Passifloraceae

L Used in southern Nigeria and Ghana as a fish poison and as a remedy for lumbago. The Mano of Liberia use the plant to produce amnesia (Dalziel, 1937; Harley, 1941; Watt, 1967).

C In the related South African A. digitata Engl, a toxalbumin and a cyanogenetic glycoside were reported by Watt and Breyer-Brandwijk (1962).

P Pharmacological investigations showed that aqueous extracts of the Nigerian climber had a graded depressor effect on the blood pressure of the anaesthetized cat. The effect was neutralized by small doses of atropine. A second active principle might be sympathomimetic with vasoconstrictive action (Adesogan and Olatunde, 1974).

Achyranthes aspera L. AMARANTHACEAE

L A common weed locally used in Nigeria as a diuretic and expectorant (Oliver, 1960). C Chemical and pharmacological analyses have been undertaken on the Indian plants.

A betaine derived from AT-methylpyrrolidine 3-carboxylic acid was located by Basu and called achyranthine (Basu etal. ,1957; Kapoor and Singh, 1966). The seeds were found to contain a saponin fraction composed of glycosides (glucose, galactose, xylose and rhamnose) of the genin oleanic acid (Gopalachari and Dhar, 1958). Later work led to the isolation of two pure saponins, Achyranthes saponins A and B (Hariharan and Ranjaswani, 1970).

P Achyranthine has hypotensive, cardiac depressant, vasodilatating and respiratory analeptic actions. It also has a spasmogenic effect on smooth muscles (guinea pig, rabbit, rat) and is diuretic, purgative and slightly antipyretic (Neogi et al., 1970). The diuretic action of the plant has been attributed to its high potassium content. The total saponosides of the Indian plant significantly increase the tone and force of contraction of isolated frog, guinea pig and rabbit hearts. The effect was quicker in onset and shorter in duration than that exerted by digitoxin (Kapoor and Singh, 1966; Neogi et al., 1970; Gupta et al., 1972a, b). It is suggested that the increased contractility caused by the saponin could be related to its Phosphorylase activity (Ram etal., 1971; Indian Council of Medical Research, 1976). It has also been noted that an extract of the plant, when given orally (5 mg/kg), exerts a diuretic, purgative and hypoglycaemic action in rats (Dhar etal., 1968; Neogi etal., 1970; Oliver-Bever and Zahnd, 1979) and that it is also useful in treating subacute and mild reactions in leprosy (Ojha et al., 1966).

Group A2: hypertensives

Musa sapientum L. syn. (M. paradisiaca var. sapientum Ktze.) MUSACEAE

Banana

C Analysis of the bracts of ten wild species of bananas has shown the presence of six anthocyanidins (pelargonidin, cyanidin, delphinidin, malvidin, paeonidin and petunidin). The ripe and unripe fruit also contains 5-hydroxytryptainine (= serotonin) (HoodandLowburry, 1954; Hegnauer, 1962-8; Sinhaetal., 1962). Further, dopamine and noradrenaline (adrenaline precursors) have also been reported in banana plants (Harborne et al., 1974, p. 1013). The three amino phenols are sympathomimetic and in other plants (Sarothamnus scoparius Koch.) have proved to have marked vasoconstrictive properties and to be hypertensive. Banana flowers also have an oral hypoglycaemic action (Jain, 1968; Oliver-Bever and Zahnd, 1979).

Moringa oleĆ­fera Lam. syn. (M. pterygosperma Gaertn.) MORINGACEAE

Horseradish tree (native of India, cultivated throughout the tropics)

L In Nigeria root and bark are considered to be antiscorbutic and are used externally as counter-irritants (Dalziel, 1937). In India the root is used as a stimulant in paralytic affections, epilepsy, nervous debility, hysteria, spasmodic affections of the bowel and as a cardiac and circulatory tonic et al., (Chopra et al., 1956; Watt and Breyer-Brandwijk, 1962; Ramachandran et al., 1980).

C In the rootbark the sulphurated aminobases moringinine and spirochine have been reported, as well as benzylamine (first called moringine) and glucotropaeoline.

