Hibiscus (PROSEA Medicinal plants)

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Plant Resources of South-East Asia
Introduction
List of species


Hibiscus L.

Protologue: Sp. pl. 2: 693 (1753); Gen. pl. ed. 5: 310 (1754).
Family: Malvaceae
Chromosome number: x= 8, 9, 11, 12, 18, 20, 21; H. mutabilis: 2n= 84, 92, 110; H. rosa-sinensis: 2n= 36, 44, 46, 70, 72, 84, 90, 92, 118, 144, 168; H. sabdariffa: 2n= 36, 72; H. syriacus: 2n= 80, 90, 92; H. tiliaceus: 2n= 80, (86), (92), 96

Major species

Hibiscus mutabilis L., H. rosa-sinensis L., H. tiliaceus L.

Vernacular names

  • Hibiscus, roselle, rose mallow (En). Roselle (Fr)
  • Indonesia: baru, waru
  • Malaysia: baru, bebaru bulu (Peninsular), baru laut (Sarawak)
  • Thailand: ehaba
  • Vietnam: d√¢m b·ª•t, ph√π dung.

Origin and geographic distribution

Hibiscus (excluding Abelmoschus ) comprises about 275 species in the tropics and subtropics of the Old and New World; only 2 species occur in the temperate zone. Within the Malesian region 43 species are found.

Uses

Hibiscus is widely used for ornamental, medicinal, vegetable and fibre purposes. The leaves, root and bark contain much mucilage, and are generally used in decoction (like the flowers) as an emollient and demulcent for ripening abscesses, ulcers, and to treat cutaneous infections, swellings, boils and mumps. In India, Indo-China, China and Malesia, they are also considered resolvent, cooling, expectorant, antidotal to all kinds of poison, anodyne, and are used for burns and scalds that are slow in healing. They are also used as a medication for persistent coughs, bronchitis and other pulmonary complaints, menorrhagia and dysuria. The mucilage is also applied by midwives to facilitate expulsion in labour. Mainly the flowers and leaves are used of H. mutabilis , and mainly the flowers and the bark of the stem of H. rosa-sinensis . In Indonesia, an infusion of the red flowers of H. rosa-sinensis is considered somewhat purgative, and is even said to cause abortion. In India, the flowers are used for their contraceptive properties, and also for irritable conditions of the genito-urinary tract. In Papua New Guinea and Fiji, the juice from the crushed leaves mixed with sea water is drunk to treat stomach-ache. The seeds, pounded into a pulp and mixed with water, are a cure for gonorrhoea, as is the juice of the leaves.

Mainly the bark and root are used of H. syriacus . A decoction of these parts is considered to improve the eyesight. An infusion of the dried flowers is used in Malaysia as a diuretic, as well as against skin complaints and itch. The seeds are employed in headaches and colds, and combined with pig marrow, as an application to discharging ulcers. H. syriacus is also widely used in Africa.

All parts of H. tiliaceus are used. In Papua New Guinea, an infusion of the bark is drunk to relieve coughs and tuberculosis. In Fiji, the leaves are wrapped on bone fractures, and the stem is said to be part of an internal remedy for ulcers and internal injuries. In Indo-China, the leaves are used as a laxative and resolutive. The flowers, boiled in milk, are dropped in the ear against earache. In China, the flowers are used for headaches.

Mainly the calyx, seed and leaves of H. sabdariffa are used. The calyx in decoction is reported to be aphrodisiac, cholagogue, digestive, diuretic, purgative, resolvent, stomachic and tonic, and is a folk remedy for abscesses, bilious conditions, cancer, cough, dyspepsia, dysuria, fever, hangover, heart ailments, hypertension, neurosis, scurvy and strangury. The whole plant, and especially the seed, is antiscorbutic. In Burma (Myanmar), the seeds are used for debility, and in Taiwan, they are regarded as a gentle laxative, diuretic and tonic. In the Philippines, the bitter root is used as a tonic. Other Hibiscus species occurring in Malesia, including H. surattensis L. and H. elatus L. and Abelmoschus esculentus (L.) Moench are also used as an emollient for skin complaints, for venereal sores and urethritis. H. trionum L. is used in southern Africa for roundworm. It is reported to be poisonous to horses. In China, the dried leaves are considered stomachic. The roots of H. radiatus Cav. are used to poultice swellings of finger nodes, which remain after framboesia (yaws).

H. mutabilis , H. radiatus , H. rosa-sinensis and H. syriacus are widely planted as ornamentals. The bast fibre is sometimes used as a substitute for jute.

