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Chapter: Pharmacognosy and Phytochemistry : Drugs Containing Resins

Jalap consists of dried tuberous roots or tubercles of Ipomoea purga Hayne, belonging to family Convolvulaceae.






Radix jalapae, Jalap root, Vera cruz or Mexican Jalap.


Biological Source


Jalap consists of dried tuberous roots or tubercles of Ipomoea purga Hayne, belonging to family Convolvulaceae.


Geographical Source


It is mainly found in Mexican Andes, India, West Indies, and South America.




The plant is large and twinning perennial herb, and it pro-duces thin horizontal slender runners. Adventitious roots (fusiform or napiform roots) are produced from the nodes of the runners. Some of the roots remain thin but few of them swell due to the storage of starch. These roots are collected after the rainy season, that is, in May. As a result of unfavourable environmental conditions they are dried by woodfire in nets. Since the drug is artificially dried it gains a smoky odour. Some slits are also made on the drug to facilitate the escape of the moisture.




Jalap is cylindrical, fusiform or napiform, irregularly oblong about 5 to 10 cm long and 2 to 10 cm wide. It is hard, resinous, compact, and heavy. The outer surface is dark brown in colour with furrows and wrinkles and internally it is yellowish grey in colour. Odour is smoky and taste is sweet and starchy in the beginning and later it is acrid.




Cork is the outermost layer consisting of tabular polygonal cells which are brown in colour. Just below the cork it has the secondary phloem. The secondary phloem is formed by the circular cambium and is about 2 mm wide. Inside the cambium it has the secondary xylem. The secondary xylem has vessels, which are either in small groups or scattered. Latex cells are present in the phloem tissues arranged longitudinally and form a dark and resinous point scattered in the drug. The parenchymatous cells contain starch which are simple, rounded, or in groups of two to four. Small prism types of calcium oxalate crystals are present in the parenchyma and very few sclerenchymatous cells are seen in the phelloderm region.


Chemical Constituents


Jalap contains 8 to 12% of glycosidal resin and the other constituents are mannitol, sugar, β-methyl-aesculetin, phytosterin, ipurganol, starch and calcium oxalate. Jalap resin is the resinous constituent that has a soluble portion and an insoluble portion when dissolved in ether. The soluble portion constitutes to 10%, whereas the remaining is the insoluble portion. Ether insoluble portion is called convolvulin and the ether soluble portion is called julapin. Convolvulin is a substance with some 18 hydroxyl groups esterified with valeric, tiglic, and exogonic acids. Exogonic acid is 3,6-6,9-dioxidodecanoic acid.





Jalap can stimulate the intestinal secretion, it act as laxative in small doses and purgative in large doses, and it is also used as hydragogue cathartic.


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