Pharmacognostical Characterization on the Rhizome of Ginger

Wungsem Rungsung*, Sreya Dutta, Dhirendra Nath Mondal, Jayram Hazra,

National Research Institute for Ayurvedic Drug Development, Department of AYUSH,

4-CN Block, Sector-V, Salt Lake, Kolkata-91.

*Corresponding Author E-mail: asemosem@yahoo.com

ABSTRACT:

People the world over are increasingly turning to indigenous systems of medicine, which are mainly derived from the plant materials. The use of plant drugs, however, demands correct identification and characterization because their efficacy and safety depend on the use of proper plant part and its biological potency. Zingiber officinale Rosc., commonly known as ginger, is recorded to have been used in the traditional healthcare system of India since time immemorial. Transverse section of its rhizome showed that starch accumulates in the cortical cells and stele; and also revealed the presence of numerous suberized oil cells. The cell contents of diagnostic value are suberized oil cells containing yellowish to reddish-brown oleoresins, ovate starch grains, reticulate vessels and septate fibres.

KEYWORDS: Ginger, rhizome, oleoresin, starch grain, HPTLC fingerprints.

INTRODUCTION:

Zingiber officinale Rosc., belonging to the family zingiberaceae and indigenous to south-east Asia, is a rhizomatous perennial herb reaching up to 90cm in height when fully grown (Kochhhar, 1981; Meena et al., 2010). Ginger ranks third in value among all the spices exported from India, being next to pepper and cardamom. And India still remains the world’s largest producer of ginger, accounting for more than 50% of the world production. It is a pungent and biting tropical spice popularly known for its medicinal value. It is analgesic, carminative, anti-inflammatory, anti-emetic and aids in digestion, blood circulation, throat clearing, common cough and cold (Biswas, 2009). It is also much in vogue as a household remedy for flatulence and colic, and is valued throughout the world as a spice or flavouring agent (Meena et al., 2010; Tyler et al., 1988). Earlier studies on ginger gave only the general anatomical features (Solereder and Meyer, 1930; Tomlinson, 1956), while Shah and Raju (1975) studied the general morphology, growth and branching pattern of ginger and turmeric. Bell (1980) described the vascular pattern of rhizomatous ginger. The characteristic aroma of ginger is due to a volatile oil (ginger oil), while the pungent taste for which ginger is so highly esteemed is due to the presence of a non-volatile oleoresin, gingerin (Kochhhar, 1981). Rhizome, the storage organ in ginger (Remashree et al., 1997), is the part used in medicine.

The present investigation was undertaken to evaluate various qualitative and quantitative parameters on the rhizome of ginger, the findings of which will be helpful in setting standards for the medicinal plant.

MATERIALS AND METHODS:

The material for study was procured from the farmland of Salt Lake (Kolkata), got identified through detailed taxonomic study and then air-dried for pharmacognostical study. Macroscopical study was carried out with the naked eyes/aid of a magnifying lens to determine the shape, size, texture, etc. as per requirement of Indian Herbal Pharmacopoeia. Microscopical study was performed by preparing a thin hand section of the rhizome, cleared with chloral hydrate solution and stained as per the standard protocol (Brain and Turner, 1975; Johansen, 1940). The dried material was coarsely powdered in a blender and subjected to various tests- powder analysis was carried out with reference to the presence or absence of particular diagnostic characters for rapid and accurate determination of their identity following the procedures mentioned in the Pharmacopoeia of India (2001) and Textbook of Pharmacognosy (Wallis, 1999); fluorescence analysis was carried out as per the method advocated by Chase and Pratt (1949); and quantitative tests such as total ash, acid-insoluble ash, etc. on the basis of protocol prescribed by WHO on Quality Control Methods for Medicinal Plants (Anonymous, 1998). For chemical profiling of the plant, 100gm of the dried powder was subjected to cold extraction with ethanol and chloroform (1:1) for 7 days; the extract concentrated and then performed High Performance Thin Layer Chromatography (HPTLC) following the method of Egon Stahl (2005).

RESULTS:

A. Macroscopic Characters:

The rhizome is tuberous, thick and fleshy with distinct nodes and internodes, scaly leaves at the nodes; pale yellowish-buff in colour, emitting a characteristic and pleasing aroma with a sharp and pungent taste; branching sympodial, and the branched pieces (commonly known as races or hands) about 5-15 cm long, and 1.5-6.5 cm broad; surface smooth, longitudinally striated and somewhat fibrous; laterally compressed, bearing short, ovate and oblique branches on upper side, each having at its apex a depressed scar; lens view of transverse section shows a narrow cortex, a well-marked endodermis, a wide stele with numerous and scattered fibro-vascular bundles (greyish) and yellow secreting cells; similar bundles also observed in the cortex (Fig. 1).