H. rosa-sinensis is also planted as a hedge and fencing, and H. tiliaceus is used to reforest eroded land for firewood production, and is suitable as a shade tree, hedge or wind break, along the seashore. In China and India, the sap of petals of H. rosa-sinensis is used for blackening eyebrows, or for colouring food, and in Indonesia it has been used for polishing shoes black. In India, the juice of the fresh flowers is believed to increase hair growth. Young shoots and leaves of H. sabdariffa are used raw or cooked as a vegetable, and the fleshy calyces are widely used to make red, fresh but sourish beverages and jams. In the Pacific islands, the bark of H. tiliaceus is sometimes used as fodder when other food is lacking. In Java, the leaves are used as a food wrapper.

Production and international trade

The Hibiscus species treated here are only used on a local scale for medicinal purposes. Chinese herbalists in Malaysia import the dried flowers of several species.

Properties

The flowers of H. sabdariffa contain several flavonoids e.g. gossypetin, hibiscetin, sabdaretin, gossytrin, hibiscin and hibicitrin, as well as anthocyanins e.g. cyanidin-diglucoside and cyanidin-glucosyl-rutinoside. The latter compounds are reported to have diuretic and chloretic effects, to decrease the viscosity of the blood, to reduce blood pressure and to stimulate intestinal peristalsis. All parts of the plant contain large quantities of viscous polysaccharides, the greatest amount being in the calyces. The seeds contain 17-20% edible fatty oil. Callus tissue derived from H. sabdariffa seedlings produce two cyanidin glycosides as major anthocyanin pigments, which are used as food colorants. The production of callus and colorants is markedly stimulated by 2,4-D.

An aqueous extract of the calyces inhibited the tone of isolated rabbit aortic strips, but contracted rat uterus, guinea-pig tracheal chain, rat diaphragm and frog rectus abdominis preparations. Intravenous injection of the extract to anaesthetized rats and cats lowered the blood pressure in a dose-response manner. This hypotensive effect was blocked by atropine, so it does not seem to be mediated through inhibition of the sympathetic nervous system but through acetylcholine-like and histamine-like mechanisms, as well as via direct vaso-relaxant effects. Other pharmacological effects of extracts include antimutagenic and chemoprotective activity in a colon carcinogenesis model by the 80% ethanol extract of the aerial parts, chemoprotective effects in a colon carcinogen model in F344 rats with induced aberrant crypt focus formation, and antimutagenic effects (60-90% reduction) towards 9 different colon mutagens in the Salmonella mutation assay. In addition, protocatechuic acid, a phenolic acid isolated from the flowers, was evaluated for its topically applied ability to inhibit the TPA-induced promotion of skin tumours of female CD-1 mice. It inhibited the incidence of tumours in mice by 55-80%. The extract of the dried flowers also had a strong inhibitory effect on xanthine oxidase activity as a free radical scavenger. Antioxidant bioactivity was further investigated using a model of t-butyl-hydroperoxide-induced oxidative damage in rat primary hepatocytes, and found to be significantly protective. Furthermore, in vivo, the aqueous extract of the aerial parts had a significant inhibitory effect on yeast induced pyrexia, and a significant effect on the hot plate reaction time, but not on the carrageenan induced hind paw oedema model in rats. Also 3 polysaccharides isolated from the flower buds showed some tumour-growing-retarding effect on the transplanted tumour sarcoma 180/CD-1 mice. Changes in urine composition of healthy human volunteers after consuming the juice of H. sabdariffa calyces in different concentrations and durations were evaluated. The urine showed a decrease of creatinine, uric acid, citrate, tartrate, calcium, sodium, potassium and phosphate, but not oxalate. Interestingly, the low dose of juice caused a more significant decrease in salt output in the urine than did a higher dose. Finally, the oil from the seeds exhibits antibacterial activity against e.g. Bacillus subtilis , Corynebacterium pyogenes , Escherichia coli , Klebsiella pneumoniae , Salmonella typhi , Staphylococcus aureus , S. albus ,a nd antifungal activity against some species of Alternaria , Aspergillus , Colletotrichum , Cryptococcus , Helminthosporium , Trichophyton and Trichoderma .

