Aristolochia (PROSEA)

Plant Resources of South-East Asia
Introduction

List of species

Aristolochia L.

Protologue: Sp. pl. 2: 960 (1753); Gen. pl. ed. 5: 410 (1754).

Family: Aristolochiaceae

Chromosome number: x= 7; A. tagala: 2n= 14

Major species

Aristolochia tagala Cham.

Vernacular names

Birthwort, Dutchman's pipe (En). Snakeroot (Am).
Aristoloche (Fr).

Origin and geographic distribution

Aristolochia consists of approximately 300 species and is mainly distributed throughout the tropics, but some species occur in warmer temperate regions. The greatest diversity in species is found in Central and South America. In the Malesian region 28 species have been found; A. tagala has the largest area of distribution, occurring from India and China, throughout South-East Asia, to Australia.

Uses

Aristolochia is not much used in local medicine in South-East Asia. The use of a decoction of the roots as a stomachic, emmenagogue and febrifuge is most common. A poultice of the leaves is sometimes used to treat skin diseases. Some extra-Malesian species are, however, renowned in Chinese, Indian and South American health care systems, and are included in pharmacopoeias.

The Chinese Pharmacopoeia lists e.g. the dry ripe fruits of A. contorta Bunge and of A. debilis Sieb. & Zucc. which are used in the treatment of respiratory diseases as an antitussive and antiasthmatic. Their dry aerial parts are also used as a diuretic against oedema and as an antirheumatic. The root of A. fangchi Y.C. Wu ex L.D. Chou & S.M. Hwang is valued as an antirheumatic and diuretic and the dried vine of A. mandshuriensis Kom. is a well-known diuretic and antiphlogistic for treatment of oedema and rheumatic pain. In China and Japan, extracts from the roots of A. debilis are furthermore used to treat high blood pressure.

A. bracteolata Lamk (synonym: A. bracteata Retz.) and A. indica L. have a considerable reputation in India. A. bracteolata is reputed for its purgative and anthelmintic properties; a root decoction is employed to expel roundworms, and is known as an emmenagogue. In Africa, A. bracteolata has a local reputation as a powerful anthelmintic mostly used in veterinary practice. The dried rhizomes and roots of A. indica constitute an important drug in India, much esteemed as a gastric stimulant and bitter tonic and used to treat intermittent fevers. The drug is prescribed as a tincture, and sometimes administered as a powder. The juice of fresh leaves is used to treat coughs, and the seeds to treat inflammations, biliousness and cough. Juice from the leaves is applied to ulcers and, mixed with castor oil, to eczema. A. indica is also used in India as an antidote for snakebites and scorpion stings. In traditional Thai medicine, the roots are used as antipyretic, emmenagogue, expectorant and tonic. The leaves are used in the treatment of snakebites. Its roots possess antifertility activity. A. tagala roots are considered in India to be tonic, carminative and emmenagogue. They are frequently used there to adulterate A. indica for use in medicine. A. elegans Masters from tropical America has medicinal and insecticidal properties and is locally cultivated in South-East Asia, e.g. in the Philippines and Thailand. In Vietnam, some species are imported from China to be used in local medicine, e.g. A. heterophylla Hemsley and A. westlandii Hemsley, which are used as diuretic and prescribed to treat oedema and dysuria. A. serpentaria L. is used in local medicine in North America.

Several American species are cultivated as ornamentals for their beautiful flowers. Some species are cultivated as food plants for the larvae of commercially traded swallowtail and birdwing butterflies.

Production and international trade

None of the Malesian Aristolochia species are traded, but fruits of A. debilis are imported from China and sold in Chinese medicine shops in Peninsular Malaysia.

Properties

The chemical constituents of Aristolochia species can generally be divided into three chemical groups: aristolochic acids (derivatives), alkaloids and sesquiterpenes.

The aristolochic acids are a family of at least 14 closely related structures, derived from the phenanthrene system and bearing a carboxyl function and a nitro substituent. These compounds are intensely bitter, and it is hypothesized that in their biosynthesis oxidative coupling of orientaline gives prestephanine, which is converted into stephanine; oxidative cleavage of stephanine then furnishes aristolochic acids. When the nitro group is replaced biosynthetically by an amino group, the carboxyl group forms a lactam ring, giving a number of aristolactams. Aristolochic acid can furthermore be converted to aristolic acid by a one-step removal of the nitro group.

