It is also used as an anti-inflammatory¹⁴ and Immunomodulatory¹⁵ for various inflammatory diseases. Many published data report that Bauhinia variegata have antimicrobial^16,17, antiplasmoidal¹⁸, and antihyperlipidemic¹⁹ activity.

Since the data about pharmacognosy of the Bauhinia variegata was not noted, the present study was undertaken to study the pharmacognostical and phytochemical screening of Bauhinia variegata Linn leaves which could be used as one of the parameters for the standardization of the crude drug.

MATERIAL AND METHODS:

Chemical: All the chemicals and solvents used in experiment were of analytical grade.

Materials:

Bauhinia variegata leaves were collected locally (from Chennai)and it was authenticated by Dr P.Jayaraman, Director, National Institute of Herbal Science (authentication reference no. PARC/2010/670 dated 22/12/2010). The samples after removal of soil and adhering material was dried at room temperature for 5-6 days powdered to 60 # and were used for the powder study. Free hand transverse section of fresh leaf was taken²⁰ .

Methods:

Leaf constant such as stomatal index, palisade ratio, vein islet and vein termination number were also determined. Physicochemical parameters such as ash values (total ash, acid insoluble ash, water soluble ash); extractive values (alcohol and water soluble extractive values), loss on drying and preliminary phytochemical analysis were determined²¹.

RESULTS AND DISCUSSION:

Pharmacognostical characteristics of the leaf:

Macroscopical characteristics:

The leaves of B.variegata was rigidly subcoriaceous and deeply cordate with running parallel venation, length varying from 10-15 cm and breadth is broader than length, green when fresh and brown when it dry, weak odour and slightly bitter in taste(Fig. 1).

Figure 1. Bauhinia variegata leaves

Microscopic studies of the leaf:

The leaf is dorsiventral with prominent abaxial midrib and their lamina (fig. 2.1.)

Figure 2.1. T.S. of Leaf With Midrib And Lamina

Ad-Adaxial,X-Xylem,Ph-phloem,La-lamina,SC-Sclerenchyma,MR-midrib.

Midrib (Fig.3.1, 2):

The midrib is flat on the adaxial side and broadly conical on the abaxial side. It is 700 µm thick and the abaxial part is 400 – 600 µm wide. The midrib consists of a thin epidermal layer of small cells with prominent echinate cuticle (fig.2.2). The ground tissue is angular, compact and fairly thick walled. A triangular thick cylinder of sclerenchyma sheath encloses an arc shaped vascular strand. The sheath is 3 cells thick; at the adaxial end, the sclerenchyma sheath dilates into wide spindle shaped segment (fig.3.1 and 3.2.)

The vascular strand consists of a wide, thick arc of xylem with about 15 radial parallel rows of xylem elements; in each row, there are up to 6 xylem elements. Along the lower end of the xylem strand is an arc of phloem with small diffuse mucilage cavities.

Figure 2.2. T.S. of Midrib

AdSC-Adaxial Sclerenchyma,X-Xylem,Ph-phloem,SC- Sclerenchyma, GT-Ground tissue ,

Ep-Epidermis

Figure 3.1. T.S. of Midrib Showing Sclerenchyma Sheath And XylemStrand(UnderPolarizedlight)

X-Xylem,Ph-phloem,SC- Sclerenchyma,GT- Ground tissue ,Ep-Epidermis

Figure 3.2. A Portion of Vascular Strand Of The Midrib

X-Xylem,Ph-phloem,SC- Sclerenchyma,Mu-Mucilage

Lamina:

The lamina is smooth and even on both upper and lower sides. It is 110 µm thick. The adaxial epidermis is thicker, comprising dilated cylindrical cells and they secrete mucilage which is seed on the surface as their layer. The abaxial epidermis consists of semicircular cells with convex lower walls. The adaxial epidermis is 15 µm thick, while abaxial layer is 10 µm thick (Fig.4.1).

Figure 4.1.T.S. of Lamina

LV-Lateral vein ,PM-Palilsade Mesophyll,SC- Sclerenchyma,SM-Spongy Mesophyll, AbE-Abaxial epidermis

The palisade mesophyll consists of a single layer of cylindrical short, loosely arranged cells. The spongy parenchyma includes four or five layers of small lobed cells which form wide air chambers. The lateral veins are in thick vertical pillars extending from lower to upper ends. They consist of a small cluster of xylem elements and a group of phloem elements. Sclerenchyma forms a thick sheath with adaxial and abaxial extensions.

Adaxial epidermal cells:

The adaxial epidermal cells in surface view are polyhedral with thick straight anticlinal walls. The walls are smooth. No stomata are seen on the adaxial epidermis (Fig.4.2.).

