Tree gum: Gum kondagogu

Abstract

Tree gums are obtained as the natural exudates of different tree species and exhibit unique properties with a wide variety of applications. Commercially, gums have a separate niche in the world market as a commodity of international trade. These biopolymers are abundant, come from renewable sources, are relatively inexpensive and nontoxic, and are amenable to both chemical and biochemical modifications that find widespread and extensive food and nonfood applications. Most gums are heterogeneous polysaccharides with complicated structures and extremely high molecular masses. Major tree exudate gums include gum arabic, gum tragacanth, gum karaya, ghatti, and gum kondagogu. Exudate gums possess a unique combination of functionalities and properties that can never be matched by any other alternative synthetic polymers, which makes their complete substitution impossible. Importantly, these biopolymers are eco-friendly as they are biodeteriorable. Gum kondagogu is a naturally occurring nontoxic polysaccharide derived as an exudate from the bark of Cochlospermum gossypium (Bixaceae family), a native tree of India. To exploit its potential commercial applications, its morphological, structural, physicochemical, compositional, solution, conformational, rheological, emulsifying, and metal-biosorption properties have been elucidated. Gum kondagogu is an acidic gum with high content of uronic acid and the major functional groups identified in the gum are hydroxyl, acetyl, carbonyl, and carboxylic groups. The primary structure of this biopolymer contains sugars, such as arabinose, rhamnose, glucose, galactose, mannose, glucuronic acid, and galacturonic acid. Based on the spectroscopic categorization, the probable structural feature consigned to gum kondagogu is (1-2) -d-Gal p, (1-6) -d-Gal p, (1-4) -d-Glc p A, 4-0-Me-d-Glc p A, (1-2) l-Rha, and (1-4) d-Gal p A. The outcome of the experimental studies carried out with gum kondagogu has established its efficacy as a proficient biopolymer for (i) bioremediation of toxic metals, (ii) green synthesis of metal nanoparticles and magnetic iron oxide nanoparticles (MNP), (iii) mercury biosensor, and (iv) nanosilver-based antibacterial agent for medical applications. Additionally, appropriate chemical modification of the functional groups present in gum kondagogu may lead to the development of novel technologies for applications in pharmaceutical and food and biotechnology industries.