Preparation and characterization of sulfated galactomannan from guar gum: Optimization of reaction conditions by BBD and molecule conformational studies

A comprehensive review on guar gum and its modified biopolymers: Their potential applications in tissue engineering

Guar gum (GG), as a non-exudate gum, is extracted from the seed's embryos of Cyamopsis tetragonoloba (a member of Leguminosae family). Recently, this biopolymer has received extensive attention due to its low cost, notable properties, non-toxic biodegradation, ease of availability, and biocompatibility. However, disadvantages such as uncontrolled hydration rate and susceptibility to microbial attack have led many researchers to further modification of guar gum. Further modifications of guar gum heteropolysaccharide have been performed to improve properties and explore and expand its potential. The favorable biostability, improved solubility, and swelling, increased pH sensitivity, and good antibacterial and antioxidant properties indicate the significant advantages of the modified gum structures with different functional groups. In this review, the rapid growth in research on GG derivatives-based materials has been discovered. Besides, the production methods of GG and its derivatives have been discussed in tissue engineering and regenerative medical. Consequently, this review highlights the advances in the production of guar-based products to outline a promising future for this biopolymer by changing its properties and expanding its applications in potential targets.

The immunomodulatory activity of degradation products of Sesbania cannabina galactomannan with different molecular weights

Galactomannan (GM) is widely recognized as an immune enhancer; however, the underlying molecular mechanism is still unknown. Herein, four products with molecular weights in descending order, namely GM40, GM50, GM65, and GMOS, were separated from incomplete degradation products of Sesbania cannabina GM by ethanol precipitation, followed by their immunomodulatory activity. Through FTIR and XPS spectra, the amount of free hydroxyl groups was shown to decrease in the following order: GM > GM50 > GMOS > GM40 > GM65. Moreover, the immunomodulatory activity of different products decreased in abovementioned order. The TNF-α, IL-6 and TLR4 content in RAW 264.7 cells treated with different GM products in the presence or absence of TAK-242 (TLR4 inhibitor) suggested that the immunomodulatory activity of GM and its degradation products is TLR4-dependent. Overall, the preliminary relationship indicated here between the hydroxyl groups or the possible deeper structural changes of GM and the immunomodulatory activity need to be further investigated.

Recent Progress in Chemical Modification of the Natural Polysaccharide Guar Gum

Guar gum (GG) is a natural heteropolysaccharide. Due to its non-toxic, eco-friendly, and biodegradable nature, GG has found wide applications in many areas, in particular food, paper, textile, petroleum, and pharmaceutical industries. Therefore, GG is often called "Black Gold" as well. Due to the presence of hydroxyl groups, GG can be modified by various methods. The physical and biological properties of GG can be modulated by chemical modifications. In this manuscript, various methods for the chemical modifications of GG have been discussed according to the type of modifications. Mechanistic insights have also been provided whenever possible. In addition, potential applications of new GG derivatives have also been briefly mentioned.

Gallic Acid-Laminarin Conjugate Is a Better Antioxidant than Sulfated or Carboxylated Laminarin

A 12.4 kDa laminarin (LM) composed of β(1→3)-glucan with β(1→6)-branches was extracted from brown seaweed Lobophora variegata and modified via carboxylation using dielectric barrier discharge (LMC), conjugation with gallic acid (LMG), and sulfation (LMS). Analyses of the chemical composition of LMC, LMG, and LMS yielded 11.7% carboxyl groups, 1.5% gallic acid, and 1.4% sulfate content, respectively. Antioxidant activities of native and modified laminarins were assessed using six different in vitro methods. Sulfation stopped the antioxidant activities of LM. On the other hand, carboxylation improved cooper chelation (1.2 times). LMG was found to be a more efficient antioxidant agent than LM in terms of copper chelation (1.3 times), reducing power (1.3 times), and total antioxidant capacity (80 times). Gallic acid conjugation was further confirmed using Fourier transform infrared spectroscopy (FT-IR) and one- and two-dimensional NMR spectroscopy analyses. LMG also did not induce cell death or affect the cell cycle of Madin–Darby canine kidney (MDCK) cells. On the contrary, LMG protected MDCK cells from H₂O₂-induced oxidative damage. Taken together, these results show that LMG has the potent antioxidant capacity, and, therefore, potential applications in pharmacological and functional food products.

Extraction Optimization, Purification, Antioxidant Activity, and Preliminary Structural Characterization of Crude Polysaccharide from an Arctic Chlorella sp

The arctic strain of Chlorella sp. (Chlorella-Arc) exists in the coldest and driest arctic ecosystems, and it is a new resource of active polysaccharides. The extraction of crude polysaccharide from Chlorella-Arc was optimized using the response surface methodology. A crude polysaccharide yield of approximately 9.62 ± 0.11% dry weight was obtained under these optimized conditions. Three fractions (P-I, P-II, and P-III) were present after purification by 2-diethylaminoethanol Sepharose Fast Flow and Sephadex G-100 chromatography. The P-IIa fraction demonstrated significant antioxidant activities. Moreover, P-IIa was an α- and β-type heteropolysaccharide with a pyran group and contained variable amounts of rhamnose, arabinose, glucose, and galactose based on fourier-transform infrared spectroscopy, high-performance liquid chromatography, and ¹H and 13C nuclear magnetic resonance imaging. Production of high amounts of polysaccharide may allow further exploration of the microalgae Chlorella-Arc as a natural antioxidant.