2323

12(3): Medicinal and poisonous plants 3

Acacia Miller

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

LEGUMINOSAE

x = 13; Acacia concinna, Acacia pennata: 2n = 26

Acacia is a very large genus of over 1300 species and occurs throughout tropical and subtropical regions. Australia is richest with about 700 species occurring naturally. In Malesia, about 30 species have been found.

The 4 Acacia species treated here are all used medicinally in South-East Asia. In traditional medicine in Peninsular Malaysia a poultice of leaves is applied to the head for headache, and in Java leaves are used to treat fever. Boiled roots are applied as a poultice against rheumatism and smallpox in Malaysia, and the roots are used against cough and in a complex mixture of dart poison. The stem juice is used in Sumatra to treat sprue. Ash from the pods has been used in Peninsular Malaysia to treat itch. In Thailand the roots are used as an antipyretic and pods as an expectorant and to treat cough.
Acacia species are economically important as sources of timber (e.g. Acacia mangium Willd.), gum (e.g. Acacia nilotica (L.) Willd. ex Del.), tannin (e.g. Acacia catechu (L.f.) Willd. and Acacia mearnsii De Wild.) and essential oil (e.g. Acacia farnesiana (L.) Willd.). Moreover, they may be useful in reafforestation (e.g. Acacia auriculiformis A. Cunn. ex Benth.), for fire protection, to prevent soil erosion, to rehabilitate poor and degraded soils as nitrogen-fixing plants, and as ornamentals. Several of these species have medicinal importance. For example, cutch isolated from the heartwood of Acacia catechu is used to treat cough and sore throat, and its bark is said to be effective against dysentery, diarrhoea and in healing wounds. Acacia farnesiana has numerous medicinal applications in South-East Asia, e.g. the bark is used to treat cough, bleeding gums, gonorrhoea and bladder complaints, the leaves are applied to ulcers and sores, the roots are used against sore throat and tuberculosis, and the fruits against dysentery and inflammation of the skin and mucous membranes.

The seeds of Acacia pennata contain the biogenic amine N-methyltyramine (about 0.5% on a dry weight basis). This compound increased blood pressure in anaesthetized rats, relaxed guinea-pig ileum and increased the force and rate of contraction of guinea-pig right atrium by inducing the release of noradrenaline. It has similar pharmacological properties to tyramine, which is a known cause of dietary migraine. The fruit pulp of Acacia concinna and Acacia pennata has fish stupefying properties and is used in India to catch fish in ponds. The bark contains lupeol, a-spinasterol and tannin (about 9%), and the stem contains sitosterol. The fruit pulp of Acacia concinna contains about 5% saponin. A saponin fraction of the bark showed strong cytotoxic activity against KB cells, as well as spermicidal activity in vitro. Upon alkaline hydrolysis this saponin mixture gave prosapogenols. A monoterpenoidal amide, concinnamide, was isolated from the seeds; it can be synthesized from (—)-linalool, which has antimicrobial activity. Kinmoonosides A—C were isolated as cytotoxic saponins from the fruits.
Extracts of Acacia nilotica bark and pods showed inhibitory effects against HIV-1 replication, and also antibacterial and molluscicidal activities. They inhibited platelet aggregation and had inhibitory effects on paw oedema and pyrexia in rats; they also produced a significant increase in the hot plate reaction time in mice. Triterpenoid saponins isolated from Acacia auriculiformis showed anthelmintic properties and antifilarial activity. Several species (e.g. Acacia nilotica and Acacia farnesiana) showed antimicrobial effects. Some of the pharmacological properties of Acacia species are reported to be at least partly due to the presence of tannins.

The following description is applicable to the 4 species treated here.
Scandent shrubs or woody climbers up to 40 m long; branchlets armed with prickles. Leaves alternate, bipinnate, stipulate; petiole and rachis with extrafloral nectaries; leaflets opposite, numerous, small, asymmetrical at base. Inflorescence consisting of pedunculate glomerules aggregated into a raceme or panicle. Flowers bisexual or male, 5-merous, yellowish or creamy, with numerous stamens. Fruit a pod, brownish. Seeds flattened, with a hard blackish-brown testa with pleurogram.
In Malesia, Acacia pennata flowers from November to March and fruits have been found from April to August, Acacia concinna and Acacia pluricapitata can be found flowering and fruiting throughout the year.
Acacia concinna, Acacia pennata, Acacia pluricapitata and Acacia pseudointsia all belong to the subgenus Aculeiferum. They are closely related and sometimes confused. Acacia pennata is a variable species in which 4 subspecies have been distinguished; only subsp. kerrii Nielsen is found in Malesia.

Acacia concinna, Acacia pluricapitata and Acacia pseudointsia occur in primary and secondary rain forests, often at riversides, the former two species also in forest margins and clearings, up to 1000 m altitude. Acacia pennata is found in the drier parts of Malesia in monsoon forest and scrub vegetation, up to 1200 m altitude.

In tests in India, vegetative propagation by cuttings proved successful. Terminal branch cuttings treated with indole-butyric acid (1500 ppm) showed the highest percentage of rooting (54%).

The 4 Acacia species treated here do not seem to be endangered because they often occur in secondary forest and scrub vegetation and are widespread. However, in some regions a species can be rare, e.g. Acacia pluricapitata and Acacia pseudointsia in Thailand.

The bioactivity of the saponins present in the Acacia species treated here deserves more attention, particularly the antimicrobial and cytotoxic activities.

[239]Faridah Hanum, I. & van der Maesen, L.J.G. (Editors), 1997. Plant Resources of South-East Asia No 11. Auxiliary plants. Backhuys Publishers, Leiden, the Netherlands. 389 pp.
[247]Flora Malesiana (various editors), 1950—. Foundation Flora Malesiana. Rijksherbarium/Hortus Botanicus, Leiden, the Netherlands.
[263]Gafur, M.A., Obata, T., Kiuchi, F. & Tsuda, Y., 1997. Acacia concinna saponins. I. Structures of prosapogenols, concinnosides A—F, isolated from the alkaline hydrolysate of the highly polar saponin fraction. Chemical and Pharmaceutical Bulletin 45(4): 620—625.
[541]Lemmens, R.H.M.J., Soerianegara, I. & Wong, W.C. (Editors), 1995. Plant Resources of South-East Asia No 5(2). Timber trees: Minor commercial timbers. Backhuys Publishers, Leiden, the Netherlands. 655 pp.
[542]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. 196 pp.
[711]Oyen, L.P.A. & Nguyen Xuan Dung (Editors), 1999. Plant Resources of South-East Asia No 19. Essential-oil plants. Backhuys Publishers, Leiden, the Netherlands. 277 pp.
[760]Quisumbing, E., 1978. Medicinal plants of the Philippines. Katha Publishing Co., Quezon City, the Philippines. 1262 pp.

S. Aggarwal

Acacia concinna
Acacia pennata
Acacia pluricapitata
Acacia pseudointsia

Aggarwal, S., 2003. Acacia Miller. In: Lemmens, R.H.M.J. and Bunyapraphatsara, N. (Editors): Plant Resources of South-East Asia No 12(3): Medicinal and poisonous plants 3. 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:
Acacia concinna
Acacia pennata
Acacia pluricapitata
Acacia pseudointsia