1127

12(2): Medicinal and poisonous plants 2

Impatiens L.

Sp. pl. 2: 937 (1753); Gen. pl. ed. 5: 403 (1754).

BALSAMINACEAE

x = (3), 6, 7, 8, (9); Impatiens balsamina: 2n = (12), 14 (+2B), (18, 20, 24, 28 (+2B), 44, 56 (+2B)); Impatiens hawkeri: 2n = 48; Impatiens platypetala: 2n = 12, 14, 16

Major species Impatiens balsamina L.

Balsamine (En, Fr).

Impatiens is a large genus with about 600 species, widely distributed throughout the tropics, subtropics and temperate zone of Europe, Asia, Africa, and Central and North America.

In China, Malaysia, Indonesia and the Philippines, the leaves of Impatiens balsamina are used as a poultice to heal wounds, chronic ulcers and furuncles. The root and leaves are considered to be expulsive, and are thus described for all sorts of foreign bodies in the throat, such as coins and other metals, as well as for thorns and splinters in the flesh. The roots are also considered antiphlogistic and used for rheumatism. In Thailand, the fresh pounded leaves and stems are used for infections of the nails and ingrowing nails, the leaves and roots for treatment of thorn- or glass-puncture wounds. In China, the aerial parts are used to treat rheumatism, bruises and beri-beri, and in Korea they are used for the treatment of scrofulosis, hard ulcers and dysentery. The flowers are mucilaginous and cooling, and are used for snake bites, lumbago, intercostal neuralgia, to cure broken or torn nails, and infections of the nail base. They are thought to improve the blood circulation and to have fungicidal properties. In Indonesia, the flowers are considered abortive, and are also used against furuncles and dermatitis. In Japan, the squeezed juice from white petals is massaged into the skin for dermatitis. A powder of the seeds, mixed with arsenic acid, is sometimes used to ease the removal of teeth with caries. The seeds are also used in difficult labour or as an emmenagogue. A few seeds cooked with fish help soften the bones. In Indo-China, the seeds are used for amenorrhoea.
In Papua New Guinea, the whole plant of Impatiens hawkeri is cooked and eaten by children with stomach-ache. The juice from the fruit and leaves is rubbed onto the legs of small children who are retarded in their walking. In East Africa, the herb is used as an abortifacient. In Java, the leaves of Impatiens platypetala are applied to skin rash, and young leaves mashed with dill are given to children as a diuretic.
Impatiens balsamina is used in Bali as a vegetable, mixed with other leaves, as they are slightly bitter. The leaves or flowers are widely used to dye the nails red, and in India they are also used for dyeing wool. In Vietnam, a slightly sweet smelling decoction of the leaves is used to wash the head to promote hair growth. The seeds are edible, the oil can be used for cooking and burning in lamps.
Impatiens is widely cultivated as an ornamental in gardens or as a potplant.

Impatiens is used for medicinal purposes on a local scale only. Ornamental Impatiens is traded internationally on a large scale.

Besides flavonoids, cyanidins and cinnamic acid derivatives, the aerial parts of Impatiens balsamina contain the quinone derivatives lawsone (2-hydroxy-1,4-naphtaquinone) and lawsone-methylether (2-methoxy-1,4-naphtaquinone). These compounds are also found in several other Impatiens species, and also in henna (Lawsonia inermis L.), and are responsible for the red colourations of hair and skin.
Lawsone and lawsone-methylether show antifungal activity, and are active in vitro against Epidermophyton floccosum, Trichophyton mentagrophytes, and Trichophyton rubrum, which cause ringworm, tinea pedis and athlete's foot. Both cream and ointment preparations containing 1% of a chloroform extract of the plant, were effective against these 3 fungi in vivo, and in vitro also showed equal activity against Candida albicans and Microsporum gypseum. Studies on the toxicity of Impatiens balsamina in mice showed that the LD₅₀ of a chloroform extract intraperitoneally injected was 0.67 g/kg. However, the cream preparation containing 1% of the chloroform extract caused irritation of the skin of rabbits and guinea-pigs. In addition, an ether extract of the leaves was found to be effective against the bacteria Shigella flexneri, Shigella sonnei, Staphylococcus aureus and 'BETA'-haemolytic streptococcus group A.
The dinaphthofuran-7,12ne derivates balsaminones A and B were isolated, together with lawsone-methylether from the white petals of Impatiens balsamina. These compounds exhibited significant antipruritic activity in histamine-treated mice. Mice with a murine hypersensitivity reaction system induced by hen egg-white lysozyme and a rat with a passive cutaneous anaphylaxis (PCA) reaction system were treated with a 35% ethanol extract of the white petals. The extract prevented fatal anaphylactic shock and inhibited heterologous PCA reactions.
Other pharmacological effects of Impatiens balsamina include some activity against human epidermoid carcinoma of nasopharynx in vitro (alcoholic extract of the whole plant), and a significant protection and therapeutic activity against rice brown spot (Helminthosporium oryzae), when sprayed at intervals of 4—8 days (extract of the aerial parts).
Seeds of Impatiens balsamina contain parinaric acid, hosenkosides A—O and baccharane glycosides. In China, the antifertility effect of the seeds was tested on mice. A decoction of 3g/kg for 10 days caused up to 100% contraceptive rate in male and female mice caged together on the 5th day of medication and dissected after 35 days. An anti-implantation rate of 33% was obtained with the decoction at a dose of 80 g/kg; this effect is probably related to suppression of ovulation. Furthermore, a syrup prepared from the seeds had a prominent stimulant effect on isolated mice uteri, increasing the frequency of contraction and enhancing the tone.

