Phyllanthus (PROSEA)

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Plant Resources of South-East Asia
Introduction
List of species


Phyllanthus L.


Protologue: Sp. pl. 2: 981 (1753); Gen. pl. ed. 5: 422 (1754).
Family: Euphorbiaceae
Chromosome number: x= 6, 7, 8, 9, 13, 15, most commonly 13; P. acidus: 2n= 26, P. amarus: 2n= 26, 52, P. emblica: 2n= 98, 104, P. maderaspatensis: 2n= 26, 52, P. pulcher: 2n= 78, P. reticulatus: 2n= 26, P. simplex: 2n= 26, P. urinaria: 2n= 52

Major species

  • Phyllanthus acidus (L.) Skeels,
  • P. amarus Schum.,
  • P. emblica L.,
  • P. reticulatus Poiret.

Vernacular names

  • Phyllanthus, seaside laurel (En).
  • Phyllanthe, bois à enivrer, bois de gaulettes (Fr)
  • Vietnam: phèn den, me rừng.

Origin and geographic distribution

Phyllanthus comprises over 700 species and has a pantropical distribution. It is primarily an Asiatic genus, with only about 100 species being native to Africa and some 200 to the New World. Most of the New World species are found in the West Indian region. Southern Brazil appears to be another important centre of speciation. The most important centres of diversity in the Old World are located in India, Indo-China, the Philippines and New Guinea. Within Malesia about 100 species occur.

Uses

The medicinal applications of Phyllanthus have a long history. Several Phyllanthus species have been used in India for about 2000 years in the Ayurveda, Unani and Siddha systems of medicine, especially for the treatment of jaundice. Although the species may vary locally, Phyllanthus is used in virtually the whole of South-East Asia, the Pacific, East, West and Central Africa, the Caribbean and South America. Generally Phyllanthus has aphrodisiac, diuretic and purgative properties, and is used in the treatment of chest complaints, conjunctivitis, cough, diabetes, diarrhoea, oedema, fevers, hepatitis, nephritis, ophthalmic diseases, smallpox and venereal diseases. Some of the medicinal Phyllanthus species are also used for dye and tanning purposes (e.g. P. emblica, P. reticulatus), as edible fruits (P. acidus, P. emblica), and as ornamentals (P. pulcher). The wood of Phyllanthus (P. acidus, P. emblica, P. reticulatus) can be used for utensils and other small objects, and as firewood.

Crushed young leaves of P. gomphocarpus Hook.f. are used in Indonesia to heal wounds. The roots of P. elegans Wallich are used in Indo-China as a febrifuge; the leaves are given to children with a coated tongue.

Production and international trade

In India, P. amarus, P. debilis and P. fraternus Webster are generally collected from natural stands, often on well-drained, cultivated ground in the rainy season. P. amarus is sometimes also cultivated in small plots and sold on local markets. Fruits of P. emblica are gathered from wild and garden trees and used for local consumption or sold on the market. In India, preserves made from these fruits are manufactured and marketed on a large scale.

