Poussetera/. (1974) Levéqueáía/. (1975) Ross et al. (1980) Dhar etal. (1968) Nara etal. (1977) N N
Ogunlana and Ramstad (1975) Deláveauefaí, (1979) CV
Dhar etal. (1968) Sato and Muro (1974)
(e) Antimetazoal plants (anthelmintics)
Some anthelmintics act by paralysing worms (such as tapeworm), which then may have to be expelled by a purge. However, some drugs are also purgative themselves. Other anthelmintics can destroy the parasite through lysis, for example those containing proteolytic enzymes like bromelain from Ananas comosus, calotro-pain from Calotropis procera and papain from Carica papaya can digest worms. In other cases drugs (like antimony in the case of trematodes) act through inhibition of phospho-fructokinase, thus reducing the energy required by the worms to maintain their attachment to the walls of the mesenteric vessels and forcing them to emigrate into intra-hepatic portal veins, where they are destroyed by phagocytosis. Certain filaricides also cause the iilaria embryos to emigrate to the liver, where they are subject to lysis by the cells of the reticulo-histiocytal system (Lechat et al., 1978).
Many constituents with antibacterial activity are also anthelmintic. Apart from the vermicidal action already mentioned under antibacterial constituents, plumbagin (naphthoquinone) also appears to be active against cestodes; thus, Diospyros mollis also acts on Hymenolepis nana. Other plants containing gallic acid and ethylgallate such as Acacia arabica, A. famesiana and A. nilotica also act on cestodes. This applies also to Combretum racemosum and another Combretaceae, Anogeissus leiocarpus, which contain gallic acid and tannins.
Alkaloids are often the active agents. Echitamine from Alstonia boonei acts against loa loa filariasis (Calabar swellings). The anthelmintic action of Spigelia anthelmia is attributed to spigeline, that of Andira inermis to berberine and/or andirine, that of Punica granatum to pelletierine tannate (acts on cestodes), that of Quisqualis indica to an alkaloid contained in the seeds and that of Hunteria umbellata to hunteramine or related alkaloids.
Flavonoids found in Citrus acida and Albizia lebbeck have antinematodal properties. In Bixa orellana the wax-like substances from the seed coat have been said to paralyse intestinal parasites.
Terpenoids. Many plants contain glucosides with terpenoids or resins as a genin and for many of these plants the action may be due to the genin. Amongst them we find some well-known anthelmintic plants such as Chenopodium ambrosioides* (ascaridole, monocyclic terpene) and Cucurbita maxima* and C. pepo* (fruits), which have glucosides of tetracyclic triterpenes (cucurbitacines). These and ascaridole also force cestodes to emigrate but do not destroy them and their administration must therefore be followed up by a purge. Triterpenes are also found in Melia azedarach roots (act on cestodes and ascarides) and Santalum album (santalenes, tricyclic sesquiterpenes) both plants also being insecticides. Tetracyclic sesquiterpenes are reported in Euphorbia resins (euphol and euphorbol). Pentacyclic triterpenes derive from a- and /3-amyrine, and oleanolic acid has been found as a constituent of the stembark of Opilia celtidifolia*, which stimulates the activity of Taenia pisiformis. Several anthelmintics owe their action to resins or glucoside resin-compounds. Albizia lebbeck, Embelia schimperi*, Mallotus philippinensis and Phytolacca dodecartdra have been mentioned as such.
Mustard-oil heterosides. Plants with antibiotic properties that contain mustard-oil heterosides, such as Allium spp., Cleome gynandra and Ritchiea longipedicilata* are also anthelmintic, and an active benzylisothiocyanate derivative (pterygospermine) is present in Morittga oleifera as well as triterpenoids.
The plants containing proteolytic enzymes have been mentioned above and under Antibacterial plants. In Harrisonia abyssinica*, warburganal is considered to be the active agent.
American or Indian wormseed, sweet pigweed L Cultivated and naturalized as a domestic anthelmintic. The pounded leaves are also applied to sores (Dalziel, 1937). C The fresh aerial parts, harvested when the plant is flowering, yield 0.2-0.5% of an essential oil from the leaves, 0.5-1% of the oil from the flowering tops and over 1% from the fruits. The oil contains 20-30% of terpenoids (p-cymene, limonene, terpene) and 60-80% of ascaridol (peroxide of a terpenoid), which is mainly abundant in the fruit (Paris and Moyse, 1967, p. 131). P Ascaridol is toxic to cold-blooded animals. It kills and paralyses Ascaris and hookworms (Ankylostoma) and to a lesser extent oxyurides and cestodes. Its administration must be followed by a saline or oily purge. In Man it may induce vertigo, vomiting and headaches, and is more often used in veterinary medicine (Paris and Moyse, 1967, p. 132; Kerharo and Adam, 1974).
