Estimativa por infravermelho da concentração da unidade estrutural b-O-4 em ligninas de angiospermas tropicais

Abreu, Heber dos Santos

doi:10.1590/s0100-40421997000600005

Cited by 7 publications

(6 citation statements)

References 5 publications

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“…Figure 1 presents the IR spectrum of the MWL in KBr pellet. The band profile in the finger print region is typical of lignins [19][20] . Figure 2 shows the IR spectrum of the methanolic extract B.…”

Section: Resultsmentioning

confidence: 98%

Studies on polyphenols and lignin of Astronium urundeuva wood

Morais¹,

Nascimento²,

Queiroz³

et al. 1999

J. Braz. Chem. Soc.

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Uma amostra da madeira de aroeira preta (Astronium urundeuva) moída em moinho de bolas foi extraída, sucessivamente, com benzeno, benzeno:etanol (2:1, vv -1 ), clorofórmio e água num soxhlet. A madeira extraída foi secada ao ar livre resultando o resíduo A que, em seguida, foi extraído com acetona:água (9:1, vv -1 ), também num soxhlet. Do extrato resultante foi obtida a lignina de madeira moída (MWL). Não considerando a MWL, a soma de todos os extratos alcançou 18,19% da madeira seca. O conteúdo em lignina de Klason de A e o conteúdo de grupos metoxila da MWL foram 23,84% e 19,00%, respectivamente. Outra amostra de A apresentou conteúdos em polissacarídeos de difícil e fácil hidrólise de 34,86% e 18,81%, respectivamente. Uma Segunda amostra de madeira moída foi submetida a uma extração única com metanol, à temperatura ambiente, fornecendo o extrato metanólico B (23,85% da madeira seca). Espectros de RMN do

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Section: Resultsmentioning

confidence: 98%

Studies on polyphenols and lignin of Astronium urundeuva wood

Morais¹,

Nascimento²,

Queiroz³

et al. 1999

J. Braz. Chem. Soc.

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show abstract

“…The presence of the three basic units of lignin was also evidenced, where the syringyl (S) ring absorption is observed at 1327 cm −1 , the guaiacyl (G) ring appears with a small shoulder at 1267 cm −1 , and for p -hydroxyphenyl (H) units, an absorption band is observed at 833 cm −1 . The presence of both absorption bands at 1267 and 833 cm −1 and a dominating peak at 1121 cm −1 are typical of S:G:H lignins [ 42 , 43 , 44 ]. The absorption band at 1717 cm −1 in lignin indicates the presence of unconjugated C=O stretching (vibration of unconjugated ketones, ester, or carboxylic groups).…”

Section: Resultsmentioning

confidence: 99%

“…Asymmetric C-H deformation in -CH 2 - and -CH 3 - groups can be found at 1461 cm −1 . The band at 1221 cm −1 is attributed to C-C plus C-O plus C=O stretch, whereby G condensed > G esterified [ 42 , 43 , 44 ], and the band at 1028 cm −1 is associated with C-H (in-plane) deformation of the guaiacyl ring plus deformation of primary C-O and in ether with contribution from the stretching of unconjugated C=O [ 44 ].…”

Section: Resultsmentioning

confidence: 99%

Exploring the Potential of Vine Shoots as a Source of Valuable Extracts and Stable Lignin Nanoparticles for Multiple Applications

Pereira

Costa

Mateus

et al. 2023

IJMS

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Large amounts of vine shoots are generated every year during vine pruning. This residue still presents many of the compounds found in the original plant, including low molecular weight phenolic compounds and structural compounds such as cellulose, hemicellulose, and lignin. For wine-producing regions, the challenge is to develop alternatives that will increase the value of this residue. This work proposes the full valorization of vine shoots, focusing on the extraction of lignin by mild acidolysis for the preparation of nanoparticles. The effect of the pretreatment solvents (ethanol/toluene, E/T, and water/ethanol, W/E), on the chemical and structural features of lignin, was evaluated. The chemical analysis suggests similar composition and structure regardless of the pretreatment solvent, although lignin isolated after pretreatment of biomass with E/T showed a higher content of proanthocyanidins (11%) compared with W/E (5%). Lignin nanoparticles (LNPs) presented an average size ranging from 130–200 nm and showed good stability for 30 days. Lignin and LNPs showed excellent antioxidant properties (half maximal inhibitory concentration, IC50 0.016–0.031 mg/mL) when compared to commercial antioxidants. In addition, extracts resulting from biomass pretreatment showed antioxidant activity, with W/E presenting a lower IC50 (0.170 mg/mL) than E/T (0.270 mg/mL), correlated with the higher polyphenol content of W/E, with (+)-catechin and (−)-epicatechin being the main compounds detected. Overall, this work shows that the pre-treatment of vine shoots with green solvents can yield (i) the production of high-purity lignin samples with antioxidant properties and (ii) phenolic-rich extracts, promoting the integral reuse of this byproduct and contributing to sustainability.

