Oxidation of cashew tree gum exudate polysaccharide with TEMPO reagent

Abstract

A goma do cajueiro, um polissacarídeo exsudado da árvore Anacardium ocidentale, foi oxidada com o reagente TEMPO e o produto (CGOX) foi caracterizado por técnicas espectroscópicas (FT-IR e RMN), análises cromatográficas (HPLC e GPC), viscosidade e análise térmica (TGA). O rendimento do produto da reação foi de 96%. O teor de ácido urônico da goma nativa (7,2%) aumentou para 36% após a reação. O grau de oxidação, tendo como base as unidades de galactose e glucose livres, foi de 68%. Os dados de RMN mostraram que a oxidação ocorreu preferencialmente nos carbonos primários das unidades de galactose. A grande diferença entre o valor esperado de η CGOX /η CG e o valor observado indica que a degradação, durante a oxidação, ocorreu em grande extensão. A presença de impurezas orgânicas e inorgânicas no novo polieletrólito foi detectada por TGA. A goma do cajueiro após a modificação com TEMPO apresentou mais baixa estabilidade térmica que a goma nativa, indicada pelos valores de temperatura inicial de decomposição e IPDT. Cashew gum (CG), an exudate polysaccharide from Anacardium ocidentale trees, was oxidized with TEMPO reagent and the 7product (CGOX) characterized by spectroscopic techniques (FT-IR and NMR), chromatographic analyses (HPLC and GPC), viscosity measurements and thermal analysis (TGA). The yield of the reaction product was 96%. The uronic acid content in starting gum (7.2 m%) was increased to 36 m%. The degree of oxidation based on free galactose and glucose units was 68%. NMR data show that oxidation occurred preferentially at primary carbons of galactose units. High degradation degree after oxidation was estimated by the difference on the expected and observed η CGOX /η CG ratio. The presence of organic and inorganic impurities in the new polyelectrolyte was detected by TGA. A less thermally stable cashew gum is formed after the oxidation with TEMPO based on initial decomposition temperature and IPDT.

Hydrophobic Modification of Cashew Gum with Alkenyl Succinic Anhydride

“…Further confirmation of the structures of CG derivatives was obtained from 13 C NMR (Figures 3 and 4). The 13 C NMR assignments for CG were previously reported [52,53] and were compatible with the general assignments of polysaccharides [50]. The CG sugar residues resonated at 58-110 ppm, with C1 at ca.…”

Oxidized Cashew Gum Scaffolds for Tissue Engineering

“…Figure shows the FTIR spectra of both CG and CGO8 derivative. Characteristic bands and peaks can be found in both spectra: the bands shown in regions 3700–3000 cm −1 and 1200–800 cm −1 are related with the vibrations of OH stretching and CO and CC stretching of hexa‐pyranosyl, respectively; the peaks at i) 2900, ii) 1649 , iii) 1415, iv) 1150, v) 1080, and vi) 1030 cm −1 are attributed to i) the symmetrical and asymmetrical CH stretching vibration, ii) the OH scissor vibrations of bonded water molecules, iii) the OH stretching and iv–vi) the COC stretching and deformation of the OH bonds of monomeric units . The presence of CG in samples can be confirmed by the shoulders at 1600 and 1414 cm −1 , which correspond to asymmetrical and symmetrical carboxylate vibrations from the uronic acid present in the gum .…”

“…On our previous work, TEMPO reagent was used to promote the oxidation of CG and enhance its polyelectrolyte character . The proposed oxidation method of CG uses NaIO 4 to obtain reactive aldehyde groups.…”

Polissacarídeos da biodiversidade brasileira: uma oportunidade de transformar conhecimento em valor econômico

“…Inserção de grupos carboxilato, 113,114 oxidação dos grupos hidroxila a ácido, 115 e enxertia com acrilamida 116 são algumas das modificações feitas.…”