Boerhavia (PROSEA)

Plant Resources of South-East Asia
Introduction

List of species

Boerhavia L.

Protologue: Sp. pl. 1: 3 (1753), Gen. pl. ed. 5: 4 (1754).

Family: Nyctaginaceae

Chromosome number: x= 13, 26; B. chinensis: 2n= 40, 42; B. diffusa: 2n= 26

Major species

Boerhavia diffusa L.

Origin and geographic distribution

Boerhavia is found in all warm or tropical countries, possibly originating from the Old World tropics. Three Boerhavia species occur widely in Malesia: B. diffusa and B. erecta are pantropical, occurring between 35°N and 40°S, while B. chinensis occurs only in the Old World tropics.

Uses

In Malaysia, B. diffusa is used medicinally on a small scale, mainly as a diuretic. In India, the whole herb is a very popular medicine, called "Punarnava" and the root has entered the Indian Pharmacopoeia. B. diffusa is applied as a stomachic, cardiotonic, hepatoprotective, laxative, diuretic, anthelmintic, febrifuge, expectorant and, in higher doses, as an emetic and purgative. As a diuretic it is useful in strangury, jaundice, enlarged spleen, gonorrhoea and other internal inflammations. In moderate doses it is successful in asthma, in large doses it produces vomiting. A decoction of the roots is also applied to corneal ulcers and to treat night blindness. Sometimes B. chinensis or B. erecta is substituted for B. diffusa. In Vietnam, the roots of a variety of B. diffusa with narrow leaves and axillary inflorescences (the former B. repens L.) are used to treat cough, liver complaints or hydrops. The uses of B. diffusa in West Africa and Central America are largely the same as in India. In Nigeria, an infusion of the whole plant is considered a mild laxative and febrifuge for children, also given for convulsions and to regulate menses. In Ivory Coast, the powdered leaves are made into a paste and are applied to the chest to relieve asthma in infants. Generally in West Africa, the roots are boiled and used on ulcers, abscesses and to assist in the extraction of Guinea worm. The roots and leaves are considered expectorant, and in large doses emetic. In East Africa, the plant is used against scabies, abscesses and boils. In Haiti and Uruguay, the leaves and roots are regarded as stimulant, tonic, sudorific, vermifugal and antispasmodic.

B. erecta is not used medicinally in South-East Asia, but it is thought to have similar properties as B. diffusa. In Tanzania, B. erecta plants that are reduced to ash, are mixed with oil and rubbed on for rheumatism and for scabies. The dried root is powdered and added to local beer as an aphrodisiac. Sap from the leaves is squeezed into the eye for conjunctivitis. In Mexico, a decoction of the whole plant is employed for bathing sores, and internally as an antispasmodic in epilepsy.

In Madura (Indonesia), the crushed leaves of B. chinensis are used for poulticing itch or scabies. Sometimes they are pounded with fragrant flowers and rice flour.

Boerhavia leaves are widely eaten by sheep and cattle, and in some parts of India and Africa, by humans as a vegetable. The roots of B. diffusa are traditionally eaten in times of scarcity in Australia and Fiji, and in Nigeria they are added to cakes. The seeds are added to cereals in Senegal and Mali. Fresh leaves of B. erecta are sold in the market in Mali, for the preparation of sauces. In Benin, B. erecta was found to be very palatable for breeding rabbits. B. diffusa and B. erecta are also considered notorious weeds in numerous annual crops.

Production and international trade

Boerhavia is mainly used at a local scale, except in India where especially the roots enter in popular medicinal formulations.

