Effect of Carrageenans on Biological Properties of Echinochrome

With increasing awareness of functional properties of products from marine organisms, their attractiveness both as a source of nutritious food items and stockpot of novel, biologically active compounds continuously expands (Sumich, and Pinkard-Meier, 2016). For example, the gonads of sea urchins have been consumed by humans since ancient times; at the same time, the characteristic colour of spines and shells of these organisms is attributed to calcium salts of naphthoquinone derivatives – spinochromes or polyhydroxynaphthoquinone pigments exhibiting a vast range of pharmacological activities.

One of the most famous of these derivatives is pigment echinochrome A (6-ethyl-2,3,5,7,8-pentahydroxy-1,4-naphthoquinone) and its synthetic analogues are known as biologically active compounds with antimicrobial, antialgal, and antioxidant activities (Pozharitskaya et al. , 2015). Most of all, it has been ascertained that treatment with echinochrome protected mitochondrial function in cardiomyocytes against cardiotoxic drugs (Jeong et al. , 2014a). In Russia echinochrome (Ech, registration number P N002362/01) is the active substance in the cardioprotective and antioxidant drug Histochrome®, produced from the sand dollar Scaphechinus mirabilis and available in ampoules (Mishchenko et al. , 2003, Elyakov et al. , 2007). One of the main setbacks to the wide use of Ech is its insolubility in aqueous solutions and high susceptibility to oxidative destruction. Improvement of therapeutic efficacy of drugs can be achieved by modifying the formulation technique, for instance, by means of polymeric systems. Natural edible polymers have established substantial consideration to date because of their benefits comprising such advantages as biocompatibility, biodegradability, adhesiveness, and their ability to form hydrogels by way of matrices in delivering drugs (Shit and Shah, 2014). In order to provide a stable and biocompatible environment to the Ech, polymeric matrix systems based on polysaccharides from red algae have been proposed as the suitable candidates for the oral delivery (Yermak et al. , 2017).

Polysaccharides of red algae, carrageenans (CRGs) are sulfated linear galactans, consisting of alternating b-1,4- and a-1,3- linked d-galactosyl residues (D- and G-units) and several types of these polysaccharides are identified on the basis of the structure of the disaccharide repeating unit, by the pattern of sulfation, and the presence of 3,6-anhydrogalactose (DA-unit) as a 4-linked residue (Knutsen, Myslabodski, 1994). The three most industrially exploited types, namely κ-, ι- and λ- CRGs, are distinguished by the presence of one, two, and three ester-sulfate groups per repeating disaccharide unit, respectively. Natural CRGs are often hybrids of more than one of these units and are composed of several carrabiose moieties, the proportions and structures of which vary with species, the life stages of seaweeds, ecophysiological, and development conditions (Falshaw, Furneaux, 1994; Yermak, Khotimchenko, 2003; Pereira et al. , 2017). CRGs are widely utilized due to their excellent physical properties as thickening, gelling, and stabilizing agents in the food industry (Pereira, 2016). Recently we have shown that Ech interacts with CRGs and is incorporated into the macromolecular structure of the polysaccharide. The inclusion of Ech in complexes with CRGs decreased its oxidative degradation and improved its solubility (Yermak et al. , 2017).