Galactomannans are the heterogeneous polysaccharides also known as seed gums, mostly isolated from the legume seed endosperm (
Anderson, 1949;
Kapoor, 1992;
Srivastava and Kapoor, 2005). Because of their viscous behaviour in aqueous media, emulsifying and gelling property, they are preferred as hydrocolloids and they are cheap, eco-friendly and non-polluting while production and in several applications (
Smith and Montigomery, 1959). They are also using in different ways for human consumption (
Srivastava and Kapoor, 2005). Legumes (sensu lato Legumnosae = Fabaceae family) seed endosperm is the main source of galactomannans. The galactomannans distribution in the plant kingdom is limited
(Bailey et al., 1971).
Seed galactomannans have highly variable chemical structure in the nature. It includes wide variation in the degree of galactose and mannose ratio, which are commonly formed by a linear chain of β-1, 4-Dmannopyranosides branched with single unit of D galactopyranosides through α-1,6 linkages. Their mannose/galactose ratios depend on their source. It varies from species to species (
Dea and Morrison, 1975;
Dey, 1978;
Winter et al., 1984). The mannose to galactose ratio influences the solubility and the chain stiffness
(Wu et al., 2012). The galactomannans are considered as multipurpose macromolecules basically neutral polysaccharides (
Reid and Bewley, 1979). The galactomannans accumulate moisture at the early stage of seed swelling and play an important role in seed imbibitions (
Reid and Bewley, 1979), germination, when the galactomannans are catabolised and transferred to the embryo as a carbon and energy source and also in the protection of the seed.
The different chemical properties of these gums made them versatile materials which are used for many different applications, they are largely used in thermoplastic, rubber industries and preparation of food products additives ice creams in food industries, pharmaceutical industry as a drug carrier and emulsifier, cosmetics, pastes, toiletries industries, thickener in toothpastes, conditioner in shampoos and textile industries. Also used for the sizing, finishing in printing industries, in crude oil drilling and explosives (
Schneider and Soster-Turk, 2003; Sharma et al., 2008; Vendruscolo et al., 2009; Williams and Phillips, 2003). Recently come to know that these are also used in the preparation of nano-particles
(Soumya et al., 2010).
Nanoparticles are the ultrafine solid particles with sizes ranging from 1 to 100 nm and have gained attention as potential carriers for drugs, immune modulators, hormones, nucleic acids, proteins and antibodies (
Akagi et al.,
2006). These nanoparticles can either be constituted by inorganic components (
e.g. metals, silica) or by synthetic or natural polymers. Due to their physicochemical and bioactive properties of these materials have a broad variety of applications in various fields such as medicine, food, cosmetics and environment
(Sathishkumar et al., 2014; Chaudhry and Castle 2011;
Borase et al., 2013; Pant et al., 2013; Zuas et al., 2014)
. There are several methods used for the preparation of nanoparticles, namely by self-assembly by dialysis, nanoprecipitation, ionic or covalent crosslinkling, spray drying, among other
(Gaucher et al., 2005). Guar gum is an industrial galactomannan of high degree of substitution (D-mannose/D-galactose molar ratio ~2.0) and it has been used in drug-delivery, because of its low cost and other desirable functions
(Cheng et al., 2002). The formation of nanoparticles depends on the molecular mass of the galactomannans, crosslinking agents, solvent and surfactant
(Soumya et al., 2010). Nano precipitation is one of the major technique for the preparation of nanoparticles
(Becer et al., 2009).
Genipin is a natural dye extracted from the plant
Gardenia jasminoides from the family Rubiaceae. It is an intermediate of alkaloid synthesis, plays an important role in alkaloid synthesis. It is an excellent cross-linking agent for proteins, collagens and chitosan
[Fujikawa et al., 1987, 1988], also used for regulating agent in drug delivery
[Zhang et al., 2006; Djerassi et al., 1961]. To the best of our knowledge, genipin has not so far been used to crosslink galactomannans as an strategy to obtain small nanoparticles.
In a recent accompanying paper we have documented the extraction, purification and characteristics of galactomannan sourced from
Adenanthera pavonia (
Ceraqueira et al., 2009). Also, the galactomannan from
Mimosa pudica L. and
Dichrostachys cineria L has been studied in our laboratories
(Harikrishna et al., 2017; 2018) and these legume trees are indigenous to Southern India. In the present study we have investigated the potential applications of these new galactomannans as building blocks of emulsifier, nanoparticles with potential use in pharmacy and food industry.