Properties

The latex of many members of the Euphorbiaceae is known for its toxicity; it causes inflammations of the skin and mucous membranes, conjunctivitis and sometimes even blindness. The latex of Phyllanthus can also cause allergic reactions. Several Phyllanthus species are poisonous to livestock or fish and can be allelopathic to desirable forage plants. Various groups of medicinally interesting compounds are present in Phyllanthus, including triterpenoids, flavonoids, tannins, alkaloids and phenolic acids. Triterpenoids have been isolated from P. acidus (phyllanthol, β-amyrin), P. discoides Muell. Arg. (betulinic acid), P. emblica (lupeol, lupenone), P. reticulatus (friedelin, β-sitosterol, betulinic acid, glochidonol, friedelan-3-β-ol, 21α-hydroxyfriedelan-3-one, 21α-hydroxyfriedel-4(23)-en-3-one) and P. urinaria (β-amyrin, β-sitosterol, triacontanol). Flavonoids have been found in P. amarus (quercetin-3-O-glucoside, rutin), P. emblica (quercetin, kaempferol, kaempferol-3-O-glucoside (= astragalin)) and P. urinaria (quercetin, kaempferol, rutin). Tannins have been isolated from P. amarus (mainly geraniin, amariin and gallocatechin) and P. emblica (e.g. phyllembin, gallotannin as 1,2,3-trigalloylglucose and the ellagitannins terchebin, corilagin, chebulagic acid and chebulinic acid). Alkaloids, mainly of the quinolizidine type, have been reported for P. amarus (phyllantine, securinine, norsecurinine, isobubbialine, epibubbialine) and P. discoides (allosecurine, phyllantidine, phyllantine). The quinolizidine alkaloid phyllantine (= methoxy-securinine) must not be confused with phyllanthin and hypophyllanthin, which are lignans isolated from e.g. P. amarus and P. urinaria. Furthermore, a range of phenolic acids has been isolated from P. acidus, P. emblica, P. maderaspatensis, P. reticulatus and P. simplex.

P. amarus, P. debilis and P. urinaria have all been found to inhibit DNA polymerase of the hepatitis B virus and other hepatitis-DNA-viruses, such as the woodchuck hepatitis virus (WHV). Lesser known species of the same subgenus Phyllanthus also showed this effect, but species from other subgenera generally show much weaker inhibitory activity. However, intraspecific differences make it difficult to compare the activity of the different species. In some other studies, P. urinaria extracts showed inhibitive effects on duck hepatitis B virus (DHBV) polymerase, whereas P. amarus and P. maderaspatensis extracts were found to lack antiviral activity against DHBV.

P. amarus possesses in vitro and possibly in vivo activity against hepatitis B virus (HBV) and related viruses, together with in vitro activity against the enzyme reverse-transcriptase of retroviruses and possibly in vivo activity against retroviruses. The efficacy of P. amarus preparations in treating hepatitis B carriers is unclear: both success and failure have been reported.

P. amarus has also shown antibacterial and antifungal activity. Whole plant extracts of P. amarus reduce digestive tract motility, delay gastric emptying in rats, and cause relaxation of isolated rat fundus and ileum. This confirms the use of P. amarus in the treatment of diarrhoea and other gastro-intestinal disorders in Nigeria. Whole plant extracts of P. amarus also have diuretic, hypotensive and hypoglycaemic effects in humans. An alcohol extract of P. amarus has been found to induce declining fertility in male mice.

P. amarus contains the lignans phyllanthin and hypophyllanthin, which have shown endothelin antagonistic effects. P. debilis and P. urinaria also contain phyllanthin. Furthermore, phyllanthin and hypophyllanthin have been reported to have protective activity in rat hepatocytes against cytotoxicity induced by carbon tetrachloride and galactosamine, and it has been suggested that phyllanthin is responsible for antigenotoxic effects reported for P. amarus extracts. But phyllanthin has also been reported to be toxic to the nervous system and liver.

A range of hydrolysable tannins isolated from P. amarus has shown inhibitory activity on signal-regulated protein kinases. Aqueous extracts of P. debilis leaves have shown immunomodulatory activity, whereas leaf decoctions have a high potassium content, producing diuretic effects.

The triterpenoid triacontanol isolated from P. urinaria has hepatoprotective properties, e.g. against galactosamine-induced cytotoxicity in rat hepatocytes. This may, at least partly, confirm the hepatoprotective action shown by alcohol extracts of P. urinaria in rats. Furthermore, hydroalcoholic extracts of P. urinaria have shown analgesic effects against formalin-induced and capsaicin-induced pain in mice (antinociceptive activity), and methanol extracts have demonstrated hypoglycaemic activity in diabetic rats. P. urinaria plant extracts exhibited some antibiotic activity against Staphylococcus, Escherichia coli, Salmonella typhi, Vibrio cholerae and Shigella dysenteriae bacteria.

