Pharmacognostic standardization of leaves of Calotropis procera (Ait.) R. Br. (Asclepiadaceae)

Calotropis procera, belonging to the Asclepidaceae family, is present more or less throughout India and in other warm, dry places such as, Warizistan, Afghanistan, Egypt, and tropical Africa. Its common names are Akra, Akanal, and Madar. The leaves of Calotropis procera are said to be valuable as an antidote for snake bite, sinus fistula, rheumatism, mumps, burn injuries, and body pain. The leaves of Calotropis procera are also used to treat jaundice. A study on Calotropis procera leaf samples extracted the air-dried leaf powder with different solvents such as petroleum-ether (60-80°C), benzene, chloroform, ethanol, and sterile water. Preliminary phytochemical analysis was done long with measurement of the leaf constants, fluorescence characteristics, and extractive values. Quantitative estimation of total ash value, acid insoluble ash, and water- soluble ash may serve as useful indices for identification of the powdered drug. Histochemical studies which reveal rows of cylindrical palisade cells and, vascular bundles may also serve as useful indices for identification of the tissues. These studies suggested that the observed pharmacognostic and physiochemical parameters are of great value in quality control and formulation development of Calotropis procera.


INTRODUCTION
were examined under ordinary day light and in UV-light (254 nm). The fl uorescence was determined according to the methods of Chase and Pratt. [9] The total ash, water-soluble ash, and acid-insoluble ash content was determined by employing standard methods of analysis as described [10] in the Indian Pharmacopoeia (1966). Quantitative determinations of the powdered drug like physicochemical constants, [11] fl uorescence, [12] and a preliminary phytochemical screening [13,14] were carried out.

Microscopical characteristics of the leaf
Transverse sections through the midrib showed an upper and lower, single-layered epidermis that was externally covered with a thick, striated cuticle, a few epidermal cells on both lower and upper surfaces, parenchymatous cells that were thin-walled and isodiametric to circular. Intracellular spaces were present in ground tissue and the stele was crescent-shaped and composed of bicollateral and open vascular bundles. The xylem consisted mostly of vessels and tracheids, and a strip of cambium was present between the xylem and phloem tissues. Laticifers were also present along with the phloem and parenchymatous zone.
The lamina which was dorsiventral with the mesophyll, was seen to be differentiated into a palisade and spongy tissue. The upper and lower epidermise were covered externally with a thick, striated cuticle. Below the upper epidermis were three rows of elongated, closely arranged, palisade parenchyma. Spongy parenchyma tissues were almost radially elongated with intracellular spaces. Central cells were irregular in shape; laticifers and vascular bundles were also present scattered in this region; the details are shown in Figure 2.

RESULTS
The present study highlights the results of a comprehensive study on the microscopic parameters including the gross  anatomical features, leaf constants, cellular composition, tissue organization, and cellular inclusion of the leaf. The lamina which was dorsiventral with the mesophyll, was seen to be differentiated into a palisade and spongy tissue. The upper and lower epidermis were covered externally with a thick, striated cuticle. Below the upper epidermis were three rows of elongated, closely arranged, palisade parenchyma. Spongy parenchyma tissues were almost radially elongated with intracellular spaces. Central cells were irregular in shape; laticifers and vascular bundles were also present scattered in this region; the details are shown in Figure 2.
The results of the quantitative and qualitative analysis of the leaf samples are depicted in Tables 1-4.

DISCUSSION
By virtue of their photosynthetic machinery, leaves serve as a sink for several metabolites and as an important source of several bioactive compounds. The macroscopic and microscopic evaluation of leaves of Calotropis procera, the quantitative estimation of leaf constants, ash values, and fl uorescence, and preliminary phytochemical screening of the leaf powder would be of considerable use in the identifi cation of this drug. Empirical knowledge about medicinal plants plays a vital role in primary health care and has great potential for the discovery of new herbal drugs. These fi ndings may be useful to supplement existing information with regard to the identifi cation and standardization of Calotropis procera, even in the powdered form of the plant drug, to distinguish it from substitutes and adulterants. These studies also suggested that the observed pharmacognostic and physiochemical parameters are of great value in quality control and formulation development. In conclusion, the present study may be useful to supplement information with regard to its identifi cation and, standardization, and in carrying out further research and revalidation of its use in the Ayurvedic System of Medicine.