B. Microscopic Characters:

T.S. of the unpeeled, dried rhizome is circular in outline and shows a zone of cork tissue being differentiated into an outer irregularly arranged tangentially elongated cells and an inner zone of radially arranged thin-walled cells. Beneath the cork is a broad cortex differentiating into an outer zone of flattened parenchyma and an inner zone of isodiametric, thin-walled normal parenchyma with scattered fibro-vascular bundles and numerous suberized oil cells (idioblasts), the oil cells containing yellowish to reddish-brown globules of oleoresins. Vascular bundles are scattered as a typical monocotyledonous stem, collateral and closed, each consisting of a few unlignified, reticulate or spiral vessels, a group of phloem cells and unlignified, thin-walled, septate fibres with oblique slit-like pits on their walls. The cortical cells are also packed with simple and ovate starch grains, each being provided with concentric striations and hilum. The cortex is limited by a single-layered endodermis, which is devoid of starch and a layer of pericycle encloses the stele. The vascular bundles of stele resemble those of cortex but are larger in size. The parenchyma cells of stele also contain numerous starch grains and oil cells (Fig. 2 & 3).

C. Analysis of Powdered Drug:

Powder pale yellowish in colour, fine, somehow gritty when the powder is gently rubbed on the hand; isodiametric, thin-walled parenchyma cells with idioblasts containing oleoresins present; numerous flattened and ovate starch grains with concentric striations and hilum observed; unlignified, reticulate vessels (about 60µ in diameter) and few thin-walled septate fibres (about 30µ wide and 600µ long) also present (Fig. 4).

D. Physico-chemical Analysis (Determination of Identity, Purity and Strength):

Material	Parameter	Value in %
Material	Parameter	Observation I	Observation I1	Observation I11	Mean
Rhizome of Ginger	Total Ash	5.40	5.70	5.50	5.53
	Acid-insoluble Ash	1.10	1.20	0.90	1.07
	Alcohol-soluble Extractive	3.40	3.60	3.20	3.40
	Water-soluble Extractive	11.20	10.80	11.10	11.03
	Loss on Drying at 105°C	10.80	11.10	11.30	11.07

Inference (mean of triplicate): Total Ash=5.53%; Acid-insoluble Ash=1.07%; Alcohol-soluble Extractive=3.40%; Water-soluble Extractive=11.03%; Loss on Drying at 105°C=11.07%.

E. Fluorescence Analysis (inside UV chamber): The powdered drug exhibited the following characteristic colours under UV light:

Material	Solvent	Distinctive Colours Observed
Material	Solvent	Short UV (254nm)	Long UV (366nm)
Rhizome of Ginger	Water	Pinkish grey	Grey
	Methanol	Pinkish grey	Deep grey
	Ethanol	Bluish grey	Deep grey
	Ethyl Acetate	Pinkish grey	Deep grey
	Chloroform	Light grey	Light grey
	Pet. Ether	Pinkish grey	Light grey

F. HPTLC Profile of Extract:

Stationary Phase:

Precoated (support on Aluminum Sheets) Silica Gel Plate. Specification: TLC Silica Gel 60F₂₅₄ Mfg. by Merck.

Mobile Phase:

Hexane, Ethyl acetate, Formic acid and Ethylformate: 4.5:2.0: 0.5:0.5 (G R grade solvent mfg. by Merck, India).

Sample application:

Applied volume 20 µL as 10 mm band and applied at 10 mm from the base of the plate. Plate size 10 × 10 cm.

Development :

Developed up to 85 mm in CAMAG Twin trough chamber. Plate preconditioning (temp. 27°C and average relative humidity 48%).

Derivatising Reagent:

Dipped in 20% aqueous sulphuric acid and charred at 105°C for 10 minutes.

R_f Values:

Plate 1: 0.05, 0.24, 0.27, 0.41, 0.46, 0.58, 0.81; Plate 2: 0.17, 0.21, 0.26, 0.39, 0.44, 0.49; Plate 3: 0.05, 0.08, 0.13, 0.23, 0.27, 0.41, 0.45, 0.50, 0.57, 0.65, 0.81.

