Exocellular (1→6)-β-D-Glucan (Lasiodiplodan): Carboxymethylation, Thermal Behavior, Antioxidant and Antimicrobial Activity

Abstract

β-Glucans are biomacromolecules of industrial interest for its biological and technological properties, including ability to modify the rheology of food systems and different biological functionalities. In this study, lasiodiplodan an exocellular polysaccharide of the (1→6)-β-Dglucan type produced by the fungus Lasiodiplodia theobromae MMPI was obtained in a bench-scale bioreactor operated in discontinuous mode. Lasiodiplodan produced was derivatized by carboxymethylation and characterized by Fourier Transform Infrared spectroscopy (FT-IR), Thermogravimetry and Differential Thermal Analysis (TG-DTA), X-Ray Diffraction (XRD), scan electron microscopy (SEM) and their antioxidant and antimicrobial potential also was assessed. Two strong absorption bands in the regions of 1422 to 1598 cm −1 , resulting from symmetric and asymmetric stretching vibrations of the -COO-group respectively, were observed in the FT-IR spectrum of the derivatized sample and indicated the carboxymethylation of the macromolecule. TG-DTA curves indicated that native (LAS-N) and carboxymethylated (LAS-C) lasiodiplodan did not suffer significant changes in relation to the heating rates. Native and carboxymethylated lasiodiplodan demonstrated high thermal stability considering the usual standards of the pharmaceutical industry. The final temperature of thermal decomposition increased when the heating rate was increased and less number of steps for thermal decomposition was observed when air was substituted for nitrogen. XRD analysis showed the LAS-N and LAS-C have no crystalline structure, but carboxymethylation led to the arising of regions with certain molecular orientation in biopolymer structure. SEM analysis showed that the carboxymethylation promoted changes in biopolymer macrostructure, including breaking of the polymeric structure and arising of bubbles on the surface area. Carboxymethylation contributed to improving the polysaccharide's antioxidant capacity and LAS-C demonstrated antimicrobial activity against Candida tropicalis.

Fungal Exocellular (1-6)-β-d-glucan: Carboxymethylation, Characterization, and Antioxidant Activity

“…Carboxymethylation consists of an etherification reaction that promotes the replacement of hydroxyls present in the monomeric units of glucose with carboxymethyl groups (CH 2 COO − ) [5]. Besides increasing the solubility of the polysaccharides, carboxymethylation has contributed to the potentiation of antiviral and antitumor activities [6] and improved antioxidant activity [7] and antimicrobial activity [8].…”

Fermentative Production of Lasiodiplodan by Lasiodiplodia theobromae CCT3966 from Pretreated Sugarcane Straw

“…Among them, the filamentous fungus Lasiodiplodia theobromae has received a growing interest by researchers for the biosynthesis of an extracellular β-glucan polymer, namely lasiodiplodan, since this fungus has a high potential for industrial production level [1,4]. In this regard, the tremendous biological characteristics of lasiodiplodan such as anti-proliferative effect on breast cancer cells, hypoglycemic function, and antioxidant activities have made it an attractive biopolymer for commercial applications [5,6]. Generally, the production costs of the fermentative products highly depend on the fermentation substrates, mainly carbon source, as the use of raw materials such as lignocellulosic biomass and agro-industrial residues decrease the manufacturing costs [7].…”

Sulfonation of (1→6)-β-D-Glucan (Lasiodiplodan) and Its Antioxidant and Antimicrobial Potential

“…These biomacromolecules present peculiar physical, chemical and biological characteristics that are associated with their molecular structure and conformation, type of branching and glycosidic bonds, which makes them interesting for different applications in the medical, pharmaceutical, cosmetic and food sectors [1,3,4].…”