Further, the root contains two antibiotic constituents, athomine and ptery-gospermine; the latter is probably a condensation product of two benzylisothio-cyanate molecules with one benzoquinone molecule (Kurup and Narasimha Rao, 1954; Hegnauer, 1962-8, vol. 5, p. 130; KondagboandDelaveau, 1974; Salujaetal., 1978).

P Moringinine has a sympathomimetic action similar to that of adrenaline; it produces peripheral vasoconstriction, raises the blood pressure and acts as a cardiac stimulant. However, Chopra et al. (1938) consider that the quantities present in the plant are too small to make it of interest for cardiology. Moringinine also depresses the smooth muscle fibres; it relaxes the bronchioles and inhibits the tone and movement of the intestine in rabbits and guinea pigs (Das et al., 1957a, b).

Spirochine accelerates and amplifies the heartbeat in Man in doses of 0.035 g/kg and has an opposite effect at a dose of 0.35 g/kg (Watt and Breyer-Brandwijk, 1962). It can produce general paralysis of the CNS. Spirochine also has an antibiotic action, mainly in gram-positive infections, and is used as an external antiseptic and prophylactic in infected wounds (Chatterjee and Mitra, 1951).

Pterygospermine has a powerful antibiotic and antimycotic effect and athomine is particularly active against the cholera vibrion (Kurup and Narasimha Rao, 1954; Sen Gupta et al., 1956; Das et al., 1957a, b; Kurup et al., 1957).

Group B: plants acting on vascular resistance (vitamin P action)

Citrus limonum. C. aurantium, C. decumana RUTACEAE

Largely cultivated

C Citroflavanoids are extracted from the peel of citrus fruit (as a by-product of fruit-juice preparation). They consist of a mixture of which the main constituents are hesperidoside (rhamnoglucoside of hesperetol), naringoside and eryodictyoside (flavanones). The peel also contains essential oils and vitamin C. The inconvenience of the citroflavanones is their low solubility in water, which has led to research with a view to finding more soluble hemisynthetic derivatives like Mg2+ chelates (Horhammer and Wagner, 1962; Ravina, 1964; Paris, 1971 etal., 1972).

P Citroflavonoids control the permeability of the blood vessels by decreasing the porosity of the walls and thus improving the exchange of liquids and the diffusion of proteins. They are therefore used in complaints in which the permeability is increased, such as venous insufficiency (varicose veins, haemorrhoids, capillaritis), and in oedema and ascites in cirrhosis (Paris and Delaveau, 1977; Pourrat, 1977).

The increase in the resistance of the capillaries through the citroflavonoids is based on a complex mechanism including the protective action of o-diphenols on catecholamines participating in vascular solidity. When capillary resistance is diminished, citroflavonoids can prevent bleeding in hypertensive or diabetic patients (diabetic retinopathy) or in purpurea and where there is a tendency to haematoma (Paris and Moury, 1964; Vogel and Strocker, 1966; Paris, 1977).

The citroflavonoids are also said to have anti-inflaminatory, antihistamine and diuretic actions and can cause dilatation of the coronaries (Paris and Delaveau, 1977).

Piliostigma reticulatum (DC.) Hochst. syn (Bauhinia reticulata DC., B. benzoin Kotschy) CAESALPINIACEAE

Bauhinia purpurea L., B. tomentosa L., B. variegata L. (introduced spp.) St Thomas tree

L A poultice of the leaves and bark of Piliostigma is used in Senegal and northern Nigeria as a haemostatic, and an infusion of the bark and buds of B. variegata is given to control bleeding in haematuria and menorrhagia and as an astringent in diarrhoea. The powdered bark of B. thonningii is applied to wounds and ulcers (Dalziel, 1937; Kerharo and Adam, 1974).

C In all species flavonoids (quercetol and kaempferol glycosides) have been found in the leaves, bark and flowers. In B. variegata and B. tomentosa rutosides and isoquercitroside have been reported; from B. tomentosa flower petals 4.6% of rutin has been extracted (Visnawadham et al., 1970; Duret and Paris, 1977). Piliostigma contains tartaric acid and tartrates in fruit and leaves. In the leaves 5.9% free (- )-tartaric acid and 0.5% quercitroside have been reported. The flavonoids seem to justify their local use as coagulants.