Properties

Several compounds were isolated from the roots of Indian B. diffusa, e.g. punarnavine, triacontanol hentriacontane, β-sitosterol, ursolic acid and 5,7-dihydroxy-6,8-dimethylflavone. The roots also contain the rotenoid boeravinones A1, B1, C2, D-F, as well as dihydro-isofurenoxanthin, boerhavine (a dihydro-isofuranoxanthone) and an antifibrinolytic compound, punarnavoside (a phenolic glycoside). Indian B. diffusa also contains boerhavic acid, punarnavine, tannins and phlobaphenes. Plants from Nigeria, however, have been shown to contain only traces of alkaloids and tannins, and no anthraquinones or saponins at all. These differences are probably regional as plants from several West African countries, including Nigeria, do show pharmacological activity. In India, B. diffusa is included in the Pharmacopoeia as a diuretic, and this action has since been confirmed. The diuretic activity is probably due to depression of tubular excretion, inhibiting kidney succinic dehydrogenase and stimulating D-amino oxidase. An aqueous extract of the dry or fresh plant produces diuresis in cases of oedema and ascites, especially in early liver and kidney conditions. The high amounts of potassium salts present in the whole plants increase the action of punarnavine. In India, an intravenous injection of punarnavine in cats produced a distinct and persistent rise of blood pressure and a marked diuresis. In a clinical trial for treatment of nephrotic syndrome, the extract was found to improve diuresis, to relieve oedema, and to cause an overall improvement of the patient, including a decrease in albuminuria, rise in serum protein and fall in serum cholesterol level.

The alcoholic extract of Indian B. diffusa showed anti-inflammatory effects against carrageenan-induced paw oedema and increased urinary output in rats. The action can be compared with that of corticosteroids. The anti-nociceptive effect of a decoction of the leaves (DE) or the fresh juice (JE) was also tested in acetic acid writhing and hot-plate models of hyperalgesia in mice. Both DE and JE were found to produce a significant inhibition of the induced abdominal writhing in the acetic acid model, but in the hot-plate test, DE raised the pain threshold only during the first 30 minutes of observation while JE raised it for much longer. The extracts were also investigated for their anti-oedematogenic effect on carrageenan-induced oedema in mice, but neither DE nor JE inhibited this oedema.

The alkaloidal fraction of the roots of B. diffusa was studied for its effect on cellular and humoral function in mice. Oral administration of the fraction, at 25-100 mg/kg, significantly inhibited sheep red blood cells-induced delayed hypersensitivity reactions in mice, in a dose-related way. However, the inhibition was observed only during post-immunization drug treatment, while no effect during pre-immunization drug treatment was observed. The alkaloidal fraction also failed to show any blastogenic responsiveness of murine splenocytes to concanvalin A and lipopolysaccharide. Similarly, it did not display any mitogenic activity. Thus, the present study has shown the in vivo immunomodulatory activity of B. diffusa alkaloid fraction without an in vitro effect.

A methanol extract from the whole plant of B. diffusa was found to inhibit bone calcium resorption induced by parathyroid hormone in tissue cultures of neonatal mouse calvaria. The activity was found to be induced by 2 flavonoid glycosides, eupalitin-3-O-β-D-galactose and eupalitin-3-O-β-D-galactose-(1->2)-β-D-glucose.

The chloroform and methanol extracts of the whole plant of B. diffusa also exhibited hepatoprotective activity against carbontetrachloride intoxication in rats. The rotenoid, steroid and flavone exhibited a lowering of the serum enzyme GOT. The effect of season, thickness of roots and type of application (either aqueous or powder) were studied in thioacetamide intoxicated rats for their hepatoprotective action. The results showed that an aqueous extract (2 ml/kg) of roots of a diameter of 1-3 cm, collected in May (summer), exhibited marked protection of a majority of serum parameters, i.e. GOT, GPT, ACP and ALP, but not GLDH and bilirubin. Also, the studies proved that the aqueous form of drug (2 ml/kg) administration has more hepatoprotective activity than the powder form. This is probably due to the better absorption of the liquid form through the intestinal tract.

The water-soluble fraction of a methanol extract of the whole plant B. diffusa exhibited various pharmacological effects including anticonvulsant, hypotensive, myocardial depressant, skeleton and smooth muscle stimulant activity in rats. No teratogenic effects were detected in pregnant albino rats, after daily administration of the ethanol extract at a dose of 250 mg/kg, orally.

