1.1 30-40% of the whole fruit (Kumar

1.1   Polymers in drug delivery

            Polymers
play an important role in the design and development of drug delivery systems. It
provides sustained or controlled release of hydrophilic and hydrophobic drugs
for long period of time (Rajpurohit et al. 2010). These novel
drug delivery systems may be in the form of tablet, capsules, gels, implants, films,
etc (Srivastava et al. 2016). Amongst
various polymers natural origin polysaccharides are gaining importance due to
its biocompatibility and biodegradability than the synthetic polymers.

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1.2   Polysaccharides in drug delivery

Polysaccharides are
easily available bio-based materials that have a unique combination of
functional properties and eco friendly. Nature produces polysaccharides at a
thousand billion tons a year. The annual synthetic polymer production is a
thousand time less than this and mainly uses oil as a raw material which is
non-renewable. Polysaccharides are generally non-toxic and biodegradable. These
features make polysaccharide materials a natural fit for sustainable
development (Mishra and Malhotra 2009).

Natural and
semi-synthetic polysaccharides represent a group of polymers extensively used
in pharmaceuticals. Natural gums like sodium alginate, xanthan gum, guar gum, keraya
gum, agar, gellan gum, cellulose ethers, chitosan, pectin, starch etc are widely
used in the food industry and considered as safe for human consumption. These
natural polysaccharides are obtained from plant exudates, components of land
and marine plants and from plant seeds. Polysaccharides are often preferred due
to their low cost, availability and low toxicity than the synthetic polymers.
Natural polysaccharides can also be modified to have tailor-made materials for
drug delivery systems and hence can compete with existing synthetic
biodegradable polymers (Bhardwaj et al. 2000).

1.3   Tamarind seed polysaccharide

Tamarind is an arboreal
fruit of Tamarind indica Linn., belongs to the family Leguminosae. It is used as a
condiment, or more precisely, as an ‘acidulant’ like amchur (Gupta et al. 2010). India produces
about 0.3 million tons tamarind yearly, of which the seed constitutes 30-40% of
the whole fruit (Kumar and Bhattacharya 2008).

            The
seed is the major byproduct of the tamarind pulp industry and is used to
manufacture tamarind kernel powder (TKP). The seed is gaining importance as an
alternative source of proteins (13-26%) and polysaccharide (50-57%). Hence, a
lot of interest is shown by the chemists, technologist and nutritionists on the
chemical aspects of tamarind seed. TKP contains about 65 to 72 % polysaccharide
which can be extracted by suitable solvent (Rao and Srivastava 1973).

Tamarind seed
polysaccharide (TSP) gum is extracted from seed endosperm of plant. Tamarind gum
is a polymer with average molecular weight of 52,350 and a monomer of mainly
three sugars- glucose, galactose and xylose- in molar ratio of 3:1:2. It is
neutral, nonionic and branched polysaccharide. It is insoluble in organic
solvents and dispersible in hot water to form a highly viscous gel and
possesses properties like high viscosity, broad pH tolerance and adhesion. It
is non-carcinogenic, nontoxic, mucoadhesive, biodegradable and biocompatible
with high drug holding capacity and high thermal stability. Tamarind gum
contains cellulose-like backbone that carries xylose and galactoxylose
substituents and chemical residues similar to mucin MUC-1 and episialin. As
similar nature to mucin, tamarind gum is able to bind the cell surface and
intensify the contact between drugs and the adsorbing biological membrane.
Tamarind gum is comparatively cheap, non-irritant, eco-friendly and
non-polluting during production and application than other semisynthetic or
synthetic polymers. Tamarind gum is used as polymer in the fields of
pharmaceutical, cosmetic and food applications (Gupta et al. 2010; Singh et al. 2011).

1.4   Pharmaceutical uses of tamarind gum

            Tamarind
gum is extensively tested and employed in various drug delivery applications as
successful pharmaceutical excipients. Tamarind gum is used as stabilizer,
binder, release retardant, viscosity enhancer, suspending agent and emulsifying
agent in the development of novel drug delivery systems for oral, buccal, ophthalmic,
ocular, nasal and topical routes (Joseph et al. 2012; Nayak and Pal 2017).