Evaluation methods for identification of crude drugs
Plant products are used throughout the developed and developing countries as home remedies over the counter products and raw materials for pharmaceutical industries and represent a substantial propotion of global drug market. It is therefore essential to establish recognized guidelines for assessing their quality. The function of drug quality evaluation is to value raw materials and to ensure that final product will be of standard drug.
Evaluation methods for crude drugs:
1.
Organoleptic evaluation
2.
Microscopic evaluation
3.
Physical evaluation
4.
Chemical evaluation
5.
Biological evaluation
Our present intrest on review is Microscopic evaluation as it is the simplest, reliable and appropriate method to check the purity and quality of herbs.
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Microscopic evaluation |
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Quantitative Microscopy ·
Stomatal number ·
Stomatal index ·
Vein islet number · Vein termination number ·
Palisade ratio |
Qualitative
Microscopy ·
Stomata ·
Trichomes ·
Starch grains · Calcium oxalate crystals ·
Xylem vessels |
QUALITATIVE MICROSCOPY
A] Stomata
The stomata are minute pores which occur in the epidermis of the plants. Each stoma remains surrounded by two kidneys or bean shaped epidermal cells the guard cells. The stomata may occur on any part of a plant except the roots. The epidermal cells bordering the guard cells are called accessory cells or subsidiary cells.
Stomata is one of the best standard to identify the plant microscopically. There are various types of stomata present in plants like
1.
Paracytic stomata
2.
Diacytic stomata
3.
Anisocytic stomata
4.
Anomocytic stomata
5.
Actioncytic stomata
B] Trichomes
Trichomes
are outer growth of epidermal cells mostly found on leaves and stem, sometimes
on fruits and flowers. Trichomes are important tool to identify herbs in
powders to identify the standard plant as well to check the adulteration.
C] Starch grains
Starch analysis or starch grain analysis is a technique that is useful in archaeological research to determine plant taxa. In certain samples of food plants, spices, drugs and desiccated archaeological plant matter, the histological elements can survive and thus be identified. Plant starch grain analysis is a diagnostic feature of multiple applications according to the peculiarities and to the origin of the plant material. The size, shape and structure of grains from plant species, varies little, which can lead to identification. Features that allow toidentify starch grains are presence of hilum, layering, birefringence, and extinction cross, and also testing for presence of starch using iodine (staining black to blue in presence of starch).
D] Xylem Vessels
Xylem is one of the essential tissue of vascular system of plants. It transports water from downwards to upwards. Plants has specific type of xylem vessels according to lignin present on its wall. One can easily check the purity of drug powder in microscopy by pattern of xylem vessel in comparison to standard literature.
CONCLUSION
Advancement in the microscopy technique could help to achieve the goal of standardizations of the herbal products. Moreover, majority of the regulatory procedure and pharmacopoeias propose macroscopic and microscopic evaluation for herbal standardization .To ensure the quality of plant material, the microscopic description is the first step towards establishing its identity and purity. In conclusion, for identification and evaluation of medicinal plants by pharmacognostical studies microscopic method is one of the cheapest, reliable and simplest methods to start with establishing the correct identification of the source material.
World Journal of Pharmaceutical Research
ISSN 2277–7105
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