Pharmacognostic Standardization of Solanum melongena var. insanum Linn.

 

Jiby Elias, Rajesh M.G.*, Anish N.P., Ragitha E.V. and      Jayan N.

 

Department of Biotechnology, Navajyothi Sree Karunakara Guru Research Centre for Ayurveda and Siddha, Uzhavoor, Kottayam, Kerala, India – 686 634

 

ABSTRACT:

Solanum melongena var. insanum Linn. (Solanaceae) is an undershrub used for the preparation of various Ayurvedic formulations.  Macroscopic, microscopic, physico-chemical and phytochemical studies of the root, fruit and leaf of the plant were done. Leaves are simple, alternate, pubescent and prickly. The tap root is dark yellow to brown in colour with fewer branches. Powdered samples were observed under the microscope and distinctive features of each part were noticed. Anatomical features of the root, pericarp of fruit and leaves were studied using hand sections. Moisture content was higher in the leaf (94.25%) compared to root (93.50%) and leaf (91.70%).  Ash analysis of the samples showed that the percentage of ash was higher in fruit portion (7%). Ethanol (6%) and water (7%) extractive values were higher in the root. Preliminary phytochemical analysis showed that the methanolic extract of root contained the maximum number of phytoconstituents such as flavanoids, coumarins, alkaloids, tannins, anthroquinines, phenols, resins, glycosides/reducing sugars, proteins and carbohydrates. Estimations such as carbohydrate, protein and phenol and TLC finger print profile were carried out. Total protein content was found to be higher in fruit (308mg/g). However, carbohydrate (384mg/g) and phenol content (22.2 mg/g) were found to be higher in root. These parameters, which are being reported for the first time in S. melongena var. insanum provide referential information for the correct identification and standardization of this plant material.

 

KEYWORDS: TLC, organoleptic evaluation, phytoconstituents.

 

INTRODUCTION:

Solanum melongena var. insanum Linn. (San: Brihati; Hin: Baigan; Mal: Cheruvazhuthina), an undershrub of the family Solanaceae is found in the warm humid tropics. Roots are the major officinal part, but fruits and leaves are also used occasionally. Its fruits stimulate the intrahepatic metabolism of cholesterol. Leaves are used in cholera, bronchitis and asthma. Roots are used to cure dyspepsia, fever, skin ailments, vomiting, ulcer and poisonous affections1. The formulations like Brihatyadi Kashaya, Dasamoolarishta, Indukantaghritam, Dasamoolaharithaki etc are the important preparations with its roots.

 

Herbal drugs are getting popularity in the developing and developed countries owing to its natural origin and lesser side effects. They are manufactured on a large scale in mechanical units, where manufactures are facing many problems such as unavailability of good quality raw material, lack of proper standardization of drugs and formulations, quality control parameters etc2. The present study aims to assess the pharmacognostic profile of S. melongena var. insanum, which will assist in the standardization for quality, purity and identification of the raw drug.

MATERIALS AND METHODS:

Plant material:

Solanum melongena var. insanum was collected during the months of November and December from the herbal garden of the research centre. It was identified, authenticated and the voucher specimens were deposited in the herbarium of the institution.

 

The macroscopic features of the plant such as morphological features of leaf, stem, root, flower and fruit were recorded. Hand sections of root, fruit and leaf were taken for microscopic characterization. Quantitative microscopy of the leaf was done to determine stomatal number, stomatal index, vein islets number and palisade ratio. The plant materials - leaves, roots and fruits were washed thoroughly with water and dried in an oven at 45oC. Powdered samples were subjected to powder microscopy analysis3. Various physico-chemical parameters such as moisture content, total ash, acid-insoluble ash, water-soluble ash, water and ethanol soluble extractives and foreign organic matters were determined4, 5. Powder of root, fruit and leaves were successively extracted in a soxhlet apparatus using solvents such as petroleum ether (40-60°C), chloroform (59.5-61.5°C) and methanol (64-65.5°C) for 16-18 hours. The extract was concentrated and subjected to various qualitative phytochemical tests for the identification of chemical constituents present in the plant materials6. Total carbohydrate content of the samples was estimated by Anthrone method7. Total protein content was estimated by Lowry’s method8. Estimation of total phenol was done with Folin-Ciocalteau reagent, according to the method of Slinkard and Singleton9. Thin layer chromatographic studies of the petroleum ether, chloroform and methanol extracts of root, fruit and leaf of S. melongena var. insanum were carried out using Silicagel 60 F254 pre-coated TLC plates.

 

RESULTS AND DISCUSION:

Indian systems of medicine such as Ayurveda and Siddha use crude drugs, majority of which are of plant origin. It is necessary that standards have to be laid down to control and check the identity of the plant and ascertain its quality before use. Thus in recent years there has been an emphasis in the standardization of medicinal plants of therapeutic potential. According to World Health Organization, the macroscopic and microscopic description of a medicinal plant is the first step towards establishing its identity and purity and should be carried out before any tests are undertaken10.

