San: Visaghni, Anadana;
Importance: Alstonia is a large shrub with straight bole and growing upto about 6m height. The roots are useful in skin diseases, erysipelas, leprosy, cobra bite and other venomous bites, epilepsy, fatigue, fever and otalgia. The fruits are useful in syphilis, insanity and epilepsy. The plant is believed to repel snakes.
Distribution: The plant is distributed throughout India in deciduous forests in areas up to 1800m elevation.
Botany: Alstonia venenata R.Br., belonging to the family Apocynaceae, is a large shrub to small tree up to 6m in height with greyish brown bark and bright yellow hard and woody root. Leaves are simple, arranged in whorls of 3-6, membranous, lanceolate, margins wavy, finely acuminate, main nerves numerous, close, parallel and united by inter marginal nerve. Flowers are white, arranged in terminal sub umbellate cymes or in racemes. Fruits are fusiform with stalked and beaked follicles, tapering at both ends. Seeds are many flattened with a tuft of hair at each end (Warrier et al, 1993). Other important species belonging to the genus Alstonia are the following.
1. A. scholaris R. Br.
This tree is common throughout India. The bark is valuable in debility and after effects of fever, chronic diarrhoea, dysentery and catarrhal fever. The milky juice is applied to ulcers and rheumatic pains, mixed with oil and dropped into ear to relieve earache. Ditanin is the active principle of the bark, possessing powerful febrifuge properties. The bark is astringent, tonic and febrifuge (Nadkarni, 1998).
2. A. spectabilis R. Br.
It is a large evergreen tree seen in tropical forests of Andamans. The bark contains alkaloids such as alstonamine, ditamine, echitamine and echitenine (Chopra et al,1980)
Agrotechnology: The plant is propagated mainly by seeds. Seeds are to be sown on seedbeds and germinated ones are to be transferred to polybags. About three months old seedlings are used for transplanting. If seeds are not available, thin stem cuttings can be planted in polybags and rooted cuttings used. Pits of size 60cm cube are to be taken at 3m spacing, filled with dried cowdung, sand and topsoil and made into a mound. To this mounds seedlings from polybags are to be transplanted. Irrigation is essential during early stages of growth. Application of organic manure every year is beneficial. Regular weeding is to be done. The plant is not attacked by any serious pests or diseases. Flowers are formed in the first year itself. It can be used for medicinal purposes after seven years of growth. Fruits and roots are the economical parts (Prasad et al,1997).
Properties and activity: The plant is a rich source of indole alkaloids. Alkaloids are present in various parts. Stem bark and root contain venenatine, alstovenine, 3-dehydroalstovenine and reserpine. Stem bark contains venoxidine (venenatine Nb -oxide), anhydroalstonatine, kopsinine, venalstonine, venalstonidine(venalstonine-6,7-epoxide), echitovenine and veneserpine. Fruits contain echitovenidine, (+)minovincinine, echitoserpidine, echitoserpine, echitoveniline, 11-methoxy echitovonidine, 11-methoxy (-) minovinicinine, echitoserpiline, (-)vincadifformine, 11-methoxy(-)vincadifformine and venoterpine. Leaves contain echitovenaldine, echitoveniline, alstolenine, deacetylakuammiline, polynuridine, dihydropolynuridine and raucaffrininoline. The yellow tint in bark is because of the presence of 3-alstovenine. A number of indole alkaloids have been further isolated from the plant. In addition to alkaloids fruits contain -amyrin acetate and lupeol ester of -hydroxy acid (Husain et al,1992).
The root is bitter, astringent, thermogenic, depurative, antitoxic, febrifuge and anodyne. The alkaloid alstovenine in lower doses exhibited monoamine oxidase inhibitor activity, while in higher doses it showed marked central stimulant effect. Veninatine exhibited reserpine like activity. Alcoholic extract of the fruits showed initial activation effect on acetylcholine esterase, followed alternately by inhibition and activation of the enzyme.