One of the alkaloids isolated from some Aristolochia species is magnoflorine (an aporphine type alkaloid derived from phenylalanine/tyrosine), which is structurally and phylogenetically strongly related to aristolochic acid derivatives. The sesquiterpenes are mainly constituents of the volatile oil.

Not much is known about the properties and chemical constituents of the South-East Asian species, except for some information on A. tagala from the root of which aristolochic acid I (= aristolochic acid A), aristolochic acid IIIa (aristolochic acid C), 9-hydroxyaristolochic acid I and allantoine have been isolated. Much more research has been done on some Indian and Chinese species.

Aristolochic acid I (0.1-0.6%) and debilic acid have been isolated from the roots of A. debilis, together with 9-hydroxy and 9-methoxyaristolochic acid I, aristolochic acid II, aristolochic acid IIIa, aristolochic acid IV, aristolochic acid IVa (= aristolochic acid D) and some aristolactams. Furthermore isolation of the alkaloidal constituents magnoflorine, cyclanoline, tetrandrine, N-acetyl-nornuciferine and allantoine has been reported. The sesquiterpenes isolated are mainly of the aristolane type: e.g. aristolone (about 0.42%), 9-aristolene, 1(10)-aristolene and debilone. Aristolochic acid I methyl ester, aristolochic acid IV methyl ester and aristolochic acid IVa were isolated from the stems of A. mandshuriensis, and magnoflorine detected. In addition, a new glycoside of aristolochic acid D was also isolated and named aristoloside or aristolochin. Phytochemical analysis of the constituents in the roots of A. fangchi revealed amongst others the presence of aristolochic acid I, aristolochic acid IVa, aristolochic acid IV methyl ester, magnoflorine, p-coumaric acid and N-(p-hydroxyphenyl)-p-coumaramide in the ethanol extract. Together with aristolochic acid I, magnoflorine and allantoine, a new compound aristolochic acid E was isolated from the root of A. contorta. Several aristolochic acids and derivatives (e.g. aristolic acid), sesquiterpenes, alkaloids (e.g. l-curine), steroids, p-coumaric acid and a naphthaquinone (aristolindiquinone) have been identified from the roots of A. indica. A phytochemical investigation of the leaves of A. elegans indicated the presence of sterols and 5 alkaloids. The steroidal material was isolated and identified as β-sitosterol. The seeds of A. bracteolata contain aristolochic acid and magnoflorine. Aristolochic acid I and IVa, magnoflorine, allantoine and β-sitosterol have been isolated and identified from the roots of A. heterophylla.

The biological activities of aristolochic acid I have been studied extensively. A number of gram-positive bacteria (including Bacillus, Diplococus, Mycobacterium, Sarcina, Staphylococcus and Streptococcus) are inhibited by this acid at a concentration of 50-200 μg/ml. A concentration of aristolochic acid I higher than 200 μg/ml was needed to inhibit gram-negative bacteria and fungi. Mice infected with Diplococcus pneumoniae, Staphylococcus aureus or Streptococcus pyogenes were found to be protected from disease by intraperitoneal administration of aristolochic acid I at a dose of 50 μg/kg. The phagocytic activity of peritoneal macrophages of treated mice was markedly stimulated. Some results of studies on the immunostimulating and antitumour activities of aristolochic acid I contradicted each other. It has been reported that the survival time of mice bearing ascitic sarcoma-37 tumours treated with aristolochic acid by intraperitoneal administration at a daily dose of 1-5 mg/kg for 5 days was appreciably prolonged. Growth of mouse sarcoma-37 cells was found to be completely inhibited by incubation with aristolochic acid I. Treating mice with aristolochic acid I at a daily dose of 2.5-5 mg/kg for 3 days after subcutaneous implantation of sarcoma-37 cells resulted in 40-50% inhibition of tumour growth. Aristolochic acid I, administered orally, reduced the number of tumours induced by methylcholanthrene in mice. Aristolochic acid I increased oxygen consumption in a dose-dependent manner in liver cells and splenocytes of mice. The metabolic activity of guinea-pig peritoneal macrophages and human leucocytes was also enhanced by aristolochic acid I, as shown by measuring oxygen consumption. Both aristolochic acid I and II exhibited a stimulation of lucigenine-enhanced, opsonized Zymosan-induced neutrophil chemiluminescence as a sensitive assay for immunomodulating activity. In a leucocyte adherence inhibition test, an activity of aristolochic acid I could also be demonstrated; however, it was weaker than that of prednisolone. Following the administration of aristolochic acid I to guinea-pigs immunized with Q-fever antigen, the antigen-induced decrease in bone marrow lymphocyte count was restored to normal levels much faster than was observed in untreated immunized controls. In contrast to these results, there is also a report that aristolochic acid I did not prolong the survival time of tumour-bearing mice or enhance the immune function of the mouse reticuloendothelial system, or the phagocytic activity of mouse peritoneal macrophages. Aristolochic acid has been shown to be a non-competitive inhibitor of phospholipase A2 from snake venom. It inhibited the oedema-inducing and haemolytic activity of this compound in the venom, but failed in tests to inhibit other pathological activities of the enzyme.