Cucurbita maxima Duchesne Cucurbita pepo L. CUCURBITACEAE
Pumpkin, squash gourd L The fruit (pulp) and leafy shoots of these plants are eaten as a vegetable and in soup whilst the gourds are used as domestic utensils. The seed kernels of both species are used in India and in some parts of Europe as an anthelmintic for tapeworm and as a diuretic, and the scraped pulp is applied as a poultice to burns, boils and swellings or even as a cooling application for headache or neuralgia (Dalziel, 1937). C The pulp of the fruit of both species has been found to contain highly nutritive proteins, carbohydrates and minerals and also contains an amino acid, cucurbitine (amino-3-carboxy-3-pyrrolidine), believed to be responsible for the anthelmintic effect (Schabort, 1978). The seed oil of C. maxima is composed of 20.5% palmitic, 28% oleic, 8.5% stearic and 43% linoleic acids (Tewari and Srivasta, 1968) and that of C. pepo contains the same fatty acids but in slightly different proportions. In some bitter varieties of C. pepo (var. ovifera) the cucurbitacines B, D, E and I (toxic tetracyclic terpenes) have been found. Some of these which act as purgatives are also present in other Cucurbitaceae, particularly cucurbitacine E. P The aqueous, ethereal and alcoholic extracts of the seeds of both plants have been found to have anthelmintic properties in vitro and in vivo. In vitro they significantly affect trematodes (Fasciolopsis buski) but they seem to be virtually inactive on nematodes and on Ascaris lumbricoides (Srivasta and Singh, 1967) and they are also inactive on cestodes (Rallietina casticillus in fowl) (Lahon et al., 1978). The extracts have some cardiotonic action. The active principle is believed to be cucurbitine, which paralyses earthworms (Lumbricoides terrestris) within 117 min after application of a 2.9 x 10"3 M solution. This is an effect comparable to that of piperazine, a standard anthelmintic drug (Bailenger and Sequin, 1966). Gonzalez et al. (1974) noted that cucurbitine had a contractile action on the isolated rabbit intestine, which was counteracted by atropine but not by papaverine. Similarly cucurbitine paralyses Taenia spp. but its administration must be followed after 4-5 h by a saline purge to expel the parasite. Oral administration of a preparation of a stable, concentrated and deproteinized extract of the fresh seeds of C. maxima was, according to Junod (1964), not only well tolerated but in 80 patients with Taenia saginata produced 84.6% success. When the extract was given by duodenal or gastric tube, the treatment was successful in all of 54 cases (Gonzalez et al., 1974; Bizyulyavichyus, 1969). The seeds of C. pepo are also reported to be an excellent anthelmintic especially against Taenia and Botriocephalus; in adults, doses of 50-60 g of fresh seeds are non-poisonous. Two fractions (not only cucurbitine) are thought by Bailenger and Sequin (1966) to be responsible.
Furthermore, it has been noted that the crude aqueous extract of the ripe fruit of C. pepo inhibited in vitro virulent strains of Mycobacterium tuberculosis in 1:10000 dilution and retarded over 50% at a 1:100000 dilution. This efficiency was confirmed in vivo in mice. Peposin (obtained from the acetone extract) inhibited the growth of Mycob. tuberculosis in a dilution of 1:50000 for a period of 3 weeks (Gangadharan and Sirsi, 1955).
Opilia celtidifolia (Guill. ex Perr.) End. ex Walp. syn. (Groutia celtidifolia (Guill. & Perr.) Endl. ex Walp., O. amentaceae of Chev.; of Aubrev.) OPILIACEAE
L An extract of the bark of Opilia is used as an anthelmintic while its leaves are used in the treatment of sleeping sickness and as a diuretic.
C A methanol extract of the stembark yielded four saponins, the sugar moiety of all of these being arabinose and mannose. The aglycones of two of them have been identified as aleonalic acid whilst the aglycone of a third was found to be hederagin (Haerdi, 1964; Bouquet, 1972; Shihata etal., 1977).
P Pharmacological studies by Shihata et al. (1977) revealed that intravenous injection of the saponin fraction of the stembark into anaesthetized dogs in doses of 20 mg/kg caused an increase in respiratory rate and a fall in blood pressure, which started to increase slightly after 30 min but did not return to its normal level. There was no effect on the renal circulation. The non-pregnant rat uterus was stimulated by doses of 40-100 mg/50 ml bath whilst the pregnant uterus did not respond. Doses higher than 10 mg inhibited intestinal motility but did not affect the intestinal response to acetylcholine. On the isolated rabbit heart 5-25 mg produced severe reduction in coronary outflow.
A study on the anthelmintic action of the saponins on intestinal worms isolated from dogs has shown slight stimulation of motility in Toxocara leonani by high doses (100-150 mg/50 ml bath). Taenia pisiformis was more easily affected: 50-150 mg/50 ml produced distinct stimulation of motility (Shihata et al., 1977).