The flowers of H. rosa-sinensis contain flavonoids and anthocyans e.g. hibiscetin, cyanidin diglucoside, and an acidic polysaccharide (L-rhamnose

D-galactose : D-galacturonic acid : D-glucuronic acid; 5:8:3:2), called Hibiscus -mucilage RL, was isolated from the leaves. In a test in rats and mice, orally effective antifertility activity was found, when administered from day 1 to 10 of pregnancy. The extract was found not to affect the tubal transport of the zygote, but to inhibit the blastocyst from implanting, causing the termination of the pregnancy. Furthermore, the oral administration of a benzene extract of the flowers (250 mg/kg for 30, 45 and 60 days) affected the spermatogenesis and the endocrine function of the testis in adult male albino rats. Reduction in testicular weight, and that of the epididymis, seminal vesicle, prostrate and pituitary was observed and spermatogenesis ceased. Also a significant reduction in ventral prostrate alkaline phosphatase activity, citric acid content in the seminal vesicles, and fructose content in dorsolateral prostrate was reported. All effects were reversible; 30 days after discontinuation of the treatment organs were fully recovered. Other pharmacological effects of extracts include a partial inhibition of skin-, liver- or colon tumour formation in mice of a flower extract, and antibacterial and antifungal activity of the neutral leaf extract.

The leaves of H. syriacus contain a mucilage consisting mainly of L-rhamnose, D-galactose, D-galacturonic acid and D-glucuronic acid (8:1:8:4), and the seeds contain an oil with moderate antimicrobial activity. The water extract of the leaves showed potent inhibition of HIV-1-induced cytopathic effects, while a methanol extract of the leaves and stems showed more than 40% inhibition of protease andα-glucosidase activities at a concentration of 100μg/ml.Hibispeptin A and B, and the napthalenes syriacusins A-C were isolated from the root bark. The latter compounds inhibited lipid peroxidation, while syriacusin A (2,7-dihydroxy-6-methyl-8-methoxy-1-naphthalenecarbaldehyde) showed cytotoxicity against some human cancer cell lines. Two isolated triterpene caffeates from the root bark inhibited lipid peroxidation and exhibited significant cytotoxicity against a panel of human cancer cell lines.

H. tiliaceus contains sesquiterpenoid quinones and lapachol. The anthers contain gossypetin glucosides, gossypitrin and gossytrin. An acetone extract of the leaves showed antibacterial activity against Staphylococcus aureus .

The change in colour of the flowers of H. mutabilis is due to the progressive synthesis of flavonoids and anthocyans. In the morning the pigments are isoquercetin, hyperoside, rutin, quercetin-4-glycoside and quercimeritin, and in the evening cyanin, cyanin-3-sambubioside and cyanidin. An aqueous extract was found to be highly effective in an experimental clinical assessment of the anti-HSV-II action.

Adulterations and substitutes

Sida is used as a substitute for Hibiscus, as an emollient for wounds and ulcers.

Description

  • Herbs, undershrubs, shrubs or trees, with stellate hairs and (or) scales.
  • Leaves alternate, simple, often (deeply) lobed, often with extrafloral nectaries; petiole present; stipules present.
  • Inflorescence composed of a raceme or panicle by reduction of the upper leaves, or flowers solitary, axillary, pedicel mostly articulate, at apex rarely thickened into a hypanthium; bracteoles of epicalyx 3-many, rarely lacking, usually free, or short connate, mostly persistent.
  • Flowers bisexual, 5-merous; calyx usually campanulate, 5-lobed to 5-parted, rarely splitting on one side, persistent; corolla with 5 distinct petals, mostly large and showy, often yellow with a dark purple centre; staminal column as long as or shorter than the petals, antheriferous throughout or only in the upper half; ovary mostly 5-celled, style 1, distally 5-branched, stigmas usually discoid, ovules 3-many per cell.
  • Fruit a loculicidally dehiscent capsule, 5(-10)-celled.
  • Seeds 3-many per cell, globose or reniform, glabrous or hairy.
  • Seedling with epigeal germination; cotyledons emergent.

Growth and development

Hibiscus species are strong and profuse growers, and thrive under a wide range of conditions. The flowers of most species last one day, sometimes two days. In H. sabdariffa, pinching of the apical bud induces branching. Flowering lasts for about 2 months, but most of the flowers are initiated during the first few weeks. It is a primarily self-pollinating crop. Fruit ripening takes 2-3 months from pollination. H. tiliaceus has a rapid growth and in 2-3 years the tree is large enough to provide shade. It flowers throughout the year in Java, but on other Indonesian islands flowering is restricted to 1-3 months/year. Flowers are pollinated by insects and birds. The seeds can float in sea water for several months and are commonly found along the shore.

