1225

12(2): Medicinal and poisonous plants 2

Persicaria Miller

Gard. Dict. abr. ed. 4 (1754).

POLYGONACEAE

x = 10, 11; Persicaria barbata: 2n = 20, 22, 40, 60; Persicaria chinensis: 2n = 22, 32; Persicaria minor: 2n = 40

Major species Persicaria chinensis (L.) H. Gross.

Knot grass, smart weed, joint weed (En). Renouée des oiseaux (Fr).

Persicaria comprises about 150 species with an almost cosmopolitan distribution, and is widely distributed in South-East Asia.

A decoction or the juice of the crushed leaves or plant of many Persicaria species, including Persicaria barbata and Persicaria chinensis, are applied to skin problems such as scabies, ringworm, boils, and ulcers, and also to fresh wounds, bites of snakes, dogs or insects for their disinfectant properties. It is also applied as a maturative, a resolvent and a cicatrizant, and as a wash for haemorrhoids, venereal sores and leucorrhoea.
In Java, Persicaria barbata is reported to be a fish poison, but this has not been proven. The seeds are taken against cholera, dysentery and colds. The juice of the plant is taken as a haemostatic, antifebrile, diuretic and laxative. In India, the dried rhizome is taken as an astringent and refreshing beverage. In Peninsular Malaysia, the powdered leaves are applied to infected wounds of goats. In Indonesia, the juice of the stem and leaves of Persicaria chinensis is employed in the treatment of eye diseases. A decoction of the plant is used against cholera, dysentery and headache. In Vietnam, the aerial parts are externally used to treat pimples, eczema, skin infections and snake bites, and internally against fever, dysentery and throat infections. In Peninsular Malaysia, a poultice of Persicaria chinensis or Persicaria barbata is applied to the abdomen to treat stomach-ache. In Peninsular Malaysia, a decoction of the leaves of Persicaria minor is taken for indigestion and also after childbirth.
In Vietnam, the roots of Persicaria maculosa Gray (synonym Polygonum persicaria L.) are used against pulmonary complaints.
In South-East Asia, the young shoots or leaves of most Persicaria species are sometimes eaten as a vegetable or mixed into salads. Persicaria hydropiper (L.) Spach, Persicaria odorata (Lour.) Sojak and Persicaria pubescens (Blume) H. Hara have a sharp or pungent taste and are therefore mainly used as a spice, but also medicinally. Persicaria barbata and Persicaria tinctoria (Aiton) Spach are used to make a dark-blue dye especially in China.

The dried plants of Persicaria are found on Chinese markets in Indo-China and Malaysia.

The rhizomes of Persicaria barbata contain indole alkaloids, pterocarpanes (2',4-epoxy-isoflavones) and flavonones. The pterocarpanes showed molluscicidal activity, and an extract of the aerial parts exhibited antimicrobial activity.
The leaves of Persicaria chinensis contain flavonoids, e.g. kaempferol-3-O-glucuronide and 5,6,7,4'-tetrahydroxy-3'-methoxyflavone. The extract of the aerial parts showed antifungal activity against Drechslera oryzae, and antibacterial activity against both Gram positive and Gram negative bacteria. Several steroidal compounds were isolated from roots and stems: 25R-spirost-4-ene-3,12-dione, stigmast-4-ene-3,6-dione, stigmastane-3,6-dione and hecogenin (steroid sapogenin). Several of these compounds have anti-inflammatory and anti-allergic properties.
The aerial parts of Persicaria minor contain the flavones 6,7-methylenedioxy-5,3',4',5'-tetramethoxyflavone and 6,7,4',5'-dimethylenedioxy-3,5,3'-trimethoxyflavone. Extracts showed antimicrobial activity against Gram positive bacteria (Bacillus cereus, B. megaterium) and Gram negative bacteria (Escherichia coli, Pseudomonas aeruginosa), and antifungal activity against Aspergillus ochraceus and Cryptococcus neoformans. Other in vitro effects include cytotoxic activity against human cervical carcinoma, and antiviral activity against the herpes simplex type-1 and vesicular stomatitis virus.

