Tamarind seeds or Kernel is a byproduct of Tamarind pulp industry. Tamarind gum is obtained from endosperm of seeds of the tamarind tree, which is a seed gum with potential industrial applications.

Tamarind gum is having applications in paper, food, textile industry etc. Recent years research has been initiated on the use of tamarind gum in pharmaceutical and cosmetic applications. Tamarind kernel powder disperses and hydrates quickly in cold water but does not reach maximum viscosity unless it is heated for 20-30 mins. Chemically tamarind kernel powder is highly branched carbohydrate polymer. The solution exhibits typical nonnewtonian flow properties common to most other hydrocolloids. Tamarind kernel powder is evaluated for its suitability as a carrier to improve the dissolution rate of poorly water-soluble drug celecoxcib. Tamarind gum along with xanthan gum and hydroxypropyl cellulose (water soluble neutral polymer) used for nasal mucoadhesion studies in powder formulation. Tamarind gum was also evaluated in bioadhesive tablets. Polysaccharide present in tamarind kernel powder is called as tamarind seed polysaccharide. Tamarind seed polysaccharide is having molecular weight 52350 units and monomer of glucose, galactose and xylose in molar ratio of 3:1:2. It is used as potential polysaccharide having high drug holding capacity for sustained release of verapamil hydrochloride. It is also used as suitable polymer for sustained release formulations of low drug loading. Tamarind seed polysaccharide could be used for controlled release of both water-soluble and water insoluble drugs.

Introduction:

Gums and Mucilages are polysaccharide complexes formed from sugar and uronic acid units. They can absorb large quantity of water and swell. They find wide range of pharmaceutical applications that includes their use as binder, disintegrants in tablets, emulsifiers, suspending agents, gelling agents and also used as sustaining agents in tablets.¹ Synthetic hydrophilic polymers are used more often than natural polymers, but because of cost associated with synthetic polymers, researchers are now showing interest in natural polymers (Non-Synthetic) such as gums. Tamarind (Tamarindus Indica L.) is amongst the most common and commercially important, large evergreen tree that grows abundantly in dry tracks of central and south Indian states, also in other south east asian countries. The pulpy portion of fruit is mainly used as acidulant in Indian receipes.² Tamarind seeds or kernel is a byproduct of Tamarind pulp industry. Tamarind gum is obtained from endosperm of seeds of the tamarind tree, which is a seed gum with potential industrial applications. Tamarind gum or tamarind kernel powder came into commercial production in 1943 as a replacement for starch in cotton sizing in Indian textile market.³ It is also used in microbial production of lipids.⁴ It is an important sizing material for textile, a good creaming agent for concentration of rubber latex used as a soil stabilizer, a rich source of proteins and amino acids.⁵ Moreover tamarind kernel powder may also be used as a feed for cattle and pigs.⁶ It is also used as food ingredient.⁷ Currently purified and refined tamarind kernel powder is produced and permitted in Japan as a thickening, stabilizing and gelling agent in the food industry.⁵ Gum solution of good adhesive strength from tamarind gum and sisal fibers were prepared which have potential industrial applications such as for false roofing and room partioning.⁸ Tamarind gum is used as a creamer for latex, in explosives, in borax printing and paper manufacturing. It is also used as stabilizer in ice creams and as an emulsion textile paste. Thus tamarind gum is having applications in paper, food, textile industry etc. Recent years research has been initiated on the use of tamarind gum in pharmaceutical and cosmetic applications. This review specifically focused on pharmaceutical overview of tamarind gum.