 

Organoleptic or macroscopic evaluation is a technique of qualitative evaluation based on the study of morphological and sensory profile of whole drugs. The leaves of S. melongena var. insanum are simple, alternate, ovate or elliptic ovate, acute, 10-15×8-10 cm, oblique at base, irregularly lobed, stellate-pubescent and prickly along the nerves. The flowers are solitary, extra-axillary and white. Calyx consists of five lobes, lanceolate, thick and stellate-pubescent with spines. Corolla is rotate, five lobed and triangular. Stamens are five; free, epipetalous and the ovary is villous; berry oblong-globose. The tap root is woody, dark yellow to brown in colour with fewer branches (Fig. 1 and 2).

 

Transverse section of root (Fig. 3) shows 5-6 layered periderm with lenticels. Inner to the periderm, about 8-10 layered parenchymatous cortex is present. The cortical cells contain numerous starch grains and tannins. Next to the cortex, a single layer of broken ring of sclerieds is present. Endodermis is distinct and single layered while the pericycle is indistinct. Cambium gives rise to secondary phloem externally and secondary xylem internally. Uniseriate parenchymatous medullary rays are present. Xylem consists of vessels, xylem parenchyma and fibers. Sclerenchymatous secondary tissues are also seen.

 

The leaf is dorsiventral with uniseriate epidermis; both the upper and lower epidermis contain trichomes. In younger leaves, the epidermis is traversed by two types of trichomes- short stalked multicellular globose glandular trichomes and stellate trichomes with 6-9 arms. Stomata are seen on both surfaces, mainly paracytic. Anisocytic stoma was also seen in some area. Just below the epidermis, mesophyll is seen. Upper region of mesophyll tissue is made up of a single layer of compactly arranged columnar palisade tissues and the lower region consists of oval- spherical spongy tissue, with numerous intercellular spaces. A central solitary midrib is present which shows a single layered epidermis, followed by cortex, which is divisible into 4-6 layered collenchyma followed by multilayered parenchyma. Endodermis and pericycle are found inner to the cortex. A single arc-shaped vascular bundle is present in the central region (Fig.4). Quantitative leaf microscopy of the lower leaf surface such as stomatal number (189), stomatal index (23.2), vein islets number (55) and palisade ratio (2.5) were observed.

 

Transverse section of pericarp of the fruit (Fig.5) shows a single layered and yellow coloured epidermis. Just below the epidermal cells, 5-8 layered sclerenchymatous region is present. It is followed by many-layered and thin walled, small round and polygonal parenchymatous cells containing starch grains, oil globules and tannin containing cells. In between the parenchymatous cells, vascular strands are present.

 

Powdered samples of root, fruit and leaf were observed under the microscope. The powder of root was cream to yellow coloured, which contained oval and round starch grains. Pitted vessels and sieve elements were also observed. The fruit powder was yellow in colour with a characteristic smell. Powder microscopy of the fruit showed fragments of epidermis, cortex and placenta. The cortical cells contained starch grains. Different types of hairs such as unicellular, bicellular and hooked hairs were present. Stellate and 6-9 armed glandless trichomes were present. Both spiral and annular vessels were present.


Table 1: Physico-chemical parameters of Solanum melongena var. insanum

Sl. No.
Parameter

Mean Value

Root

Fruit

Leaf

1

Moisture content

93.50%

91.70%

94.25%

2

Solid content

6.45%

8.23%

5.72%

3

pH  of 1% aqueous solution

5.66

5.55

5.87

4

pH  of 10% aqueous solution

5.54

5.46

5.76

5

Water soluble extractive value  (%w/w)

7%

6%

4%

6

Ethanol soluble extractive value  (%w/w)

6%

5%

3%

7

Total ash (% w/w)

6.5%

7%

6%

8

Water soluble ash

4.0%

4.5%

3.5%

9

Acid insoluble ash (%w/w)

1%

3%

2.5%

10

Foreign organic matters

0.2 %

0.05%

0.05%

 

Table 2: Preliminary phytochemical screening of three different extracts of Solanum melongena var. insanum

Extracts tested ®

Petroleum ether

Chloroform

Methanol

Components  ¯

Fruit

Root

Leaf

Fruit

Root

Leaf

Fruit

Root

Leaf

Flavanoids

-

-

-

-

-

-

+

+

-

Coumarins

+

+

-

+

+

-

-

+

-

Alkaloids

-

-

-

-

-

-

+

+

+

Tannin

-

-

-

+

+

+

-

+

+

Steroids

+

+

-

-

+

+

-

-

-

Quinines

+

+

+

-

+

+

+

-

+

Anthroquinines

-

-

-

-

-

-

-

+

-

Phenol

-

-

-

-

-

-

+

+

+

Resin

+

+

+

+

+

+

-

+

+

Glycoside /Reducing sugar

-

-

-

-

-

-

+

+

-

Protein

-

-

-

+

+

-

+

+

+

Carbohydrate

+

+

+

+

+

+

+

+

+

 