The fruit of P. acidus is very acidic, and, similar to lemon or grapefruit, contains 40 mg/100 g ascorbic acid (vitamin C). The root-bark of P. acidus contains saponins, gallic acid and tannins.

P. emblica fruits are also highly acidic and contain much vitamin C, with reported contents ranging from 470-1810 mg/100 g. The fruits also contain trigalloylglucose, ellagic acid, corilagin, terchebin, phyllemblin, phyllemblic acid and emblicol. They have strong antibacterial, antifungal and antioxidant properties. Aqueous extracts of P. emblica fruit have been found to antagonize the toxic effects of Cs+, Zn2+and metanil yellow similarly to the equivalent amount of vitamin C, but to be more effective against the effects of ethyl-parathion, Pb2+, Al3+and Ni2+than the equivalent amount of vitamin C alone. These results imply that vitamin C is an important active compound of P. emblica fruits, but that they contain other active compounds as well. Gallic acid and vitamin C both have antioxidant, antibacterial and chelating properties, whereas tannins protect vitamin C from oxidation. The antioxidant activity of P. emblica fruits may also be due to the presence of hydrolysable tannins itself, such as emblicanin A and B, punigluconin and pedunculagin.

Phyllemblin has been reported to potentiate the action of adrenaline, to have a mild depressant action on the central nervous system and to have spasmolytic properties. The administration of fruit extracts to mice reduced the cytotoxic effects of the carcinogen 3,4-benzo(a)pyrene and aqueous fruit extracts provided protection against chromosome damage in Allium sativum L. root tips induced by X-radiation: these effects were attributed to the antioxidation system of vitamin C, gallic acid, reducing sugars and tannins. Powdered P. emblica fruits have been found to enhance natural killer cell activity and antibody-dependent cellular toxicity in mice with Dalton's lymphoma ascites tumour. The fruit juice reduced cholesterol levels in humans and in rabbits fed cholesterol.

Further research has shown that methanol extracts of the fruits have a potent inhibitory activity on Human Immunodefiency Virus (HIV) reverse transcriptase, which may be exploited in the prophylaxis and intervention of AIDS. The most active compound isolated from the methanol extracts was putranjivain A, whereas 1,6-di-O-galloyl-β-D-glucose and digallic acid showed weak inhibitory activity. An alcoholic extract of P. emblica fruits, and quercetin isolated from the extract have shown in vivo hepatoprotective activity in rats and mice. Seeds of P. emblica contain about 16% oil, with linoleic acid (44%), oleic acid (28.4%), linolenic acid (8.8%), stearic acid (2.2%), palmitic acid (3.0%) and myristic acid (1.0%).

Leaves of P. emblica contain ellagic acid, kaempferol, kaempferol-3-glycoside and amlaic acid, stems and leaves lupeol, β-sitosterol and ellagic acid, and the bark lupeol and (+)-leucodelphinidin. Various P. emblica leaf extracts have shown inhibitory activity on human polymorphonuclear leukocytes and platelets, which at least partly confirms the anti-inflammatory and antipyretic properties of P. emblica leaves. A large part of the medicinal uses of P. emblica is related to the astringent action of tannins. Though short-term effects may be beneficial, the frequent systemic use of tannins might be dangerous, because of their antinutrient effects.

Finally, extracts of P. reticulatus, especially aqueous extracts of the leaves, have shown in vitro activity against Plasmodium falciparum.