Chemical composition:

The composition of tamarind kernel, the source of gum, resembles the cereals.⁹ With 15.4 % to 12.7 % protein, 3-7.5 % oil, 7-8.2 % crude fiber, 61-72.2 % nonfiber carbohydrates, 2.45-3.3 % ash; all were measured on a dry basis.³ Chemically tamarind kernel powder is highly branched carbohydrate polymer.¹⁰ Its backbone consists of D-glucose units joined with (1-4) b-linkages similar to that of cellulose. It consists of a main chain of b-D- (1-4)-galactopyranosyl unit with a side chain of single xylopyranosyl unit attached to every second, third and fourth of D-glucopyranosyl unit through a-D- (1-6) linkage (as shown in Fig 1). One galactopyranosyl unit is attached to one of the xylopyranosyl units through b-D- (1-2) linkage. The exact sequential distribution of branches along the main chain is uncertain.¹¹

Physical properties:

Tamarind kernel powder disperses and hydrates quickly in cold water but does not reach maximum viscosity unless it is heated for 20-30 mins. The solution exhibits typical nonnewtonian flow properties common to most other hydrocolloids.¹² The functional properties of tamarind kernel powder of protein concentrates were reported.¹³ The rheological properties of tamarind kernel powder suspension showed that suspension behaved like nonnewtonian, pseudoplastic fluid with yield stresses and exhibited thixotropic characteristics. An increasing concentration produces increase in nonnewtonian behavior as in consistency latex, yields stress and apparent viscosity.¹⁴

Pharmaceutical applications:

1. Dissolution improvement

Tamarind kernel powder is evaluated for its suitability as a carrier to improve the dissolution rate of poorly water-soluble drug Celecoxcib. Influence of polysaccharide concentration and method of preparation of solid mixtures on dissolution rates was investigated. Order of dissolution efficiencies was found to be solvent deposition > cogrinding > kneading > physical mixing > pure celecoxcib.¹⁵

2. Nasal Mucoadhesion

Tamarind gum along with xanthan gum and hydroxypropyl cellulose (water soluble neutral polymer) used for nasal mucoadhesion studies in powder formulation. Result of this study suggested that the residence time of drug in nasal cavity may be prolonged by using hydroxypropyl cellulose, xanthan gum and tamarind gum as a base for powder preparation of intranasal administration and residence time may be controlled by mixing two or more polymers differing in mucoadhesion.¹⁶

3. Bioadhesive Tablet

Tamarind gum was also evaluated in bioadhesive tablets. It was showed that lactoferrin tablet prepared with tamarind gum showed longest residence time in oral cavity as compared with xanthan gum and carboxymethyl cellulose but an unpleasant taste gradually developed.¹⁷

Tamarind seed polysaccharide:

Polysaccharide present in tamarind kernel powder is called as tamarind seed polysaccharide. Tamarind seed polysaccharide is having molecular weight 52350 units and monomer of glucose, galactose and xylose in molar ratio of 3:1:2.¹⁸ Various methods have been reported for isolation of tamarind seed polysaccharide from tamarind kernel powder.^{19, 20} It is insoluble in organic solvents and dispersible in hot water to form a highly viscous gel such as mucilageneous solutions with a broad pH tolerance and adhesivity.²¹ In addition it is nontoxic and nonirritant with haemostatic activity.²² Recently tamarind seed polysaccharide is widely used for pharmaceutical applications.

Pharmaceutical applications of tamarind seed polysaccharide:

1. Binder in tablet dosage form

Evaluations of tamarind seed polyose as a binder for tablet dosage forms was taken up for the weight granulation as well as direct compression methods. The results indicated that tamarind seed polyose could be used as binder for weight granulation and direct compression tableting methods.²³

2. In Ophthalmic drug delivery

Tamarind seed polysaccharide is used for production of thickened ophthalmic solutions having a pseudoplastic rheological behavior and mucoadhesive properties. Said solution is used as artificial tear and as a vehicle for sustained release ophthalmic drugs. The concentrations of tamarind seed polysaccharide preferably employed in ophthalmic preparations for use as artificial tears i.e. a products for replacing and stabilizing the natural tear fluid, particularly indicated for the treatment of eye syndrome are comprised between 0.7-1.5 % by weight. The concentrations of tamarind polysaccharides preferably employed in the production of vehicles (i.e. delivery system) for ophthalmic drugs having the function of prolonging the prevalence time of medicaments at their site of actions are comprised between 1 and 4 % by weight.²⁴

