Mal: Sarpagandhi, Amalpori
Tam: Chivan amelpodi
Introduction: Serpentwood is an erect, evergreen , perennial undershrub whose medicinal use has been known since 3000 years. Its dried root is the economical part which contains a number of alkaloids of which reserpine, rescinnamine, deserpidine, ajamalacine, ajmaline, neoajmalin, serpentine, -yohimbine are pharmacologically important. The root is a sedative and is used to control high blood pressure and certain forms of insanity. In Ayurveda it is also used for the treatment of insomnia, epilepsy, asthma, acute stomach ache and painful delivery. It is used in snake-bite, insect stings, and mental disorders. It is popular as “Madman’s medicine” among tribals. ‘Serpumsil’ tablet for high blood pressure is prepared from Rauvolfia roots. Reserpine is a potent hypotensive and tranquillizer but its prolonged usage stimulates prolactine release and causes breast cancer. The juice of the leaves is used as a remedy for the removal of opacities of the cornea.
Distribution: Rauvolfia serpentina is native to India. Several species of Rauvolfia are observed growing under varying edaphoclimatic conditions in the humid tropics of India, Nepal, Burma, Thailand, Bangladesh, Indonesia , Cambodia, Philippines and Sri Lanka. In India, it is cultivated in the states of Uttar Pradesh, Bihar, Tamil Nadu, Orissa, Kerala, Assam, West Bengal and Madhya Pradesh (Dutta and Virmani, 1964). Thailand is the chief exporter of Rauvolfia alkaloids followed by Zaire, Bangladesh, Sri Lanka, Indonesia and Nepal. In India, it has become an endangered species and hence the Government has prohibited the exploitation of wild growing plants in forest and its export since 1969.
Botany: Plumier in 1703 assigned the name Rauvolfia to the genus in honour of a German physcian -Leonhart Rauvolf of Augsburg. The genus Rauvolfia of Apocynaceae family comprises over 170 species distributed in the tropical and subtropical parts of the world including 5 species native to India. The common species of the genus Rauvolfia and their habitat as reported by Trivedi (1995) are given below.
R. serpentina Benth. ex Kurz.(Indian serpentwood) – India ,Bangladesh, Burma, Sri Lanka, Malaya, Indonesia
R. vomitoria Afz. (African serpentwood) – West Africa, Zaire, Rwanda, Tanzania R. canescens Linn. syn. R. tetraphylla (American serpentwood) – America, India R. mombasina – East Africa , Kenya, Mozambique
R. beddomei – Western ghats and hilly tracts of Kerala
R. densiflora – Maymyo, India
R. microcarpa – Thandaung
R. verticillata syn. R. chinensis – Hemsl
R. peguana – Rangoon-Burma hills
R. caffra – Nigeria, Zaire, South Africa
R. riularis – Nmai valley
R. obscura – Nigeria, Zaire
R. serpentina is an erect perennial shrub generally 15-45 cm high, but growing upto 90cm under cultivation. Roots nearly verticle, tapering up to 15 cm thick at the crown and long giving a serpent-like appearance, occasionally branched or tortuous developing small fibrous roots. Roots greenish-yellow externally and pale yellow inside, extremely bitter in taste. Leaves born in whorls of 3-4 elliptic-lanceolate or obovate, pointed. Flowers numerous borne on terminal or axillary cymose inflorscence. Corolla tubular, 5-lobed, 1-3 cm long, whitish-pink in colour. Stamens 5, epipetalous. Carpels 2, connate, style filiform with large bifid stigma. Fruit is a drupe, obliquely ovoid and purplish black in colour at maturity with stone containing 1-2 ovoid wrinkled seeds. The plant is cross-pollinated, mainly due to the protogynous flowers (Sulochana ,1959).
