West African wild indigo, Indigo vine
L The leaves are applied as a poultice to ulcers of the foot, etc. or as a dressing for skin diseases. The bark and root are a remedy for jaundice and are used as a general tonic (Dalziel, 1937). A decoction of the bark with native natron is, in certain districts, a treatment for abdominal troubles, with flatulence in horses. The leaf decoction is also used for the treatment of venereal disease and semen insufficiency (Ainslie, 1937).
C The fresh leaves of L. cyanescens contain 0.08-0.3% of indigo, yielding 43% of indigotin. The dried leaves can yield as much as 56% of indigotin (Dalziel, 1937). From the chloroform extract of the roots, glycyrrhetinic acid, rotenone and lonchoterpene have been isolated, and from the methyl alcohol extract oleanolic acid and ursolic acid have been isolated. Four unidentified minor compounds have also been reported from these extracts (Iwu and Ohiri, 1980). In the related Nigerian Lonchocarpus laxiflorus Guill. & Perr., isoflavans (laxiflorin and lonchoflavan) and pterocarpans have been reported (Pelter and Amenechi, 1969). Glycyrrhetinic acid (also known as glycyrrhetic acid) is a pentacyclic terpene. It was first obtained by hydrolysis of glycyrrhizin (or glycyrrhizic acid) from Glycyrrhiza glabra, which yielded two molecules of glucoronic acid and one of glycyrrhetic acid (Bombardelli etal., 1979).
P Chloroform and methyl alcohol extracts of L. cyanescens roots reduced carrageenan-induced rat paw oedema and adjuvant (Mycobacterium butyricum-induced) polyarthritis in rats. Daily doses of 100 and 200 mg/kg of the extracts partially inhibited primary and secondary lesions of the rat hind paw and also reduced both body weight and arthritic symptoms. In combination with phenylbutazone both extracts alleviated all symptoms of polyarthritis in rats (Iwu and Ohiri, 1980). Glycyrrhetic acid and some derivatives have been found to have an anti-arthritic activity similar to that of hydrocortisone (Kraus, 1960; Parmar et al., 1964; Tangri et al., 1965). (Linnaeus (1707-1778) himself mentions the use of Glycyrrhiza for rheumatism).
Numerous papers deal with the biochemical basis of the anti-inflammatory properties of glycyrrhizin and were summarized in a comprehensive review by Gibson (1978). It is generally concluded that glycyrrhizin has an aldosterone effect in the body, causing retention of sodium ions and a plasma depletion of potassium ions. Glycyrrhizin appears to stimulate the adrenal cortex directly increasing the production of mineral corticoids, glucocorticoids and adrenal androgens. In addition, it inhibits the inactivation of corticoids in the liver and kidneys. These two effects result in a continuous and elevated plasma level of corticoids (Matsuda et al.,
1962). Glycyrrhizin has also been found to enhance the immuno-depressive action of cortisone and to inhibit the action of cortisone on the thymus and on liver glycogen deposition (Kumigai, 1969; Kumigai et al., 1967a, b, c).
Glycyrrhizin and glycyrrhetic acid are also active against coughs and peptic ulcers and have given good results in the treatment of rheumatic thrombophlebitis (Kerharo and Adam, 1974, p. 440). The effect of glycyrrhizin in the treatment of peptic ulcer cannot be completely explained by the anti-inflammatory action, since the deglycyrrhinated drug is of considerable value in the treatment of ulcers (Brodgen et al., 1974; Gibson, 1978). The anti-arthritic and anti-inflammatory effects have also been attributed to a reduction in the activities of serum-glutamin-oxaloacetic acid transaminase and serum-glutamic-pyruvic transaminase (Parmar et al., 1964), and to an uncoupling of oxidative phosphorylation (Whitehouse et al., 1967).
Another West African plant which produces glycyrrhizin, and which is used for its commercial extraction, is Abrus precatorius (5-10% in the leaves, 1.5% in the roots).
Terminalia ivorensis A. Chev. COMBRETACEAE
Satin wood, shingle wood
L Powdered bark and bark infusions are much used in local medicine for the dressing of wounds. They are also used in the treatment of arthritic conditions and piles and as a diuretic (Ainslie, 1937; Dalziel, 1937). Anti-inflammatory properties have also been reported for the related T. avicennoides (see CV).
C From the chloroform and methanol extracts of the stembark, terminolic acid, ellagic acid, sericic acid, quercetin, /3-glycerrhetinic acid and 2-8 hydroxy 18«-glycyr-rhetinic acid have been isolated (Bombardelli et al., 1979; Iwu and Anyanwu, 1982b). The wood also contains /3-sitosterol, terminolic acid and tri- and tetramethyl ellagic acid and laxiflorin and sitosteryl palmitate were reported to be present in the stembark of most Nigerian Terminalia spp. (Ekong and Idemudia, 1967; Idemudia and Ekong, 1970).
P Extracts of the stembark with different solvents (chloroform and methanol giving the most active extracts) inhibited carrageenan-induced pedal oedema and adjuvant-induced polyarthritis (by Rosenthale method) in the rat. Daily administration of 100-300 mg/kg of the extracts reduced primary and secondary lesions of the rat's hind paws with concomitant reduction of body weight and reduction of the arthritic symptoms. The chloroform extract showed an activity comparable to that of phenylbutazone and in combination-therapy with this (100 mg/kg of each) has an activity almost equivalent to that of indomethacin. The extracts also effectively checked the diarrhoeas produced by arachidonic acid and castor oil. This action is related to the ability of anti-inflammatory drugs to interfere in the synthesis of the prostaglandins E2 and F2; this in turn reduces the inflammation associated with the prostaglandins (Awouters et al., 1978; Iwu and Anyanwu, 1982a). The authors conclude that the results lend support to the use of Terminalia ivorensis in the treatment of arthritis and other inflammatory conditions.
The antiphlogistic action of /3-glycyrrhetic acid is well known (see Lonchocarpus, above) and the anti-inflammatory action of Terminalia ivorensis could, in the view of Iwu and Anyanwu (1982a), be due at least in part to this acid and to the presence of other oleanane derivatives (terminolic acid and lonchoterpene).
Phytolacca dodecandra L'Herit syn. (P. abystinica Hoffm.?)
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