3. In sustained drug delivery

It is used as potential polysaccharide having high drug holding capacity for sustained release of verapamil hydrochloride. The release pattern was found to be comparable with matrices of other polysaccharide polymers such as ethyl cellulose, hydroxyethyl cellulose and hydroxypropylmethyl cellulose, as well as the commercially available sustained release tablets (isoptin SR).²⁵ It is also used as suitable polymer for sustained release formulations of low drug loading.²³ Sustained release behaviors of both water soluble (acetaminophen, caffeine, theophylline and salicylic acid) and water insoluble (indomethacin) drugs on tamarind seed polysaccharide was examined. Studies showed that tamarind seed polysaccharide could be used for controlled release of both water-soluble and water insoluble drugs. Zero order release can be achieved taking sparingly soluble drugs like indomethacin from tamarind seed polysaccharide. The rate of release can be controlled by using suitable diluents like lactose and microcrystalline cellulose. For water-soluble drugs, the release amount can also be controlled by partially crosslinking the matrix. The extent of release can be varied by controlling the degree of crossslinking. The mechanism of release due to effect of diluents was found to be anomalous and due to crosslinking was found to be supercase II.²⁶

4. In Ocular drug delivery

Tamarind seed polysaccharide was used for ocular delivery of 0.3 % rufloxacin in the treatment of experimental pseudomonas aeruginosa and staphylococcus aureus keratitis in rabbits. The polysaccharide significantly increases the intraocular penetration of rufloxacin in both infected and uninfected eyes. Polysaccharide allows sustained reduction of S. aureus in cornea to be achieved even when the time interval between drug administrations was extended. The results suggested that tamarind seed polysaccharide prolongs the precorneal residence time of antibiotic and enhances the drug accumulation in the cornea, probably by reducing the washout of topically administered drugs.²⁷

5. In controlled release of spheroids

Tamarind seed polysaccharide was used as release modifier for the preparation of diclofenac sodium spheroids using extrusion spheronization technique with microcrystalline cellulose as spheronization enhancer. It was found that release was sustained over a period of 7.5 hour. A credible correlation was obtained amongst swelling index, viscosity, and surface roughness of the polysaccharide particles and in vitro dissolution profile of spheroids. In the comparative bioavailability study the developed spheroids have able to sustained drug release and also was found to improve the extent of absorption and bioavailabillity of drug.²⁸

References:

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24) Saetone MF, Burgalassi S, Giannaccini B, Bodrini E, Bianchini P, Luciani G. Ophthalmic solutions viscosified with Tamarind seed powder. PCT, Int Appl WO9728. 1997.

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27) Emilia A, Arianna T, Paola D, et al. A mucoadhesive polymer extracted from Tamarind seed improves the intraocualr penetration and efficacy of Rufloxacin in Topical treatment at Experimental Bacterial Keratitis. Antimicro Agents Chem. 2004; 3396-3401.

28) Giriraj T, Kulkarni K, Gowthamarajan, et al. Development of Controlled release spheroids using natural polysaccharides as release modifier. Drug Delivery, 2005; 12: 201-206.

Fig. 1 Repeating units of tamarind gum.

About Authors:

S.V.Patil
Department of Pharmaceutics, Shree Santkrupa College of Pharmacy, A/ P/ Ghogaon, Tal. Karad, Dist. Satara. Maharashtra, 415111. INDIA.
Phone: (02164) 257404; Email: sachinpatil79@rediffmail.com

D. R. Jadge
Department of Pharmaceutics, Shree Santkrupa College of Pharmacy, A/ P/ Ghogaon, Tal. Karad, Dist. Satara. Maharashtra, 415111. INDIA.

S.C.Dhawale
Government College of Pharmacy, A/P Vidyanagar, Karad