1. Introduction
Okra is a plant which is widely
cultivated in the tropics, sub-tropics and warm, temperate regions
around the world including Africa, Asia and North America with
total trade estimated to over $5 billion. Okra extracts
obtained from fresh okra pod, are naturally available, inexpensive
and non-toxic biopolymers, which make okra an attractive resource
for industrial applications. The polysaccharides within okra extracts
are predominately pectins. Pectins are acidic heteropolysaccharides
consisting of three segments, namely
homogalacturonan (HG), rhamnogalacturonan I (RG-I) and rhamnogalacturonan
II (RG-II) regions . Homogalacturonan (HG) is mainly composed of a-(1 /4)
linked a-D-galacturonic acid (GalA) residues containing methyl
esterified carboxyl groups and partially acetylated hydroxyl groups
at O-2 and/or O-3 positions. RG-I branches consist of repeating
units of a-(1 / 4) linked a-D-galacturonic acid and a-(1 / 2)
linked a-L-rhamnose. Rhamnose residues of RG-I regions may also
contain arabinan, galactan and/or arabinogalactan side chains at
rhamnose 4-O positions. The RG-II domain
has a backbone similar to previous units but its structure is more
complex due to the presence of a diverse range of sugar monomers
. Like many other biopolymers, the physicochemical
properties of okra polysaccharides are amenable to
interdisciplinary applications between the pharmaceutical and
food industry in both dry and hydrated systems.
Hydrophilic matrix tablets are the most frequently employed
oral drug delivery devices for controlled drug release applications
. Furthermore, the use of naturally resourced
biopolymers has gained considerable attention in the last few decades,
as they have the potential to be utilised in the wide range of
pharmaceutical formulations including matrix tablets, topical gels
and emulsions . Owing to their cost effectiveness,
availability and good regulatory acceptance they have the ability to
compete with the semi-synthetic and synthetic polymers in the
market. A number of natural and
modified polysaccharides, such as xanthan gum, guar gum , grewia gum