, provided its growth is controlled well. Its aggressive growth may lead to entire forests being covered and trees dying, as has been experienced in the United States. Kudzu is a good shade plant and also popular as an ornamental climber with fragrant flowers.

Japan produces over 300 t/year of kudzu tubers.

Pueraria montana var. lobata has a high flavonoid content. In a methanol extract of the tuber 7 isoflavones were identified and quantified: puerarin (160 mg/g extract), daidzin (22 mg/g), genistin (3.7 mg/g), daidzein (2.6 mg/g), daidzein-4',7-diglucoside (1.2 mg/g), genistein (0.2 mg/g) and formononetin (0.2 mg/g).
In tests with rats the plant showed antipyretic and anti-myocardial ischemia effects. The isoflavonoid glycosides have antioxidant, anti- hepatotoxic activity and also hypotensive effect, with excellent clinical results in the treatment of hypertension. Chinese pharmacologists have reported that the isoflavonoids stimulate cerebral and coronary blood circulation. Daidzein has been found to show a papaverine-like musculotropic action. The spasmolytic activity of daidzein has been proved using excised small intestine of mice. Puerarin acts as a 'BETA'-adrenoreceptor antagonist in isolated arteries and veins. The extract showed antidipsotropic activity (suppression of ethanol intake) in golden hamsters, for which daidzin is the major active principle. This activity of the extract is greater than that of pure daidzin, and it seems that additional constituents in the methanol extract assist uptake of daidzin. The bioavailability of daidzin in the crude extract is about 10 times greater than that of the pure compound. In tests with rats, daidzin was efficacious in lowering blood alcohol levels and shortened sleeping time induced by alcohol ingestion. Daidzein and puerarin have also been effective in suppressing voluntary alcohol consumption by rats, but induced increased water intake. The compounds did not affect the activities of liver alcohol dehydrogenase and aldehyde dehydrogenase, from which it appears that the reversal of alcohol preference produced by these compounds may be mediated via the central nervous system. Antifebrile activity of the extract has been demonstrated in Vietnam. An aqueous extract of flowers and tubers showed wormicidal effect on Clonorchis sinensis.
Acute toxicity of each fraction of the tuber is very weak. High-performance liquid chromatography methods have been established for the determination of puerarin for the quality control of Chinese medicinal preparations.
Per 100 g, cooked leaves contain approximately water 89 g, protein 0.4 g, fat 0.1 g, carbohydrates 9.7 g, fibre 7.7 g and ash 0.8 g. Kudzu is nearly as nutritious as alfalfa (Medicago sativa L.) and is palatable to all types of livestock. The green forage contains 14.5-20% crude protein, 2-3.5% fat, 27-36% crude fibre and 7-8.5% ash on dry weight basis.

A perennial, woody climber, with stems up to 30 m long and up to 10 cm in diameter, initially grey to brown pubescent, later glabrescent, and with very large oblong tubers up to 2 m long and up to 45 cm in diameter. Leaves alternate, pinnately 3-foliolate; petiole 8-13(-21) cm long, rachis 1.5-7 cm long, both grey to golden-brown hairy, stipules peltate, up to 1.5(-2.5) cm long; leaflets ovate to orbicular, 8-26 cm x 5-22 cm, lateral leaflets oblique and often somewhat smaller than terminal leaflet, entire to 3-lobed, thinly appressed pubescent, petiolules 4-10 mm, stipels linear to lanceolate, up to 2(-3) cm long. Inflorescence a usually unbranched elongated pseudoraceme up to 35 cm long, with 3 flowers per node, bracts up to 10 mm long, early caducous, bracteoles up to 5 mm long, fairly persistent. Flowers bisexual, short-pedicelled; calyx campanulate with 5 unequal teeth, tube 3-5 mm long, teeth 4-9 mm long; corolla papilionaceous, petals up to 2.5 cm long, purplish to blue or pink, often with a yellow or green spot on vexillum; stamens 10, monadelphous or with one free stamen; ovary superior, elongated, 1-celled. Fruit a flattened oblong pod, 4-13 cm x 0.5-1.5 cm, straight to falcate, with golden-brown hairs, 5-15-seeded. Seeds flattened ovoid, 4-5 mm x 4 mm x 2 mm, red-brown with black mosaic. Seedling with epigeal germination; first 2 leaves simple and opposite.

Kudzu may grow 35 m or more in a single season. Bees have been reported to act as pollinators, and kudzu is said to be cross-pollinated. Outside its native area of distribution seed set is often poor.

Three varieties are distinguished within Pueraria montana, of which var. lobata (Willd.) v.d. Maesen & Almeida is particularly common in the Malesian region. This variety is often considered as a distinct species: Pueraria lobata (Willd.) Ohwi. The other two varieties, var. montana and var. chinensis (Ohwi) v.d. Maesen & Almeida (synonym: Pueraria lobata (Willd.) Ohwi var. thomsonii (Benth.) v.d. Maesen), are mainly restricted to mainland Asia, although both have been reported from the Philippines. The main distinguishing characteristics are flower size, leaflet form and fruit size.
Extracts from Pueraria tuberosa (Roxb. ex Willd.) DC., which does not occur in South-East Asia, showed anti-implantation activity in female rats. Its tubers are used in local medicine in Nepal, Pakistan and India, e.g. against renal complaints, as a febrifuge, as a cataplasm to cure swellings of joints and as a galactagogue; they are also used as a fish poison. In Thailand, the tubers of Pueraria candollei Grah. ex. Benth. var. mirifica (Airy Shaw & Suvat.) Niyomdham (synonym: Pueraria mirifica Airy Shaw & Suvat.) are used as a tonic and aphrodisiac, to treat mammary gland expansion and for their oestrogenic effect. Many flavonoids (daidzein, daidzin, genistein, genistin, kwakhurin, mirificin, miroestrol) as well as coumarins (columestrol, mirificoumestan and mirificoumestan hydrate) have been isolated. Pharmacological studies have shown oestrogenic, anti-implantation, abortifacient, antifertility, antispermatogenic and hypercalcaemic effects. Studies on the effects on birds found accelerated growth but inhibited egg-laying. The fertility in both male and female mice was effectively controlled by an aqueous extract of leaves, whereas the extract could effectively interrupt pregnancy.