Henna (Lawsonia inermis) is used in the same way as Impatiens balsamina, for colouring nails red.

Annual or perennial herbs, up to 2 m tall, generally with few-branched, fleshy, translucent stems, with swollen joints and watery juice, glabrous, or variably pubescent on the veins when young. Leaves simple, opposite, usually 3-whorled or spirally arranged, margin entire or serrate; petiole present; with or without stipules. Inflorescence axillary, flowers solitary or few together in cymes; flowers 5-merous, zygomorphic; bracts linear-lanceolate, inconspicuous; calyx lobes 3 (or 5), the lateral ones small, the lower one usually spurred, not persistent; corolla lobes 5, often simulating 3 by fusion of the lateral pairs; stamens 5, free from petals, alternate with petals, anthers connate, ultimately rupturing at the base and lifted by the elongating pistil; ovary superior, 5-locular, style 1, stigma 1 or 5, 5—50 ovules per locule, funicle present, pendulous, with dorsal raphe. Fruit a fleshy capsule, dehiscent or not, with usually numerous seeds.

Impatiens normally flowers throughout the year in the tropics. Impatiens shows flower dimorphism: besides the normal flowers, they have small, cleistogamous flowers, which never open and are autopollinated. The normal flowers are entomophilous, but do not regularly produce ripe seed. The mature fruit explodes by curling of the carpels, and the seeds are dispersed at considerable distance.

Impatiens has a high degree of endemism of its constituent species, which suggests active recent evolution, and hybridization seems important. Many varieties and cultivars have been recognized in cultivated Impatiens, including double-flowered and dwarf forms.

Wild Impatiens grows in tropical and subtropical areas, along streams, wetlands, drainage ditches and in woodland, from sea-level up to 3500 m altitude.

Impatiens is mainly propagated by seeds, sometimes by cuttings. There are 1000—2000 seeds/g, depending on the cultivar. The seeds germinate in 10—18 days, in the light, at 100% relative humidity. Optimum temperature for germination is 25—28°C, and for the seedlings a night temperature of about 20°C is needed for high quality plants. Optimum spacing is 30—40 cm, in order to display the flowers properly.

Root cultures of Impatiens balsamina were analyzed for biologically active compounds, and yielded lawsone (2-methoxy-1,4-naphthoquinone), lawsone-methylether (2-methoxy-1,4-naphtaquinone), methylene-3,3'-bilawsone, spinasterol, and the coumarin derivatives scopoletin, isofraxidin and 4,4'-biisofraxidin. In the Philippines, preliminary trials for callus formation in in vitro cultures for medicinal purposes were successful.

Impatiens is susceptible to powdery mildew, often caused by Sphaerotheca fuliginea. Fungal blights and rots, bacterial leaf spot and viruses (e.g. Impatiens necrotic spot tospovirus, Impatiens necrotic spot virus) are also common problems. Pythium and Rhyzoctonia cause damping-off in seedlings. Pests like aphids, thrips and spider mites cause distorted and stunted leaves, while slugs attack the leaves, and several nematodes attack the roots.

The parts of Impatiens to be used are usually harvested from cultivated plants.

The harvested parts of Impatiens are used fresh.

No breeding programmes of Impatiens for medicinal purposes are known to exist.

Impatiens species are considered mainly as ornamentals, therefore their value as medicinal plants is not fully exploited. Although limited work has been done so far on some valuable chemicals (e.g. lawsone, lawsone-methylether), more research attention seems justified.

Dhawan, B.N. et al., 1980. Screening of Indian plants for biological activity. Part 9. Indian Journal of Experimental Biology 18: 594.
Fukumoto, H., Yamaki, M., Isoi, K. & Ishiguro, K., 1996. Antianaphylactic effects of the principal compounds from white petals of Impatiens balsamina L. Phytotherapy Research 10(3): 202—206.
Grey-Wilson, C., 1979. Impatiens in Papuasia. Studies in Balsaminaceae: 1. Kew Bulletin 34(4): 661—688.
Grey-Wilson, C., 1989. A revision of Sumatran Impatiens. Studies in Balsaminaceae: 8. Kew Bulletin 44(1): 67—106.
Panichayupakarananth, P., Noguchi, H., De Eknamkul, W. & Sankawa, U., 1995. Naphthoquinones and coumarins from Impatiens balsamina root cultures. Phytochemistry 40(4): 1141—1143.
Phuphathanaphong, L., 1991. Impatiens balsamina L. In: Lemmens, R.H.M.J. & Wulijarni-Soetjipto, N. (Editors), 1991. Plant Resources of South-East Asia No 3. Dye and tannin-producing plants. Pudoc, Wageningen, the Netherlands. pp. 80—81.

Rosna Mat Taha

Impatiens balsamina
Impatiens hawkeri
Impatiens platypetala

Taha, R.M., 2001. Impatiens L.. 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:
Impatiens balsamina
Impatiens hawkeri
Impatiens platypetala