Agrotechnology: Among the different species of Rauvolfia, R. serpentina is preferred for cultivation because of higher reserpine content in the root. Though it grows in tropical and subtropical areas which are free from frost, tropical humid climate is most ideal. Its common habitats receive an annual rain fall of 1500-3500 mm and the annual mean temperature is 10-38 C. It grows up to an elevation of 1300-1400m from msl. It can be grown in open as well as under partial shade conditions. It grows on a wide range of soils. Medium to deep well drained fertile soils and clay-loam to silt-loam soils rich in organic matter are suitable for its cultivation. It requires slightly acidic to neutral soils for good growth.
The plant can be propagated vegetatively by root cuttings, stem cuttings or root stumps and by seeds. Seed propagation is the best method for raising commercial plantation. Seed germination is very poor and variable from 10-74%. Seeds collected during September to November give good results. It is desirable to use fresh seeds and to sock in 10% sodium chloride solution. Those seeds which sink to the bottom should only be used. Seeds are treated with ceresan or captan before planting in nursery to avoid damping off. Seed rate is 5-6 kg/ha. Nursery beds are prepared in shade, well rotten FYM is applied at 1kg/m2 and seeds are dibbled 6-7cm apart in May-June and irrigated.
Two months old seedlings with 4-6 leaves are transplanted at 45-60 x 30 cm spacing in July -August in the main field. Alternatively, rooted cuttings of 2.5-5cm long roots or 12-20cm long woody stems can also be used for transplanting. Hormone (Seradix) treatment increases rooting. In the main field 10-15 t/ha of FYM is applied basally. Fertilisers are applied at 40:30:30kg N: P2O5 :K2O/ha every year. N is applied in 2-3 splits. Monthly irrigation increases the yield. The nursery and the main field should be kept weed free by frequent weeding and hoeing. In certain regions intercroping of soybean, brinjal, cabbage, okra or chilly is followed in Rauvolfia crop.
Pests like root grubs (Anomala polita), moth (Deilephila nerii), caterpillar (Glyophodes vertumnalis), black bugs and weevils are observed on the crop, but the crop damage is not serious. The common diseases reported are leaf spot (Cercospora rauvolfiae, Corynespora cassiicola), leaf blotch (Cercospora serpentina), leaf blight (Alternaria tenuis), anthracnose (Colletotrichum gloeosporioides), die back (Colletotrichum dematrium), powdery mildew (Leviellula taurica), wilt (Fusarium oxysporum), root-knot (Meloidogyne sp.), mosaic and bunchy top virus diseases. Field sanitation, pruning and burning of diseased parts and repeated spraying of 0.2% Dithane Z-78 or Dithane M-45 are recommended for controlling various fungal diseases. Rauvolfia is harvested after 2-3 years of growth. The optimum time of harvest is in November -December when the plants shed leaves, become dormant and the roots contain maximum alkaloid content. Harvesting is done by digging up the roots by deeply penetrating implements (Guniyal et al, 1988).
Postharvest technology: The roots are cleaned washed cut into 12-15cm pieces and dried to 8-10% moisture.
The dried roots are stored in polythene lined gunny bags in cool dry place to protect it from mould. The yield is 1.5-2.5 t/ha of dry roots. The root bark constitutes 40-45% of the total weight of root and contributes 90% of the total alkaloids yield.
Properties and activity: Rauvolfia root is bitter, acrid, laxative, anthelmintic, thermogenic, diuretic and sedative. Over 200 alkaloids have been isolated from the plant. Rauvolfia serpentina root contains 1.4-3% alkaloids. The alkaloids are classsified into 3 groups, viz, reserpine, ajmaline and serpentine groups. Reserpine group comprising reserpine, rescinnamine, deserpine etc act as hypotensive, sedative and tranquillising agent. Overdose may cause diarrhoea, bradycardia and drowsiness. Ajmaline, ajmalicine, ajmalinine, iso-ajmaline etc of the ajmaline group stimulate central nervous system, respiration and intestinal movement with slight hypotensive activity. Serpentine group comprising serpentine, sepentinine, alstonine etc is mostly antihypertensive. (Husain,1993; Trivedi, 1995; Iyengar, 1985).