Pueraria montana occurs in thickets, forests, roadsides, pastures and hedges, and is common in the lowlands but is found up to 2000 m altitude. It grows on a wide range of soils, but does not grow well on poor sandy soils and poorly drained heavy clays. It is intolerant of waterlogging, and grows best on well-drained fertile loams. Kudzu is drought resistant because of its deep roots.

Kudzu is propagated by seed, except in regions outside its native area where propagation is mainly by planting young stem cuttings almost horizontally. The very hard seed coat should be scarified with acid or by mechanical means before planting; a germination rate of 70% is considered excellent. Seeds are planted in a nursery in rows 1 m apart and 0.5-1.5 cm deep, and should be inoculated with the cowpea type of rhizobia. Seedlings are transplanted into the field after about 4 months when they have developed 4-6 leaves. Seed may be sown directly into the field, in rows 2 m apart; 1 kg of seed per ha is needed.

The biosynthesis of isoflavonoids in elicitor-treated cell suspension cultures of kudzu has been studied at the enzyme level. The main secondary metabolites produced by cell cultures are daidzin and puerarin. Addition of yeast extract to the cell culture stimulates the accumulation of isoflavones and daidzein-dimers.

At planting, kudzu is fertilized. Plantings should be kept free of weeds during the first year.

Fungal diseases in kudzu include leaf-spot (caused by Alternaria spp.), anthracnose (caused by Colletotrichum sp.), stem rot (caused by Fusarium sp.), and damping-off (caused by Pellicularia solani), whereas bacteria (Pseudomonas spp.) may cause blight. Nematodes (mainly Meloidogyne spp.) have been reported to attack the roots. Velvetbean caterpillars (Anticarsia gemmatilis) eat the leaves.

Tubers of kudzu can be harvested about 1 year after planting the cuttings. If left longer in the soil they can become very large. For fodder production, the first harvest is possible in the second year, but full production is reached from the third year onwards.

Tubers of kudzu may weigh up to 180 kg when old. A forage yield of 5 t/ha can be expected from good stands on fertile soil.

A good method of preparing a decoction from kudzu is reported from China: the tuber is cut into slices of 4-7 mm, water is added at 12-15 times the weight of the tuber, and the mixture is decocted for 30 minutes.

Thanks to its large area of distribution, kudzu is not at risk of genetic erosion. Few cultivars have been developed, and breeding activities have mainly focused on its value as a forage. In Puerto Rico, crosses have been made between Pueraria montana and Pueraria phaseoloides (Roxb.) Benth. in order to combine the more vigorous growth of the former with the better adaptation to tropical conditions of the latter.

In China, the wide application of Pueraria montana var. lobata has been recommended because the flavonoid fraction increases the blood flow to the brain and heart, decreases oxygen consumption by the myocardium and exerts spasmolytic activity. Moreover, clinical trials have shown the applicability of isoflavonoids in the treatment of hypertension, angina pectoris, myocardial infarction and migraines. Furthermore, kudzu is a valuable forage, yields useful fibre from the stems and starch from the roots, and can be used for erosion control and soil improvement. Its occasional behaviour as a weed which is difficult to eradicate acts as a brake on its wide application for planting as a multipurpose crop.

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Groen, L.E., Siemonsma, J.S. & Jansen, P.C.M., 1996. Pueraria lobata (Willd.) Ohwi. In: Flach, M. & Rumawas, F. (Editors): Plant Resources of South-East Asia No 9: Plants yielding non-seed carbohydrates. Backhuys Publishers, Leiden, the Netherlands. pp. 178-179.
Harada, M. & Ueno, K., 1975. Pharmacological studies on Pueraria root 1. Fractional extraction of Pueraria root and identification of its pharmacological effects. Chemical and Pharmaceutical Bulletin 23(8): 1798-1805.
Keung, W.M., Lazo, O., Kunze, L. & Vallee, B.L., 1996. Potentiation of the bioavailability of daidzin by an extract of Radix puerariae. Proceedings of the National Academy of Sciences of the United States of America 93(9): 4284-4288.
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van der Maesen, L.J.G., 1985. Revision of the genus Pueraria DC. with some notes on Teyleria Backer (Leguminosae). Wageningen Agricultural University Papers 85-1: 1-132.
van der Maesen, L.J.G., 1994. Pueraria, the kudzu and its relatives, an update of the taxonomy. In: Sørensen, M. (Editor): Proceedings of the First International Symposium on Tuberous Legumes, Guadeloupe, F.W.I., 21-24 April 1992. Jordbrugsforlaget, Kobenhavn. pp. 55-86.

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Praptiwi

Praptiwi, 1999. Pueraria montana (Lour.) Merr.. In: de Padua, L.S., Bunyapraphatsara, N. and Lemmens, R.H.M.J. (Editors): Plant Resources of South-East Asia No 12(1): Medicinal and poisonous plants 1. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea