Abelmoschus moschatus (PROSEA)

Plant Resources of South-East Asia
Introduction

1, flowering branch; 2, lower leaf; 3, segment of epicalyx; 4, part of staminal column with anthers and stigmas; 5, capsule; 6, seeds.

Abelmoschus moschatus Medikus

Protologue: Malvenfam.: 46 (1787).

Family: Malvaceae

Chromosome number: 2n= 72

Synonyms

Hibiscus abelmoschus L. (1753).

Vernacular names

Musk mallow, ambrette, mushkdana (En).
Ambrette, ketmie musquée (Fr)
Indonesia: gandapura, kasturi (general), kakapasan (Sundanese)
Malaysia: kapas hantu, kapas hutan, gandapura
Philippines: dalupang, kastuli, kastiokastiokan (Tagalog)
Thailand: chamot-ton, som-chaba (Bangkok), mahakadaeng (northern)
Vietnam: cây bông vàng, búp vàng.

Origin and geographic distribution

A. moschatus occurs from India to southern China including Hainan and Taiwan and through South-East Asia to northern Australia and the Pacific. In Malesia it is common in the more humid areas, rare in the Lesser Sunda Islands and southern Papua New Guinea, lacking in the south-eastern Moluccas. It is cultivated commercially in Java, India (mainly in the Deccan and Carnatic), Madagascar and in parts of Central and South America. On a small scale it is cultivated and occasionally occurs as a weed throughout the tropics and in warm temperate areas.

Uses

A. moschatus is the source of ambrette seed oil used in luxury perfumery, cosmetic products and as an additive in the preparation of some kinds of chewing tobacco, baked products, sweets, alcoholic (e.g. vermouth and bitters) and non-alcoholic drinks. Arabs sometimes flavour their coffee with the seed and in India and Malaysia pounded seeds are used to perfume hair, while seeds are also placed between clothes to keep away insects. Seeds are burned as incense and used in making incense sticks (agarbattis). Tender leaves, shoots and pods are occasionally eaten as vegetable.

A. moschatus has many applications in traditional medicine. In the Philippines a decoction of the roots and leaves is taken as an emollient remedy for gonorrhoea and rheumatism, while in Burma (Myanmar) and the Philippines the seed is said to have stomachic, tonic, diuretic, antihysteric, stimulating and antispasmodic properties. In Indonesia pulverized seeds mixed with powder provide a useful remedy to treat prickly heat. In Indo-China the root is said to be effective in the treatment of blennorrhagia and leucorrhoea, the leaves and flowers are rubbed on scabies and applied as poultice to swellings. In traditional Vietnamese medicine the plant is used as an antivenom and a diuretic. It is also said to be an aphrodisiac. The tuberous roots of A. moschatus subsp. tuberosus (Span.) Borss. are said to be sought after by the Chinese as a substitute for ginseng.

The leaves are sometimes used by Malay people as wrappers for parcels. Fibre from the stem is a substitute for jute, but offers no advantages over the latter. The mucilage from the roots is used in China for sizing paper. A. moschatus is sometimes grown as an ornamental.

Production and international trade

Less than 1000 kg ambrette seed oil are produced annually. The main producers are India, Colombia, Ecuador and Martinique. Ambrette seed oil is traded in small quantities only and rarely mentioned separately in trade statistics. The world market price is about US$ 5000/kg (1998).

Properties

The seed of A. moschatus contains per 100 g: 13-15 g fatty oil and 0.2-0.6% essential oil. The main constituents of the fatty oil are: palmitic acid (20%), oleic acid (20-25%), linoleic acid (50-57%), stearic acid (2.5-4%) and smaller amounts of myristic acid and palmitoleic acid. When ambrette seed is crushed before steam distillation, the odourless, palmitic acid is distilled over together with the aromatic components yielding a crude oil of paste-like consistency. The aromatic components are concentrated in the outer seed coat and distillation of whole seed gives a liquid essential oil, containing only small amounts of fatty oil, but also a lower yield of essential oil. This ambrette seed oil should be allowed to age for several months before being used in aroma or flavour materials. By ageing, the original fatty notes become subdued and a rich sweet floral-musky aroma with distinctly wine-like or brandy-like notes develops, with a uniquely rich bouquet known for the exalting effect it imparts to perfumes. The odour has notes also found in a great variety of products, e.g. cypress oil, Bulgarian rose oil, sage clary oil and cognac oil; there are also some notes with a similarity to the aroma of higher dodecyl esters. The aroma is strong and long lasting and the recommended concentration in a final product is about 1-3 mg/kg, while the minimum perceptible concentration is 0.1-0.4 mg/kg (0.1-0.4 ppm). The essential oil is classified by the Food and Drugs Administration of the United States (FDA) as "generally recognized as safe" (GRAS No 2051). The chemical characteristics of the essential oil are only incompletely known and are affected by the method and conditions of extraction. The characteristic musk-like odour is due mainly to ambrettolide (Z-hexadec-7-en-16-olide) and Z-tetradec-5-en-14-olide, both macrocyclic lactones. Other major components are farnesol and farnesyl esters and other acyclic aliphatic esters and terpenes. The composition of the volatile fraction of the oleoresin obtained by solvent-extraction of the seed is similar to the composition of the steam-distilled essential oil. An ambrette seed oil from Vietnam was characterized by (E)-2,3-dihydrofarnesyl acetate (32-67%), (E,E)-farnesyl acetate (15-36%), ambrettolide (3-6%) and (Z,E)-farnesyl acetate (1-5%). See also: Composition of essential-oil samples and the Table on standard physical properties.

The weight of 1000 seeds is about 13 g.

Adulterations and substitutes

Ambrette seed oil was originally a substitute for deer musk, but became an essential oil in its own right because of its subtly different, flowery fragrance. The characteristic constituent of ambrette seed oil, ambrettolide, is made synthetically. Musk ambrette, a synthetic nitro-musk compound is used as a fragrance and fixative material. It is olfactively different from ambrette seed oil.

Description

A variable, annual or biennial, erect herb or undershrub, 0.5-3.5 m tall, hispid, often woody at base, with taproot or tuberous root; stem usually solid, sometimes hollow; stem apices and petioles with many obliquely downwardly directed long sharp bristles, rarely sparsely hairy or glabrous.
Leaves alternate, extremely variable in shape and size; petiole 6-30 cm long; stipules linear-filiform, simply hairy; lower leaves orbicular to transversely elliptical in outline, 6-22 cm × 8-24 cm, base cordate, angular or 3-7-palmately lobed or parted; higher leaves usually narrower and often hastate or sagittate, lobes spreading, oblong-lanceolate, coarsely serrate-dentate, rarely entire, both surfaces hispid with simple hairs and usually also minute stellate hairs, rarely glabrous.
Flowers axillary, solitary; pedicel 2-19 cm long, somewhat accrescent; epicalyx segments (4-)7-10(-16), free, persistent, linear-lanceolate or oblong, 0.75-2.5 cm long, not enveloping the entire fruit as a lattice and much shorter, usually acute, simply hairy; calyx spathaceous, apex 5-toothed, splitting on one side during expansion of the corolla, adnate to and falling with the corolla, outside stellate-tomentose, inside simply sericeous; petals 5, obovate, 3.5-10 cm × 2.5-5.5 cm, yellow with crimson centre or white to red, with scattered gland-hairs or glabrous, apex rounded, base fleshy and ciliate with simple hairs; staminal column much shorter than the petals, antheriferous throughout, usually yellow, but dark purple at base, glabrous; ovary ovoid, 5-celled, hirsute; style 1, distally 5-branched but branches sometimes united to various degree, hairy; stigmas discoid.
Fruit a loculicidally dehiscent, many seeded, ovoid or globose capsule, 2-8 cm long, occasionally fusiform, acuminate with a short rostrum, somewhat angular, usually hispid with simple stiff hairs, often also with short simple hairs and minute stellate hairs, rarely glabrous, black or dark brown; valves chartaceous or coriaceous, inside smooth and shining.
Seed reniform, 3-4.5 mm long, concentrically ribbed, somewhat warty, mostly glabrous, sometimes ferrugineously stellate-tomentose, black-brown, often smelling of musk.

Growth and development

In India the first flowers of A. moschatus are formed in the axil of the 3rd to 8th leaf depending on the cultivar. The first buds are formed 25-39 days after germination. Flower buds take 22-25 days to reach full bloom and flowering continues for 45-80 days. Anthesis occurs between 9 a.m. and 11 a.m. and the stigma is receptive on the day of anthesis. The fruit takes about 25 days from setting to maturity.

Other botanical information

A. moschatus is a very variable species with many synonyms and subclassifications. At present 3 subspecies are distinguished:

subsp. biakensis (Hochr.) Borss. A stout herb or undershrub, up to about 2 m tall, minutely stellate-hairy, with a long slender taproot; stem usually hollow; leaves large, orbicular, 10-19 cm in diameter, palmatilobed; petiole 6-13 cm long; pedicel very long and stout, after flowering up to 19 cm × 3-4 mm; epicalyx segments 8, lanceolate, 15-20 mm × 3-4 mm, in fruit appressed; corolla white or yellow with dark purple centre; capsule 5-8 cm long, with coriaceous valves; seed subglabrous. Distributed in New Guinea, possibly also cultivated as a vegetable.

subsp. moschatus. A stout herb or undershrub, up to about 1.5 m tall, with a long, slender taproot; stem usually retrorsely hispid; pedicel 3-8 cm long; epicalyx segments 6-10, 8-20 mm × 1-2.5 mm, in fruit appressed; corolla yellow with dark purple centre; capsule 5-8 cm long, thinly hispid, with chartaceous valves; seed subglabrous. In this subspecies 2 varieties can be distinguished:
- var. betulifolius (Mast.) Hochr. Stem mostly glabrous, spotted red, hollow; epicalyx segments 6-8, lanceolate, 17-25 mm × 2.5-5 mm. Distributed in Indo-China, in Malesia rare.
- var. moschatus. Stem always hispid, mostly evenly tinged red, rarely hollow; epicalyx segments 7-10, linear, 8-15 mm × 1-2 mm. Distribution as given for the species.

subsp. tuberosus (Span.) Borss. An erect or decumbent herb up to 75 cm tall with a short, tuberous, turgid taproot; stem usually patently hairy, sometimes prickly; epicalyx segments 9-10, in fruit spreading or reflexed, never appressed; corolla usually white or pink, sometimes yellow; capsule 2-5 cm long, densely hispid; seed ferrugineously tomentose. Distributed in Indo-China, Hainan, Malesia and northern Australia.

A. moschatus subsp. moschatus is tetraploid (2 n = 72); subsp. tuberosus is diploid (2 n = 36).

Ecology

A. moschatus can grow in a variety of places, e.g. roadsides, brushwood, fallow land, and on the bunds of rice fields. In the tropics it occurs up to 1650 m altitude in Indonesia, while in India it is cultivated up to 1000 m. A. moschatus requires a humid tropical or subtropical climate, although heavy and continuous rain affects crop growth negatively. The optimum temperature for vegetative growth is about 20-28°C, but it can tolerate temperatures up to 45°C. Frost is not tolerated. It is daylength sensitive, short days promoting early flowering. Flowering is also stimulated by low night temperatures. During flowering and fruiting dry weather is preferred. A. moschatus thrives in fertile loamy or sandy-loamy soil. Growth is often poor on clay and sandy soils and on saline or strongly alkaline soils. Waterlogging is not tolerated. Subsp. biakensis grows near beaches, subsp. tuberosus prefers locations with an annual dry period and where the vegetation is periodically burnt.

Propagation and planting

A. moschatus is propagated by seed. It requires a fine but compact seedbed for uniform germination. In India about 5 kg/ha of seed are used for sowing in rows spaced 75-90 cm apart. When the seed is dibbled at a spacing of 90 cm × 90 cm, 1-1.5 kg/ha is needed. Soaking the seed in water overnight accelerates germination. Seed is sown 1-2 cm deep. Under favourable conditions, germination starts 4-15 days after sowing and is complete after 15-30 days. The optimum temperature for germination is about 30°C. The germination rate of good commercial seed is about 85%. In row planting, thinning is required; in India it is done to about 60 cm, in China to 45-50 cm between plants.

Husbandry

A. moschatus needs to be weeded 2-3 times during early growth. Later, the superficial root system may be damaged by hoeing. In northern India where lush vegetative growth often leads to poor fruit set, pruning 50-60 days after transplanting tended to increase seed yield by about 40%. Earlier pruning was not beneficial. In a fertilizer trial in India on a sandy loam poor in P and rich in K, seed yield increased from 0.5 to 1.2 t/ha in response to an application of 120 kg N/ha, while a yield of 1.5 t/ha was obtained with 120 kg N/ha in combination with 35 kg P/ha.

Diseases and pests

A. moschatus suffers from several diseases, the most important being Hibiscus mosaic virus (HMV), anthracnose and leaf spot. Plants infected with HMV should be uprooted and destroyed as there is no other effective control. Anthracnose, caused by Colletotrichum hibisci, affects all plant parts and may start in the seedling stage. Seed treatment and spraying with fungicides, e.g. Bordeaux mixture, can control the disease. Alternaria leaf spot and Phytophthora leaf blight can cause damage, the latter especially under humid conditions. Seed treatment can reduce losses. In India, spotted bollworm (Earias insulana) attacks the crop during vegetative growth and the fruiting stage. Infested shoots turn brown above the point of infestation, bend down and die. Fruits are also affected. Preventive spraying with thiodan at 10-15 day intervals from the seedling stage until harvesting effectively controls the pest, but is rarely practised by small farmers. Pink bollworm (Pectinophora gossipialla) causes some damage to pods and seeds in northern India. A cotton semilooper (Anomis flava) is observed in India during the rainy season, the intensity of attack decreases as temperatures become lower, and the pest disappears in mid-November.

Harvesting

In India fruit sets continuously from October to April. As mature pods open and shatter their seed, several picking rounds are needed. Harvesting starts when most pods begin to turn from green to brown and just start to open. Pods are picked when three-quarters of their body has turned blackish-brown; the seed is removed manually. Picking is an arduous task as the plants, including the pods, possess hairs that cause itching. In India harvesting has often stopped by the end of February, as later harvesting rounds yield too little to be economical.

Yield

Average seed yield obtained in India is 0.8-1 t/ha.

Handling after harvest

After drying in the shade, the pods are mostly threshed by being beaten with sticks. The husk is then removed by winnowing.

Steam distillation of whole seed yields ambrette seed oil, while distillation of ground seed and hydrocarbon extraction of ground seed produces ambrette seed concrete, largely consisting of palmitic and myristic acids, which are unstable and odourless. Ambrette seed absolute is prepared from the seed concrete either by neutralization and subsequent elimination of fatty acids or by steam distillation of the concrete followed by washing with alcohol.

Genetic resources

The main centre of diversity for Abelmoschus DC. is India where A. esculentus (L.) Moench, A. manihot (L.) Medikus, A. moschatus and 7 related wild species occur. An Abelmoschus germplasm collection is kept in Thailand with 78 accessions, 30 of which are of A. moschatus, mostly of subsp. tuberosus. In China, the National Genebank holds 20 accessions of okra and several related species including A. moschatus; the Genebank of the Beijing Academy of Agricultural Sciences holds 10 accessions. Germplasm of Abelmoschus, including A. moschatus, has also been collected in Nepal.

Breeding

A. moschatus is autogamous and methods of manual emasculation have been developed for breeding work. However, very little breeding work has been done. A. moschatus is highly resistant to the cotton jassid Empoasca biguttula which attacks Abelmoschus manihot and A. esculentus. Although A. moschatus is reproductively incompatible with the other 2 cultivated Abelmoschus species, tissue and protoplast fusion techniques may be useful for transferring the resistance.

Prospects

As musk from the musk deer becomes increasingly rare and as the safety of synthetic nitro-musk remains uncertain, ambrette seed oil remains a valuable source of musk-like fragrances. Such fragrances remain in high demand in perfumes and skin-care products and demand for A. moschatus is therefore likely to remain strong.

