Habitat
It grows in India, Pakistan, Sri Lanka, Burma and Thailand. In India, it is widely distributed in the sub-Himalayan tract from Punjab to Nepal, Sikkim and Bhutan. It is also found in the lower hills of Gangetic plains, eastern and western Ghats and Andamans. It is mostly found in moist deciduous forests at altitudes ranging from sea level to an altitude of 1,200 m high. In the Deccan, it is associated with bamboo forests.

Morphology Description (Habit)
It is an evergreen, perennial, glabrous and errect undershrub grows up to a height of 60 cm (rarely more than it). Roots are tuberous with pale brown cork. Leaves are in whorls of three, elliptic to lanceolate or obovate, bright green above, pale green below, tip acute or acuminate, base tapering and slender. Petioles long. Flowers are in many flowered irregular corymbose cymes. Peduncles long but pedicels stout. Flowers white, often has violet coloured tinge. Calyx glabrous, bright red and lanceolate. Corolla is longer than calyx, tube slender, swollen a little above the middle, lobes 3, and elliptic-oblong. Disc is cup shaped. Drupes are slightly connate, obliquely ovoid and purplish black in colour.

Principal Constituents
Reserpine is the most important alkaloid present in root, stem and leaves of the plant. It varies from 1.7 to 3.0 %. The root barks has more than 90% of the total alkaloids in roots. The % of the alkaloid depends on the geographical place from where the plant is collected and also the season of collection. Generally samples from Assam have a higher % of alkaloids (2.57 %) than the other parts of India and December is the best month for the collection for getting more % of alkaloids. But, age of the plant has no effect on the % of alkaloid content (up to 4 years). Ajmalicine, ajmaline, isoajmaline, ajmalinine, chandrine, rauwolfinine, renoxidine, rescin-namine, reserpiline, reserpin, reserpinine, sarpagine, serpentine, serpentinine, tetraphyllicine, yohimbine, 3-epi-a-yohimbine are the minor alkaloids identified from samples collected from India.

Pharmacology
Reserpine has a highly complex pattern of activity. Besides the amine concentration in brain, it is also reported to influence the concentration of glycogen, acetyl choline, g-amino butyric acid, nucleic acids and anti-diuretic hormone. The effects of reserpine include respiratory inhibition, stimulation of peristalsis, myosis, relaxation of nictating membranes, and influence on the temperature regulating centre. It increases the volume and free acidity of gastric secretion. Reserpine reduces glycaemia in some cases but the effect is short-lived. In some patients it has a stimulating effect on prothrombin activity. Reserpine also favors permeation of blood into areas rendered ischemic by burns1. It produces sedation and a lowering of blood pressure. If administered orally, in hypertension, the effects of reserpine are slow, seldom appearing before 3-6 days of administration and continuing for some time after withdrawal of the drug and have a cumulative effect. It is most valuable in young patients with mild labile hypertension associated with tachycardia. In long established hypertension, it is best used in conjunction with more potent hypertensive drugs such as hexamethonium or hydralazine. Combined with polythiazide, it is a useful hypotensive in mild to moderate thiazide, it is a useful hypotensive in mild to moderate conditions. The response to reserpine varies in patients and the dosage must be adjusted to individual requirements. In severe hypertension, it may be given by intravenous or intramuscular injection when the effect begins within a few hours. Parenteral therapy of reserpine is indicated in the treatment of hypertension only when oral administration is impracticable2.

Deserpidine is almost as active as reserpine in its hypotensive and sedative activity. reduces hypotension and inhibits intestinal movements. Given with an equal amount of reserpine it was more hypotensive than either of the drugs in equivalent doses. It possesses anti-fibrillar activity. Serpentina causes marked inhibition of succinate dehydrogenase in brain and liver tissues. It produces a systemic and pulmonary hypotension due to a decrease in cardiac output; there is no change in coronary flow, but coronary vascular resistance is decreased and myocardial oxygen consumption is unaffected. Ajmaline has been reported to stimulate respirartion and intestinal movements. The action of ajmaline on systemic and pulmonary blood pressure is similar to that of serpentine Rauwolfinine has hypertensive properties on the autolysis of rat brain and liver tissue, but to a lesser extent than reserpine. In contrast to reserpine, the total extract of R. serpentina inhibited the acetylcholine-induced contraction of the enervated dorsal leech muscle. The whole crude drug is reported to contain some principles which bring about undesirable side effects such as purgation and sexual debility.

Toxicology
In patients with cardiac arrhythmia, myocardial infarction or severe cardiac damage, bronchitis, asthma or gastric ulcer, reserpine has a relatively low toxicity, but even the minimum therapeutic doses may give rise to nasal congestion, lethargy, drowsiness, peculiar dreams, vertigo and gastro-intestinal upsets; sometimes dyspnea and urticarial rash may occur. Higher doses may cause flushing, injection of conjunctivae, insomnia, bradycardia, occasionally parkinsonism, and severe mental depression which may lead to suicide. Cases of asthenia and edema have also been reported. Side effects of reserpine are usually transient and quickly disappear on reducing the dosage or discontinuing treatment. Tolerance to reserpine does not develop and it does not appear to be habit-forming. Prolonged previous use of reserpine may cause disturbances in blood pressure during operation under general anesthesia, while some patients may be highly susceptible to a small parenteral dosage. When give to nursing mothers to increase the secretion of milk, it is excreted with milk but the amount is not therapeutically harmful3. Minimum therapeutic doses may give rise to nasal congestion, lethargy drowsiness, peculiar dreams, vertigo and gastro-intestinal upsets; sometimes dyspnea and urticarial rash may occur. Higher doses may cause flushing, injection of conjunctivae, insomnia, bradycardia, occasionally parkinsonism, and severe mental depression which may lead to suicide. Cases of asthenia and edema have also been reported. Side effects of reserpine are usually transient and quickly disappear on reducing the dosage or discontinuing treatment. Serpentine is more toxic than ajmaline or serpentinine.

Indications
Rauwolfia has been employed for centuries for the relief of various central nervous system disorders, both psychic and motor, including anxiety states, excitement, maniacal behaviour associated with psychosis, schizophrenia, insanity insomnia and epilepsy. Extracts of the roots are valued for the treatment of intestinal disorders, particularly diarrhoea and dysentery and also as anthelmintic. Mixed with other plant extracts, they have been used in the treatment of cholera, colic and fever. The root was believed to stimulate uterine contration and recommended for use in child-birth in difficult cases. The juice of the leaves has been used as a remedy for opacity of the cornea.

1. Bein in Chen & Mukerji, 87-92; Ann. N.Y. Acad. Sci., 1955, 61, 4; Woodson et. al., 119-29; Martindale, I, 742; Chem. Abstr., 1965, 63, 17002; 1966, 64, 20491; 1965, 62, 5689; Vavrik, Experientia, 1965, 21, 701.
2. B.P.C., 1963, 704; U.S.D., 1955, 1825; Shah et. al., J. Ass Physicians India, 1965, 13, 845; Chem. Abstr., 1965, 63, 3523.
3. B.P.C., 1963, 704; Chem. Abstr., 1966, 65, 4505; 1965, 63, 13862.