Baissea leonensis Benth. syn. (B. brachyantha Stapf) APOCYNACEAE

C The leaves contain no alkaloids but they do contain flavonoids, mainly coumarins. A new crystallized coumarin heteroside, baisseoside, which is a 6-rutinoside of esculetol, was isolated in 1970 by Pousset et al. Other heterosides reported are isoquercitroside, kaempferol 3-glucoside and kaempferol heteroside (Duret and Paris, 1972).

Adansonia digitata L. (Fig. 2.9) BOMBACACEAE

Baobab, monkey bread L The fruit, seeds andleavesofthe baobab are used in food and the bark provides fibre. In West African local medicine all parts are used; they are said to be diaphoretic, antipyretic, antidysenteric, emmenagogic, antifilarial, vulnerary, etc. (Sebire, 1899; Dalziel, 1937; Oliver, 1960). C The leaves contain a mucilage consisting mainly of galacturonic acid and rhamnose, free sugars, tannins, catechins and a dehydroxyflavanol, adansonia flavonoside. They also contain calcium oxalate, potassium tartrate and sodium chloride. Bark and roots also contain a mucilage as well as pectins and an antipyretic agent, adansonin, said to have a strophanthin-like action (Merck Index, 1960; Oliver, 1960; Watt and Breyer-Brandwijk, 1962).

P Adansonia flavonoside showed low toxicity; mice tolerated 1 g/kg given subcu-taneously. Given intravenously, 0.01 g/kg produced only slight hypertension in dogs and decreased the permeability of the capillaries in rabbits, but to a lesser extent than does rutoside (Paris and Moyse-Mignon, 1951).

Mangifera indica L. ANACARDIACEAE

Mango tree

L Naturalized in West Africa. The bark and leaves have astringent properties and are used in Nigeria as a lotion to relieve toothache, sore gums, sore throat, etc., or as an infusion in diarrhoea and dysentery (Dalziel, 1937).

C All organs are rich in tannins. In the leaves of the West African species four anthocyanidins (3-monosides of delphinidin, petunidin, paeonidin and cyanidin), leucoanthocyanins, catechic and gallic tannins, mangiferin (flavonic heteroside), kaempferol and quercitin (both free and as glycosides) were reported (Jacquemain, 1970,1971).

In pharmacological tests anthocyanidins similar to those found in mango leaves but extracted from Vaccinium myrtillus leaves increased the resistance and decreased the permeability of capillary vessels, and have been successfully used for over 20 years m treating vascular troubles, eye complaints and diabetes (Pourrat, 1977). In diabetic angiopathy they inhibit, or slow down, the modifications of the capillary wall, and it is believed that the improvement obtained in diabetes with anthocyanosides can well be due to recovery of the vascularization of the pancreas.

Excellent results were also obtained in retinopathy of hypertensive or diabetic origin and anthocyanosides are in general a valuable aid in venous complaints, capillary fragility, purpura, cirrhosis and in the prevention of haemorrhagic accidents through the use of anticoagulants (Pourrat, 1977).

Feng et al., (1964) noted that injection of an aqueous extract of leaves and stems of Mangifera produces in dogs a distinct hypotensive action. In rabbits a similar effect was obtained with an alcoholic extract (Feng et al., 1964). It seems that a suitable fraction with vitamin P action should be easily obtainable from mango leaves. Some toxic constituent may have to be eliminated first, as absorption of preparations based on the leaves, stems and bark produces irritation of the stomach and kidneys, and ingestion of the fruit in large quantities can produce shock reactions (Ruben et al., 1965).

The aqueous extract of the stembark showed favourable results in transplantable cancer tumours. These have been reduced by 47% in adenocarcinoma 765, and by 53% in sarcoma 180 (Abbot et al., 1966).

Sophora occidentalis L. syn. (S. nitens Schum. & Thonn., 5. tomentosa (of FT A)

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