The root extract of B. diffusa showed noticeable reduction of the duration of menstrual flow, menstrual iron loss and activity of uterine tissue plasminogen activator in monkeys fited with an intra-uterine contraceptive device. Two lignans, liriodendrin and syringaresinol mono-β-D-glucoside, have been isolated from the methanol extract of the roots of B. diffusa. The first compound exhibited a significant calcium channel antagonistic effect in the frog heart single cell assay, using the whole-cell voltage clamp method.

The root extract of B. diffusa, which was found to inhibit the infection of several plant viruses (tobacco mosaic virus, cucumber mosaic virus, cucumber green mottle virus and sun hemp rosette virus), was tested by the agar diffusion hole method for its action on RNA-containing bacterial viruses, and was found to cause only partial and not uniform plaque formation of the phages. B. diffusa seedlings, germinated in cattle dung, showed large inhibition zones for the fungi Bacillus subtilis, Escherichia coli, Pseudomonas cichorii and Salmonella typhimurium. Extracts of all parts of B. diffusa significantly reduced germination and growth of the notorious weed Echinochloa colona (L.) Link seedlings in petri dishes.

The antibacterial activity of the aqueous residue of the aerial parts of B. erecta was tested by the filter paper disk diffusion method and was found to be highly active against Alkaligens viscolactis and Bacillus cereus. B. diffusa, however, failed to show activity against any of the tested bacteria.

An extract of the aerial parts of B. diffusa significantly increased the growth and development of silkworms (Bombyx mori), silk gland weight and silk thread length.

Adulterations and substitutes

In India, Trianthema portulacastrum L. (Aizoaceae) is used in the same way as B. diffusa, as a diuretic.

Description

Annual to perennial herbs, erect, ascending or creeping, puberulous to glabrous, with sessile or stalked, club-shaped glands or hairs; stems often tinged red and swollen at the nodes.
Leaves simple, opposite, subequal in each pair, pale green beneath, epidermis with irregular sculptures or reddish glands; petiole present; stipules absent.
Inflorescence a 2-10-flowered (sub)umbel, in axil of smallest leaf of a pair, or by reduction of leaves forming a large thyrsoid inflorescence, appearing terminal; bracts and bracteoles small, fimbriate, caducous.
Flowers bisexual, actinomorphic, pedicel jointed with the flower, short; perianth tubular-campanulate, distinct constriction halfway, lower part obconical, 5-10-ribbed, upper part 5-lobed, plicate in bud, white or pink; stamens 1-4, exserted; ovary subsessile, smooth, style as long as the perianth or longer, stigma capitate.
Fruit an anthocarp, closed at apex, 5-10-ribbed, glabrous or glandulously hairy, swelling and slimy in water.
Seed with longitudinally folded embryo, cotyledons with recurved margin, surrounding the mealy endosperm.
Seedling with epigeal germination; hypocotyl well developed, puberulous; cotyledons rounded, purplish beneath, midvein distinct; first leaves alternate, puberulous, purplish beneath.

Growth and development

Boerhavia flowers and fruits throughout the year, when sufficient water is available.

Other botanical information

Two major taxonomic problems are apparent in Boerhavia, one at the supra-specific level and the other being the large polymorphism within the species. The first problem is that in Boerhavia s.l. 4 groups of species can be recognized as separate genera: Anulocaulis, from Mexico and southern North America, with 10-ribbed fruits and a sticky band around the internodes, Commicarpus, from the Old World and partly pantropical, with faintly 10-ribbed fruits and relatively large, zygomorphic and tubular flowers, Cyphomeris, from Mexico, with asymmetric, glabrous fruits, and large, tubular flowers, and finally Boerhavia s.s., pantropical and in warm countries, with 3-5-ribbed, glabrous to glandular fruits and small, regular flowers. Here, the concept of Boerhavia s.l. is followed, and the segregate genera are regarded as subgenera.

Boerhavia s.s. (orthographic variation " Boerhaavia ") consists of 3-20 species, depending on the opinion of different authors. Especially B. diffusa is very variable, and some taxa, like B. repens and B. coccinea Miller, are often distinguished as separate species. This opinion is not shared here, as several differentiating characters vary with soil type, temperature and rainfall, and intermediate plants occur frequently.

