Greater ammi Health Dictionary

Ammi majus

Apiaceae

Importance: Greater Ammi, also known as Bishop’s weed or Honey plant is an annual or biennial herb which is extensively used in the treatment of leucoderma (vitiligo) and psoriasis. The compounds responsible for this are reported to be furocoumarins like ammoidin (xanthotoxin), ammidin (imperatorin) and majudin (bergapten) present in the seed. Xanthotoxin is marketed under the trade name “Ox soralen” which is administered orally in doses of 50 mg t.d. or applied externally as 1% liniment followed by exposure of affected areas to sunlight or UV light for 2 hours. It is also used in “Suntan lotion”. Meladinine is a by-product of Ammi majus processing, containing both xanthotoxin and imperatorin sold in various formulations increases pigmentation of normal skin and induces repigmentation in vitiligo. Imperatorin has antitumour activity. Fruit or seed causes photosensitization in fouls and sheep.

Distribution: The plant is indigenous to Egypt and it grows in the Nile Valley, especially in Behira and Fayoom. It is also found in the basin of the Mediterranean Sea, in Syria, Palestine, Abyssinia, West Africa, in some regions of Iran and the mountains of Kohaz (Ramadan, 1982). It grows wild in the wild state in Abbottabad, Mainwali, Mahran and is cultivated in Pakistan. The crop was introduced to India in the Forest Research Institute, Dehra Dun, in 1955 through the courtesy of UNESCO. Since then, the crop has been grown for its medicinal fruit in several places in Uttar Pradesh, Gujarat, Kashmir and Tamil Nadu.

Botany: Ammi majus Linn. belongs to the family Apiaceae (Umbelliferae). A. visnaga is another related species of medicinal importance. A. majus is an annual or beinnial herb growing to a height of 80 to 120 cm. It has a long tap root, solid erect stem, decompound leaves, light green alternate, variously pinnately divided, having lanceolate to oval segments. Inflorescence is axillary and terminal compound umbels with white flowers. The fruits are ribbed, ellipsoid, green to greenish brown when immature, turning reddish brown at maturity and having a characteristic terebinthinate odour becoming strong on crushing with extremely pungent and slightly bitter taste.

Agrotechnology: Ammi is relatively cold loving and it comes up well under subtropical and temperate conditions. It does not prefer heavy rainfall. Though the plant is biennial it behaves as an annual under cultivation in India. A mild cool climate in the early stages of crop growth and a warm dry weather at maturity is ideal. It is cultivated as a winter annual crop in rabi season. A wide variety of soils from sandy loam to clay loam are suitable. However, a well drained loamy soil is the best. Waterlogged soils are not good. Being a hardy crop, it thrives on poor and degraded soils.

The plant is seed propagated. Seeds germinate within 10-12 days of sowing. The best time of sowing is October and the crop duration is 160-170 days in north India. Crop sown later gives lower yield. The crop can be raised either by direct sowing of seed or by raising a nursery and then transplanting the crop. Seed rate is 2 kg/ha. The land is brought to a fine tilth by repeated ploughing and harrowing. Ridges and furrows are then formed at 45-60 cm spacing. Well decomposed FYM at 10-15 t/ha and basal fertilisers are incorporated in the furrows. Seeds being very small are mixed with fine sand or soil, sown in furrows and covered lightly with a thin layer of soil. A fertilizer dose of 80:30:30 kg N, P2O5 and K2O/ha is generally recommended for the crop while 150:40:40 kg/ha is suggested in poor soils for better yields. The furocoumarin content of Ammi majus is increased by N fertiliser and the N use efficiency increases with split application of N at sowing, branching and at flowering. For obtaining high yields it is essential to give one or two hoeings during November to February which keeps down the weeds. If winter rains fail, one irrigation is essential during November to January. As the harvesting season is spread over a long period of time, two irrigations during March and April meets the requirements of the crop (Chadha and Gupta, 1995).

White ants and cut worms are reported to attack the crop which can be controlled by spraying the crop with 40g carbaryl in 10 l of water. Damping off and powdery mildew are the common diseases of the crop. Seed treatment with organomercuric compounds is recommended for damping off. To control powdery mildew the crop is to be sprayed with 30g wettable sulphur in 10 l of water whenever noticed.

The crop flowers in February. Flowering and maturity of seed is spread over a long period of two months. The primary umbels and the early maturing secondary umbels are the major contributors to yield. A little delay in harvesting results in the shattering of the seed which is the main constraint in the commercial cultivation of the crop and the main reason for low yields in India. Sobti et al (1978) have reported increased yield by 50 - 60% by the application of planofix at 5 ppm at flower initiation and fruit formation stages. The optimum time of harvest is the mature green stage of the fruit in view of the reduced losses due to shattering and maximum contents of furocoumarins. The primary umbels mature first within 35-45 days. These are harvested at an interval of 2-4 days. Later, the early appearing secondary umbels are harvested. Afterwards, the entire crop is harvested, stored for a couple of days and then threshed to separate the seeds. The seed yield is 900-1200 kg/ha.

Postharvest technology: The processing of seed involves solvent extraction of powdered seeds, followed by chilling and liquid extraction and chromatographic separation after treatment with alcoholic HCl. Bergapten, xanthotoxin and xanthotoxol can be separated. Xanthotoxol can be methylated and the total xanthotoxin can be purified by charcoal treatment in acetone or alcohol.

Properties and activity: Ammi majus fruit contains amorphous glucoside 1%, tannin 0.45%, oleoresin 4.76%, acrid oil 3.2%, fixed oil 12.92%, proteins 13.83% and cellulose 22.4%. This is one of the richest sources of linear furocoumarins. Ivie (1978) evaluated the furocoumarin chemistry of taxa Ammi majus and reported the presence of xanthotoxin, bergapten, imperatorin, oxypencedanin, heraclenin, sexalin, pabulenol and many other compounds. Furocoumarins have bactericidal, fungicidal, insecticidal, larvicidal, moluscicidal, nematicidal, ovicidal, viricidal and herbicidal activities (Duke, 1988).