Aristolochic acids are known for their nephrotoxicity in humans and several animal species, and their mutagenic and carcinogenic activities have also been extensively studied. Aristolochic acid I has been proved to be a direct mutagen in Salmonella typhimurium strains TA 1537 and TA 100, but had no mutagenic effect on TA 1535, TA 1538 or TA 98. Aristolochic acid II had almost equal mutagenic potency, and the aristolactams were mutagenic in both strains too, when a metabolizing system was present. The mutagenic activity of aristolochic acid I was also tested in the granuloma pouch assay, which detects gene mutations induced in subcutaneous granuloma tissue of rats. After direct exposure of the target tissue, aristolochic acid I induced high frequencies of mutations at a relatively low cytotoxic level. After oral administration of aristolochic acid I to rats, a dose dependent mutagenic activity was registered. The carcinogenic activity of aristolochic acid I has been demonstrated in experimental animals. Male and female rats treated orally with aristolochic acid I at daily doses of 0.1, 1.0 or 10.0 mg/kg developed a high incidence of tumours, dependent on dose and time. Rats treated for 3 months with either 1.0 or 10.0 mg/kg aristolochic acid I developed severe papillomatosis of the forestomach, with occasional signs of malignancy. Without further treatment, the rats developed squamous cell carcinomas in the forestomach 3-6 months later and formation of metastases. For these reasons, many European countries (e.g. Germany and France) have restrictive regulations for preparations containing Aristolochia, even including homeopathic preparations with their great dilution.

The alkaloid magnoflorine is a hypotensive principle. In rabbits it decreased arterial blood pressure and induced hypothermia. In anaesthetized cats, intravenous injection of 2 mg/kg magnoflorine produced a prompt and significant fall in blood pressure. Oral administration at a dose of 20-40 mg/kg also resulted in hypotension. The acute LD₅₀ of magnoflorine by intravenous injection in mice was 20 mg/kg. Oral administration with a tenfold higher dose daily for 4 weeks did not elicit any toxic symptoms or retard growth.

Aristolic acid (biosynthetically derived from aristolochic acid through removal of the nitro group) obtained from A. indica disrupted nidation in mice when administered on the first day of pregnancy. It showed implantation-inhibiting effects. Possibly this compound interferes with steroidal conditioning of the uterus. Furthermore, both aristolochic acid I and magnoflorine induced contractions in isolated pregnant rat uterus and stimulated guinea-pig ileum. p-Coumaric acid isolated from A. indica roots is known to be an inhibitor of prolactin secretion.

Ethanol extracts of A. indica roots decreased fertility in rats and hamsters. The petroleum ether extract of the roots showed 100% interceptive activity in mice at a single dose of 100 mg/kg. The sesquiterpene (12S)-7,12-secoishwaran-12-ol is reported as another active principle. Other laboratory experiments have failed to demonstrate activity on uterine contraction, and experiments on abortifacient activity have been inconclusive.

Tests on rats with ethanolic extracts of A. indica showed no antipyretic activity. The ethanol extract of A. bracteolata exhibited uterine stimulant and anthelmintic properties. Aqueous and alcohol extracts of A. debilis were found to be highly effective against herpes simplex virus in vitro, and also showed some effect on respiratory syncytial virus and coxsackie virus. Extracts of A. mandshuriensis showed significant inhibitory activity on the mutagenicity of 3-amino-1,4-dimethyl-5H-pyrido-(4,3-b)-indole, and anglotensin converting enzyme.