Ecology

Boerhavia is heliophilous, occurring on beaches and ruderal localities, preferring a slightly seasonal climate, indifferent to soil, from sea-level up to 1000 m altitude. They are often weeds in cultivated land. B. erecta prefers drier localities than B. chinensis or B. diffusa.

Propagation and planting

Boerhavia is propagated by seed. The subepidermal slime coat of the anthocarp of Boerhavia shows a distinct sticky swelling when ripe, with which it clings to animals and birds.

In vitro production of active compounds

In India, B. diffusa is propagated in vitro, using segments of the upper leaves. Roots were induced by culturing the segments on Murashige and Skoog medium, supplemented with sucrose and indole acetic acid (IAA). Roots formed with 0.5μM IAA contained 15% punarnavine on dry weight basis, while roots formed with higher concentrations of IAA contained less of the compound. In the presence of 2,4-D, leaf segments produced callus with regenerated roots, containing traces of punarnavine.

Diseases and pests

In India, several host-specific diseases have been identified on Boerhavia, i.e. Cercospora diffusa causing chlorotic leaf spots, and Colletotrichum boerhaavia causing brown necrotic spots. In India, B. diffusa is recorded as a host for the virus causing aubergine mosaic disease, and in Costa Rica as a host of zucchini yellow mosaic potyvirus. In several countries, Boerhavia is an alternative host for insect pests in crops. In Cameroon, B. diffusa is an alternative host for the cotton aphid (Aphis gossipii), in India, for the groundnut leaf miner (Aproaerema modicella), and in Nigeria, caterpillars of Aegocera rectilinea and Hippotion celerio were found feeding almost solely on B. diffusa, and much less on food crops.

Harvesting

All plant parts of Boerhavia are collected throughout the year for traditional medicinal use.

Handling after harvest

The harvested parts of Boerhavia are often used fresh, except for the roots which are dried in the sun for later use.

Genetic resources and breeding

All Boerhavia species treated here have a large area of distribution, often as weeds, and are not at risk of genetic erosion. There seems to be a large geographical variation in the composition of pharmacological compounds of B. diffusa, and more research is needed in order to evaluate the most promising populations. There are no known breeding programmes of Boerhavia.

Prospects

Various extracts and purified compounds from B. diffusa show a range of interesting pharmacological effects (in vitro and in vivo), e.g. in the field of diuresis and fibrinolysis. No data, however, are available for humans, and therefore this merits further research in order to fully evaluate the potential for future medicine.

Literature

Fosberg, F.R., 1978. Studies in the genus Boerhavia L. (Nyctaginaceae), parts 1-5. Smithsonian Contributions to Botany 39: 1-20.
Hiruma-Lima, C.A., Gracioso, J.S., Bighetti, E.J.B., Germonsén Robineou, L. & Souza Brito, A.R.M., 2000. The juice of fresh leaves of Boerhaavia diffusa L. (Nyctaginaceae) markedly reduces pain in mice. Journal of Ethnopharmacology 71(1-2): 267-274.
Mungantiwar, A.A., Nair, A.M., Shinde, U.A., Dikshit, V.J., Saraf, M.N., Thakur, V.S. & Sainis, K.B., 1999. Studies on the immunomodulatory effects of Boerhavia diffusa alkaloidal fraction. Journal of Ethnopharmacology 65(2): 125-131.
Quisumbing, E., 1978. Medicinal plants of the Philippines. Katha Publishing Co., Quezon City, the Philippines. pp. 273-275.
Rawat, A.K., Mehrotra, S., Tripathi, S.C. & Shome, U., 1997. Hepatoprotective activity of Boerhaavia diffusa L. roots - a popular Indian ethnomedicine. Journal of Ethnopharmacology 56(1): 61-66.
Stemmerik, J.F., 1964. Boerhavia. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana. Series 1, Vol. 6. Noordhoff-Kolff, Djakarta, Indonesia. pp. 452-455.

Selection of species

Authors

Slamet Sutanti Budi Rahayu