Other botanical information

Hibiscus belongs to the tribe Hibisceae, to which also the genera Abelmoschus and Gossypium belong. Abelmoschus differs from Hibiscus by having a deeply splitting calyx on one side, which falls off together with the corolla, while the calyx of Hibiscus is normally 5-lobed to 5-parted, and semi-persistent. Gossypium has an undivided style, and 3 epicalyx segments, in contrast to the other 2 genera. H. schizopetalus (Mast.) Hook.f. is very closely related to H. rosa-sinensis, and is sometimes only considered a cultivar of this species.

Ecology

Most Hibiscus are heliophilous and prefer low altitudes. Herbaceous species and undershrubs occur particularly in waste places, and along roadsides. H. rosa-sinensis requires a relatively dry atmosphere for fruit setting. The arboreous species occur especially in secondary forest, although H. tiliaceus prefers coastal areas. When cultivated, Hibiscus prefers deep rich soils and a reliable moisture supply. H. sabdariffa is a short-day plant and on Java usually no flowering is observed during December-March.

Propagation and planting

H. sabdariffa and H. mutabilis are usually grown from seed, but can also be propagated from stem cuttings. Seed viability of H. sabdariffa is about 85%, and the optimum temperature for germination is 25-35°C. H. rosa-sinensis propagates readily by softwood cuttings in spring or by hardwood cuttings in fall. It seldom produces seed in cultivation, although it seeds freely in some tropical regions, but not in South-East Asia. Cuttings of H. rosa-sinensis treated with indole butyric acid 100 ppm resulted in the highest percentage of rooted cuttings and number of roots per cutting under greenhouse conditions. H. syriacus is propagated by seed, by cuttings of ripened wood, and by grafting on common seedling stock. In vitro shoot regeneration, either directly from cotyledons and hypocotyls or through callus showed the best adventitious shoot formation when cultured on a Murashige and Skoog medium supplemented with 1 mg butyric acid and 0.1 mg naphthalene acetic acid per litre. H. tiliaceus is easily raised from seed or stem cuttings. Seed shows 30% germination in 23-48 days.

Diseases and pests

Diseases of Hibiscus are leaf-spot (Cercospora hibisci) and foot rot (Phytophthora parasitica). Common pests are cotton stainer bugs (Dysdercus species), bollworms (Earias biplaga, E. insulana), flea beetles (Podagrica spp.), white fly (Bemisia spp.), woolly aphids and nematodes.

Harvesting

The parts used are just picked from the plants, whenever the need arises.

Handling after harvest

The harvested plant parts of Hibiscus are used fresh or dried.

Genetic resources and breeding

Large germplasm collections of Hibiscus sabdariffa as a fibre crop are maintained in Australia, India, Bangladesh, Sudan and in the United States. Some H. radiatus , H. tiliaceus and H. mutabilis germplasm is kept in Bangladesh and in the United States. Selection and breeding work has been limited to Hibiscus grown for fibre or as ornamentals. Most Hibiscus species havea large distribution area, so there seems to be no risk of genetic erosion.

Prospects

Referring to their uses and properties, many Hibiscus species have good potential as medicinals. Especially H. sabdariffa shows this potential, because it combines food products with antioxidant properties. Pharmacological and industrial information is still rather preliminary, and a full evaluation requires more research.

Literature

  • Adegunloye, B.J., Omoniyi, J.O., Owolabi, O.A., Ajagbonna, O.P., Sofola, O.A. & Coker, H.A., 1996. Mechanisms of the blood pressure lowering effect of the calyx extract of Hibiscus sabdariffa in rats. African Journal of Medicinal and Medical Sciences 25(3): 235-238.
  • Chua, N.M., Solevilla, R.C., Guevara, B.Q. & Santos, P.S., 1987. Anti-microbial properties of Hibiscus sabdariffa Linn. Acta Manilana 36(1): 3-16.
  • Nguyen Van Duong, 1993. Medicinal plants of Vietnam, Cambodia and Laos. Mekong Printing, Santa Ana, California, United States. pp. 240-245.
  • Pakrashi, A., Bhattacharya, K., Kabir, S.N. & Pal, A.K., 1986. Flowers of Hibiscus rosa-sinensis, a potential source of contragestive agent. III: Interceptive effect of benzene extract in mouse. Contraception 34(5): 523-536.
  • Van Borssum Waalkes, J., 1966. Malesian Malvaceae revised. Blumea 14(1): 1-251.
  • Yu, Y.B., Park, J.C., Lee, J.H., Kim, G.E., Jo, S.K., Byun, M.W., Miyashiro, H. & Hattori, M., 1998. Screening of some plant extracts for inhibitory effects on HIV-1 and its essential enzymes. Korean Journal of Pharmacognosy 29(4): 338-346. (in Korean)

Authors

Undang A. Dasuki