Description

  • Monoecious or dioecious herbs, shrubs or trees of various habit; branching either unspecialized (the phyllotaxy spiral or distichous) or phyllanthoid, i.e. the spiralled leaves on the main axes reduced to cataphylls which subtend a deciduous branchlet with distichous leaves, the latter resembling a compound leaf; indumentum present or absent, simple or rarely dendritic.
  • Leaves alternate, simple, entire, shortly petiolate; stipules present, those of cataphylls larger than those of foliage leaves.
  • Inflorescence axillary, composed of a solitary flower or of a vestigial, bisexual or unisexual cyme, these cymes occasionally aggregated into thyrses.
  • Flowers unisexual, small, apetalous; calyx 4-6-lobed, the lobes imbricate in bud; disk nearly always present. Male flowers with 2-6(-15) stamens, filaments free or connate, anthers free or connate (and forming a "synandrium"), extrorse; pistillode absent. Female flowers usually without staminodes; ovary superior, sessile or stipitate, 3(-12)-locular with 2 ovules in each cell, styles 3 or rarely more, free or connate at base, bifid, multifid, or dilated into an entire or lacerate stigma.
  • Fruit usually a dehiscent capsule, less commonly baccate or drupaceous.
  • Seeds usually triquetrous, smooth or variously ornamented, testa usually thinly crustaceous; endosperm present.
  • Seedling with epigeal germination; cotyledons emergent, leafy, persistent; hypocotyl elongated, often first curved in a loop above the soil; all leaves alternate, sometimes the first few scale-like, in species showing phyllanthoid branching a few normal leaves are generally produced, followed by cataphylls.

Growth and development

Phyllanthus seedlings are of the Macaranga seedling type and develop according to Cook's architectural model, which is determined by continuous growth of a monopodial trunk with phyllomorphic branches. Two types of shoots are produced: indeterminate and determinate. The indeterminate shoots provide annual extension growth, but do not flower and do not abscise. The determinate shoots are often short, bear flowers, and abscise.

In Java, all medicinal Phyllanthus species flower throughout the year, except for P. emblica, which flowers in August. In India, the fruits of P. emblica remain dormant throughout the summer and begin to develop as the monsoon starts.

The seeds of the often explosively dehiscing fruits are ejected and thus dispersed over some distance. Under experimental conditions in Florida P. amarus reached maximum height at 5-7 months after sowing, and senescence began after 7 months. P. acidus trees start producing a substantial crop after 4 years. P. emblica seedlings start bearing after about 8 years, whereas budded trees take about 6 years.

Other botanical information

Phyllanthus belongs to the subfamily Phyllanthoideae and is related to Breynia, Glochidion, Phyllanthodendron and Sauropus which all show phyllanthoid branching. The genera Cicca and Emblica are incorporated in Phyllanthus, although occasionally still treated as being distinct. Phyllanthus has been subdivided into 10 subgenera which are sometimes further divided into a number of sections.

The species P. simplex and P. virgatus P. Forst. are sometimes regarded as a single species, P. virgatus sensu lato, but the mainland populations (P. simplex) appear separable from those in the Pacific (P. virgatus sensu stricto) although there are records of intermediate specimens. Another taxonomic problem concerns P. niruri L. Asiatic specimens formerly assigned to this species actually belong to either P. amarus, P. debilis or P. fraternus Webster, whereas true P. niruri is restricted to the West Indies. Much of the research performed with " P. niruri " in Asia, mainly in India, thus needs botanical correction.

Ecology

P. amarus (often reported as P. niruri) is a troublesome weed in pulses, soya bean, groundnut, cereals, sugar cane, cassava, taro, sesame, sunflower, and cotton. Less important weeds are P. debilis, P. maderaspatensis, P. simplex and P. urinaria, outside South-East Asia also P. fraternus. The species belonging to the subgenera Phyllanthus (e.g. P. amarus, P. debilis, P. emblica, P.urinaria) and Isocladus (e.g. P. maderaspatensis) show a marked preference for calcareous sites in humid tropical areas. In China, warm, well-drained sandy soils and fertilization with N and K are recommended for cultivated P. urinaria. P. urinaria is more drought-sensitive than P. amarus and P. debilis and is generally found in wetter sites. P. amarus grown in greenhouses at a temperature of 15°C showed much less inhibitory activity on the DNA polymerase of woodchuck hepatitis virus (WHV) than when grown at 25°C. P. emblica is a short-day plant, requiring photoperiods of 12-13.5 hours for flowering. It can be grown in both light and heavy soils, but it prefers well-drained, fertile loamy soils. Seeds of the herbaceous P. debilis, P. simplex and P. urinaria are dispersed by water and animals.