The aristolochic acids extracted from A. bracteolata showed chemosterilizing effects on several insect species including mosquitoes. In the Philippines, extracts from A. tagala showed insecticidal properties against the yponomeutid crucifer pest Plutella xylostella, the maize pest Ostrinia furnacalis and the common cutworm (Spodoptera litura). A methanolic extract of A. bracteolata showed significant inhibitory effect on the aflatoxin production of Aspergillus flavus, and the plant may have potential as an antifungal agent.

Adulterations and substitutes

There are indications that Aristolochia extracts are sometimes mistaken for Menispermaceae extracts. Rapidly progressive renal fibrosis has been described in young women who had taken Chinese herbs as part of a slimming regime. Aristolochic acid was suspected as its causal factor, but this compound is not present in the Stephania extract, which is one of the ingredients of the drug. Possibly an Aristolochia extract and not a Stephania extract was used to prepare the drug in question.

Description

Woody or herbaceous perennial climbers or erect, scandent to scrambling shrubs often woody at base; tuberous or prostrate rhizomes or rootstocks often present; older woody stems usually with a thick corky and fissured bark.
Leaves arranged spirally or alternate, simple, usually entire but sometimes 3-lobed, venation palmate or pinnate, secondary veins often extending obliquely towards the leaf margin; petiole grooved above; stipules absent.
Flowers solitary or in fascicles or in cymose, racemose, spicate or paniculate inflorescences, in the axils of leaves or borne on the stems, bisexual, zygomorphic (rarely actinomorphic), bracts usually present and persistent, pedicel usually hardly distinct from the ovary; perianth consisting of 3 parts with a basal inflated part (utricle), a straight or curved cylindrical tube, and the expanded 3(-6)-lobed limb with valvate or induplicate lobes or (usually) 1-lipped; stamens 6(-10), in a single whorl, adnate to the style column to form a gynostemium, anthers extrorse and dehiscing longitudinally; ovary inferior, oblong or elongate, 6-celled, style column 6-lobed.
Fruit a 6-celled capsule, dehiscing septicidally, usually basally towards the apex, many-seeded.
Seeds ovate, deltoid or triangular, flat, often winged, testa crustaceous or hard, finely verrucose or smooth, funicle often thickened and covering the whole seed, with fleshy and copious albumen and minute embryo.
Seedling with epigeal germination; cotyledons rather fleshy; first 2 leaves opposite, subsequent ones alternate.

Growth and development

In Aristolochia the flowers of an inflorescence open only singly or very few at a time. Their form is related to the flytrap pollination mechanism. The flowers are insect-pollinated, usually by flies and sometimes by ants attracted by the putrid odour of the flowers and trapped in a kettle-like part (utricle), after having passed a "slide zone" on the limb. The flower tube in between the limb and utricle is usually provided with retrorse hairs preventing insects from leaving the utricle. The flowers are proterogynous and the ripe stigmas may be pollinated by insects when entering the utricle, where glands provide feed to keep them alive until the stamens have ripened. Mostly flowers open around daybreak and wither after about 24 hours, but sometimes they last longer. After the stamens have shed their pollen, the flower withers, the hairs in the tube lose turgescence, and the insects can leave the utricle and possibly visit another flower, leading to cross-pollination. However, some Aristolochia species are not furnished with such specialized systems to promote cross-pollination and are then self-fertilized.

The fleshy funicle of the seed forms an elaiosome which is probably attractive for ants dispersing the seeds. The seed wing present in some Aristolochia (e.g. A. tagala) may serve wind dispersal.

Other botanical information

Flowering material of Aristolochia is generally needed for correct identification, but flowers are often scantily represented in herbaria, and are commonly deformed by drying.

Ecology

Aristolochia usually occurs scattered, often in primary forest, but some species (e.g. those discussed here) are also found in secondary forest and scrub vegetation. Most species are confined to lowland forest, but some occur above 1500 m altitude.