Embelia schimperi Vatke syn. (E. abyssinica Bak.) MYRSINACEAE
L In Uganda the leaf is used as a foodstuff; in different parts of Africa the berries are used as an anthelmintic against Taenia (an overdose is said to be often fatal). Related Indian species like E. ribes are also anthelmintic and mainly used against ascarides.
C The berries of the African species contain 6-7.5% embelin (2.5-dihydroxy-3-undecylbenzoquinone) whilst those of the Indian species contain 2.5-3% of embelin. In addition, quercitol, fatty ingredients and an alkaloid, christembine, are reported to be present (Chopra et al., 1956; Kapoor et al., 1975). The African Embelia is said to contain a toxalbumin (Watt and Breyer-Brandwijk, 1962, p. 786).
P In Africa embelin has been used in doses of 0.2-0.4 g as a taeniacide. In India embelin is said to have no effect on Taenia and hookworm but to be very effective in the treatment of ascarid infections. Clinical studies on 40 children infected by ascarides have shown a positive effect in 80% of the cases using an alcoholic and aqueous percolation of the berries whilst an aqueous extract cured 55% in both cases, eliminating ova from patients' stools. The worms were also expelled from the stools and no purging was required. No evidence of toxicity was noted during or after the treatment (Guru and Mishra, 1966). Perhaps the same results might be obtained in Africa if the toxalbumin could be eliminated. Aqueous extracts of the berries have proved to be antibacterial against Staphylococcus aureus and Escherichia coli in India (Chopra et al., 1956) and have also been found to reduce fertility (Arora et al., 1971). Gupta et al. (1976) have reported that the anthelmintic properties of embelin were greatly improved by using analogues obtained by chemical substitution such as isobutyl-embelin or n-hexylaminoembelin whilst di-imines were inactive. In concentrations of 1-3 x 10"3 the analogues were active (contact period 30 min) on the parasites tested: Paramphistomum cervi, Trichuris ovis, Oesophagostomum columbianum, Dipylidium caninum (flukes, roundworms and tapeworms).
L In Nigeria, an extract of/?, reflexa is used to treat guinea worm infection, the roots being used to treat earache (Dalziel, 1937). The leaves of the related R. cap-paroides (Andr.) Britten are reputed in Senegal to be antivenomous and andfilarial, and the roots plus leaves are used externally in the treatment of snake bites and of guinea worms infection. Roots and twigs are used as a plaster on the cervical (enlarged lymph nodes) 'ganglia' of patients suffering from Gambiense trypanosomiasis (Kerharo and Adam, 1974, p. 323).
C Cleomin has been isolated from the rootbark and identified as S(-)-ethyl-5-methyl-2-oxazolidine-thione, which is obtained by enzymatic hydrolysis of glucoc-leomin, a mustard-oil glycoside; it has also been found in Gynandropsis gynandra
(L.) Briq. (Misra and Sikhibhushan Dutt, 1937; Ahmed et al., 1972; Oguakwa et al., 1981).
P Mustard oils, including the oils of Allium spp., and senevols are reputed to have antiseptic, rubefacient and anthelmintic properties; this seems to justify the local uses of the plant.
Harrisonia abyssinica Oliv. syn. (H. occidentalis Engl.) SIMAROUBACEAE
L In Ghana the rootbark is boiled and drunk with palm wine as a laxative (Irvine, 1930). Watt and Breyer-Brandwijk (1962) report that the Teita and Jaluo tribes use the root as a remedy for bubonic plague, and the Sukuma administer it as an anthelmintic against oxyures and ascarides. The Nyamwezi swallow the smoke from the burning rootbark for ancylostomiasis until 'the smoke passes through the intestine'. The leaf is applied to abscesses and carbuncles.
C From Harrisonia (root?) cantine-6-one, harrisonin, obacunin, obacunoic acid, warburganal and muzigadial have been isolated (Mitscher et al., 1972b; Kubo et al., 1976, 1977).
P Githens (1949) has reported the action of Harrisonia roots against roundworm. In experimental malaria the roots proved ineffective (Spencer et al., 1947a). Warburganal is a potent antifungal, antiyeast agent and a potent antifeeding agent against army worms (Spodoptera littoralis and S. exempta) (Kubo et al., 1977; Vigneron, 1978), thus confirming local anthelmintic uses. Ether extracts of the root are reported to have an antimicrobial effect against Neisseria gonorrhoea and Trichophyton mentagrophytes (Uiso, 1979).
For a more comprehensive list of plants with antimetazoal action see Table 4.5.
Fig. 4.9. Quisqualis indica L.
Fig. 4.9. Quisqualis indica L.
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