Synthesis and properties of curdlan branched and linear mixed ester derivatives

Synthesis of divanillic acid-based aromatic polyamides with linear and branched side-chains and the effect of side-chain structure on thermal and mechanical properties

Divanillic acid (DVA)-based aromatic polyamides (PAs) consisting of DVA with linear (methyl, butyl, hexyl, and octyl groups) or branched (isopropyl and isobutyl groups) side chains and 4,4'-methyldianillin were synthesized as high-performance and ultra-high-performance biomass plastics. The DVA PAs were amorphous with high thermal stability (decomposition temperature of ca. 380 °C). The glass transition temperature (Tg) of the DVA PAs depended on the side-chain composition in a linear manner, indicating the PA main chain possessed a random structure. The polymers were pressed to form melt-pressed films. The DVA PAs with a higher content of shorter side chains exhibited both higher Tg and tensile strength than those of polymers with a lower content of shorter side chains. The PAs exhibited Tg in the range of ca. 150-253 °C. The branched PA with isopropyl side chains exhibited the highest Tg of 253 °C and highest tensile strength of 63 MPa among the DVA PAs. The PAs with isopropyl side chains and some linear side chains (methyl/hexyl combination) exhibited high tensile strength of approximately 60-70 MPa; however, their Tg varied from 170 to 253 °C. The branched PA exhibited the highest Tg, tensile strength, and Young's modulus of the polymers. The thermal stability and mechanical properties of the PAs were tuned by their side-chain structure and composition.

Microbial Polysaccharides as Functional Components of Packaging and Drug Delivery Applications

This review examines microbial polysaccharides' properties relevant to their use in packaging and pharmaceutical applications. Microbial polysaccharides are produced by enzymes found in the cell walls of microbes. Xanthan gum, curdlan gum, pullulan, and bacterial cellulose are high-molecular-weight substances consisting of sugar residues linked by glycoside bonds. These polysaccharides have linear or highly branched molecular structures. Packaging based on microbial polysaccharides is readily biodegradable and can be considered as a renewable energy source with the potential to reduce environmental impact. In addition, microbial polysaccharides have antioxidant and prebiotic properties. The physico-chemical properties of microbial polysaccharide-based films, including tensile strength and elongation at break, are also evaluated. These materials' potential as multifunctional packaging solutions in the food industry is demonstrated. In addition, their possible use in medicine as a drug delivery system is also considered.

Synthesis and characterization of bioplastic curdlan esters with an introduced flexible carboxylic acid side chain

Curdlan, a linear β-1,3-glucan, was reacted with glutaric anhydride and heptanoyl chloride to afford thermoplastic curdlan esters (CrdE(HepGlu)) with a carboxylic acid side chain. CrdE(HepGlu) with a degree of substitution of the glutaric acid monoester moiety (DS_Glu) in the range of 0-0.58 and that of the heptanoate moiety (DS_Hep = 3 - DS_Glu) was prepared. The esterification of the hydroxy groups in the glucan skeleton effectively caused the cleavage of the interchain hydrogen bonds of curdlan and enhanced the formability of CrdE(HepGlu). Moreover, the flexible carboxylic acid side chain moderately affected hydrogen bonding. Thus, the glass transition temperature of CrdE(HepGlu), estimated by differential scanning calorimetry, increased with increasing DS_Glu. CrdE(HepGlu) with DS_Glu between 0 and 0.58 displayed high solubility in organic solvents and thermoplasticity, enabling the formation of homogeneous and free-standing films by solution casting. The mechanical properties of CrdE(HepGlu) films were evaluated by a stress-strain test, which showed that Young's modulus and the maximum stress increased with increasing DS_Glu. CrdE(HepGlu) exhibited higher mechanical strength than non-hydrogen-bonded curdlan triheptanoate and hydrogen-bonded curdlan alkylcarbamates, with thermal stability comparable to that of thermally stable curdlan esters. In addition, these properties can be regulated by controlling DS_Glu.

Therapeutic and Industrial Applications of Curdlan With Overview on Its Recent Patents

Curdlan is an exopolysaccharide, which is composed of glucose linked with β-(1,3)-glycosidic bond and is produced by bacteria, such as Alcaligenes spp., Agrobacterium spp., Paenibacillus spp., Rhizobium spp., Saccharomyces cerevisiae, Candida spp., and fungal sources like Aureobasidium pullulan, Poria cocos, etc. Curdlan has been utilized in the food and pharmaceutical industries for its prebiotic, viscosifying, and water-holding properties for decades. Recently, the usefulness of curdlan has been further explored by the pharmaceutical industry for its potential therapeutic applications. Curdlan has exhibited immunoregulatory and antitumor activity in preclinical settings. It was observed that curdlan can prevent the proliferation of malarial merozoites in vivo; therefore, it may be considered as a promising therapy for the treatment of end-stage malaria. In addition, curdlan has demonstrated potent antiviral effects against human immunodeficiency virus (HIV) and Aedes aegypti virus. It has been suggested that the virucidal properties of curdlans should be extended further for other deadly viruses, such as severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and the current severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2/COVID-19). The prebiotic property of curdlan would confer beneficial effects on the host by promoting the growth of healthy microbiota in the gut and consequently help to reduce gastrointestinal disorders. Therefore, curdlan can be employed in the manufacture of prebiotics for the management of various gastrointestinal dysbiosis problems. Studies on the mechanism of action of curdlan-induced suppression in microbial and tumor cells at the cellular and molecular levels would not only enhance our understanding regarding the therapeutic effectiveness of curdlan but also help in the discovery of new drugs and dietary supplements. The primary focus of this review is to highlight the therapeutic interventions of curdlan as an anticancer, anti-malaria, antiviral, and antibacterial agent in humans. In addition, our review provides the latest information about the chemistry and biosynthesis of curdlan and its applications for making novel dairy products, functional foods, and nutraceuticals and also details about the recent patents of curdlan and its derivatives.

The synthysis and crystal structure of cyclohexyl 5-amino-1-(2,6-dichloro-4-(trifluoromethyl)phenyl)-4-((trifluoromethyl)sulfinyl)-1H-pyrazole-3-carboxylate, C18H15N3Cl2F6O3S

C18H15N3Cl2F6O3S, monoclinic, P21/n (no. 14), a = 5.6682(7) Å, b = 31.130(4) Å, c = 12.2829(16) Å, β = 98.328(2)°, V = 2144.5(5) Å3, Z = 4, R gt(F) = 0.0535, wR ref(F 2) = 0.1133, T = 173 K.