Propagation and planting

Seed of P. amarus and P. urinaria requires light to germinate. P. urinaria seed showed adequate germination at temperatures of 25-35°C, but germination was poor at 20°C or 40°C. Germination of P. urinaria seed is poor under moisture stress conditions too (osmotic potential higher than 300 kPa). A 1000-seed weight of 150 mg has been reported for P. amarus seed harvested in Puerto Rico. There is some speculation that seed production in P. amarus may be parthenocarpic. P. acidus is generally grown from seed, but vegetative propagation such as budding, greenwood cuttings or air layering can also be used, whereas P. emblica may also be propagated through seed and vegetative methods (budding, grafting, cutting, root sprouting). Inarching is also possible, but gives only limited success. P. emblica has been successfully propagated in vitro. In India, P. emblica is often grown at spacings of 9-12 m × 9-12 m, P. acidus in Indonesia at 8 m × 8 m.

In vitro production of active compounds

Callus can be induced from stem or phyllanthoid branch pieces of P. amarus and P. urinaria, but callus extracts showed less activity against viral DNA polymerase and reverse transcriptase than extracts from field-grown plants. Phyllemblin present in extracts of in vitro P. emblica tissue cultures showed antimicrobial activity against bacteria (Escherichia coli, Staphylococcus aureus, Salmonella typhosa) and a fungus (Candida albicans).

Husbandry

Most material used for medicinal purposes is collected from the wild. Though P. amarus is also cultivated in India, there is no information on any specific cultivation measures. Soil fertility and soil moisture experiments in the United States affected morphology and yield of P. debilis and P. urinaria, with plants being shorter, more branched and with a higher dry weight under favourable conditions. Differences in soil fertility and soil moisture generally did not affect these species' in vitro inhibitory activity on WHV viral DNA polymerase. In P. amarus, maximum dry weight is obtained in wet neutral soils, but differences in soil moisture, pH and Ca content did not affect the inhibitory activity of plant extracts. These findings imply that plant yields can be maximized through cultivation measures, without affecting the antiviral activity of plant material.

Where P. urinaria is not desired, it may be controlled by mulching. Young plantations of P. emblica need regular weeding. Established P. emblica trees do not need frequent irrigation, which makes them well suited for drier regions. However, the crop benefits from 2-3 irrigations at full bloom stage and fruit set. Irrigation is not beneficial during fruit dormancy. P. emblica does not need regular pruning, but pruning in the early years promotes the development of a proper shape and a strong frame.

Diseases and pests

In India, P. simplex is infected by mildew (Erysiphe cichoracearum), which appears as small, circular, whitish powdery spots on leaves, petioles and stems.

Caterpillars of Parallelia absentimacula and P. joviana feed on Phyllanthus acidus in Indonesia. The main pest of P. emblica in India is the bark-eating caterpillar Indarbela sp., which tunnels into the trunk and branches. P. urinaria weed in Indian rice fields is infested with the rice root-knot nematode (Meloidogyne graminicola).

Yield

Since most Phyllanthus products are collected from the wild, yield data are scarce. Under experimental conditions in Florida, 6-7 months old P. amarus reached an average dry weight of about 40 g/plant when harvested in July or August. Annual fruit yields of P. emblica vary considerably, depending on cultivar, plant age and management: from 15 kg per tree for wild trees to 25-200 kg per tree for some cultivars.

Handling after harvest

Sun-drying of P. emblica fruits leads to loss of vitamin C, but this is not the case when fruits are vacuum-dried. Once dried, the vitamin C is very stable, even when stored for prolonged periods; this has been attributed to tannins and polyphenols retarding oxidation. Vitamin-rich syrups and concentrates have been prepared from P. emblica fruits in India.