Literature

Charrier, A., 1984. Genetic resources of the genus Abelmoschus Med. (okra). International Board for Plant Genetic Resources, Rome, Italy. 61 pp.
Cravo, L., Périnau, F., Gaset, A. & Bessiere, J.M., 1992. Study of the chemical composition of the essential oil, oleoresin and its volatile product obtained from ambrette (Abelmoschus moschatus Moench) seeds. Flavour and Fragrance Journal 7: 65-67.
Duhan, S.P.S. & Singh, D.V., 1992. Cultivation and utilization of mushkdana. Current Research on Medicinal and Aromatic Plants 14: 181-191.
Dung, N.X., Khien, P.V., Nhuan, D.D., Hoi, T.M., Ban, N.K., Leclercq, P.A., Muselli, A., Bighelli, A. & Casanova, J., 1998. The seed oil of Hibiscus abelmoschus L. (Malvaceae) growing in Vietnam: a valuable source of fixative fragrance components. Journal of Essential Oil Research 10: in press.
Hamon, S., Charrier, A., Koechin, J. & van Sloten, D.H., 1991. Les apports potentiels à l'amélioration génétique des gombos (Abelmoschus spp.) par l'étude de leurs ressources génétiques [Potential improvement of okra (Abelmoschus spp.) through the study of its genetic resources]. Plant Genetic Resources Newsletter 86: 9-15.
Nee, T.Y., Cartt, S. & Pallard, M.R., 1986. Seedcoat components of Hibiscus abelmoschus. Phytochemistry 25: 2157-2161.
Perry, L.M., 1980. Medicinal plants of East and Southeast Asia. Attributed properties and uses. MIT Press, Cambridge, United States. p. 252.
Singh, V.P. & Duhan, S.P.S., 1981. Note on the response of ambrette (Abelmoschus moschatus Medic.) to graded doses of nitrogen and phosphorus. Indian Journal of Agricultural Science 51: 356.
Srivastava, U.C., 1995. Ambrette seed. In: Chadha, K.L. & Rajendra Gupta (Editors): Advances in Horticulture. Vol. 11: Medicinal and aromatic plants. Malhotra Publishing House, New Delhi, India. pp. 887-897.
van Borssum Waalkes, J., 1966. Malesian Malvaceae revised. Blumea 14: 1-251, in particular pp. 90-95.

Composition of essential-oil of Ambrette seed oil

59.1% (E,E)-farnesyl acetate
7.8% ambrettolide
5.6% decyl acetate
4.0% dodecyl acetate
3.8% (Z,E)-farnesyl acetate
3.5% (E,E)-farnesol
1.8% (Z)-tetradec-5-en-14-olide
1.6% tetradecenyl acetate (unknown isomer)
1.4% hexadecanoic acid
1.1% (E,E)-farnesyl propionate
1.0% (Z)-octadec-9-en-18-olide
0.9% oleic acid
0.8% (E,E)-2,4-decadienal
0.7% dodecenyl acetate (unknown isomer)
0.6% 1-decanol
0.5% linoleic acid
0.4% nerolidol (unknown isomer)
0.4% (E,Z)-2,4-decadienal
0.3% 1-dodecanol
0.3% (Z,E)-farnesol
0.3% (E,E)-farnesyl pentanoate
0.3% geranylacetone
0.3% methyl linoleate
0.2% β-farnesene
0.2% decyl propionate
0.2% ethyl linoleate
0.2% hexyl propionate
0.2% octyl butyrate
0.1% octyl-2-methylbutyrate
0.1% 1-octanol
0.1% 2-decanone
0.1% ethyl hexadecanoate
0.1% ethyl oleate
0.1% octadecanoic acid
0.1% methyl oleate
98.2% total

Source: Cravo et al., 1992.

Physical properties of essential oil

ambrette seed oil

Relative density : 0.898-0.920
Refractive index : 1.468-1.485
Optical rotation : -2.5° to +3°
Miscibility in ethanol : passes test
ISO/EOA : EOA 147

See comments : Physical properties of essential oils (PROSEA)

Sources of illustrations

Chang, C.E., 1977. Malvaceae. In: Li, H.L. et al. (Editors): Flora of Taiwan. Vol. 3. Epoch Publishing Company, Taipei, Taiwan. Fig. 782, p. 712. Redrawn and adapted by P. Verheij-Hayes.

Authors

Sri Hajati Widodo