Annual or perennial herbs, rarely erect, ascending or climbing shrubs, stems jointed. Leaves alternate, simple, linear, lanceolate to broadly ovate or hastate, with well-developed amplexicaul ocrea, upper margin often with bristles. Inflorescence a terminal or axillary spike, raceme or panicle or flowers solitary in bracts. Flowers actinomorphic, bisexual, small, perianth segments 5, venation trifid, pink or white, accrescent and juicy after anthesis or not; pedicel short, jointed; stamens 6—9, filaments filiform, free or connate at base; interstaminal nectaries present; ovary superior, 1-ovulate, styles 2—3, stigmas capitate. Fruit a nutlet, lenticular or trigonous, nearly covered by persistent perianth; embryo curved on one side of albumen. Seedling with epigeal germination.

Persicaria can be found flowering and fruiting throughout the year.

Persicaria is a segregate from Polygonum s.l. and contains four sections: Aconogonon, Bistorta, Persicaria, and Tovara. Section Persicaria includes the former sections Amblygonon, Cephalophilon and Echinocaulon, as the characteristics used to differentiate these groups are not clear. The main characteristics distinguishing Persicaria from Polygonum are the tepals with trifid venation, interstaminal free or fused nectaries, and cylindrical and filiform filaments. Persicaria is considered the most advanced in the tribe Persicarieae.
The status of Persicaria minor is not clear and needs to be studied further. It is supposedly close to Persicaria decipiens (R.Br.) K.L. Wilson and Persicaria subsessilis (R.Br.) K.L. Wilson, but has a different distribution area.

Persicaria species prefer humid growing conditions with half shade or full sunlight, some species preferring temperate climates, others tropical climates.

Persicaria is propagated by seed, which is dispersed by water, and by stem or root cuttings.

Slugs and caterpillars are the main problems in Persicaria. Persicaria chinensis is also a host for the fungus Colletotrichum capsici.

Persicaria plants are collected from the wild when needed.

Persicaria plants, including the roots or rhizomes, can be sun-dried for later use.

Persicaria produces many seeds and grows where water is available. Therefore they are not likely to be threatened by genetic erosion. Neither germplasm collections nor breeding programmes are known to exist.

Little information is available about the phytochemistry and pharmacology of compounds of Persicaria. Further research is needed to fully investigate its potential.

Ganesan, T. & Krishnaraju, J., 1995. Antifungal properties of wild plants — 2. Advances in Plant Sciences 8(1): 194—196.
Hoque, M.M., Hassan, M.A. & Khan, M.R., 1989. Screening of plants available in Bangladesh for antibacterial activity 2. Polygonum L. Bangladesh Journal of Botany 18(2): 141—146.
Nguyen Van Duong, 1993. Medicinal plants of Vietnam, Cambodia and Laos. Mekong Printing, Santa Ana, California, United States. pp. 341—342.
Ronse Decraene, L.-P. & Akeroyd, J.R., 1988. Generic limits in Polygonum and related genera (Polygonaceae) on the basis of floral characters. Botanical Journal of the Linnean Society 98: 321—371.
Tsai, P.L., Wang, J.P., Chang, C.W., Kuo, S.C. & Lee, C.P.D., 1998. Constituents and bioactive principles of Polygonum chinensis. Phytochemistry 49(6): 1663—1666.
Wilson, K.L., 1990. Some widespread species of Persicaria (Polygonaceae) and their allies. Kew Bulletin 45(4): 621—636.

Nguyen Thi Do

Persicaria barbata
Persicaria chinensis
Persicaria minor

Do, N.T., 2001. Persicaria Miller. In: van Valkenburg, J.L.C.H. and Bunyapraphatsara, N. (Editors): Plant Resources of South-East Asia No 12(2): Medicinal and poisonous plants 2. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea

The following species in this genus are important in this commodity group and are treated separatedly in this database:
Persicaria barbata
Persicaria chinensis
Persicaria minor