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Pharmaceutical Applications of Sterculia Gum
Published in Amit Kumar Nayak, Md Saquib Hasnain, Dilipkumar Pal, Natural Polymers for Pharmaceutical Applications, 2019
Md Nurus Sakib, Md Minhajul Islam, Md Shahruzzaman, Abul K. Mallik, Papia Haque, Mohammed Mizanur Rahman
Sterculia gum or Karaya gum is a complex, partially acetylated polysaccharide obtained as a calcium and magnesium salt. The karaya gum collection starts after wounding the Sterculia tree. The exudation is higher in the first few days. The exude solidifies into the form of drops when dried. Dried gums are then collected. Generally, a mature tree gives around 1–5 kg of gum per season. The gum collection is best from April to June. It is prepared by first removing impurities such as bark, stones, fibers, and sand by manually or mechanically. Then it is then milled, blended. Finally, the gum is classified on the basis of mesh size, viscosity, and purity. Commercial karaya gum can be of five grades depending on the quality. The gum is available as granules or in powder form. The color of the powder may be light to pinkish gray and has a slight acetic taste and odor. The higher grade is of a lighter color. The granule size ranges from 4–8 mesh and 8–14 mesh and powder size is 160 mesh with a viscosity ranging from 500–1200 cps (López-Franco et al., 2009; Verbeken et al., 2003).
Study of a cross-linked hydrogel of Karaya gum and Starch as a controlled drug delivery system
Published in Journal of Biomaterials Science, Polymer Edition, 2019
Sapna Sethi, Balbir Singh Kaith, Mandeep Kaur, Neeraj Sharma, Sadhika Khullar
Karaya or sterculia gum is a highly branched, complex, anionic heteropolysaccharide and is composed of galacturonic acid, β-d-galactose, glucuronic acid, l-rhamnose and other residues. It is obtained from the tree Sterculia urens belonging to the family sterculiaceae and commonly used in treating gastrointestinal problems as well as an effective laxative [1]. Karaya gum is hydrophilic, biocompatible with high viscosity and gel forming adhesion abilities but suffers from uncontrolled rates of hydration, pH dependent solubility and microbial contamination [2]. Certain limitations can be controlled by means of grafting and cross-linking of gums with other biopolymers and further transforming them into hydrophilic hydrogels with improved-rheology, swelling capacity, mechanical and thermal properties [3]. Karaya gum-based hydrogels have good swelling and water retention capacity and can act as a potential drug delivery system for sustained drug release [1,4]. These hydrogels-based drug delivery systems are designed to achieve prolonged therapeutic effect by continuously releasing drug over an extended period of time after an oral administration of drug embedded in hydrogel. The sustained drug release maintains non-toxicity by control of drug release in the body, further enables maximum utilization of drug and reduces the frequency of drug dosage. Finally after the drug release, the polysaccharide-based drug delivery device gets degraded in the colon by enzymes and remains harmless to the organism [5]. In hydrogel-drug system, the release of drug from the hydrogel matrix is governed by hydrogel drug interactions, release environment and swelling capacity of hydrogel as well as by chemical characteristics of drug [6]. The release profile of a drug from hydrogel matrix can be regulated by controlling the cross-linking density as well as functional groups of hydrogel [7]. The hydrogel acting as a drug delivery device needs to be physically stable to avoid burst or premature release of drug into the body. In this regard, physically stable multipolymer architectures of hydrogels tailored to drug delivery applications have received attention in last few decades [8]. Multicomponent hydrogels display better mechanical strength, faster response rate and diffusion of solutes [9].