Plate 1 Plate 2 Plate 3

HPTLC Fingerprints observed at 254 nm (Plate 1), 366 nm (Plate 2) and after derivatisation/white light (Plate 3)

DISCUSSION

Crude drug is the base material for manufacturing herbal medicines, and efficacy of any crude drug depends on the genuineness of the raw material used for its preparation. Therefore, the authenticity and quality control of a drug material must be ensured before using it for manufacturing medicines. In the present investigation, the macroscopic study reveals the rhizome to be thick and fleshy with distinct nodes and internodes, scaly leaves at the nodes, longitudinally striated and somewhat fibrous, emitting a characteristic pleasing aroma with a sharp and pungent taste. The microscopical and histological study gives a preliminary idea about the nature and disposition of cells and tissues, and helps understand where the compounds of interest are located. The internal structure of rhizome shows a zone of cork tissue being differentiated into an outer suberized cells and an inner thin-walled cells, followed by cortex inside which are present scattered vascular bundles and numerous suberized oil cells containing oleoresins. The cortical cells and the parenchyma cells of stele contain numerous starch grains. The cell contents of diagnostic value as confirmed from the powder analysis are isodiametric thin-walled parenchyma cells containing suberized oil cells and starch grains, ovate starch grains with concentric striations and hilum, unlignified reticulate vessels and thin-walled, septate fibres. Fluorescence analysis under the various reagents exhibited different shades of colour, and thus will help in fulfilling the inadequacy of physical and chemical methods for identification of the crude drug; and the physico-chemical analysis will be helpful in judging its identity and purity (even from the crushed or powdered plant material). HPTLC is a valuable quality assessment tool for the identification and quantification of chemical constituents present in botanical materials. The retention factor (R_f) values obtained from it can be used to identify compounds due to their uniqueness for each compound. In the present study, the R_f values of individual compounds appearing as spots separated vertically have been noted (the less polar compounds moving higher up the plates resulting in higher R_f values), which may be used as a quality control profile for this drug.

REFERENCES

Kochhhar SL. Economic Botany in the Tropics. Macmillan India, Delhi. 1981.

Meena AK, Rao MM,Preet K, Padhi MM, Singh A and Babu R. Comparative Study on Family Zingiberaceae Plants Used In Ayurvedic Drugs. International Journal of Pharmaceutical and Clinical Research. 2(2); 2010: 58-60.

Biswas TK. Medicinal plants used in Ayurveda. Department of AYUSH, New Delhi. 2009.

Tyler VE, Brady LR and Robbers JE. Pharmacognosy. Lea and Febiger, Philadelphia. 1988; 9th ed: pp.150.

Solereder H and Meyer F. Zingiberaceae. In Systemalische Anatomic der monokoty le donen; Hefl VI. 1930; pp 27-56.

Tomlinson PB. Studies in the systematic anatomy of the Zingiberaceae; J. Linn. Soc. 55; 1956: 547-592.

Shah I and Raju EC. General morphology, growth and branching behaviour of the rhizome of ginger, turmeric and mango ginger; New Botanist. 2; 1975:59-69.

Bell A. The vascular pattern of rhizomatous ginger (Alpinia speciosa L. Zingiberaceae) 1. Aerial axis and its development; Ann. Bot. 46; 1980: 203-212.

Remashree AB, Sherlija KK, Unnikrishnan K and Ravindran PN. Histological studies on ginger rhizome (Zingiber officinale Rosc.). Phytomorphology. 41(1); 1997: 67-75.

Brain KR and Turner TD. The Practical evaluation of pharmaceuticals. Wright Scientechnica Britol. 1975.

Johansen DA. Plant Microtechnique. Mc Graw Hill Book Co., New York, USA. 1940.

Anonymous. The Ayurvedic Pharmacopoeia of India. Department of Indian System of Medicine and Homoeopathy, New Delhi. 2001.

Wallis TE. Textbook of Pharmacognosy. CBS Publishers and Distributors, Delhi. 1999.

Chase CR and Pratt RJ. Fluorescence analysis of powdered vegetable drugs with particular reference to development system of identification, J. Amer. Pharm. Asso. (Sci. Ed.). 38; 1949: 324.

Anonymous. Quality control methods for medicinal plant materials. Geneva: World Health Organization. 1998.

Egon Stahl (2005): Thin-Layer Chromatography-A Laboratory Handbook. Springer International Edition. 2005.

Received on 31.01.2014 Modified on 01.03.2014

Res. J. Pharmacognosy & Phytochem. 6(2): April-June 2014; Page 88-91