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“…The signals at 1635, 1507, 1455, 1336-1330 and 1246 cm -1 obtained by infrared microscopy corroborated with the previous results in determining lignin (Figure 3a, b). The guaiacyl and syringyl lignin are questioned base on structural resistance as found in special tissue in trees, however in Lophanthera lactescens wood the original lignin compositions were characterized as guaiacyl/syringyl lignin, as well as in vitro (Abreu, 1997).…”

Section: Lignification Status Of Young Stemsmentioning

confidence: 99%

Anatomy and lignification status of the Lophanthera lactescens Ducke plant grown in vitro

et al. 2012

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This aim of this study was to evaluate the lignification in young stems of the Lophanthera lactescens Ducke plant grown in vitro L. lactescens (Malpighiaceae), a species endemic in the Brazilian Amazon that possesses both medicinal properties and could be used in the forest product industry. Plants grown in vitro condition in MS medium were analyzed using Infrared (IR) microspectroscopy in a diffuse reflectance mode, fluorescence microscopy. Moreover, histochemical tests such as the Wiesner and Maüle test were run to monitor the process of lignification in cell walls. The spectra of IR microscopy recorded using cross section tissue are representative of guaiacyl/syringyl lignin, based on the 1336 and 1246 cm -1 signal. Individuals presenting stem sprains, resulting from the marked development, produced gelatinous fibers with a clear cellulose layer. Initially, fluorescence microscopy demonstrated lignin deposition in the cell corner region having progressive deposition in the secondary wall of tracheary elements of the stem.Keywords: lignification, fluorescence, infrared microspectroscopy. Anatomia e status da lignificação de plantas de Lophanthera lactescens Ducke crescidas in vitro ResumoEsta pesquisa teve como objetivo avaliar a lignificação em caules jovens de plantas de Lophanthera lactescens Ducke crescidas in vitro. L. lactescens (Malpighiaceae) é uma espécie endêmica da Amazônia Brasileira que, além de propriedades medicinais, apresenta potencial para a indústria de produtos florestais. As plantas foram crescidas in vitro, usando-se meio nutritivo MS. As análises foram realizadas por microespectrometria no infravermelho, no modo reflectância difusa. Microscopia com fluorescência e testes histoquímicos de Wiesner e Maüle foram realizados para o acompanhamento do processo de lignificação. Os espectros registrados a partir da microscopia no infravermelho mostraram sinais em 1336 e 1246 cm -1 , característicos de ligninas siringílica e guaiacílica. Indivíduos que apresentaram entorses no caule, em decorrência do acentuado desenvolvimento, produziram fibras gelatinosas, com a camada de celulose evidente. A microscopia com fluorescência evidenciou deposição de lignina inicialmente nos ângulos das células, com depósito progressivo ocorrendo na parede secundária dos elementos traqueais do caule.Palavras-chave: lignificação, fluorescência, microscopia infravermelho.

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Estimativa por infravermelho da concentração da unidade estrutural b-O-4 em ligninas de angiospermas tropicais

Cited by 7 publications

References 5 publications

Studies on polyphenols and lignin of Astronium urundeuva wood

Studies on polyphenols and lignin of Astronium urundeuva wood

Exploring the Potential of Vine Shoots as a Source of Valuable Extracts and Stable Lignin Nanoparticles for Multiple Applications

Anatomy and lignification status of the Lophanthera lactescens Ducke plant grown in vitro

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