Caterpillars of several butterfly species (particularly swallowtail butterflies of the family Papilionidae) are known to feed exclusively on leaves and young shoots of Aristolochia. They use chemical compounds in the plants to become poisonous for predators. For instance, it has been shown that aristolochic acid I present in larvae feeding on A. debilis deterred feeding of tree sparrows, but also triggered cannibalistic activity of the larvae against eggs and pupae, which also contain the compound. It has also been demonstrated that aristolochic acid induces a significant oviposition response in female swallowtail butterflies.

Propagation and planting

In India, Aristolochia is usually propagated by seed, which germinates in about 2 weeks. Sometimes it is grown from rhizomes collected from the wild.

Experimental in vitro propagation has been successful for A. bracteolata in India. The formation of callus was observed from young leaves and nodes placed on Murashige and Skoog medium supplemented with kinetin, naphthalene acetic acid and indole acetic acid. Roots were initiated from the callus when the concentrations of kinetin and indole acetic acid were increased. From a single nodal segment 1-4 shoots were raised, and shoots grew 5-6 cm tall within 30 days.

Diseases and pests

Although caterpillars of various butterfly species feed on the leaves of Aristolochia, they are rarely reported to cause extensive defoliation.

Harvesting

In India, A. indica is allowed to grow for 2 years to yield rootstocks of marketable size.

Yield

The yield of A. indica rootstocks in India is estimated at 4.5-5.6 t/ha in 2-year-old plantations.

Handling after harvest

No information available.

Genetic resources and breeding

Most Aristolochia species have a limited area of distribution and occur very scattered in lowland forest. This makes them very vulnerable to genetic erosion due to rapid changes in land use. Some species (e.g. A. indica in India) have already become rare in the wild because of their popularity for medicinal purposes.

Prospects

The medicinal uses of Aristolochia are extremely local in South-East Asia and in addition many of them were reported more than 100 years ago. However, Aristolochia is widely used medicinally, particularly in China and India, and the activity for several applications has been demonstrated by research. The South-East Asian Aristolochia probably have similar properties, but these still have to be confirmed by experiments. A major drawback for use in medicine is the carcinogenic activity of some of the major active compounds, limiting the application in modern medicine. The viricidal, fungicidal and insecticidal properties might offer prospects for wider use.

Literature

Bruneton, J., 1995. Pharmacognosy, phytochemistry, medicinal plants. Lavoisier Publishing, Paris, France. pp. 748-749.
Council of Scientific and Industrial Research (various editors), 1985. The wealth of India. Revised Edition. Vol. 1. Publications and Information Directorate, New Delhi, India. pp. 422-427.
Ding Hou, 1984. Aristolochiaceae. In: van Steenis, C.G.G.J. & de Wilde, W.J.J.O. (Editors): Flora Malesiana. Series 1, Vol. 10. Kluwer Academic Publishers, Dordrecht, Boston, London. pp. 53-108.
El Tahir, K.E.H., 1991. Pharmacological actions of magnoflorine and aristolochic acid-1 isolated from the seeds of Aristolochia bracteata. International Journal of Pharmacognosy 29(2): 101-111.
Ganguly, T., Pakrashi, A. & Pal, A.K., 1986. Disruption of pregnancy in mouse by aristolic acid I. Plausible explanation: relation to early pregnancy events. Contraception 34(6): 625-638.
Phuphathanaphong, L., 1987. Aristolochiaceae. In: Smitinand, T. & Larsen, K. (Editors): Flora of Thailand. Vol. 5, Part 1. The Forest Herbarium, Royal Forest Department, Bangkok. pp. 1-31.
Quisumbing, E., 1978. Medicinal plants of the Philippines. Katha Publishing Co., Quezon City, the Philippines. pp. 254-256.
Remeshree, A.B., Hariharan, M. & Unnikrishnan, K., 1994. Micropropagation and callus induction of Aristolochia bracteolata Lam. - a medicinal plant. Phytomorphology 44(3-4): 247-252.
Schmeiser, H.H., Bieler, C.A., Wiessler, M., van Ypersele de Strihou, C. & Cosyns, J.P., 1996. Detection of DNA adducts formed by aristolochic acid in renal tissue from patients with Chinese herbs nephropathy. Cancer Research 56(9): 2025-2028.
Tang, W. & Eisenbrand, G., 1992. Chinese drugs of plant origin. Springer Verlag, Berlin, Heidelberg, New York. pp. 145-157.

Selection of species

Authors

R. Kiew