Ajuga bracteosa (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Ajuga bracteosa Wallich ex Benth.

Protologue: Wallich, Pl. asiat. rar. 1: 59 (1830).

Family: Labiatae

Chromosome number: 2n= 32, 64

Ajuga remota Benth. (1830).

• Indonesia: tilad (Sulawesi), sabasasi (Yapen Island).

A. bracteosa is widely distributed, from Afghanistan and India, through Burma (Myanmar), Indo-China and Thailand, to the Philippines, the Talaud Islands, northern and eastern Sulawesi, the Moluccas (Ternate, Halmahera) and Yapen Island.

In the Ayurvedic system of medicine in India A. bracteosa is credited with astringent, febrifugal, stimulant, aperient, tonic, diuretic and depurative properties, and it is used to treat gout, rheumatism, palsy and amenorrhoea. The leaf juice is used to purify the blood and against fever, and powdered leaves are applied to burns and boils. In Pakistan, the plant juice is used to treat bile duct problems.

The leaves of an eastern African Ajuga species are used as a remedy for fever, toothache, dysentery and high blood pressure.

From the petroleum-ether extract of the plant, ceryl alcohol, β-sitosterol, γ-sitosterol, daucosterol, hexacosan-1-ol, triacontan-1-ol-docosanoate, and cerotic and palmitic acids have been isolated.

The ethanol (50%) extract of A. bracteosa exhibited antispasmodic activity in guinea-pigs. It also showed antitumour activity against sarcoma HS1, but was inactive against Ca-9KB cell lines.

An aqueous extract of the leaves showed diuretic activity in rats almost equal to that of urea. An alkaloidal fraction isolated from the leaves showed stimulant action on isolated perfused frog heart, rabbit auricle and rat ventricle preparations.

In tests with rats, treatment with a leaf extract of an Ajuga species from eastern Africa arrested and reversed the progression of an induced hypertensive cardiovascular disease.

Several pharmacologically interesting compounds have been isolated from other Ajuga species: phytoecdysteroids in A. turkestanica (Regel) Briq. from central Asia showed a marked effect on blood regeneration in haemotoxic phenylhydrazine anaemia in rats and furthermore stimulated bile secretion in rats. In addition, an iridoid glycoside which is a nonsteroidal ecdysteroid agonist, and an iridoid with vasoconstrictor activity is present in the European A. reptans L. Other interesting compounds include diterpenoids with antibacterial activity from the Chinese A. lupulina Maxim., and a flavone in the Chinese and Japanese A. decumbens Thunberg with inhibitory activity on HIV reverse transcriptase. The iridoid glycoside 8-acetylharpagide isolated from A. decumbens exhibited potent anti-tumour-promoting activity in mice.

A low, diffuse, much-branched hispid herb, usually less than 20 cm tall, with rhizome and erect to ascending branches. Leaves opposite, simple, oblanceolate to narrowly obovate or subspatulate, 4-8 cm × 2-3 cm, margin undulate; petiole short in lower leaves, absent in upper leaves; stipules absent. Inflorescence an axillary verticillaster. Flowers bisexual, 5-merous; calyx campanulate, oblique, with triangular teeth; corolla gamopetalous, 2-lipped with upper lip very short and lower lip long and 3-lobed, white or pale blue; stamens 4, exserted; ovary superior, shortly 4-lobed, style bifid at the apex. Fruit consisting of 4 dry 1-seeded schizocarpous nutlets enclosed in the persistent calyx; nutlets obovoid, 1.5-2 mm × 1 mm, shallowly rugose-reticulate, yellowish, with large scar.

A. bracteosa is capable of flowering throughout the year.

Ajuga consists of approximately 50 species and occurs mainly in temperate regions of the Old World, with few species extending into tropical regions. Specific delimitation is often difficult in this genus, and differs considerably between taxonomists and floras. Some authors consider A. bracteosa a variable species with an extremely large area of distribution including e.g. eastern Africa and Japan, but others distinguish a number of closely related species within the complex. Until recently only A. bracteosa was mentioned for the Malesian region, but the closely related A. taiwanensis Nakai ex Murata is recorded for the Philippines.

A. bracteosa occurs on stream banks and in shaded ravines, but also in grassland, forest clearings, rice fields and coffee plantations, mostly in damp locations in the lowland, but in the Philippines up to 1700 m altitude.

A. bracteosa has a large area of distribution and also occurs in anthropogenic habitats, and is not endangered.

A. bracteosa and related species show interesting pharmacological properties, which deserve more attention. There is much confusion in the literature about the specific delimitations within the A. bracteosa complex and other groups of Ajuga species, and this can only be solved by a worldwide revision of the genus Ajuga .

182, 247, 690.

501, 760.

• '

R.H.M.J. Lemmens