Figure 4.2.Adaxial Epidermis – Paradermal Section

EC- Epidermal cells,AW-Anticlinalwalls

Abaxial epidermis and stomata:

The abaxial epidermal cells are also polyhedral with thick straight anticlinal walls. The epidermis is stomatiferous (Fig. 5.1and 5.2). The guard cells are small and elliptical. The stomata are paracytic type with two parallel subsidiary cells, one on either side of the guard cells. The stomata have fairly wide elliptical pores.

Figure 5.1 & 5.2. Paradermal Sections Of Abaxial Epidermis Showing Stomata

Ve-venule,SC-sclerenchyma, St-stomata

Venation:

The venation is densely reticulate. The veins and vein lets are quite thick and prominent. The vein islets are small in area, polyhedral in outline. The islets are surrounded by thick and straight veins (Fig 6.1, 6.2 and 6.3). The vein terminations are short, thick and unbranched. The terminations are seen only in some of the islets.

Figure 6.1, 6.2 & 6.3. Lamina Cleared To Show the Venation Pattern

Ve- Vein, PV- parellel vein, SV- small vein VT-Veinlet, VI-Vein termination

Powder microscopy:

The powder of the leaf exhibits the following inclusions:

Epidermal fragments bearing epidermal trichomes are frequently seen in the powder. The trichomes occur both on the veins and in the intercostals areas (fig.7.1.). The trichomes are non glandular type. They are unicellular, unbranched, narrow, long and pointed at the tip. The walls are thick and the outer surface is minutely echinate (fig.8.1). The trichomes are 40 – 150 µm long and 10 µm thick. There are also fragments of adaxial epidermis where the cells are narrow, thick walled and straight. No stomata are present (Fig.8.2.)

Figure 7.1 & 7.2. Epidermal Trichomes (Powder Microscopy)

Tr-Trichome, La-Lamina

Figure 8.1. Single Trichome On The Vein Enlarged

Lu-lumen,Ve-Venule,W-wall

Figure 8.2. Adaxial Epidermal Peeling

AdE-AdaxialEpidermis,AW-Anticlinalwall

Physico chemical parameters:

Physicochemical parameters includes extractive value, ash value and loss on drying were determined and were given in the Table 1.

Table 1: Physicochemical Parameters of Bauhinia Variegata Linn. leaves

PHYSICOCHEMICAL PARAMETERS	VALUE(w/w)
Alcohol soluble extractive value	8 %
Water soluble extractive value	18.4 %
Total ash	8.2 %
Water soluble ash	2.1 %
Acid insoluble ash	6 %
Loss on drying	6.89 %

Leaf Constants

Leaf constant such as stomatal index, palisade ratio, vein islet number and vein termination number were determined and were given in the Table 2.

Table 2. Leaf constants of Bauhinia variegata

Leaf constants	*Bauhinia variegata*
Stomatal index	5.32
Palisade ratio	7.5
Vein –islet number	8.35
Vein termination number	6.7

Preliminary phytochemical screening:

Phytochemical screening shows the presence of saponins, steroids, flavonoids, alkaloids, tannins, cardiac glycosides, sugars in various solvent extracts and is given in the Table3.

Table 3. Preliminary Phytochemical Analysis of Bauhinia variegata Linn. leaves

PHYTOCHEMICALS	Petroleum ether	Chloroform	Ethanol	Water
Tannins	-	-	+	-
Saponins	-	-	+	+
Cardiac glycosides	-	-	+	+
Steroid	+	+	+	-
Alkaloids	-	+	+	-
Flavonoids	-	-	+	-
Carbohydrates	-	+	+	+
Protein	-	-	+	-
Coumarin	-	-	-	-
Quinones	-	-	-	-
Phenols	-	-	-	-
Gum	-	-	-	-
Starch	-	+	+	+
Fixed oil	-	-	-	-

+ = present, - = absent

CONCLUSION:

In the present study, Pharmacognostical characters of the leaves of Bauhinia variegata were studied including physicochemical parameters and leaf constants. The preliminary qualitative analysis of various extracts (petroleum ether, chloroform, ethanol and water) for phytoconstituents showed that it contains steroids, saponins, flavonoids, alkaloids, sugars and tannins. The data obtained from the pharmacognostical, preliminary screening and physicochemical parameters of Bauhinia variegata Linn can therefore be used as one of the tool for standardization of the crude drug.

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Received on 21.07.2011

Accepted on 29.08.2011

Research Journal of Pharmacognosy and Phytochemistry. 3(5): Sept.- Oct.2011, 236-240