Table 3. TLC studies of Solanum melongena var. insanum

Plant part used

Extracts

Solvent system

No. of visible bands

No. of bands in Iodine

Rf values in visible

Rf values in Iodine

 

 

 

Fruit

Petroleum ether

chloroform: hexane

(1:1)

5

5

0.07,0.14,0.25, 0.28, 0.34

0.07,0.14,0.25, 0.28, 0.34

Chloroform

hexane: chloroform: methanol (5:3:0.2)

2

10

0.07, 0.76

0.07,0.107,0.16,0.19,0.26,0.35,0.58, 0.76,0.87,0.92

Methanol

hexane: chloroform: methanol (3:4:2)

2

5

0.54, 0.87

0.42,0.54,0.70,0.77,0.87

 

 

 

Root

Petroleum ether

hexane: ethyl acetate

(6:4)

3

5

0.35, 0.5, 0.82

0.22,0.35,0.43,0.5,0.82

Chloroform

hexane: chloroform:  methanol (3:5:0.5)

1

6

0.21

0.061,0.169, 0.21,0.24,

0.32,0.55

Methanol

hexane: chloroform: methanol (3:5:1)

1

4

0.58

0.58,0.64,0.69, 0.76

 

 

 

Leaf

Petroleum ether

hexane: chloroform: methanol (3:3:0.5)

4

6

0.08, 0.43, 0.57, 0.78

0.062, 0.08, 0.43, 0.57, 0.78, 0.92

Chloroform

hexane: chloroform: methanol (3:5:0.3)

10

12

0.08, 0.16, 0.21, 0.24, 0.29, 0.42, 0.65, 0.84, 0.88, 0.90

0.08, 0.16, 0.21, 0.24, 0.29, 0.42, 0.65, 0.76, 0.84, 0.88, 0.90, 0.94

Methanol

hexane: chloroform: methanol (3:5:0.2)

10

13

0.14,0.18,0.23,0.26,0.38,0.44,0.65,0.72,0.91,0.95

0.07,0.14,0.18,0.23,0.26,0.34,0.38,0.44, 0.65,0.72,0.86, 0.91,0.95

 

 

Yellow coloured storage cells and oil granules were observed during powder microscopy. Powder microscopy of the leaf showed light pink coloured unicellular trichomes- both single and in clusters, light yellow coloured pitted xylem vessels and brown epidermal strips.

 

Various physico-chemical parameters such as total ash, acid insoluble ash, foreign organic matters, loss of weight on drying, solid content and extractive values of fruit, root and leaf were determined and are depicted in table 1.

 

The plant materials such as root, fruit and leaves were subjected to preliminary phytochemical screening involving successive solvent extraction by different solvents in the order of increasing polarity to obtain diverse non polar and polar phytoconstituents. The results are showed in table- 2.

 

Thin layer chromatography is particularly valuable for the preliminary separation and determination of phytoconstituents. The results of TLC of the petroleum ether, chloroform and methanol extracts of root, fruit and leaves of S. melongena var. insanum are shown in table 3.

 

.

1) Habit 2) Root 3) T.S of root. 4) T.S of leaf. 5) T.S of pericarp of fruit. (SX- Secondary Xylem, SP- Secondary Phloem, XR- Xylem Rays, PF- Phloem Fiber, PD- Periderm, TR- Trichome, VB- Vascular Bundle, LA- Lamina, GT- Ground Tissue, EP- Epidermis, PC-Parenchyma, SC- Sclerenchyma).

 

The amount of total carbohydrate was analyzed by Anthrone method. The findings revealed that roots possess higher amount of carbohydrate (384mg/g) compared to fruit (308mg/g) and leaf (11mg/g). The protein content was estimated by using Lowry’s method. It was higher in fruit (113.3mg/g) compared to root (23.65mg/g) and leaf (15.5mg/g). Total phenols were estimated by using Folin- Ciocalteau reagent. The observation revealed that leaf possesses higher percentage of phenols (22.2mg/g) compared to root (21.0 mg/g) and fruit (19.0 mg/g).

 

CONCLUSION:

The pharmacognostic profile of S. melongena var. insanum provides a set of qualitative and quantitative parameters or standards that can serve as an important source of information to ascertain the identity, quality and purity of the plant material.

 

ACKNOWLEDGEMENTS:

The authors are grateful to Swami Gururethnam Jnana Thapaswi, Director, NSKGRC, Uzhavoor, Kottayam, Kerala for providing the necessary facilities for the study. Technical assistance rendered by Sri. Janeesh MP is also acknowledged.

 

REFERENCE:

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Received on 24.05.2010

Accepted on 12.06.2010        

© A&V Publication all right reserved

Research Journal of Pharmacognosy  and Phytochemistry. 2(5): Sept.-Oct. 2010, 364-367