Genetic resources and breeding

There is rich genetic diversity in cultivated and wild relatives of P. emblica in India, but genetic erosion is severe because of deforestation and the use of only a few popular cultivars. Germplasm survey, collection and evaluation work has been done and accessions are maintained at Narendra Dava University of Agriculture and Technology in Faizabad (India). Other accessions are reported to be kept in Havana (Cuba), Uttar Pradesh (India), Udaipur (India), Bangkok (Thailand) and Miami (United States). No breeding has been done on other Phyllanthus, except for P. emblica.

Prospects

Phyllanthus seems under-exploited. A considerable number of its species have been used against jaundice for a long time. More research is needed to ascertain its activity against the hepatitis virus and other viruses and to obtain the necessary information on possible side-effects. Phyllanthus has potential beneficial therapeutic action in the management of hepatitis B, nephrolithiasis and in painful disorders (as antinociceptive agent). However, well-controlled, double-blind clinical trials are lacking. The possible anti-AIDS activity deserves further research. Some Phyllanthus also produce edible fruits, others can be used for tanning and dyeing. The fruits of P. emblica are somewhat under-valued. Not only are they highly nutritious and contain much vitamin C, but they also have many medicinal properties. The ease of long-distance transportation and the stability of the vitamin C make P. emblica interesting for commercial exploitation.

Literature

  • Calixto, J.B., Santos, A.R., Cechinel-Filho, V. & Yunes, R.A., 1998. A review of the plants of the genus Phyllanthus: their chemistry, pharmacology, and therapeutic potential. Medicinal Research Reviews 18(4): 225-258.
  • Doshi, J.C., Vaidya, A.B., Antarkar, D.S., Deolalikar, R. & Antani, D.H., 1994. A two-stage clinical trial of Phyllanthus amarus in hepatitis B carriers: failure to eradicate the surface antigen. Indian Journal of Gastroenterology 13(1): 7-8.
  • Hussain, R.A., Dickey, J.K., Rosser, M.P., Matson, J.A., Kozlowski, M.R., Brittain, R.J., Webb, M.L., Rose, P.M. & Fernandes, P., 1995. A novel class of non-peptidic endothelin antagonists isolated from the medicinal herb Phyllanthus niruri. Journal of Natural Products 58(10): 1515-1520.
  • Ihantola-Vormisto, A., Summanen, J., Kankaanranta, H., Vuorela, H., Asmawi, Z.M. & Moilanen, E., 1997. Anti-inflammatory activity of extracts from leaves of Phyllanthus emblica. Planta Medica 63(6): 518-524.
  • Mitra, R.L. & Jain, S.K., 1985. Concept of Phyllanthus niruri (Euphorbiaceae) in Indian floras. Bulletin of the Botanical Survey of India 27(1-4): 161-176.
  • Ott, M., Thyagarajan, S.P. & Gupta, S., 1997. Phyllanthus amarus suppresses hepatitis B virus by interrupting interactions between HBV enhancer I and cellular transcription factors. European Journal of Clinical Investigation 27(11): 908-915.
  • Rizk, A.M., 1987. The chemical constituents and economic plants of the Euphorbiaceae. Botanical Journal of the Linnean Society 94: 293-326.
  • Suresh, K. & Vasudevan, D.M., 1994. Augmentation of murine natural killer cell and antibody dependent cellular cytotoxicity activities by Phyllanthus emblica, a new immunomodulator. Journal of Ethnopharmacology 44(1): 55-60.
  • Unander, D.W., 1991. Callus induction in Phyllanthus species and inhibition of viral DNA polymerase and reverse transcriptase by callus extracts. Plant Cell Reports 10: 461-466.
  • Unander, D.W., Bryan, H.H., Lance, C.J. & McMillan Jr., R.T., 1995. Factors affecting germination and stand establisment of Phyllanthus amarus (Euphorbiaceae). Economic Botany 49(1): 49-55.

Selection of species

See also :

Authors

F.L. van Holthoon