Barleria (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Barleria L.

Protologue: Sp. pl. 2: 636 (1753); Gen. pl. ed. 5: 283 (1754).

Family: Acanthaceae

Chromosome number: x= 10, 20; B. cristata: 2n= (34, 36, 38), 40; B. lupulina: 2n= 40; B. prionitis: 2n= 30, 40

• Barleria lupulina Lindley,
• B. prionitis L.

Barleria is a large pantropical genus of herbs and shrubs, comprising at a conservative estimate some 300 species. Most species occur in Africa and Asia, only 1 species is native to Central America.

The leaves, roots or sometimes the seeds of Barleria occurring in South-East Asia are chewed against toothache, and a poultice of the leaves is put onto snake bites. An infusion of the roots and leaves is applied to boils and sores to reduce swellings, and to soothe urticaria skin rash. In India, Indo-China and Malaysia, the bitter juice of the leaves or roots of B. cristata and B. prionitis is given with sugar as a diaphoretic and expectorant to children for catarrhal infections accompanied by fever and much phlegm. The leaves are chewed for aphthae, bleeding gums and whooping cough, and as a paste or infusion they are used to cure earache, backache and headache.

In Java, India and Vietnam, the leaves of B. prionitis are considered diuretic and chewed for intermittent fever, rheumatism, liver diseases, indigestion with constipation, jaundice and dropsy, asthma, urinary troubles and paralysis. They are also applied to cure cracking and laceration of the feet in the rainy season. The pulverized roots mixed with lemon juice are widely used as a poultice against ringworm. In India, the plant is used in mixtures against several forms of cancer. In Africa, a decoction of the root is taken as a mouth wash to relieve toothache. In Java, the young leaves and stems of B. lupulina are used as a poultice on wounds and rheumatism. In decoction, they are counter-indicated for pregnant women. In Thailand, the fresh leaves are applied to herpes simplex and herpes zoster, while the root is used as an anti-inflammatory for centipede bites.

Barleria species are widely cultivated for ornamental purposes due to their showy flowers. They are often planted as hedges, because of the spines.

The ethanol extract of B. cristata contains flavonoids, malvidin-3,5-diglucoside and quercetin. The extract showed hypoglycaemic, antispasmodic and uterine stimulant activity.

The fresh aerial parts of B. lupulina contain the iridoid glycosides shanzhiside methylester, 6-O-acetyl-shanzhiside methylester, 8-O-acetyl-shanzhiside methylester (or barlerin) and 6,8-O-acetyl shanzhiside methylester (or acetyl-barlerin). These iridoid glycosides were tested for their anti-inflammatory effect in carrageenan-induced rat paw oedema and acetic acid-induced writhing in mice, and all were found to be active. Plant extracts also show an antagonistic activity on the effects of cobra-poison.

The aerial parts of B. prionitis contain the phenylpropanoid glycoside verbascoside (or acetoside), barlerin, 6-O-trans-p-coumaroyl-8-O-acetyl-shanzhiside methylester, its cis isomer and some flavonoids. The latter 2 compounds showed potent in vitro activity against the respiratory syncytial virus, antifungal activity against Aspergillus flavus, Candida albicans, Microsporium gypseum and Trichophyton mentagrophytes, and antibacterial activity against some gram-positive bacteria. Finally, from the flowers of B. prionitis the flavone glycosides scutellarein-7-neo-hesperidoside and scutellarein-7-rhamnosyl glucoside were isolated.

• Armed or unarmed herbs or shrubs, with 2 axillary serial buds present, either forming spines or shoots.
• Leaves decussate, simple, normally entire, epidermal cells with double cystoliths; petiole short; stipules absent.
• Inflorescence simple or compound, composed of axillary or terminal cymes or spikes, or flowers solitary.
• Flowers normally subtended by 2 linear bracteoles; bracts foliaceous, often spiny, or reduced; calyx with 2 long and 2 shorter segments, the outer ones prominently veined, acuminate; corolla variable, tubular, sub-actinomorphic, zygomorphic or bilabiate, lobes 4-5, showy, yellow, white or blue-purple; androecium of 5, 4 or 2 epipetalous stamens, 2 median abaxial stamens fertile, filaments usually hairy at base, twisted through 180° near the base, anthers 2-celled, pollen spheroidal, deeply honeycombed; ovary superior, 2-locular, with 1-2 ovules per locule; stigma entire or 2-fid.
• Fruit a dry bilocular capsule, beak long or short.
• Seeds 2 or 4, usually discoid, flattened on one side, asymmetrical about the hilum, covered with hygroscopic hairs.

Barleria tends to flower throughout the year, when sufficient water is available.

A satisfactory subdivision in Barleria has long been problematic, because of its largeness, but is now solved by the classification of the genus into 2 subgenera (Barleria and Prionitis) and 7 sections. There is a high degree of regional endemism, with only a few widespread species. Barleria is closely related to Lepidagathis.

Many Barleria species occur in dry regions on plains and in lower mountainous regions, in brushwood and thickets, and along roadsides. B. prionitis is considered a weed in Australia.

Barleria is propagated by seed and stem cuttings. Seeds germinate readily within 7 days after sowing.

Barleria is attacked by several leaf-spot fungi, including Alternaria tenuis, and also the leaf-spot bacterium Pseudomonas cichorri. It is also a host for the mycoplasma-like disease of Santalum album L. in India, which causes little-leaf disease.

Many Barleria pests are known in India, especially the larvae of the lepidopterous insects Syngamia latimarginalis and Spilosoma obliqua (synonym Diacrisia obliqua) and the Barleria lacebug (Habrochila laeta), but also the nematode Aphelenchoides fragariae, and leaf galls induced by Ferrisia virgata (Coccidae), causing abnormal rolling and twisting.

Leaves or roots of Barleria are harvested mostly from garden plants, whenever the need arises, and mainly used fresh.

The Malesian Barleria species are not endangered because they are widespread as ornamentals. Breeding programmes only exist for ornamental purposes.

Not very much is known about the pharmacology of Barleria. In general, their flavonoids and iridoid glycosides show several interesting activities, which merit further research.

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• Chen, J.L., Blanc, P., Stoddart, C.A., Bogan, M., Rozhon, E.J., Parkinson, N., Ye, Z., Cooper, R., Balick, M., Nanakorn, W. & Kernan, M.R., 1998. New iridoids from the medicinal plant Barleria prionitis with potent activity against respiratory syncytial virus. Journal of Natural Products 61(10): 1295-1297.
• Malik, K.A. & Ghafoor, A., 1988. Acanthaceae. In: Nasir, E. & Ali, S.I. (Editors): Flora of Pakistan No 188. National Herbarium (Stewart Collection), Pakistan Agricultural Research Council, Islamabad, Pakistan. 79 pp.
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• N.O. Aguilar